Ticket History #5587: PRF for non-AES enctypes

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To: krb5-bugs@mit.edu
Subject: PRF for des3-cbc-hmac-sha1-kd
From: Yukiyo <akisada@tahi.org>
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Hi, all.

I may misunderstand RFC 3961,
but in my understanding, des3-cbc-hmac-sha1-kd (etype=16) uses
PRF on Simplified Profile as its pseudo-random function.

Now, I want to use PRF function
from Krb5-1.8 perl module which is based on MIT krb5-1.6.3 implementation.

Krb5: <http://search.cpan.org/dist/Krb5/>

But, PRF function for ENCTYPE_DES3_CBC_SHA1 has not be
defined in <krb5-1.6.3/src/lib/crypto/etypes.c>.

Indeed,
I need some modification into Krb5-1.8 to export prf function from krb5-1.6.3,
but I also need the following modification into krb5-1.6.3.

In this moment,
the following modification (described at Fix: section) matches with my expected behavior,
but I'm not sure whether this modification against krb5-1.6.3 is correct or not.

Please investigate this.

Thanks,
just by calling krb5_c_prf() function under des3-cbc-hmac-sha1-kd
--- krb5-1.6.3/src/lib/crypto/etypes.c.orig 2009-04-01 17:02:56.000000000 +0900
+++ krb5-1.6.3/src/lib/crypto/etypes.c 2009-04-01 14:42:01.000000000 +0900
@@ -94,26 +94,26 @@
{ ENCTYPE_DES3_CBC_SHA1,
"des3-cbc-sha1", "Triple DES cbc mode with HMAC/sha1",
&krb5int_enc_des3, &krb5int_hash_sha1,
- 8,
+ 16,
krb5_dk_encrypt_length, krb5_dk_encrypt, krb5_dk_decrypt,
krb5int_dk_string_to_key,
- NULL, /*PRF*/
+ krb5int_dk_prf, /*PRF*/
CKSUMTYPE_HMAC_SHA1_DES3 },
{ ENCTYPE_DES3_CBC_SHA1, /* alias */
"des3-hmac-sha1", "Triple DES cbc mode with HMAC/sha1",
&krb5int_enc_des3, &krb5int_hash_sha1,
- 8,
+ 16,
krb5_dk_encrypt_length, krb5_dk_encrypt, krb5_dk_decrypt,
krb5int_dk_string_to_key,
- NULL, /*PRF*/
+ krb5int_dk_prf, /*PRF*/
CKSUMTYPE_HMAC_SHA1_DES3 },
{ ENCTYPE_DES3_CBC_SHA1, /* alias */
"des3-cbc-sha1-kd", "Triple DES cbc mode with HMAC/sha1",
&krb5int_enc_des3, &krb5int_hash_sha1,
- 8,
+ 16,
krb5_dk_encrypt_length, krb5_dk_encrypt, krb5_dk_decrypt,
krb5int_dk_string_to_key,
- NULL, /*PRF*/
+ krb5int_dk_prf, /*PRF*/
CKSUMTYPE_HMAC_SHA1_DES3 },

{ ENCTYPE_DES_HMAC_SHA1,

Hi. In your patch in ticket 5587 you indicated that you could send along DES diffs if we wanted them.
How difficult would that be to do?
If you can send us DES diffs in the next day or so we'd really appreciate them.

--Sam

Implement DES and 3DES PRF. Patch fromKAMADA Ken'ichi

Currently the DES and 3DES PRF output 16-byte results. This is
consistent with RFC 3961, but we need to confirm it is consistent with
Heimdal and WG decisions. See IETF 74 minutes for some discussion of
the concern as it applies to AES and thus possibly all simplified
profile enctypes.

https://github.com/krb5/krb5/commit/6991564a69ba53b12c4efdcc9daf85041f0e2697
Commit By: hartmans
Revision: 22298
Changed Files:
U trunk/src/lib/crypto/des/Makefile.in
U trunk/src/lib/crypto/des/des_int.h
A trunk/src/lib/crypto/des/des_prf.c
U trunk/src/lib/crypto/etypes.c
U trunk/src/lib/crypto/t_cf2.comments
U trunk/src/lib/crypto/t_cf2.expected
U trunk/src/lib/crypto/t_cf2.in

pull up r22298 from trunk

------------------------------------------------------------------------
r22298 | hartmans | 2009-04-30 16:17:42 -0400 (Thu, 30 Apr 2009) | 10 lines
Changed paths:
M /trunk/src/lib/crypto/des/Makefile.in
M /trunk/src/lib/crypto/des/des_int.h
A /trunk/src/lib/crypto/des/des_prf.c (from /trunk/src/lib/crypto/dk/dk_prf.c:22295)
M /trunk/src/lib/crypto/etypes.c
M /trunk/src/lib/crypto/t_cf2.comments
M /trunk/src/lib/crypto/t_cf2.expected
M /trunk/src/lib/crypto/t_cf2.in

ticket: 5587
Tags: pullup

Implement DES and 3DES PRF. Patch fromKAMADA Ken'ichi

Currently the DES and 3DES PRF output 16-byte results. This is
consistent with RFC 3961, but we need to confirm it is consistent with
Heimdal and WG decisions. See IETF 74 minutes for some discussion of
the concern as it applies to AES and thus possibly all simplified
profile enctypes.

https://github.com/krb5/krb5/commit/83b94e13d92d4a2102b390eb0c4f66ecd83db918
Commit By: tlyu
Revision: 22335
Changed Files:
U branches/krb5-1-7/src/lib/crypto/des/Makefile.in
U branches/krb5-1-7/src/lib/crypto/des/des_int.h
A branches/krb5-1-7/src/lib/crypto/des/des_prf.c
U branches/krb5-1-7/src/lib/crypto/etypes.c
U branches/krb5-1-7/src/lib/crypto/t_cf2.comments
U branches/krb5-1-7/src/lib/crypto/t_cf2.expected
U branches/krb5-1-7/src/lib/crypto/t_cf2.in