GSSAPI-CFX

1
GSSAPI-CFX

• Larry Zhu
• Microsoft Corporation
• IETF 58

2
Goals

• Support cryptosystem framework
• Support AES enctypes in GSSAPI
• Backward compatible with existing apps
• Interoperability

3
Status of the draft

• Latest revision
• draft-ietf-krb-wg-gssapi-cfx-03.txt
• Submitted on 10/26/2003
• Design team
• Ken Raeburn, Nicolas Williams, Sam Hartman,
  Karthik Jaganathan, Larry Zhu, Paul Leach et al

4
Open issues in draft -03

• Generic token framing in per-message tokens (call
  for consensus)
• MUST vs SHOULD acceptor-asserted-subkey
  (resolved)
• List of not-newer enctypes name and values
  (resolved)

5
Questions and Comments
6
Kcrypto Enctypes

• des-cbc-crc
  1 6.2.3
• des-cbc-md4
  2 6.2.2
• des-cbc-md5
  3 6.2.1
• reserved
  4
• des3-cbc-md5
  5
• reserved
  6
• des3-cbc-sha1
  7
• dsaWithSHA1-CmsOID 9
  (pkinit)
• md5WithRSAEncryption-CmsOID 10
  (pkinit)
• sha1WithRSAEncryption-CmsOID 11
  (pkinit)
• rc2CBC-EnvOID
  12 (pkinit)
• rsaEncryption-EnvOID
  13 (pkinit from PKCS1 v1.5)
• rsaES-OAEP-ENV-OID 14
  (pkinit from PKCS1 v2.0)
• des-ede3-cbc-Env-OID 15
  (pkinit)
• des3-cbc-sha1-kd
  16 6.3
• aes128-cts-hmac-sha1-96 17
  KRB5-AES
• aes256-cts-hmac-sha1-96 18
  KRB5-AES
• rc4-hmac
  23 (Microsoft)

7
What is new (from 1964)

• Directional keys
• 64bit sequence numbers
• Generic token framing
• New token IDs
• 0404 for MIC tokens, 0504 for Wrap tokens
• Direction indicator as a single flag bit
• Extra Count
• Right Rotation Count
• Empty context deletion tokens

8
What is new (contd)

• Acceptor asserted subkey
• Token ID assignment considerations
• Handling of unknown token IDs

9
Inherited from 1964

• Everything else, with minor improvements
• Delegation KRB_CRED MUST be encrypted in session
  key
• Channel binding encoding clarified