Ok, I'm stupid... DES-CBC-CRC - here's the data before encryption, after
checksumming (octal escapes used throughout):
N\211\225f\322r\004=\322\316e\302This is a test.\000\000\000\000\000
So, the checksum of this data:
N\211\225f\322r\004=\000\000\000\000This is a test.\000\000\000\000\000
Should be \322\316e\302 - *I* get this CRC: t\240\021\213
My CRC32 code looks like this (although I've tried other versions, based on
the MIT and Heimdal code):
class CRC32:
poly = 0xEDB88320L
table = [0L,]*256
for i in range(256):
crc = long(i)
for j in range(8,0,-1):
if crc & 1:
crc = (crc >> 1) ^ poly
else:
crc = crc >> 1
table[i] = crc
digestsize = 4
def __init__(self, data=''):
self.data = data
def digest(self):
crc = 0l
for c in self.data:
idx = crc ^ ord(c)
idx = int(idx & 0xff)
crc = self.table[idx] ^ (crc>>8)
return
chr(crc&0xff)+chr((crc>>8)&0xff)+chr((crc>>16)&0xff)+chr((crc>>24)&0xff)
Help! What am I doing wrong? As far as I can tell, I pass the MIT test data.
I'm stumped...
Regards,
Phil
+------------------------------------------+
| Phil Mayers |
| Network & Infrastructure Group |
| Information & Communication Technologies |
| Imperial College |
+------------------------------------------+
-----Original Message-----
From: Sam Hartman [mailto:[EMAIL PROTECTED]]
Sent: 29 November 2001 18:45
To: Mayers, Philip J
Cc: 'Booker C. Bense'; '[EMAIL PROTECTED]'; [EMAIL PROTECTED]
Subject: Re: Having trouble reading MIT CredCache programatically
>>>>> "Mayers," == Mayers, Philip J <[EMAIL PROTECTED]> writes:
Mayers,> I wouldn't worry. It's highly likely that I'll never get
Mayers,> to a release, since I can't seem to figure the
Mayers,> des-cbc-crc enctype out...
Sorry I didn't get around to this earlier, but have been fairly busy
with IETf. I'm amused at the concept of combining des-cbc-crc with
pkinit.
But anyway, have you read the current IETF draft on Kerberos
revisions? IN particular, section 6.5.4 of
draft-ietf-cat-kerberos-revisions? That seems to have a fairly clear
explanation of the encryption system. If you want to generate test
vectors for yourself, you may find a simple program to call the MIT
crypto functions useful. Please see
http://www.meepzorp.org/~hartmans/t_encrypt.c for a test program out
of the current snapshot. It demonstrates encrypting and decrypting
short strings.
