The first collision for full SHA-1 2017

encryption #security

MD4, MD5, SHA-1, SHA-2 and SHA-256 are all cryptographic hashing algorithms

• a cryptographic hashing function is h: {0,1}^* -> {0,1}ⁿ, * denoting any natural number
  • maps any aribitrarily long bit string to a finite one, deterministically
• a collision between x and y is when h(x) = h(y)
• cryptographic hashing relies on the assumption that it is practically impossible to find collisions, through the birthday paradox
  • (π/2)^1/2 • 2^(n/2) expected attempts to brute force a collision, for a n-bit output hash
  • SHA-1 is 160-bit, which translates to
• SHA-1 has been deprecated since 2011, this is the first construction of a chosen-prefix collision
  • implications of forgery through HTTPS or SHA-1 checksums for documents