Network Working Group                                      J. Galbraith
INTERNET-DRAFT                              Van Dyke Technologies, Inc.
draft-ietf-secsh-publickeyfile-02                             R. Thayer
Expires December 2001                              The Tillerman Group
                                                             March 2001


                      SECSH Public Key File Format


STATUS OF THIS MEMO:

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of [RFC-2026].

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups. Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six
   months and may be updated, replaced, or obsoleted by other documents
   at any time. It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

Abstract

   This document formally documents the existing public key file format
   in use for exchanging public keys between different SECSH
   implementations.

1. 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].

2. Introduction

   In order to use public key authentication, public keys must be
   exchanged between client and server.  This document formally
   describes the existing public key file format, with few exceptions.

   Where this document departs from current practice, it also suggests
   a mechanism for backwards compatibility.





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                      SECSH Public Key File Format            March 2001


3. Key File Format

   SECSH implementations must share public key files between the client
   and the server in order interoperate.

   A key file is a text file, containing a sequence of lines. Each line
   in the file MUST NOT be longer than 72 bytes.

3.1 Line termination Characters

   In order to achieve the goal of being able to exchange public key
   files between servers, implementations are REQUIRED to read files
   using any of the common line termination sequence, <CR>, <LF> or
   <CR><LF>.

   Implementations may generate files using which ever line termination
   convention is most convenient

4. Begin and end markers

   The first line of a conforming key file MUST be a begin marker,
   which is the literal text:

   ---- BEGIN SSH2 PUBLIC KEY ----

   The last line of a conforming key file MUST be a end marker, which
   is the literal text:

   ---- END SSH2 PUBLIC KEY ----

5. Key File Header

   The key file header section consists of multiple RFC822 - style
   header fields.  Each field is a line of the following format:

   Header-tag ':' ' ' Header-value

   The Header-tag MUST NOT be more than 64 bytes.  The Header-value
   MUST NOT be more than 1024 bytes.  Each line in the header MUST NOT
   be more than 72 bytes.

   A line is continued if the last character in the line is a '\'.  If
   the last character of a line is a '\', then the logical contents of
   the line is formed by removing the '\' and appending the contents of
   the next line.

   The Header-tag MUST be US-ASCII.  The Header-value MUST be encoded
   in UTF-8 ([RFC-2044]).

   A line that is not a continuation line that has no ':' in it is
   assumed to be the first line of the base 64 encoded body (Section 8)



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                      SECSH Public Key File Format            March 2001


   Compliant implementations MUST ignore unrecognized header fields.
   Implementations SHOULD preserve unrecognized header fields when
   manipulating the key file.

   Existing implementations may not correctly handle unrecognized
   fields. During a transition period, implementations SHOULD generate
   key file headers that contain only a Subject field followed by a
   Comment field.

6. Subject Header

   This field currently is used to store the login-name that the key
   was generated under.  For example:

   Subject: user

7. Comment Header

   Contain a user specified comment which will be displayed when using
   the key.

   It is suggested that this field default to user@hostname for the
   user and machine used to generate the key.  For example:

   Comment: user@mycompany.com

   Currently, common practice is to quote the Header-value of the
   Comment, and some existing implementations fail if these quotes are
   omitted.

   Compliant implementations MUST function correctly if the quotes are
   omitted.

   During an interim period implementations MAY include the quotes. If
   the first and last characters of the Header-value are matching
   quotes, implementations SHOULD remove them before using the value.

8. Public Key File Body

   The body of a public key file consists of the public key blob as
   described in [SSH-TRANS], section 4.6, "Public Key Algorithms",
   encoded in base 64 as specified in [RFC-2045] section 6.8, "Base64
   Content-Transfer-Encoding".

   As with all other lines, each line in the body MUST NOT be longer
   than 72 characters.

9. Examples

   The following are some example public key files that are compliant:




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                      SECSH Public Key File Format            March 2001


---- BEGIN SSH2 PUBLIC KEY ----
Comment: "1024-bit RSA, converted from OpenSSH by galb@test1"
AAAAB3NzaC1yc2EAAAABIwAAAIEA1on8gxCGJJWSRT4uOrR13mUaUk0hRf4RzxSZ1zRbYY
Fw8pfGesIFoEuVth4HKyF8k1y4mRUnYHP1XNMNMJl1JcEArC2asV8sHf6zSPVffozZ5TT4
SfsUu/iKy9lUcCfXzwre4WWZSXXcPff+EHtWshahu3WzBdnGxm5Xoi89zcE=
---- END SSH2 PUBLIC KEY ----

---- BEGIN SSH2 PUBLIC KEY ----
Comment: DSA Public Key for use with MyIsp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---- END SSH2 PUBLIC KEY ----

---- BEGIN SSH2 PUBLIC KEY ----
Subject: galb
Comment: 1024-bit rsa, created by galb@shimi Mon Jan 15 08:31:24 2001
AAAAB3NzaC1yc2EAAAABJQAAAIEAiPWx6WM4lhHNedGfBpPJNPpZ7yKu+dnn1SJejgt459
6k6YjzGGphH2TUxwKzxcKDKKezwkpfnxPkSMkuEspGRt/aZZ9wa++Oi7Qkr8prgHc4soW6
NUlfDzpvZK2H5E7eQaSeP3SAwGmQKUFHCddNaP0L+hM7zhFNzjFvpaMgJw0=
---- END SSH2 PUBLIC KEY ----

10. References

   [SSH-TRANS] Ylonen, T., et al: "SSH Transport Layer Protocol",
   Internet Draft, draft-secsh-transport-09.txt

   [RFC-2044] Yergeau, F: "UTF-8, a Transformation Format of Unicode
   and ISO 10646", October 1996.

   [RFC-2026] S. Bradner: "The Internet Standards Process -- Revision
   3", October 1996.

   [RFC-2119] S. Bradner: "Key words for use in RFCs to Indicate
   Requirement Levels", March 1997.

   [RFC-2045] Freed & Borenstein: "Multipurpose Internet Mail
   Extensions (MIME) Part One: Format of Internet Message Bodies",
   November 1996.

11. Author's Address

   Joseph Galbraith
   Van Dyke Technologies, Inc.
   4848 Tramway Ridge Rd.
   Suite 101


J. Galbraith, R. Thayer                                         [Page 4]


                      SECSH Public Key File Format            March 2001


   Albuquerque, NM 87111
   Email: galb@vandyke.com
   Phone: +1 505 332 5700

   Rodney Thayer
   The Tillerman Group
   370 Altair Way, PMB 321
   Sunnyvale, CA 94086
   Email: rodney@tillerman.to
   Phone: +1 408 757 9693












































J. Galbraith, R. Thayer                                         [Page 5]