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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