What makes a hash function cryptographically strong?

What makes a hash function cryptographically strong?

Certain properties of cryptographic hash functions impact the security of password storage. Non-reversibility, or one-way function. A good hash should make it very hard to reconstruct the original password from the output or hash. Diffusion, or avalanche effect.

What are two requirements for a hash function?

The basic requirements for a cryptographic hash function are:

• the input can be of any length,
• the output has a fixed length,
• H(x) is relatively easy to compute for any given x ,
• H(x) is one-way,
• H(x) is collision-free.

Which hash function is best?

Probably the one most commonly used is SHA-256, which the National Institute of Standards and Technology (NIST) recommends using instead of MD5 or SHA-1. The SHA-256 algorithm returns hash value of 256-bits, or 64 hexadecimal digits.

How do you create a hash function?

With modular hashing, the hash function is simply h(k) = k mod m for some m (usually, the number of buckets). The value k is an integer hash code generated from the key. If m is a power of two (i.e., m=2p), then h(k) is just the p lowest-order bits of k.

What are some requirement of hashing?

A hash procedure must be deterministic—meaning that for a given input value it must always generate the same hash value. In other words, it must be a function of the data to be hashed, in the mathematical sense of the term.

Which hash is fastest?

SHA-1 is fastest hashing function with ~587.9 ms per 1M operations for short strings and 881.7 ms per 1M for longer strings. MD5 is 7.6\% slower than SHA-1 for short strings and 1.3\% for longer strings. SHA-256 is 15.5\% slower than SHA-1 for short strings and 23.4\% for longer strings.

What are the four properties of an ideal cryptographic hash function?

Cryptographic Hash Functions Preimage resistance. Second preimage resistance (weak collision resistance) Strong collision resistance.