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# Cryptography Ashik

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List cryptographic hash algorithms and list their applications. MD5 hash algorithm Description.

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### Cryptography Ashik

1. 1. Welcome<br />Presentation on<br />Cryptography & Information Security<br />
2. 2. Topic<br />5<br />List cryptographic hash algorithms and list their applications. Discuss MD5 hash algorithm or any other hash algorithm in detail.<br />Submitted By:<br />Muhammad AshikIqbal<br />M.Sc. in CSE<br />ID: 092-25-127<br />DIU<br />ashik.email@gmail.com<br />http://ashikiqbal.blogspot.com<br />
3. 3. Cryptographic Hash Algorithms<br />
4. 4. List of Hash Algorithms<br />
5. 5. Applications of Hash Algorithms<br />Used Alone<br />File integrity verification<br />Public key fingerprint<br />Password storage<br />Combined with encryption functions<br />
6. 6. MD5<br />Message-Digest algorithm 5<br />
7. 7. MD5<br />Designed by Ronald Rivest in 1991 and replaces an earlier hash function MD4<br />MD5 is a widely used cryptographic hash function<br />128-bit hash function<br />Uses 512 bit blocks<br />Uses 128-bit keys or states<br />The 128-bit key is split into 4 sub-keys of 32 bits each<br />Four rounds are used to produce the hash<br />In each round addition, XOR, AND, OR, rotation are used<br />
8. 8. MD5 Example<br />hello<br />5d41402abc4b2a76b9719d911017c592<br />
9. 9. MD5 Algorithms<br />2. Append length (64bits)<br />1. Append padding bits<br />(to 448 mod 512)<br />3. Initialize MD buffer<br />Word A = 01 23 45 67<br />Word B = 89 AB CD EF<br />Word C = FE DC BA 98<br />Word D = 76 54 32 10<br />
10. 10. MD5 Algorithms<br />F(X,Y,Z) = (X ∧ Y) ∨ (¬X ∧ Z)<br />G(X,Y,Z) = (X ∧ Z) ∨ (Y ∧ ¬Z)<br />H(X,Y,Z) = X ⊕ Y ⊕ Z<br />I(X,Y,Z) = Y ⊕ (X ∨ ¬Z)<br />Round 0: Steps 0 to 15<br />Round 1: Steps 16 to 31<br />Round 2: Steps 32 to 47<br />16 steps<br />Round 4: Steps 47 to 63<br />X[k] = M [q*16+k] (32 bit)<br />Constructed from sine function<br />
11. 11. MD5 Applications<br />MD5 has been employed in a wide variety of security applications and is also commonly used to check the integrity of files<br />Used in the software world to provide some assurance that a transferred file has arrived intact<br />Unix-based operating systems include MD5 sum utilities in their distribution packages<br />MD5 can provide error-checking functionality<br />It recognizes corrupt or incomplete download, which becomes more likely when downloading larger files<br />Widely used to store passwords after adding salt<br />
12. 12. MD5 Attack History<br />Dobbertin “almost” able to break MD5 using his MD4 attack in 1996<br />Showed that MD5 might be at risk<br />In 2004, Wang published one MD5 collision<br />No explanation of method was given<br />Based on one collision, Wang’s method was reverse engineered by Australian team<br />Ironically, this reverse engineering work has been primary source to improve Wang’s attack<br />
13. 13. Thank You<br />