AES Encryption with HMAC-SHA2 for Kerberos 5
RFC 8009
Document | Type | RFC - Informational (October 2016; No errata) | |
---|---|---|---|
Authors | Michael Jenkins , Michael Peck , Kelley Burgin | ||
Last updated | 2016-10-27 | ||
Replaces | draft-ietf-kitten-aes-cbc-hmac-sha2 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Benjamin Kaduk | ||
Shepherd write-up | Show (last changed 2016-07-05) | ||
IESG | IESG state | RFC 8009 (Informational) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Stephen Farrell | ||
Send notices to | "Benjamin Kaduk" <kaduk@mit.edu> | ||
IANA | IANA review state | Version Changed - Review Needed | |
IANA action state | RFC-Ed-Ack |
Internet Engineering Task Force (IETF) M. Jenkins Request for Comments: 8009 National Security Agency Category: Informational M. Peck ISSN: 2070-1721 The MITRE Corporation K. Burgin October 2016 AES Encryption with HMAC-SHA2 for Kerberos 5 Abstract This document specifies two encryption types and two corresponding checksum types for Kerberos 5. The new types use AES in CTS mode (CBC mode with ciphertext stealing) for confidentiality and HMAC with a SHA-2 hash for integrity. Status of This Memo This document is not an Internet Standards Track specification; it is published for informational purposes. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc8009. Copyright Notice Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Jenkins, et al. Informational [Page 1] RFC 8009 AES-CTS HMAC-SHA2 For Kerberos 5 October 2016 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Protocol Key Representation . . . . . . . . . . . . . . . . . 3 3. Key Derivation Function . . . . . . . . . . . . . . . . . . . 3 4. Key Generation from Pass Phrases . . . . . . . . . . . . . . . 4 5. Kerberos Algorithm Protocol Parameters . . . . . . . . . . . . 5 6. Checksum Parameters . . . . . . . . . . . . . . . . . . . . . 7 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 8. Security Considerations . . . . . . . . . . . . . . . . . . . 8 8.1. Random Values in Salt Strings . . . . . . . . . . . . . . 9 8.2. Algorithm Rationale . . . . . . . . . . . . . . . . . . . 9 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 9.1. Normative References . . . . . . . . . . . . . . . . . . . 10 9.2. Informative References . . . . . . . . . . . . . . . . . . 11 Appendix A. Test Vectors . . . . . . . . . . . . . . . . . . . . 12 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19 1. Introduction This document defines two encryption types and two corresponding checksum types for Kerberos 5 using AES with 128-bit or 256-bit keys. To avoid ciphertext expansion, we use a variation of the CBC-CS3 mode defined in [SP800-38A+], also referred to as ciphertext stealing or CTS mode. The new types conform to the framework specified in [RFC3961], but do not use the simplified profile, as the simplified profile is not compliant with modern cryptographic best practices such as calculating Message Authentication Codes (MACs) over ciphertext rather than plaintext. The encryption and checksum types defined in this document are intended to support environments that desire to use SHA-256 or SHA-384 (defined in [FIPS180]) as the hash algorithm. Differences between the encryption and checksum types defined in this document and the pre-existing Kerberos AES encryption and checksum types specified in [RFC3962] are: * The pseudorandom function (PRF) used by PBKDF2 is HMAC-SHA-256 or HMAC-SHA-384. (HMAC is defined in [RFC2104].) * A key derivation function from [SP800-108] using the SHA-256 or SHA-384 hash algorithm is used to produce keys for encryption, integrity protection, and checksum operations. Jenkins, et al. Informational [Page 2] RFC 8009 AES-CTS HMAC-SHA2 For Kerberos 5 October 2016 * The HMAC is calculated over the cipher state concatenated with theShow full document text