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• Overview

  《深入理解hash哈希散列函数》

  Encryption and hashing are similar in the way that they both take a string of useful text and convert it into somthing very different.

  MD5, SHA, Whirlpool are all one-way encryption methods, which mean hasing method and what makes one stronger than the other.

  The answer is actually very simple: the more bits a hash contains, the more secure.

  MD5 is a 128-bits string, SHA-1 is a 160-bit string and Whirlpool is a 512-bit string.

• MD family of hashing algorithms

  The MD family of hashing algorithms were designed by Ron Rivest during the late 1980’s and early 1990’s.

  MD actually stands for Message Digest.

• MD2 hashes

  MD2 was optimized to run on 8-bit computers and generates a 128-bit hash value the hashes are generally displayed as hexadecimal string which is a 32 character long.

• MD5 Hashes

  MD5 was developed in 1991 and it repalced the eariler function MD4 due to believed weaknesses in this algorithm.

• SHA Algorithms

  SHA (Secure Hash Algorithm) are developed by NIST. SHA algorithms weere based upon the MD4&5 algorithms developed by Ron Rivest.

• SHA-0

  SHA-0 is officially known as SHA, it was the first incainnation of the secure hasing algorithm. This first version was withdrown soon after release due to weaknesses in the design.

• SHA-1

  Released in 1994.

  SHA-1 is similar to MD4/5 . It is considered as MD5’s successor.

  Recently Xiaojun Wang managed to break the popular hashes, proving SHA-1 was not secure as it was once considered.

• SHA-2

  SHA-2 is based closely upon the SHA-1 Algorithm. SHA-2 actually combines the SHA-224, SHA-256, SHA-384 and SHA-512 algorithms.

  • SHA-256

    SHA-256 as we already mentioned is part of the SHA-2 family of products.

    It’s based on SHA-2 but with the capability for larger output strings (to 256 bits)

  • SHA-384

    It’s size increased to 384 bits.

  • SHA-512

    The string is increased in size to 512 bits.

• Whirlpool

  Whirlpool is quite a young hash algorithm it was first released in 2000.

  Whirlpool hashes are usually shown as a 128 digit hexadecimal sting, and it’s free with no patent.

• References