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ascon/AsconHash256.cry
2025-09-03 08:47:53 -07:00

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module AsconHash256 where
import Ascon
parse : {r, n} (fin n, fin r, 0 < r) => [n] -> ([n/r][r], [n%r])
parse (M_ # Ml) = (split M_, Ml)
pad : {n} (n < 64) => [n] -> [64]
pad M = bs # b # zero
where
bs : [n/8*8]
b_ : [n%8]
bs # b_ = M
b : [8]
b = zext`{8} (0b1 # b_)
/// 5.1. Specification of Ascon-Hash256
Ascon_Hash256 : {n} (fin n) => [n] -> [256]
Ascon_Hash256 M =
join [LE (head S) | S <- take (iterate Ascon_p`{12} Sn)]
where
(M1, M2) = parse M
M2' = pad M2
M' = M1 # [pad M2]
AddBlock [s0, s1, s2, s3, s4] X = Ascon_p`{12} [LE X ^ s0, s1, s2, s3, s4]
S0 = Ascon_p`{12} [Ascon_Hash256_IV, 0, 0, 0, 0]
Sn = foldl AddBlock S0 M'
Ascon_Hash256_IV : [64]
Ascon_Hash256_IV = 0x0000080100cc0002