List out criteria of a cryptographic hash function ?

  • A hash function H accepts a variable-length block of data M as input and produces a fixed-size hash value as output
    • h = H(M)
    • Principal objective of hash function  is data integrity - A change to any bit or bits in M results, in a change to the hash code.
  • Cryptographic hash function
    • The kind of hash function needed for security applications is referred to as a cryptographic hash function
    • The algorithm for this should be computationally infeasible to find either: 

(a) a data object that maps to a pre-specified hash result (the one-way property) 

(b) two data objects that map to the same hash result (the collision-free property)

Applications of Cryptographic Hash Functions

  • Main Applications are in 
    1.  Message authentication and 
    2.  Digital signatures  
  • Other applications are:
  • to create a one-way password file
  • intrusion detection and virus detection
  • to construct a pseudorandom number generator (PRNG).

Security Requirements for a Cryptographic Hash Function H

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