1. SHA: Secure Hash Algorithm

2. SHA Background Several variants of SHA
Developed by NSA and published as government standard.

3. SHA SHA-0 and SHA-1 have been broken
SHA-0 attack done in 2^51 operations and took approximately 80,000 CPU hours
SHA-1 attack done in 2^69 operations

4. How it works Hash algorithm is broken into several parts Preprocessing
Padding the message
Parsing the message
Setting initial hash values
Hash computation
Prepare message schedule
Initialize working variables
Rearrange values of variables
Compute intermediate hash values

5. Preprocessing
For -512 the message is padded to a size that is a multiple of 1024.
Message is now parsed into N blocks
Blocks broken down to bit words
Eight initial hash values set are obtained by taking the first 64 bits of the fractional part of the square root of the first 8 prime numbers.

6. Hash Computation
After preprocessing each message block is processed in order.
Set message schedule.
Initialize 8 working variables as the initial hash values.
Iterates 80 times rearranging the variables value.
Compute intermediate hash value.
After N iterations message digest results.