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52 lines
1.4 KiB
Markdown
52 lines
1.4 KiB
Markdown
## 🥐 keccak
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<br>
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### hashing
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<br>
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* hashing is a mathematical op converting an input message into a digest
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* the transformation of a str of characters into a (usually shorter) fixed-length value or key that represents the original string.
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* used to determine the integrity of a message, fast data retrieval and to encrypt/decrypt digital signatures
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* collisions found: MD5 (128, 1992), SHA-1 (160, 1995)
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* no collisions found: SHA-2 (224/256/384/512, 2001)
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<br>
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### secure hash algorithm (SHA)
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<br>
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* family of cryptographic hash functions by NIST
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* preprocessing: padding the data for blocking (fixed size message blocks)
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<br>
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### SHA-3/keccak
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<br>
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* 2012 as the winner of the NIST hash function competition
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* based on the sponge function: variable input and output length
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* parameters (decides the strength):
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* r bits: rate, defines speed
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* c bits: capacity, defines the security level
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* no key schedule, instead round constants
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* state us 5x5x64 bits block
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* the rho module rotates each 64-bit element by a triangular number: 0, 1, 3, 6, 10, 15...
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* the pi module permutes the 64-bit elements
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* the chi module adds a non-linear aspect to the permutation round
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* the iota module breaks up any symmetry caused by the other modules, through XORing one of the array elements to a round constant
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<br>
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##### application & strength
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<br>
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* high level of parallelism
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* flexibility, bit interleaving
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* suited for protection against side-channel attack
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