Re: Symmetric ciphers as hash functions

2005-11-07 Thread cyphrpunk
On 10/30/05, Arash Partow [EMAIL PROTECTED] wrote: How does one properly use a symmetric cipher as a cryptographic hash function? I seem to be going around in circles. The usual method is to feed the data into the key slot of the cipher, and to use a fixed IV in the plaintext slot. Then, add

Re: Symmetric ciphers as hash functions

2005-11-03 Thread Travis H.
Not so... the SHA family are all unbalanced Feistel structures. Sorry, I guess I am thinking of AES. I don't know where I got the doesn't need to be invertible bit, I must be conflating it with something else. He should also take a look at OCB, CCM, and CBC-MAC modes. Perhaps he intends to

Re: Symmetric ciphers as hash functions

2005-11-01 Thread Travis H.
(particularly AES) as cryptographic hash functions? btw I know that hash functions and symmetric ciphers share the same structural heritage (feistel rounds etc...), I just don't seem to be making the usage link at this point in time... :D The latest hashes, such as SHA-1, gave up on Feistel. It's

Re: Symmetric ciphers as hash functions

2005-11-01 Thread Greg Rose
At 01:33 2005-11-01 -0600, Travis H. wrote: The latest hashes, such as SHA-1, gave up on Feistel. Not so... the SHA family are all unbalanced Feistel structures. Basically, for SHA-1 a complex function of 4 words and key material (in this case expanded data to be hashed) is combined with the

Re: Symmetric ciphers as hash functions

2005-11-01 Thread Steven M. Bellovin
In message [EMAIL PROTECTED], Trav is H. writes: How does one properly use a symmetric cipher as a cryptographic hash function? I seem to be going around in circles. Isn't this is like asking a mechanic how to use a screwdriver as a hammer? Given that we seem to know much more about block

Re: Symmetric ciphers as hash functions

2005-11-01 Thread Perry E. Metzger
Travis H. [EMAIL PROTECTED] writes: How does one properly use a symmetric cipher as a cryptographic hash function? I seem to be going around in circles. Isn't this is like asking a mechanic how to use a screwdriver as a hammer? Not in the least. Building new strong tools by using older tools

Symmetric ciphers as hash functions

2005-10-31 Thread Arash Partow
/etc that explain the implementation/use of symmetric ciphers (particularly AES) as cryptographic hash functions? btw I know that hash functions and symmetric ciphers share the same structural heritage (feistel rounds etc...), I just don't seem to be making the usage link at this point in time... :D

Re: Symmetric ciphers as hash functions

2005-10-31 Thread James Muir
seem like a joy etc.. Are there any papers/books/etc that explain the implementation/use of symmetric ciphers (particularly AES) as cryptographic hash functions? btw I know that hash functions and symmetric ciphers share the same structural heritage (feistel rounds etc...), I just don't seem