HASH ALGORITHMS - Chapter 12

1. MD5 • SHA • RIPEMD-160 • HMAC HASH ALGORITHMS - Chapter 12

2. Message Digest • Compression • Elementary Operations MD5

3. MESSAGE DIGEST GENERATIONMD5

4. MD5 COMPRESSION FUNCTION

5. ELEMENTARY MD5 OPERATION

6. Table 9.1 – truth table • B C D || F G H I • -------------------------------------- • 0 0 0 || 0 0 0 1 • 0 0 1 || 1 0 1 0 • 0 1 0 || 0 1 1 0 • 0 1 1 || 1 0 0 1 • 1 0 0 || 0 0 1 1 • 1 0 1 || 0 1 0 1 • 1 1 0 || 1 1 0 0 • 1 1 1 || 1 1 1 0 KEY ELEMENTS OF MD5

7. Message Digest • Compression • Elementary Operations SECURE HASH ALGORITHM SHA-1

8. SHA-1 COMPRESSION FUNCTION

9. ELEMENTARY SHA OPERATION

10. B C D || f0..19 f20..39 f40..59 f60..79 • ---------------------------------------------------------------------------- • 0 0 0 | 0 0 0 0 • 0 0 1 | 1 1 0 1 • 0 1 0 | 0 1 0 1 • 0 1 1 | 1 0 1 0 • 0 0 | 0 1 0 1 • 1 0 1 | 0 0 1 0 • 1 0 | 1 0 1 0 • 1 1 1 | 1 1 1 1 TRUTH TABLE for ft – SHA-1

11. CREATION OF 80-WORD I/P

12. MD5 message digest – 128 bits SHA-1 message digest – 160 bits Find two messages with same digest: MD5 – 264 operations SHA-1 - 280 operations Comparison: MD5 vs SHA1

13. SHA-256 • SHA-384 • SHA-512 • message digest lengths: 256, 384, 512 • to provide compatibility with AES • (see Tables 12.3 and 12.4) NEW SHA ALGORITHMS

14. Message Digest • Compression • Elementary Operations RIPEMD - 160

15. RIPEMD – 160COMPRESSION FUNCTION

16. RIPEMD – 160ELEMENTARY OPERATION

17. Tables 12.5 – 12.9 RIPEMD – 160 - data

18. Table 12.8 - comparison Table 12.9 - relative performance HASH FUNCTIONS - comparisons

19. Why? Hash functions (e.g. MD5, SHA-1) execute faster than Sym. Key (e.g. DES) HMAC combines HASH with Secret Key to make a MAC HMACK(M) = H[(K+ + opad)||H[K+ + ipad)||M]] Security(H)  Security(HMAC) HMAC – a MAC from a HASH

20. HMAC STRUCTURE

21. EFFICIENT IMPLEMENTATION of HMAC