128 lines
3.7 KiB
Plaintext
128 lines
3.7 KiB
Plaintext
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Network Working Group M. Horowitz
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<draft-ietf-cat-kerb-des3-hmac-sha1-00.txt> Cygnus Solutions
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Internet-Draft November, 1996
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Triple DES with HMAC-SHA1 Kerberos Encryption Type
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Status of this Memo
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This document is an Internet-Draft. Internet-Drafts are working
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documents of the Internet Engineering Task Force (IETF), its areas,
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and its working groups. Note that other groups may also distribute
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working documents as Internet-Drafts.
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Internet-Drafts are draft documents valid for a maximum of six months
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and may be updated, replaced, or obsoleted by other documents at any
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time. It is inappropriate to use Internet-Drafts as reference
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material or to cite them other than as ``work in progress.''
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To learn the current status of any Internet-Draft, please check the
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``1id-abstracts.txt'' listing contained in the Internet-Drafts Shadow
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Directories on ds.internic.net (US East Coast), nic.nordu.net
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(Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific
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Rim).
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Distribution of this memo is unlimited. Please send comments to the
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<cat-ietf@mit.edu> mailing list.
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Abstract
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This document defines a new encryption type and a new checksum type
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for use with Kerberos V5 [RFC1510]. This encryption type is based on
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the Triple DES cryptosystem and the HMAC-SHA1 [Krawczyk96] message
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authentication algorithm.
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The des3-cbc-hmac-sha1 encryption type has been assigned the value 7.
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The hmac-sha1-des3 checksum type has been assigned the value 12.
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Encryption Type des3-cbc-hmac-sha1
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EncryptedData using this type must be generated as described in
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[Horowitz96]. The encryption algorithm is Triple DES in Outer-CBC
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mode. The keyed hash algorithm is HMAC-SHA1. Unless otherwise
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specified, a zero IV must be used. If the length of the input data
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is not a multiple of the block size, zero octets must be used to pad
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the plaintext to the next eight-octet boundary. The counfounder must
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be eight random octets (one block).
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Checksum Type hmac-sha1-des3
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Checksums using this type must be generated as described in
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[Horowitz96]. The keyed hash algorithm is HMAC-SHA1.
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Horowitz [Page 1]
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Internet Draft Kerberos Triple DES with HMAC-SHA1 November, 1996
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Common Requirements
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Where the Triple DES key is represented as an EncryptionKey, it shall
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be represented as three DES keys, with parity bits, concatenated
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together. The key shall be represented with the most significant bit
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first.
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When keys are generated by the derivation function, a key length of
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168 bits shall be used. The output bit string will be converted to a
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valid Triple DES key by inserting DES parity bits after every seventh
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bit.
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Any implementation which implements either of the encryption or
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checksum types in this document must support both.
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Security Considerations
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This entire document defines encryption and checksum types for use
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with Kerberos V5.
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References
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[Horowitz96] Horowitz, M., "Key Derivation for Kerberos V5", draft-
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horowitz-kerb-key-derivation-00.txt, November 1996.
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[Krawczyk96] Krawczyk, H., Bellare, and M., Canetti, R., "HMAC:
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Keyed-Hashing for Message Authentication", draft-ietf-ipsec-hmac-
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md5-01.txt, August, 1996.
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[RFC1510] Kohl, J. and Neuman, C., "The Kerberos Network
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Authentication Service (V5)", RFC 1510, September 1993.
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Author's Address
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Marc Horowitz
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Cygnus Solutions
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955 Massachusetts Avenue
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Cambridge, MA 02139
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Phone: +1 617 354 7688
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Email: marc@cygnus.com
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Horowitz [Page 2]
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