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Cryptography Ashik

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

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

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Transcript

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