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AsconHash256.cry

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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