does SecureHashAlgorithm pad correctly?

Howard Stearns howard.stearns at qwaq.com
Mon Oct 29 22:16:54 UTC 2007


And zero length messages? What should I get back?

Rob Withers wrote:
> Howard,
> 
> I think you are reading the code wrong.  In 
> #processFinalBuffer:bitLength: a final buffer of soze 64 BYTES is being 
> created and populated.  That is 512 bits.  Both SecureHashAlgorithm, 
> from the base image, and SHA1, from the Cryptography Team Package are 
> doing this.
> 
> Rob
> 
> ----- Original Message ----- From: "Howard Stearns" 
> <howard.stearns at qwaq.com>
> To: "The general-purpose Squeak developers list" 
> <squeak-dev at lists.squeakfoundation.org>
> Sent: Monday, October 29, 2007 2:05 PM
> Subject: does SecureHashAlgorithm pad correctly?
> 
> 
>> The class comment for SecureHashAlgorithm says it implements the SHA 
>> standard, but I'm not sure it's padding correctly.
>>
>> My reading of the standard is that all messages -- including zero 
>> length messages -- should be padded to 512 bit size in a certain way.
>>
>> See section "4. Message Padding" of 
>> http://www.itl.nist.gov/fipspubs/fip180-1.htm
>>
>> My reading of the code is that it explicitly fails with an error for 
>> zero length messages, and pads to 64 bit sizes.
>>
>> Am I nuts?
>>
>> -- 
>> Howard Stearns
>> AIM: qwaqHoward
>> Qwaq: +1-650-331-1437
>> office: +1-608-850-4482
>> mobile: +1-608-658-2419
>>
>>
> 
> 

-- 
Howard Stearns
AIM: qwaqHoward
Qwaq: +1-650-331-1437
office: +1-608-850-4482
mobile: +1-608-658-2419



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