95 lines
2.3 KiB
Python
95 lines
2.3 KiB
Python
#!/usr/bin/env python3
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from binascii import hexlify
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from pyblake2 import blake2s
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from sapling_jubjub import Point, JUBJUB_COFACTOR
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from sapling_utils import chunk
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# First 64 bytes of the BLAKE2s input during group hash.
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# This is chosen to be some random string that we couldn't have
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# anticipated when we designed the algorithm, for rigidity purposes.
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# We deliberately use an ASCII hex string of 32 bytes here.
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CRS = b'096b36a5804bfacef1691e173c366a47ff5ba84a44f26ddd7e8d9f79d5b42df0'
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#
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# Group hash
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#
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def group_hash(D, M):
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digest = blake2s(person=D)
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digest.update(CRS)
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digest.update(M)
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p = Point.from_bytes(digest.digest())
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if not p:
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return None
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q = p * JUBJUB_COFACTOR
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if q == Point.ZERO:
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return None
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return q
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def find_group_hash(D, M):
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i = 0
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while True:
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p = group_hash(D, M + bytes([i]))
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if p:
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return p
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i += 1
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assert i < 256
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#
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# Sapling generators
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#
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SPENDING_KEY_BASE = find_group_hash(b'Zcash_G_', b'')
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PROVING_KEY_BASE = find_group_hash(b'Zcash_H_', b'')
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NOTE_POSITION_BASE = find_group_hash(b'Zcash_J_', b'')
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WINDOWED_PEDERSEN_RANDOMNESS_BASE = find_group_hash(b'Zcash_PH', b'r')
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VALUE_COMMITMENT_VALUE_BASE = find_group_hash(b'Zcash_cv', b'v')
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VALUE_COMMITMENT_RANDOMNESS_BASE = find_group_hash(b'Zcash_cv', b'r')
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def main():
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print('''
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struct SaplingGenerators {
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skb: [u8; 32],
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pkb: [u8; 32],
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npb: [u8; 32],
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wprb: [u8; 32],
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vcvb: [u8; 32],
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vcrb: [u8; 32],
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};
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let sapling_generators = SaplingGenerators {
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skb: [
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%s
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],
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pkb: [
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%s
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],
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npb: [
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%s
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],
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wprb: [
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%s
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],
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vcvb: [
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%s
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],
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vcrb: [
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%s
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],
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};''' % (
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chunk(hexlify(bytes(SPENDING_KEY_BASE))),
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chunk(hexlify(bytes(PROVING_KEY_BASE))),
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chunk(hexlify(bytes(NOTE_POSITION_BASE))),
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chunk(hexlify(bytes(WINDOWED_PEDERSEN_RANDOMNESS_BASE))),
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chunk(hexlify(bytes(VALUE_COMMITMENT_VALUE_BASE))),
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chunk(hexlify(bytes(VALUE_COMMITMENT_RANDOMNESS_BASE))),
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))
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if __name__ == '__main__':
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main()
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