CSSE/MA479: Cryptography

Homework 8, due on the date listed on the schedule page

• Work on your term project
• (80 pts) SHA-1 Implementation. Implement and test the SHA-1 algorithm.
• Input: a file called sha_input.txt that contains a message all on a single line. The message will be composed of ASCII characters and terminated by a newline. The newline is not considered part of the message to be hashed. You may not assume that the message is a specific length (except that it will be less than 2^32 bits), but you may assume that the length of the input string is a multiple of 8 bits. An implementation that works only for small messages will have a correspondingly small grade assigned.
• Output: a 160-bit digest, expressed in hexadecimal (length 40). Pad with leading zeros if necessary to output the full 160 bits.
• Grading: totally on correctness and style. You will earn full points for efficiency unless you can't manage to pull off the 80 iterations in 5 seconds (you'd have to purpose to write inefficient code to make that happen, I think).
• Round keys: 0x5a827999, 0x6ed9eba1, 0x8f1bbcdc, 0xca62c1d6
• H0-H4: 0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476, 0xc3d2e1f0
• Debugging: the tool at http://people.eku.edu/styere/Encrypt/JS-SHA1.html gives answers and intermediate output.
• Note that the book has an error in its implementation: The addition of [a b c d e] to x should happen only once after iteration 80 (so at the end of h').