Internet Draft C. Carroll,
F. Quick
Document: Hamilton, Brook,
draft-carroll-dynmobileip-cdma-02.txt Smith & Reynolds,
P.C.,
Qualcomm Inc.
Expires: May 2004 November 2003
Dynamic Mobile IP Key Update
for
cdma2000(R) Networks
Status of this Memo
This document is an Internet-Draft and is subject to all provisions
of Section 10 of RFC2026.
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Abstract
The Dynamic Mobile IP Key Update procedure is a secure and efficient
mechanism for distributing and updating Mobile IP (MIP) cryptographic
keys in cdma2000(R) networks (including High Rate Packet Data which
is often referred to as 1xEV-DO). Because the Dynamic Mobile IP Key
Update (DMU) procedure occurs at the IP layer directly between the
MIP MN and RADIUS or DIAMETER AAA Server, DMU may be used to securely
bootstrap the MN-AAA key (and other cryptographic keys) in MIP
networks using any Radio Access Network technology.
cdma2000(R) is a registered trademark of the Telecommunications
Industry Association (TIA).
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Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [1].
Table of Contents
1. Introduction...................................................3
2. Basic Dynamic MIP Key Update Mechanism.........................3
2.1 RSA Encrypted Key Distribution.............................3
2.2 Shared Mutual Authentication...............................4
2.3 Encrypted Password / Encrypted One-Time Password
Authentication.................................................7
3. Dynamic MIP Key Update Advantages over OTASP...................8
4. Detailed DMU Procedure Description and Requirements............9
4.1 RSA Public Key Cryptography................................9
4.2 Other Public Key Algorithms...............................10
4.3 Why no Public Key Infrastructure (PKI)?...................10
4.4 Cryptographic Key Generation..............................10
4.5 MIP_Key_Data Payload......................................11
4.6 RSA Key Management........................................12
4.7 RADIUS AAA Server.........................................13
4.8 MN (Handset or Modem).....................................15
4.9 PDSN / Foreign Agent (FA).................................16
4.10 Home Agent (HA)..........................................17
4.11 DMU Procedure Network Flow...............................18
5. DMU Procedure Failure Operation...............................22
6. cdma2000(R) HRPD/1xEV-DO Support..............................25
6.1 RADIUS/DIAMETER AAA Support...............................25
6.2 MN Support................................................26
6.3 Informative MN_Authenticator Support......................27
7. Security Considerations.......................................28
7.1 Cryptographic Key Generation by the MN....................28
7.2 Man-in-the-Middle Attack..................................28
7.3 RSA Private Key Compromise................................28
7.4 RSA Encryption............................................29
7.5 False Base Station/PDSN...................................29
7.6 cdma2000(R) 1X False MN...................................29
7.7 HRPD/1xEV-DO False MN.....................................29
8. Verizon Wireless - Specific RADIUS Attributes.................29
9. Verizon Wireless Mobile IP Vendor/Organization-Specific Extensions
.................................................................30
10. Public Key Identifier and DMU Version........................32
11. Intellectual Property........................................36
12. Conclusion...................................................37
13. Formal Syntax................................................37
14. Appendix - Cleartext-Mode Operation..........................39
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1. Introduction
The Dynamic Mobile IP Key Update procedure is a secure and efficient
mechanism for distributing and updating Mobile IP (MIP) cryptographic
keys in cdma2000(R) 1xRTT (1X) [2] and High Rate Packet Data (HRPD) /
1xEV-DO networks [3]. The Dynamic Mobile IP Key Update (DMU)
procedure occurs at the IP layer directly between the MIP MN and
RADIUS or DIAMETER AAA Server. This procedure is an add-on to the
existing Telecommunications Industry Association (TIA) TR-45 Standard
IS-835 [4]. DMU, however, may be performed in any MIP network to
enable secure and efficient bootstrapping of the shared secret
between the Mobile Node (MN) and Radius AAA Server, MN-AAA key (and
other cryptographic keys).
The DMU procedure utilizes RSA Public key cryptography to securely
distribute unique MIP keys to potentially millions of cdma2000(R) 1X
and HRPD/1xEV-DO Mobile Nodes (MN) using the same RSA Public key.
By leveraging the existing cdma2000(R) 1X authentication process, the
Dynamic Mobile IP Key Update process employs a Shared Mutual
Authentication mechanism in which device-to-network authentication is
facilitated using cdma2000(R) 1X challenge-response authentication
and network-to-device authentication is facilitated using RSA
encryption.
By utilizing RSA encryption, the MN (or MN manufacturer) is able to
pre-generate MIP keys (and the CHAP key) and pre-encrypt the MIP keys
prior to initiation of the DMU procedure. By employing this pre-
computation capability, the DMU process is an order of magnitude more
efficient than Diffie-Hellman Key Exchange.
2. Basic Dynamic MIP Key Update Mechanism
The DMU procedure is basically an Authentication and Key Distribution
(AKD) protocol which is more easily understood by separately
describing the mechanism's two functional goals: 1) encrypted key
distribution and 2) shared mutual authentication.
2.1 RSA Encrypted Key Distribution
By utilizing RSA Public Key Cryptography, millions of MNs can be pre-
loaded with a common RSA Public (encryption) key (by the MN
manufacturer) while the associated RSA Private (decryption) key is
securely distributed from the MN manufacturer to each service
provider. Alternatively, a service provider can generate its own RSA
Public/Private key pair and only distribute the RSA Public key to MN
manufacturers for pre-loading of MNs.
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During the manufacturing process, the MN manufacturer pre-loads each
MN with the RSA Public key. When the MN is powered-up (or client
application initiated), the MN can pre-generate and encrypt MIP keys
for distribution to the Home RADIUS AAA Server during the DMU
process. Alternatively, the MN manufacturer can pre-generate MIP
keys, encrypt the MIP key payload, and pre-load the MN with multiple
encrypted MIP key payloads to enable the DMU procedure.
During the initial registration process (or when the AAA requires MIP
key update), the MN: 1) generates the appropriate MIP keys, CHAP key,
and authentication information, 2) uses the embedded RSA Public key
to encrypt the payload information, 3) and appends the payload to the
MIP Registration Request. When the Radius AAA Server receives the
encrypted payload (defined as MIP_Key_Data later), the AAA Server
uses the RSA Private key to decrypt the payload and recover the MIP
keys.
MN BS/PDSN/FA AAA
-- ---------- ---
------------------ -------------------
| RSA Public Key | | RSA Private Key |
| Pre-loaded by | | Pre-loaded by |
| Manufacturer | | Service Provider |
------------------ -------------------
Registration Request,
(MIP keys), RSA
Public Key
|-------------------->|
| Access Request, (MIP keys),
| RSA Public Key
|---------------------->|
-------------------
| Decrypt MIP |
| Keys using RSA |
| Private Key |
-------------------
Figure 1. RSA Encrypted Key Distribution
2.2 Shared Mutual Authentication
Mutual authentication is achieved by delegation of the MN/device
authentication by the AAA Server to cdma2000(R) 1X HLR/AC [5] while
the MN utilizes RSA encryption to authenticate the AAA Server.
MN/device authentication is based on the assumption that the MN's
Mobile Station (MS) has an existing A-key and SSD with the
cdma2000(R) 1X network. When MS call origination occurs, the AC
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authenticates the MS. If authentication is successful, the BS passes
the MSID (e.g. MIN) to the PDSN. The "Authenticated MSID" is then
included in the Radius Access Request (ARQ) message sent from the
PDSN to the AAA server. Because the Radius AAA stores the MSID
associated with an MN subscription, the AAA server is able to
"Authorize" MN access if the "Authenticated MSID" matches the RADIUS
AAA MSID, i.e. the RADIUS AAA is delegating its authentication
function to the cdma2000(R) 1X HLR/AC.
RADIUS AAA Server authentication (by the MN) is enabled by including
a random number (AAA_Authenticator) in the encrypted payload sent
from the MN to the AAA Server. Only the possessor of the proper RSA
Private key will have the ability to decrypt the payload and recover
the unique AAA_Authenticator. If the MN receives the correct
AAA_Authenticator (returned by the AAA Server), the MN is assured
that it is not interacting with a false Base Station (BS).
Because cdma2000(R) A-key/SSD authentication is not available in
1xEV-DO or a particular cdma2000(R) 1X network may not support A-key
authentication, the DMU procedure also includes a random number
(MN_Authenticator) generated by the MN (and/or pre-loaded by the
manufacturer), which enables the Radius AAA to optionally
authenticate the MN (in 1XEV DO network only).
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MN BS/PDSN/FA HLR/AC AAA
-- ---------- ------ ---
------------------ -------------------
| RSA Public Key | | RSA Private Key |
| Pre-loaded by | | Pre-loaded by |
| Manufacturer | | Service Provider |
------------------ -------------------
| Global Challenge
|<-------------|
|
| Auth_Response
|------------->|
| Auth_Response
|---------------->|
------------------
| IS-2000 |
| Authentication |
------------------
Auth_Success |
|<----------------|
------------------
| BS forwards |
| Authenticated |
| MSID to PDSN |
------------------
Registration Request
(MIP keys, AAA_Authenticator),
| RSA Public Key
|------------->|
| Access Request, MSID,
| (MIP keys, AAA_Authenticator),
| RSA Public Key
|------------------------------->|
-------------------
| Check MSID, |
| Decrypt AAA_- |
| Authenticator |
-------------------
Access Reject, AAA_Authenticator |
|<-------------------------------|
Registration Reply, AAA_Authenticator
|<-------------|
------------------
| Check AAA_- |
| Authenticator |
------------------
Figure 2. Shared Mutual Authentication
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2.3 Encrypted Password / Encrypted One-Time Password Authentication
The DMU procedure alternatively utilizes a password, the
MN_Authenticator, to support MN authentication in cdma2000(R)
HRPD/1xEV-DO or whenever 1X RAN authentication (e.g. CAVE) is not
available. Furthermore, the MN_Authenticator is transmitted from the
MN to the Home AAA Server within the RSA-encrypted MIP_Key_Data
payload to prevent interception and possible re-use by an attacker.
Ideally, the MN_Authenticator is utilized as a One-Time Password,
however, RSA encryption allows the MN_Authenticator to possibly be
re-used based on each Service Provider's key distribution policy.
When the encrypted MIP keys are decrypted at the Home AAA Server, the
MN_Authenticator is also decrypted and compared with a copy of the
MN_Authenticator stored within the AAA Server. The Home AAA Server
receives a copy of the MN_Authenticator out-of-band (not using the
cdma2000(R) network) utilizing one of numerous possible methods
outside the scope of the standard. For example, the MN_Authenticator
MAY be: 1) read out by a Point-of-Sale provisioner from the MN, input
into the subscriber profile, and delivered along with the NAI, via
the billing/provision system to the Home AAA server, or 2) verbally
communicated to a customer care representative via a call, or 3)
input by the user interfacing with an IVR. The out-of-band
MN_Authenticator delivery is purposely precluded from the standard to
maximize the Service Provider's implementation flexibility.
It is possible for an unscrupulous provisioner or distribution
employee to extract the MN_Authenticator prior to the DMU procedure,
however the risk associated with such a disclosure is minimal.
Because the HRPD/1xEV-DO MN does not transmit a device identifier
during the initial registration process, an attacker, even with a
stolen MN_Authenticator, cannot correlate the password with a
particular MN device or NAI, which is typically provisioned just
prior to DMU procedure initiation.
The MN_Authenticator is typically generated by a random/pseudorandom
number generator within the MN. MN_Authenticator generation is
initiated by the MN user, however it MAY be initially pre-loaded by
the manufacturer. When the MN_Authenticator is reset (i.e. a new
MN_Authenticator is generated), all MIP_Data_Key payloads using the
previous MN_Authenticator are discarded and the MN immediately re-
encrypts a MIP_Key_Data payload containing the new MN_Authenticator.
The MN_Authenticator MUST NOT change unless it is explicitly reset by
the MN user. Thus, the MN will generate new MIP_Key_Data payloads
using the same MN_Authenticator until the MN_Authenticator is
updated.
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-------------------------
| User-initiated |
| MN_Authenticator[x] |
| Generation |
-------------------------
|
v
----------------------------- ------------------------------
| Manufacturer | | Delete MN_Authenticator[y], |
| MN_Authenticator[y] |----->| Store MN_Authenticator[x] |
| Generation** | | in MN |
----------------------------- ------------------------------
|
v
-------------------------
| Delete MIP_Key_Data |
| Payload using |
| MN_Authenticator[y] |
-------------------------
|
v
----------------------------- -------------------------
| KEYS_VALID and committed; | | Generate MIP_Key_Data |
| delete MIP_Key_Data |----->| Payload using |
| Payload | | MN_Authenticator[x] |
----------------------------- -------------------------
^ |
| v
----------------------------- -------------------------
| DMU MIP_Key_Data | | Store MIP_Key_Data |
| Delivery |<-----| Payload |
----------------------------- -------------------------
Figure 3. MN_Authenticator and MIP_Key_Data Payload State Machine
**Note: Manufacturer pre-load of MN_Authenticator is not essential
since the MN_Authenticator is typically generated by the MN. However,
manufacturer pre-load may reduce provisioner burden of accessing a
device such as a modem to recover the MN_Authenticator for entry into
the Serivce Provider provisioning system.
3. Dynamic MIP Key Update Advantages over OTASP
The DMU procedure has numerous advantages over the current Over-the-
Air Service Provisioning (OTASP) [6] procedure including:
* MIP key distribution occurs directly between the MN and AAA
Server at the IP Layer. Eliminates the need for an interface
between the OTAF and AAA server.
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* Supports MIP key distribution for cdma2000(R) 1X and HRPD/1xEV-
DO MN. OTASP only supports cdma2000(R) 1X MIP key
distribution.
* Facilitates MIP key distribution to MN using Relay-mode MS.
OTASP only delivers MIP keys to MS. For example, OTASP cannot
delivery MIP keys to Laptop MN interfacing with MS modem.
* Pre-encryption of MIP_Key_Data allows DMU procedure to be order
of magnitude faster than Diffie-Hellman Key Exchange.
* MN manufacturer can pre-generate MIP keys, pre-encrypt the MIP
key payload, and pre-load the payload in an MN. Thus, an MN
with limited processing power is never required to use RSA
encryption. An OTASP device is always forced to perform
computationally expensive exponentiations during the key update
process.
* MN is protected against False BS Denial-of-Service (DOS) attack
in which False BS changes the MIP key for MNs in its vicinity.
OTASP Diffie-Hellman Key Exchange vulnerable to BS DOS.
* Utilizes mutual authentication. OTASP Diffie-Hellman Key
Exchange does not utilize authentication.
4. Detailed DMU Procedure Description and Requirements
The Dynamic Mobile IP Update procedure is a secure, yet extremely
efficient mechanism for distributing essential MIP cryptographic keys
(e.g. MN-AAAh key and MN-HA key) and the Simple IP CHAP key. The DMU
protocol enables pre-computation of the encrypted key material
payload, known as MIP_Key_Data. The DMU procedure purposely avoids
the use of Pubic Key Infrastructure (PKI) Certificates in order to
greatly enhance the procedure's efficiency using MIP_Key_Data pre-
encryption within the MN.
4.1 RSA Public Key Cryptography
RSA Public Key encryption and decryption MUST be performed in
accordance with RFC 2313 [7] PKCS #1: RSA Encryption Version 1.5.
DMU MUST support RSA with a 1024-bit modulus by default. DMU MAY
also support 768-bit or 2048-bit RSA depending on the MN user's
efficiency or security requirements. RSA computation speed-ups using
low exponent RSA or the value "65537" are acceptable.
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4.2 Other Public Key Algorithms
DMU does not preclude the use of other Public key technologies. The
protocol includes a Public Key Type field that defines the type of
encryption used.
4.3 Why no Public Key Infrastructure (PKI)?
DMU is designed to maximize the efficiency of Mobile IP (MIP) key
distribution for cdma2000(R) MNs. The use of a Public key
Certificate would improve the flexibility of the MIP key update
process by allowing a Certificate Authority (CA) to vouch for the RSA
Public Key delivered to the MN. Unfortunately, the use of a Public
Key Certificate would significantly reduce the efficiency (speed and
overhead) of the MIP key update process. For instance, each MN must
be pre-loaded with the CA's Public Key. During the MIP key
distribution process, the network must first deliver its RSA Public
Key (in a Certificate) to the MN. The MN must then use RSA to
decrypt the Certificate's digital signature to verify that the
presented RSA public key is legitimate. Such a process significantly
increases the number of exchanges, increases air interface overhead,
increases the amount of MN computation, and slows the MIP key update
process.
Aside from the operational efficiency issues, there are numerous
policy and procedural issues that have previously hampered the
deployment of PKI in commercial networks.
On a more theoretical basis, PKI is likely unnecessary for this key
distribution model. PKI is ideal for a Many-to-Many communications
model such as within the Internet where many different users
interface with many different Websites. However, in the cellular/PCS
Packet Data environment, a Many-to-One (or few) distribution model
exists in which many users interface with one wireless Carrier to
establish their Mobile IP security associations (i.e cryptographic
keys).
4.4 Cryptographic Key Generation
The DMU procedure relies on each MN to randomly/pseudo-randomly
generate the MN_AAAh key, MN_HA key, and Simple IP CHAP key. Each MN
MUST have the capability to generate random/pseudo-random numbers in
accordance with the guidelines specified in RFC 1750 Randomness
Recommendations for Security.
Although it may be more secure for the network to generate
cryptographic keys at the AAA server, client cryptographic key
generation is acceptable due to the significant efficiency
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improvement in the update process via pre-generation and pre-
encryption of the MIP keys.
4.5 MIP_Key_Data Payload
MIP cryptographic keys (MN_AAAh key and MN_HA key) and the Simple IP
CHAP key are encapsulated and encrypted into a MIP_Key_Data Payload
(along with the AAA_Authenticator and MN_Authenticator). The
MIP_Key_Data Payload is appended to the MN's MIP Registration Request
(RRQ) as a MIP Vendor/Organization-Specific Extension (See IETF RFC
3115 [8] Mobile IP Vendor/Organization-Specific Extensions). When
the PDSN converts the MIP RRQ to a Radius Access Request (ARQ)
message, the MIP_Key_Data Payload is converted from a MIP
Vendor/Organization-Specific Extension to a Vendor Specific Radius
Attribute.
Upon receipt of the Radius Access Request, the Radius AAA decrypts
the MIP_Key_Data payload using the RSA Private (decryption) key
associated with the RSA Public (encryption) used to encrypt the
MIP_Key_Data payload. The MIP_Key_Data is defined as follows:
MIP_Key_Data = RSA Pub_Keyi [MN_AAAh key, MN_HA key, CHAP_key,
MN_Authenticator, AAA_Authenticator], Public_Key_IDi, DMUV
Where:
MN_AAA key = 128-bit random MN / AAA Server key (encrypted)
MN_HA key = 128-bit random MN / Home Agent (HA) key (encrypted)
CHAP_key = 128-bit random Simple IP authentication key (encrypted)
Note: the Simple IP CHAP key as not the same as the AT-CHAP key
used for A12 Interface authentication [9].
MN_Authenticator = 24-bit random number (displayed as 8 decimal
digit number. To be used for 1xEV DO network.) (encrypted)
AAA_Authenticator = 64-bit random number used by MN to
authenticate AAA Server. (encrypted)
DMU Version (DMUV) = 4 bit identifier of DMU version.
Public Key Identifier (Pub _Key_ID) = PKOID, PKOI, PK_Expansion, ATV
Where:
Public Key Organization Identifier (PKOID) = 8-bit serial number
identifier of Public Key Organization (PKO) that created the
Public Key.
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Public Key Organization Index (PKOI) = 8-bit serial number used at
PKO discretion to distinguish different Public/Private key
pairs.
PK_Expansion = 8-bit field to enable possible expansion of PKOID
or PKOI fields. (Note: Default value = 0xFF)
Algorithm Type and Version (ATV) = 4-bit identifier of the
algorithm used.
Note: If 1024-bit RSA is used, the encrypted portion of the payload
is 1024 bits (128 bytes) long. With the 28 bit Public Key Identifier
and 4 bit DMUV, the total MIP_Key_Data payload is 132 bytes long.
4.6 RSA Key Management
The wireless Service Provider or carrier MUST generate the RSA
Public/Private key pair(s). An organization within the Service
Provider MUST be designated by the Service Provider to generate,
manage, protect, and distribute RSA Private keys (to the AAA Server)
and Public keys (to the MN manufacturers) in support of the DMU
procedure.
Each RSA Public/Private key pair, generated by the wireless carrier,
MUST be assigned a unique Public Key Identifier in accordance with
Section 9.
RSA Private keys MUST be protected from disclosure to unauthorized
parties. The Service Provider organization with the responsibility
of generating the RSA Public/Private key pairs MUST establish a RSA
key management policy to protect the RSA Private (decryption) keys.
RSA Public keys MAY be freely distributed to all MN manufacturers
(along with the Public Key Identifier). Because one RSA Public key
can be distributed to million of MNs, it is acceptable to distribute
the RSA Public key (and Public Key Identifier) to MN manufacturers
via e-mail, floppy disk, or VZW Website. The preferred method is to
simply publish the RSA Public key and associated Public Key
Identifier in the DMU Requirements document sent to each MN
manufacturer/OEM.
RSA Private keys MAY be loaded into the RADIUS AAA server manually.
Access to the RADIUS AAA Server RSA Private keys SHOULD be restricted
to authorized personnel only.
The wireless Service Provider MAY accept RSA Private key(s) (and
Public Key Identifier) from MN manufacturers or other Service
Providers that have preloaded MNs with manufacturer-generated RSA
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Public keys. One Service Provider MAY negotiate an agreement with
another Service Provider in which both Service Providers share and
protect each other's RSA Private keys.
4.7 RADIUS AAA Server
RADIUS or DIAMETER AAA Server MUST support the DMU Procedure. The
AAA Server MUST support RSA Public key cryptography and maintain a
database of RSA Private (decryption) keys indexed by the Public Key
Identifier.
Delivery of the RSA Private key(s) to AAA Server from the MN
manufacturer(s) is outside the scope of this documents. However, RSA
Private key(s) delivery via encrypted e-mail or physical (mail)
delivery is likely acceptable.
RADIUS AAA Server access MUST be limited to authorized personnel
only.
RADIUS AAA Server MUST support 1024-bit RSA decryption.
RADIUS AAA Server MUST maintain a database of RSA Public/Private key
pair indexed by the Public Key Identifier.
RADIUS AAA Server MUST support the RADIUS attributes specified in
Section 8.
RADIUS AAA Server MUST support a subscriber specific MIP Update State
Field. When the MIP Update State Field set to UPDATE KEYS (1), the
AAA Server MUST initiate the DMU procedure by including the
MIP_Key_Request attribute in an Access Reject message sent to the
PDSN. The MIP Update State Field MAY be set to UPDATE KEYS (1) by
Service ProviderÆs Billing/Provisioning system based on IT policy.
Upon verification of MN-AAA Authentication Extension using decrypted
MN_AAA key, the AAA Server MUST set the MIP Update State Field to
KEYS UPDATED (2). Upon verification of the MN-Authentication
Extension on a subsequent RRQ/ARQ, the AAA Server MUST set the MIP
Update State Field to KEYS VALID (0).
The AAA Server MUST maintain a MIP Update State Field, for each
subscription, in one of three states (0 = KEYS VALID, 1 = UPDATE
KEYS, 2 = KEYS UPDATED).
RADIUS AAA Server MUST decrypt the encrypted portion of the
MIP_Key_Data payload using the appropriate RSA Private (decryption)
key.
RADIUS AAA Server MUST check the MN_AAA Authentication Extension of
the DMU RRQ using the decrypted MN_AAA key.
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RADIUS AAA Server MUST include the AAA_Authenticator in the Access
Accept as a Vendor-Specific Radius Attribute.
RADIUS AAA Server MUST support the MN_Authenticator options specified
in Section 6.1.
AAA Server MUST comply with DMU Procedure failure operation specified
in Section 5.
RADIUS AAA Server MUST support manual hexadecimal entry of MN_AAA
key, MN_HA key and Simple IP CHAP key via the AAA GUI for each
subscription.
RADIUS AAA Server MUST provide a mechanism to validate the MIN/IMSI.
When the MIN/IMSI validation is on, the RADIUS AAA Server MUST
compare the MIN/IMSI sent from the PDSN with the MIN/IMSI in the AAA
subscription record/profile. If the MINs or IMSIs do not match, the
AAA Server MUST send an Access Reject to the PDSN/FA. The Access
Reject MUST NOT contain a MIP Key Data request
When the "Ignore MN_Authenticator" bit is not set, the AAA Server
MUST check whether MN_AuthenticatorMN = MN_AuthenticatorAAA. If the
MN_Authenticators do not match, the AAA Server MUST send an Access
Reject to the PDSN/FA. The Access Reject MUST NOT contain a MIP Key
Data request.
AAA Server MUST include its PKOID (or another designated PKOID) in
the MIP_Key_Request Radius Attribute.
AAA Server MUST compare the PKOID sent in the MIP_Key _Data Radius
Attribute with a list of valid PKOIDs in the AAA Server. If the
PKOID is not valid, the AAA Server MUST send an Access Reject to the
PDSN with the Verizon Wireless Vendor Specific "Invalid Public Key"
Radius attribute. Note: the same Radius attribute may be assigned a
different Vendor identifier.
AAA Server MUST support delivery of the MN-HA key from the AAA server
using 3GPP2 Radius Vendor-Specific Attributes as specified in 3GPP2
X.S0011-005-C using the MN-HA Shared Key (Vendor-Type = 58) and MN-HA
SPI (Vendor-Type = 57).
AAA Server MUST always accept the A12 Access Request for a particular
subscriber when the UPDATE KEYS (1) and KEYS UPDATED (2) states are
set. In the KEYS VALID (0) state, the AAA Server MUST check to
Access Request normally.
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AAA Server MUST reject an Access Request with the MIP_Key_Data Radius
Attribute while the AAA Server is in the KEYS VALID state, i.e., the
AAA MUST NOT allow an unsolicited key update to occur.
4.8 MN (Handset or Modem)
MN manufacturer MUST pre-load the Wireless Carrier RSA Public key
(and Public Key Identifier).
MN manufacturer MUST pre-generate and pre-load the MN_Authenticator.
MN MUST support 1024-bit RSA Encryption using the pre-loaded RSA
Public key.
MN MUST support MN_AAA, MN_HA, and CHAP random/pseudo-random key
generation (in accordance with RFC 1750).
MN MUST support random/pseudo-random AAA_Authenticator and
MN_Authenticator generation (in accordance with RFC 1750).
Upon power-up of an MN handset or launch of the MN client, the MN
MUST check whether a MIP_Key_Data payload has been computed. If no
MIP_Key_Data payload exists, the MN MUST generate and store a
MIP_Key_Data payload. The MN MUST maintain at least one pre-
generated MIP_Key_Data payload.
MN MUST construct the MIP_Key_Data payload in accordance with Section
4.5.
MN MUST initiate the DMU Procedure upon receipt of MIP Registration
Reply with the MIP_Key_Request Verizon Wireless Vendor/Organization-
specific Extension.
Upon receipt of an RR including the MIP_Key_Request, the MN MUST
check the PKOID sent in the MIP_Key_Request. If the MN has a Public
key associated with the PKOID, the MN MUST encrypt the MIP_Key_Data
payload using that Public key.
MN MUST have the capability to designate one Public key as the
Default Public key if the MN supports multiple Public keys.
MN MUST insert the Verizon Wireless Vendor/Organization-specific
MIP_Key_Data Extension (or another Organization-specific MIP_Key_Data
Extension) after the Mobile-Home Authentication Extension, but before
the MN-AAA Authentication Extension. The MIP_Key_Data Extension must
also be located after the FA Challenge Extension if present.
Upon initiation of the DMU Procedure, the MN MUST compute MIP
authentication extensions using the newly-generated temporary MN_AAA
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and MN_HA keys. Upon receipt of the AAA_Authenticator MIP Extension,
the MN MUST compare the AAA_AuthenticatorMN (sent in the encrypted
MIP_Key_Data payload) with the AAA_AuthenticatorAAA(returned by the
AAA Server). If both values are the same, the MN MUST designate the
temporary MN_AAA, MN_HA key, and Simple IP CHAP key as permanent.
The MN MUST set its MIP Update State field to KEYS VALID.
MN MUST support reset (re-generation) of the MN_Authenticator by the
MN user as specified in Section 6.2.
MN MUST enable the MN user to view the MN_Authenticator.
MN_Authenticator (24-bit random number) MUST be displayed as an 8
decimal digit number as specified in Section 6.2.
The MN manufacturer MUST pre-load each MN with a unique random 24-bit
MN_Authenticator.
Upon reset of the MN_Authenticator, the MN MUST delete all
MIP_Key_Data payloads based on the old MN_Authenticator and generate
all subsequent MIP_Key_Data payloads using the new MN_Authenticator.
(until the MN_Authenticator is explicitly re-set again by the MN
user).
MN MUST support manual entry of all cryptographic keys such as the
MN_AAA, MN_HA, and Simple IP CHAP key. MN MUST support hexadecimal
digit entry of a 128-bit key. (Note: certain Simple IP devices only
enable ASCII entry of a password as the CHAP key. It is acceptable
for future devices to provide both capabilities, i.e. ASCII for a
password or hexadecimal for a key. The authors recommend the use of
strong cryptographic keys.)
MN MUST support the Verizon Wireless MIP Vendor/Organization-Specific
Extensions specified in Section 9.
MN MUST update the RRQ Identification field when re-transmitting the
same MIP_Key_Data in a new RRQ.
MN MUST comply with DMU Procedure failure operation specified in
Section 5.
The RSA Public Key MAY be stored in the MN flash memory as a constant
while being updatable via software patch.
4.9 PDSN / Foreign Agent (FA)
PDSN MUST support Verizon Wireless Radius Vendor Specific Attributes
specified in Section 8 and Verizon Wireless MIP Vendor/Organization-
Specific Extensions specified in Section 9.
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PDSN MAY support Radius Vendor Specific Attributes specified in
Section 8 and MIP Vendor/Organization-Specific Extensions specified
in Section 9 using another Organization identifier (e.g., 3GPP2
Organization ID).
Upon receipt of an Access Reject containing the
MIP_Key_Update_Request attribute, PDSN MUST send a RR to the MN with
the MIP_Key_Request Vendor/Organization-Specific Extension. The PDSN
MUST use the RR error code = 89 (Vendor Specific) and MUST not tear
down the PPP session after transmission.
Upon receipt of an Access Reject containing the AAA_Authenticator
attribute, the PDSN MUST send a RR with AAA_Authenticator MIP
Vendor/Organization-Specific Extension. The PDSN MUST use the RR
error code = 89 (Vendor Specific) and MUST NOT tear down the PPP
session after transmission.
Upon receipt of an Access Reject containing the Public Key Invalid
attribute, the PDSN MUST send a RR with Public Key Invalid MIP
Vendor/Organization-Specific Extension. The PDSN MUST use the RR
error code = 89 (Vendor Specific) and MUST NOT tear down the PPP
session after transmission.
Upon receipt of a RRQ with the MIP_Key_Data Vendor/Organization-
Specific Extension, the PDSN MUST convert the RRQ to an ARQ with
MIP_Key_Data attribute. The PDSN MUST send the ARQ to the AAA
server.
PDSN/FA MUST comply with DMU Procedure failure operation specified in
Section 5.
PDSN/FA MUST include the PKOID from the Access Reject
MIP_Key_Update_Request attribute in the MIP_Key_Request MIP extension
sent to the MN.
4.10 Home Agent (HA)
HA MUST support Verizon Wireless MIP Vendor/Organization-Specific
Extensions specified in Section 9. (Note: HA may not encounter a DMU
MIP extension.)
HA MUST support MIP Vendor/Organization-Specific Extensions specified
in Section 9 using another Organization identifier (e.g., 3GPP2
Organization ID). (Note: HA may not encounter a DMU MIP extension.)
HA MUST support delivery of the MN-HA key from the Home AAA server
using 3GPP2 Radius Vendor-Specific Attributes as specified in 3GPP2
X.S0011-005-C using the MN-HA Shared Key (Vendor-Type = 58) and MN-HA
SPI (Vendor-Type = 57).
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4.11 DMU Procedure Network Flow
This section provides a flow diagram and detailed description of the
process flow involving the Dynamic Mobile IP Update procedure process
within the IS-2000 network.
MN BS PDSN/FA AAAh
-- -- ------- ----
--------------------- -------------------
| 1: RSA Public Key | | RSA Private Key |
| Pre-loaded by | | Pre-loaded by |
| Manufacturer | | Service Provider |
--------------------- -------------------
---------------------------------------------------------
| 2: MS/BS: IS-2000 Call Origination and Authentication |
| 3: MN/PDSN/FA: PPP Session Establishment |
---------------------------------------------------------
| 4: Registration Request (RRQ)
|--------------------------------->| 5: Access Request w/MSID
|------------>|
--------------------
| 6: MIP Update State|
| is "Update Keys" |
--------------------
7: Access Reject with |
MIP_Key_Update_Request |
Radius Attribute |
|<------------|
8: Registration Reply (RR) |
with MIP_Key_Request MIP |
Vendor/organization-specific |
attribute |
|<---------------------------------|
-------------------
| 9: MN generates |
| MIP_Key_Data |
| using temporary |
| MIP keys |
-------------------
| 10: RRQ with MIP_Key_Data
| Vendor/organization-specific attribute
|--------------------------------->| 11: Access Request
| w/MSID
| and MIP_Key_Data
| Radius attribute
|------------>|
Figure 4. DMU Procedure Flow (part 1)
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MN BS/PDSN PDSN/FA AAAh
-- ------- ------- ----
|
-------------------
| 12: decrypt |
| MIP_Key_Data, |
| verify MN-AAA |
| authentication |
| extension, set |
| MIP Update State |
| = "Keys Updated" |
-------------------
13: Access Reject with |
AAA_Authenticator |
Radius Attribute |
|<------------|
14: Registration Reply (RR) |
with AAA_Authenticator MIP |
Vendor/organization-specific |
attribute |
|<---------------------------------|
----------------------
| 15: verify |
| AAA_Authenticator, |
| store temporary |
| MIP keys as |
| permanent keys |
----------------------
| 16: RRQ
|--------------------------------->| Access Request
| w/MSID
|------------>|
--------------------
| 17: verify MN-AAA |
| authentication |
| extension, set |
| MIP Update State |
| = "Keys Valid" |
--------------------
Access Accept |
|<------------|
Figure 4. DMU Procedure Flow (part 2)
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MN PDSN/FA AAAh HA
-- ------- ---- --
| 18. Registration Request (RRQ)
|-------------------------------->|
19: Access Request |
|<-----------------|
Access Accept |
with MN-HA key |
|----------------->|
-------------------
| verify |
| mobile-home |
| authentication |
| extension |
-------------------
20. Registration Reply (RR) |
|<--------------------------------|
RR |
|<--------------|
Figure 4. DMU Procedure Flow (part 3)
Each step in the Figure 4 DMU Process is described as follows:
1. Each RSA Public/Private Key pair must be generated in
accordance with RFC 2313. Each Public/Private key pair MUST be
assigned a unique Public Key Identifier (PKOID) by its creator.
If the Service Provider does not generate the Public/Private
Key pair and deliver the RSA Public Key to the MN manufacturer
for pre-installation in the MN, the MN manufacturer MUST
generate the RSA Public/Private Key pair (using a 1024-bit
modulus) and pre-load all MNs with the RSA Public (encryption)
key. The MN manufacturer MUST distribute the RSA Private
(decryption) key, in a secure manner, to the appropriate
service provider(s). It is acceptable for the MN manufacturer
to distribute the same Private (decryption) key to multiple
service providers.
2. Assuming that the cdma2000(R) 1X MN has been provisioned with
an A-key and SSD, the cdma2000(R) 1X MS initiates a call
origination and authenticates itself to the IS-2000 network.
Upon cdma2000(R) 1X (CAVE) authentication success, the BS sends
the "authenticated" MSID (e.g. MIN) to the PDSN.
3. The MN and PDSN establish a PPP session.
4. The MN sends a MIP Registration Request (RRQ) to the PDSN.
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5. The PDSN converts the MIP RRQ into a Radius Access Request
(ARQ) message, includes the MSID in the ARQ, and forwards the
ARQ to the Home AAA server.
6. The AAA Server compares the authenticated MSID (sent from the
PDSN) with the MSID in its subscriber database (associated with
the NAI). If the AAA MIP Update State Field is set to UPDATE
KEYS (1), the AAA Server rejects Packet Data access and orders
a MIP key update.
7. The AAA Server sends an Access Reject (code = 3) message to the
PDSN with MIP_Key_Update_Request Vendor-Specific Radius
Attribute.
8. The PDSN converts the Access Reject to a MIP Registration Reply
(RR) with a MIP_Key_Request MIP Vendor/Organization-Specific
Extension and sends the RR to the MN. RR Code = 89 (Vendor
Specific).
9. The MN sets the MN MIP Update State = UPDATE KEYS. If the MN
has no pre-generated and pre-encrypted the MIP_Key_Data
payload, the MN MUST generate the MN_AAA key, MN_HA key, Chap
key, MN_Authenticator, and AAA_Authenticator in accordance with
RFC 1750. Except for the Public Key Identifier, all generated
values MUST be encrypted using the pre-loaded RSA Public
(encryption) key. The newly generated MN_AAATEMP Key and
MN_HATEMP MUST be used to calculate the MN-AAA and Mobile-Home
Authentication Extensions for the current RRQ. Note: the MN
MAY pre-compute the MIP_Key_Data payload by checking whether a
payload exists during each MN power-up or application
initiation.
10. The MN sends the RRQ with MIP_Key_Data MIP
Vendor/Organization-Specific Extension (see RFC 3115) to the
PDSN.
11. The PDSN converts the RRQ to a Radius ARQ with MIP_Key_Data
Radius Attribute and forwards the ARQ to the home AAA Server.
The MSID is included in the ARQ.
12. The AAA Server compares the authenticated MSID (sent from the
PDSN) with the MSID in its subscriber database (associated with
the NAI). If MSIDPDSN = MSIDAAA, the AAA server, using the
Public Key Identifier, determines the appropriate RSA Private
key and decrypts the encrypted portion of the MIP_Key_Data
payload. The AAA Server verifies the MN-AAA Authentication
Extension Authenticator using the decrypted MN_AAA key. If
successful, the AAA Server updates the subscriber profile with
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the decrypted MN_AAA key, MN_HA key, and CHAP key. The AAA
Server sets the AAA MIP Update State Field to KEYS UPDATED (2).
13. The AAA Server sends an Access Reject with AAA_Authenticator
Radius Attribute to the PDSN.
14. The PDSN converts the Access Reject to a MIP RR with
AAA_Authenticator MIP Vendor/Organization-Specific Extension.
RR Code = 89 (Vendor Specific).
15. If AAA_AuthenticatorMN = AAA_AuthenticatorAAA, the MN assigns
MN_AAATEMP to MN_AAA key and MN_HATEMP to MN_HA key (MN MIP
Update State = KEYS VALID). Otherwise, the MN discards the
temporary keys.
16. The MN initiates a new RRQ which is converted to an ARQ by the
PDSN and forwarded to the AAA Server.
17. The AAA Server verified the MN-AAA Authentication Extension
and sets the AAA MIP Update State Field to KEYS VALID (0). The
AAA Server sends an Access Accept to the PDSN/FA.
18. The PDSN/FA sends the RRQ to the Home Agent (HA).
19. The HA sends an Access Request to the AAA Server. The AAA
Server sends an Access Accept to the HA with the MN_HA key.
The HA verifies the Mobile-Home Authentication Extension using
the MN_HA key.
20. The HA sends RR to the PDSN/FA which forwards RR to the MN.
RR Code = 0 (Success).
5. DMU Procedure Failure Operation
This section was contributed by and is reproduced with the permission
of Qualcomm Incorporated.
To improve the robustness of the DMU Procedure to account for
interruptions due to UDP message loss, RRQ retransmission, or MN
failure, the AAA Server MUST maintain a MIP Update State Field, for
each subscription, in one of three states (0 = KEYS VALID, 1 = UPDATE
KEYS, 2 = KEYS UPDATED).
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MN PDSN/FA AAAh HA
-- ------- ---- --
---------------- ----------------
| MN state = | | AAAh state = |
| Keys Valid | | Update Keys |
---------------- ----------------
| (A) RRQ
|-------------->| ARQ
|------------->|
AR(Key_Update) |
(B) RRP (Key_Update) |<-------------|
|<--------------|
----------------
| MN state = |
| Update Keys |
----------------
| (C) RRQ (MIP_Key_Data)
|-------------->| ARQ (MIP_Key_Data)
|------------->|
----------------
| AAAh state = |
| Keys Updated |
----------------
AR (AAA_Auth) |
(D) RRP (AAA_Auth) |<-------------|
|<--------------|
----------------
| MN state = |
| Keys Valid |
----------------
| RRQ
|-------------->| ARQ
|------------->|
----------------
| AAAh state = |
| Keys Valid |
----------------
AA |
|<-------------| RRQ
|----------------------------------->|
ARQ |
|<--------------------|
| AA
|-------------------->|
RRP |
RRP |<--------------------|
|<-----------------------------|
Figure 5. DMU Failure Call Flow with MN and AAA States
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Each step in the Figure 5 is described as follows:
1. If (A) is lost, the MN retransmits (A). The AAA server expects
(A). If the AAA server is in the UPDATE KEYS state, the AAA
Server sends AR with MIP_Key_Update_Request attribute and the
PDSN/FA sends (B).
2. If (B) is lost, the MN retransmits (A). The AAA server expects
(C). If it receives (A), the AAA Server sends AR with
MIP_Key_Update_Request attribute and the PDSN/FA retransmits
(B).
3. If (C) is lost, the mobile retransmits (C). The AAA server
expects (C) and updates the MIP keys appropriately. The AAA
server transitions to KEYS UPDATED and commits the
MIP_Key_Data. The AAA Server sends the AR with
AAA_Authenticator attribute and the PDSN/FA replies to the MN
with (D).
4. If (D) is lost, the mobile retransmits (C) using the same key
data sent previously. The AAA server expects (A) using the
same keys.
a. If the AAA server receives (C) with the same keys it
received previously, it retransmits the AR with
AAA_Authenticator attribute and the PDSN replies with (D),
containing the AAA_Authenticator.
b. If the AAA server receives (C) with different keys than it
received previously, AAA Server sends AR with
MIP_Key_Update_Request attribute, the PDSN/FA retransmits
(B), and AAA server transitions to UPDATE KEYS.
c. If the AAA server receives (A) which fails authentication
using the keys sent in (C), the AAA Server sends AR with
MIP_Key_Update_Request, the PDSN/FA retransmits (B), and AAA
server transitions to UPDATE KEYS.
5. Once the PDSN/FA receives (A), forwards the ARQ to the AAA
server, and the MN-AAA Authenticator is verified using the
MN_AAA key, the AAA Server transitions to the KEYS VALID state
and the DMU process is complete.
The AAA DMU state machine is described in Figure 6.
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--------------
--------------------->| Keys Valid |---------------
| Auth success using -------------- Need Key |
| MIP_Key_Data Update |
| |
| Auth failed (invalid keys) |
| or RRQ with different MIP_Key_Data |
| --------------------------------- |
| | | |
| | v v
---------------- ---------------
| Keys Updated | | Update Keys |
---------------- ---------------
| ^ ^ |
| | | |
------- ---------------------------------
RRQ with same Got MIP_Key_Data
MIP_Key_Data
Figure 6. AAA Server DMU State Machine
6. cdma2000(R) HRPD/1xEV-DO Support
Because the DMU Procedure occurs at the IP Layer, the DMU Procedure
supports MIP key distribution in either the cdma2000(R) 1X or
HRPD/1xEV-DO network. Because the cdma2000(R) HRPD/1xEV-DO network
does not provide Radio Access Network (RAN) authentication, the DMU
Procedure is more susceptible to a false MN attack (than in an
cdma2000(R) 1X network with CAVE RAN authentication). For this
reason, the DMU Procedure has the capability to optionally support
device-to-network authentication using the MN_Authenticator.
The method of MN_Authenticator delivery to the RADIUS/DIAMETER AAA is
outside the scope of this document, allowing Service Providers the
flexibility to determine the most efficient/least intrusive procedure
to support MN authentication (during the DMU Procedure).
6.1 RADIUS/DIAMETER AAA Support
The RADIUS/DIAMETER AAA MUST support three MN_Authenticator options:
1. Ignore MN_Authenticator
Depending on other potential authentication/fraud prevention
options (outside the scope of the DMU Procedure), the
RADIUS/DIAMETER AAA Server MUST have the capability to ignore the
MN_Authenticator. For example, when the AAA Server decrypts the
MIP_Key_Data payload, the AAA Server silently discards the
MN_Authenticator.
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2. Pre-Update Validation
Prior to updating a subscription profile with the delivered MIP
keys, the AAA Server MUST compare the MN_AuthenticatorMN
(delivered via the encrypted MIP_Key_Data payload) with the
MN_AuthenticatorAAA (possibly delivered via the Service Provider
customer care or billing/provisioning system).
3. Post-Update Validation
After the DMU Procedure is complete, the AAA Server stores the
delivered MN_AuthenticatorMN and waits for delivery of the
MN_AuthenticatorAAA (via Customer Care, IVR, or some other
unspecified process). Once the MN_Authenticator is delivered to
the AAA Server, the AAA Server MUST compare the MN_AuthenticatorMN
(delivered via the encrypted MIP_Key_Data payload) with the
MN_AuthenticatorAAA. If the Authenticators match, the AAA Server
authorizes access and final update of the MIP keys.
6.2 MN Support
The Mobile Node (MN) MUST store the 24-bit MN_Authenticator.
The MN MUST display the MN_Authenticator as an 8 decimal digit number
(via LCD display on a handset or via a GUI for a modem). If the MN
resides within a handset, the user MAY display the MN_Authenticator
using the following keypad sequence: "FCN + * + * + M + I + P +
RCL". Otherwise, the MN MUST display the MN_Authenticator via the
device's GUI.
The MN MUST have the capability to reset the MN_Authenticator. In
other words, the MN MUST have the capability to randomly/pseudo-
randomly generate a new 24-bit MN_Authenticator in according with RFC
1750 upon user command. The reset feature mitigates possible
compromise of the MN_Authenticator during shipment/storage. If the
MN resides within a handset, the user MAY reset the MN_Authenticator
using the following keypad sequence: "FCN + * + * + M + I + P + C +
C + RCL". Otherwise, the MN MUST reset the MN_Authenticator via the
device's GUI.
The MN manufacturer MAY pre-load the MN with the MN_Authenticator.
For example, by pre-loading the MN_Authenticator and affixing a
sticker with the MN_Authenticator (8 decimal digit representation) to
the MN (e.g. modem), the point-of-sale representative does not have
to retrieve the MN_Authenticator from the MN interface.
[Optional] The MN MAY maintain a separate primary and secondary queue
of MN_Authenticator/MIP_Key_Data Payload pairs. When the MN user
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resets the primary MN_Authenticator, the MN discards the primary
MN_Authenticator (and any associated MIP_Key_Data Payload) and
assigns the MN_Authenticator in the secondary queue as the primary
MN_Authenticator (and assigns any associated MIP_Key_Data Payloads to
the primary queue). This feature enables the user/provisioner to
reset the MN_Authenticator and immediately initiate the DMU procedure
without losing the MIP_Key_Data Payload pre-encryption advantage.
Upon MN_Authenticator transfer from the secondary to primary queue,
the MN MUST generate a new MN_Authenticator and associated
MIP_Key_Data Payload for the secondary queue. The MN MUST check both
the primary and secondary MN_Authenticator/MIP_Key_Data Payload
queues upon power-up or application initiation. The MN MUST maintain
at least one MN_Authenticator/MIP_Key_Data Payload pair in each
queue.
6.3 Informative MN_Authenticator Support
MN authentication using the MN_Authenticator gives the service
provider the maximum flexibility in determining how to deliver the
MN_Authenticator the AAA Server. The method of MN_Authenticator
delivery is outside the scope of this document.
However, to provide some context to how the MN_Authenticator may
support MN authentication/fraud prevention in the HRPD/1xEV-DO
environment, we describe the following possible provisioning
scenario.
When a subscriber initially acquires their HRPD/1xEV-DO device and
service, the point-of-sale representative records the subscription
information into the billing/provision system via a computer terminal
at the point-of-sale. The billing/provisioning system delivers
certain information to the RADIUS AAA Server (e.g. NAI, MSID, ESN)
including the MN_Authenticator which the point-of-sale representative
retrieves via the MN device's display. In the case of a modem, the
manufacturer may have pre-loaded the MN_Authenticator and placed a
copy of the MN_Authenticator on a sticker attached to the modem. The
point-of-sale representative simply copies the 8 decimal digit value
of the MN_Authenticator into the customer profile. Once the MN is
loaded with the proper NAI and powered-up, the MN initiates the DMU
Procedure with the AAA Server. The AAA Server compares the MN-
delivered MN_Authenticator with the billing system delivered
MN_Authenticator. If the authenticators match, the AAA Server
updates the subscriber profile with the delivered MIP keys and
authorizes service. If the Post-Update option is enabled within the
AAA Server, the AAA Server tentatively updates the subscription
profile until receiving the MN_Authenticator via the
billing/provision system.
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As another option, the Service Provider MAY use an IVR system in
which the HRPD/1xEV-DO subscriber calls a provisioning number and
inputs the MN_Authenticator. The IVR system then delivers the
MN_Authenticator to the AAA Server for final validation and Packet
Data Access.
7. Security Considerations
The DMU Procedure is designed to maximize the efficiency of MIP key
distribution while providing adequate key distribution security. The
following list provides a description of potential security
vulnerabilities and their relative risk to the DMU Procedure:
7.1 Cryptographic Key Generation by the MN
Because the MN is required to properly generate the MN_AAA, MN_HA,
and CHAP key, the MN must perform cryptographic key generation in
accordance with accepted random/pseudo-random number generation
procedures. MN manufacturers MUST comply with RFC 1750 [10]
guidelines and Service Providers SHOULD ensure that manufacturers
implement acceptable key generation procedures. The use of
predictable cryptographic keys could be devastating to MIP security.
However, the risk of not using acceptable random/pseudo-random key
generation is minimal as long as MN manufacturers adhere to RFC 1750
guidelines. Furthermore, if a key generation flaw is identified, the
flaw appears readily correctable via a software patch, minimizing the
impact.
7.2 Man-in-the-Middle Attack
The DMU procedure is susceptible to a MIM attack, however such an
attack appears relatively complex and expensive. When AKA is
deployed within cdma2000(R) 1X, the MIM Attack will be eliminated.
The risk of an MIM Attack is minimal due to required expertise,
attack expense, and impending cdma2000(R) 1X mutual authentication
protection. If a particular cdma2000(R) 1X network does not support
A-key authentication, the MN_Authenticator MAY optionally be used.
7.3 RSA Private Key Compromise
Because one RSA Private key may be associated with millions of MNs
(RSA Public Key), it is important to protect the RSA Private key
from disclosure to unauthorized parties. Each MN manufacturer MUST
establish adequate security procedures/policies regarding the
dissemination of the RSA Private key. RSA Private keys SHOULD be
distributed to legitimate cdma2000(R) service providers only. It is
acceptable for a MN manufacturer to distribute the same RSA Private
key to multiple service providers to enable MIP key update. However,
each service provider MAY generate their own RSA Public/Private key
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pair and require the MN manufacturer to include their own RSA Public
key in a specific software patch if compromise of the RSA Private key
is a significant concern.
7.4 RSA Encryption
Several vulnerabilities have been identified in certain
implementations of RSA, however they do not appear applicable to the
DMU Procedure.
7.5 False Base Station/PDSN
The MN appears to be protected against a False BS denial-of-service
(DOS) attack, since only the proper AAA server can recover the
AAA_Authenticator.
7.6 cdma2000(R) 1X False MN
The cdma2000(R) 1X network appears adequately protected against a
false MN by IS-2000 challenge-response authentication.
7.7 HRPD/1xEV-DO False MN
The 1xEV-DO AAA Server MAY optionally authenticate the MN using the
MN_Authenticator to prevent a fraudulent MN activation.
8. Verizon Wireless - Specific RADIUS Attributes
Three new RADIUS Attributes are required to support the DMU Procedure
and are specified as follows:
Type: 26
Length: >9
Verizon Wireless Enterprise/Vendor ID: 12951
MIP_Key_Update_Request:
----------------------
The Home Radius AAA Server indicates MIP key update is required.
Vendor-Type = 1
Vendor-Length = 3 bytes
Vendor-Value= PKOID of the AAA Server
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MIP_Key_Data:
------------
Payload containing encrypted MN_AAA key, MN_HA key, CHAP key,
MN_Authenticator, and AAA_Authenticator. Payload also contains
Public Key Identifier.
Vendor-Type = 2
Vendor-Length = 134 bytes
NOTE: Vendor-Length depends on the size of the RSA modulus. For
example, when RSA-512 is used, Vendor-Length = 70 bytes.
Vendor-Value= 128 byte RSA encryption payload (when 1024-bit RSA
used) which contains encrypted MN_AAA key, MN_HA key, CHAP key,
MN_Authenticator, and AAA_Authenticator. The four (4) byte
Public Key Identifier is concatenated to the encrypted payload.
AAA_Authenticator:
-----------------
64-bit AAA_Authenticator value decrypted by the Home Radius AAA
Server.
Vendor-Type = 3
Vendor-Length = 10 bytes
Vendor-Value= decrypted AAA_Authenticator from Home AAA Server.
Public Key Invalid:
------------------
Home Radius AAA Server indicates that Public key used by MN is not
valid.
Vendor-Type = 4
Vendor-Length = 2 bytes
Vendor-Value= none.
Note: An Organization may define Specific Radius Attributes using
their own Organization identifier.
9. Verizon Wireless Mobile IP Vendor/Organization-Specific Extensions
Three Verizon Wireless Mobile IP Vendor/Organization-Specific
Extensions (RFC 3115), required to support the DMU Procedure, are
specified as follows:
Type: 38 (CVSE-TYPE-NUMBER)
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Verizon Wireless Vendor ID: 12951 (high-order octet is 0 and low
order octets are the SMI Network Management Private Enterprise Code
of the Vendor in the network byte order, as defined by IANA).
0 7 8 15 16 31
---------------------------------------------------
| Type | Reserved | Length |
---------------------------------------------------
| Vendor/Org-ID |
---------------------------------------------------
| Vendor-CVSE-Type | Vendor-CVSE-Value ... |
---------------------------------------------------
Figure 7. Critical Vendor/Organization Specific Extension
MIP_Key_Request:
---------------
The Home Radius AAA Server indicates MIP key update is required.
Length = 7
NOTE: The RFC 3115 Editor has stated that the Reserved field is
not included in the length determination.
Vendor-CVSE-Type = 1
Vendor-CVSE-Value= PKOID sent in the Radius MIP_Key_Update_Request
attribute.
MIP_Key_Data:
------------
Payload containing encrypted MN_AAA key, MN_HA key, CHAP key,
MN_Authenticator, and AAA_Authenticator. Payload also contains
Public Key Identifier.
Length = 138
NOTE: Length depends on the size of the RSA modulus. For example,
when RSA-512 is used, Length = 74 bytes.
Vendor-CVSE-Type = 2
Vendor-CVSE-Value= 128 byte RSA encryption payload (when 1024-bit
RSA used) which contains encrypted MN_AAA key, MN_HA key, CHAP
key, MN_Authenticator, and AAA_Authenticator. The four (4)
byte Public Key Identifier and DMUV is concatenated to the
encrypted payload.
AAA_Authenticator:
-----------------
64-bit AAA_Authenticator value decrypted by the Home Radius AAA
Server.
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Length = 14 bytes
Vendor-CVSE-Type = 3
Vendor-CVSE-Value= decrypted AAA_Authenticator from Home AAA
Server.
Public Key Invalid:
------------------
The Home Radius AAA Server indicates that Public key used by MN is
not valid.
Length = 6 bytes
Vendor-CVSE-Type = 4
Vendor-CVSE-Value= none.
Note: An Organization may define Specific Vendor/Organization
Extensions using their own Organization identifier.
10. Public Key Identifier and DMU Version
The Public Key Identifier (Pub_Key_ID) is used only during the
Dynamic Mobile IP Update (DMU) procedure to allow the AAA Server to
distinguish between different Public keys (which may be assigned by
different manufacturers, service providers, or other organizations).
The Public Key Identifier consists of the PKOID, PKOI, PK_Identifier,
and ATV fields. The DMU Version field enables subsequent revisions
of the DMU procedure.
----------------------------------------------
| PKOID | PKOI | PK_Expansion | ATV | DMUV |
----------------------------------------------
0 7 8 15 16 23 24 27 28 31
Figure 8. Public Key Identifier and DMUV
Each Public Key Organization (PKO) MUST be assigned a Public Key
Organization Identifier (PKOID) to enable the AAA Server to
distinguish between different Public keys created by different PKOs
(see Table 1). If a Service Provider does not provide the MN
manufacturer with a (RSA) Public key, the manufacturer MUST generate
a unique RSA Public/Private key pair and pre-load each MN with the
RSA Public key (1024-bit modulus by default). The manufacture MAY
share the same RSA Private key with multiple Service Providers as
long as reasonable security procedures are established and maintained
(by the manufacturer) to prevent disclosure of the RSA Private
(decryption) key to an unauthorized party.
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The Public Key Organization Index (PKOI) is an 8-bit field in which
the index the value is defined at the discretion of the PKO. For
example, a device manufacturer MAY incrementally assign a new PKOI
for each Public/Private key pair when the pair created.
The PK_Expansion field enables support for additional PKOs or
expansion of the PKOI.
The DMU Version field allows for DMU Procedure version identification
(see Table 2).
The Algorithm Type and Version (ATV) field allows for identification
of the Public Key algorithm and version used (see Table 3).
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Table 1. Public Key Organization Identification Table
PKOID Public Key PKOID Public Key
(HEX) Organization (PKO) (HEX) Organization (PKO)
----- ------------------ ----- ------------------
00 RESERVED 40 Sanyo Fisher Company
01 RESERVED 41 Sharp Laboratories of
America
02 RESERVED 42 Sierra Wireless, Inc.
03 RESERVED 43 Sony Electronics
04 RESERVED 44 Synertek, Inc.
05 RESERVED 45 Tantivy Communications,
Inc.
06 RESERVED 46 Tellus Technology, Inc.
07 RESERVED 47 Wherify Wireless, Inc.
08 RESERVED 48 Airbiquity
09 RESERVED 49 ArrayComm
0A Verizon Wireless 4A Celletra Ltd.
0B AAPT Ltd. 4B CIBERNET Corporation
0C ALLTEL Communications 4C CommWorks Corporation,
a 3Com Company
0D Angola Telecom 4D Compaq Computer
Corporation
0E Bell Mobility 4E ETRI
0F BellSouth International 4F Glenayre Electronics
Inc.
10 China Unicom 50 GTRAN, Inc.
11 KDDI Corporation 51 Logica
12 Himachal Futuristic 52 LSI Logic
Communications Ltd.
13 Hutchison Telecom (HK), 53 Metapath Software
Ltd. International, Inc.
14 IUSACELL 54 Metawave Communications
15 Komunikasi Selular 55 Openwave Systems Inc.
Indonesia (Komselindo)
16 Korea Telecom Freetel, 56 ParkerVision, Inc.
Inc.
17 Leap 57 QUALCOMM, Inc.
18 LG Telecom, Ltd. 58 QuickSilver Technologies
19 Mahanagar Telephone Nigam 59 Research Institute of
Limited (MTNL) Telecommunication
Transmission, MII (RITT)
1A Nextel Communications, 5A Schema, Ltd.
Inc.
1B Operadora UNEFON SA de CV 5B SchlumbergerSema
1C Pacific Bangladesh 5C ScoreBoard, Inc.
Telecom Limited
1D Pegaso PCS, S.A. DE C.V. 5D SignalSoft Corp.
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PKOID Public Key PKOID Public Key
(HEX) Organization (PKO) (HEX) Organization (PKO)
----- ------------------ ----- ------------------
1E Pele-Phone 5E SmartServ Online,
Communications Ltd. Inc.
1F Qwest 5F TDK Corporation
20 Reliance Infocom Limited 60 Texas Instruments
21 Shinsegi Telecomm, Inc. 61 Wherify Wireless, Inc.
22 Shyam Telelink Limited 62 Acterna
23 SK Telecom 63 Anritsu Company
24 Sprint PCS 64 Ericsson
25 Tata Teleservices Ltd. 65 Grayson Wireless
26 Telecom Mobile Limited 66 LinkAir Communications,
Inc.
27 Telstra Corporation 67 Racal Instruments
Limited
28 Telus Mobility Cellular, 68 Rohde & Schwarz
Inc.
29 US Cellular 69 Spirent Communications
2A 3G Cellular 6A Willtech, Inc.
2B Acer Communication & 6B Wireless Test Systems
Multimedia Inc.
2C AirPrime, Inc. 6C Airvana, Inc.
2D Alpine Electronics, Inc. 6D COM DEV Wireless
2E Audiovox Communications 6E Conductus, Inc.
Corporation
2F DENSO Wireless 6F Glenayre Electronics
Inc.
30 Ditrans Corporation 70 Hitachi Telecom (USA),
Inc.
31 Fujitsu Network 71 Hyundai Syscomm Inc.
Communication, Inc.
32 Gemplus Corporation 72 ISCO
33 Giga Telecom Inc. 73 LG Electronics, Inc.
34 Hyundai CURITEL, Inc. 74 LinkAir Communications,
Inc.
35 InnovICs Corp 75 Lucent Technologies,
Inc.
36 Kyocera Corporation 76 Motorola CIG
37 LG Electronics, Inc. 77 Nortel Networks
38 LinkAir Communications, 78 Repeater Technologies
Inc.
39 Motorola, Inc. 79 Samsung Electronics Co.,
Ltd.
3A Nokia Corporation 7A Starent Networks
3B Novatel Wireless, Inc. 7B Tahoe Networks, Inc.
3C OKI Network Technologies 7C Tantivy Communications,
Inc.
3D Pixo 7D WaterCove Networks
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PKOID Public Key PKOID Public Key
(HEX) Organization (PKO) (HEX) Organization (PKO)
----- ------------------ ----- ------------------
3E Research In Motion 7E Winphoria Networks, Inc.
3F Samsung Electronics 7F ZTE Corporation
Co., Ltd.
Note: 80 through FF will be assigned by the PKOID administrator
(TBD).
Table 2. DMU Version
DMU Version DMU Version
Value
----------- -----------
00 Version 1.3
01 TBD
02 TBD
03 TBD
04 TBD
05 TBD
06 TBD
07 Cleartext Mode
Table 3. Algorithm Type and Version
ATV Public Key Algorithm
Value Type and Version
----- --------------------
00 Reserved
01 RSA - 1024
02 RSA - 768
03 RSA - 2048
04 TBD
05 TBD
06 TBD
07 TBD
11. Intellectual Property
Verizon Wireless has submitted a Patent Application to the United
States Patent and Trademark Office for components of the DMU
Procedure.
Qualcomm Incorporated may have patents or copyrights that cover
information contained in this document.
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12. Conclusion
The Dynamic Mobile IP key Update (DMU) Procedure enables the
efficient, yet secure, delivery of critical Mobile IP cryptographic
keys. The use of cryptographic keys, hence the bootstrapping of such
MIP keys using the DMU Procedure, is essential to commercial delivery
of Mobile IP service in CDMA 2000 1xRTT and HRPD/1xEV-DO networks
networks or other networks that utilize Mobile IP.
13. Formal Syntax
None.
References
1 Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, Internet Engineering Task Force, March
1997
2 TIA/EIA/IS-2000 Series, Revision A, Telecommunications Industry
Association, March 2000
3 TIA/EIA/IS-856, cdma2000 High Rate Packet Data Air Interface
Specification, Telecommunications Industry Association, November
2000
4 TIA/EIA/IS-835-A, cdma2000 Wireless IP Network Standard,
Telecommunications Industry Association, May 2001
5 ANSI/TIA/EIA-41-D-97, Cellular Radiotelecommunications Intersystem
Operations, Telecommunications Industry Association, December 1997
6 ANSI/TIA/EIA-683-B-2001, Over-the-Air Service Provisioning of
Mobile Stations in Spread Spectrum Systems, Telecommunications
Industry Association, December 2001
7 B. Kaliski. PKCS #1: RSA Encryption Version 1.5. RFC 2313,
Internet Engineering Task Force, March 1998.
8 G. Dommety, K. Leung. Mobile IP Vendor/Organization-Specific
Extensions. RFC 3115, Internet Engineering Task Force, April 2001
9 TIA/EIA-IS-634-A, Interoperability Specifications (IOS) for
cdma2000 Access Network Interfaces, Telecommunications Industry
Association, August 2001
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10 D. Eastlake, 3rd, S. Crocker, and J. Schiller. Randomness
Recommendations for Security. RFC 1750, Internet Engineering Task
Force, December 1994.
Acknowledgments
Thanks to Jeffrey Dyck (Qualcomm), James Willkie (Qualcomm), Jayanth
Mandayam (Qualcomm), Marcello Lioy (Qualcomm), Michael Borella
(CommWorks), Cliff Randall (CommWorks), Daniel Cassinelli
(CommWorks), Edward Dunn (CommWorks), Suresh Sarvepalli (CommWorks),
Gabriella Ambramovici (Lucent), Semyon Mizikovsky (Lucent), Sarvar
Patel (Lucent), Peter McCann (Lucent), Ganapathy Sundaram (Lucent),
Girish Patel (Nortel), Glen Baxley (Nortel), Diane Thompson
(Ericsson), Brian Hickman(Ericsson), Somsay Sychaleun (Bridgewater),
Parm Sandhu (Sierra Wireless), Iulian Mucano (Sierra Wireless), and
Samy Touati (Ericsson) for their useful discussions and comments.
Author's Addresses
Christopher Carroll
HAMILTON, BROOK, SMITH & REYNOLDS, P.C.
530 Virginia Road
P.O. Box 9133
Concord, MA 01742-9133
Phone: 978-202-3436
Email: christopher.carroll@hbsr.com
Frank Quick
Qualcomm Incorporated
5775 Morehouse Drive
San Diego, CA 92121 USA
Phone: 858-658-3608
Email: fquick@qualcomm.com
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14. Appendix - Cleartext-Mode Operation
DMU MUST support a cleartext mode for development testing where DMUV
= 7. The MIP_Key_Data payload will assume the same size as if RSA
1024-bit encryption were applied to the payload. In this mode, the
MIP_Key_Data Radius Attribute and MIP Vendor Specific Extension will
be 134 bytes and 138 bytes in length respectively. Thus, in
cleartext mode, the payload MUST consist of 48 bytes of keys (MN_AAA,
MN_HA, and CHAP key), 8 byte AAA_Authenticator, 3 byte
MN_Authenticator. The next 69 bytes will be padded with "0" bits.
MIP_Key_Data = MN_AAAh key, MN_HA key, CHAP_key, MN_Authenticator,
AAA_Authenticator, Padding (69 bytes), Public_Key_IDi, DMUV
Where:
MN_AAA key = 128-bit random MN / AAA Server key.
MN_HA key = 128-bit random MN / Home Agent (HA) key.
CHAP_key = 128-bit random Simple IP authentication key.
MN_Authenticator = 24-bit random number.
AAA_Authenticator = 64-bit random number used by MN to
authenticate AAA Server.
Padding = 69 bytes of 0's.
DMU Version (DMUV) = 4 bit identifier of DMU version.
Public Key Identifier (Pub _Key_ID) = PKOID, PKOI, PK_Expansion, ATV
Where:
Public Key Organization Identifier (PKOID) = 8-bit serial number
identifier of Public Key Organization (PKO) that created the
Public Key.
Public Key Organization Index (PKOI) = 8-bit serial number used at
PKO discretion to distinguish different Public/Private key
pairs.
PK_Expansion = 8-bit field to enable possible expansion of PKOID
or PKOI fields. (Note: Default value = 0xFF)
Algorithm Type and Version (ATV) = 4-bit identifier of the
algorithm used.
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