Add sinsemilla.sage.

Signed-off-by: Daira Hopwood <daira@jacaranda.org>

sinsemilla.sage

@@ -0,0 +1,35 @@
+#!/usr/bin/env sage
+
+load('hashtocurve.sage')
+
+VERBOSE = False
+
+k = 10
+c = len(format((q-1)//2, 'b'))-1
+assert c == 253
+
+def grouphash(D, M):
+    (P, _, _) = hash_to_pallas_jacobian(M, D + b"-pallas_XMD:BLAKE2b_SSWU_RO_")
+    return P
+
+S = [grouphash(b"z.cash:SinsemillaS", pack('<I', j)) for j in range(0, 1<<k)]
+
+def pad(n, M):
+    assert n % k == 0
+    m = ""
+    for b in M:
+        m += format(as_byte(b), '08b')[::-1]
+
+    r = [int(m[i:i+k][::-1], 2) for i in range(0, n, k)]
+    return r
+
+def sinsemilla_hash(D, m):
+    Acc = grouphash(b"z.cash:SinsemillaQ", D)
+    if VERBOSE: print(Acc)
+    for x in m:
+        Acc = (Acc + S[x]) + Acc
+        if VERBOSE: print(Acc)
+
+    return Acc
+
+print(sinsemilla_hash(b"z.cash:test-Sinsemilla", pad(40, b"hello")))