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mirror of https://github.com/trezor/trezor-firmware.git synced 2024-11-18 13:38:12 +00:00
trezor-firmware/trezorlib/cosi.py

97 lines
2.7 KiB
Python

import sys
from functools import reduce
import binascii
from trezorlib import _ed25519
def combine_keys(pks):
P = [_ed25519.decodepoint(pk) for pk in pks]
combine = reduce(_ed25519.edwards, P)
return _ed25519.encodepoint(combine)
def combine_sig(R, sigs):
S = [_ed25519.decodeint(si) for si in sigs]
s = sum(S) % _ed25519.l
sig = R + _ed25519.encodeint(s)
return sig
def get_nonce(sk, data, ctr):
h = _ed25519.H(sk)
b = _ed25519.b
r = _ed25519.Hint(bytes([h[i] for i in range(b >> 3, b >> 2)]) + data + binascii.unhexlify('%08x' % ctr))
R = _ed25519.scalarmult(_ed25519.B, r)
return r, _ed25519.encodepoint(R)
def verify(signature, digest, pub_key):
_ed25519.checkvalid(signature, digest, pub_key)
def pubkey_from_privkey(privkey):
return _ed25519.publickey(privkey)
def sign_with_privkey(digest, privkey, global_pubkey, nonce, global_commit):
h = _ed25519.H(privkey)
b = _ed25519.b
a = 2 ** (b - 2) + sum(2 ** i * _ed25519.bit(h, i) for i in range(3, b - 2))
S = (nonce + _ed25519.Hint(global_commit + global_pubkey + digest) * a) % _ed25519.l
return _ed25519.encodeint(S)
def self_test(digest):
def to_hex(by):
return binascii.hexlify(by).decode()
N = 3
digest = binascii.unhexlify(digest)
print('Digest: %s' % to_hex(digest))
sks = []
pks = []
nonces = []
commits = []
sigs = []
for i in range(0, N):
print('----- Key %d ------' % (i + 1))
seckey = (chr(0x41 + i) * 32).encode()
pubkey = _ed25519.publickey(seckey)
print('Secret Key: %s' % to_hex(seckey))
print('Public Key: %s' % to_hex(pubkey))
sks.append(seckey)
pks.append(pubkey)
ctr = 0
r, R = get_nonce(seckey, digest, ctr)
print('Local nonce: %s' % to_hex(_ed25519.encodeint(r)))
print('Local commit: %s' % to_hex(R))
nonces.append(r)
commits.append(R)
global_pk = combine_keys(pks)
global_R = combine_keys(commits)
print('-----------------')
print('Global pubkey: %s' % to_hex(global_pk))
print('Global commit: %s' % to_hex(global_R))
print('-----------------')
sigs = [sign_with_privkey(digest, sks[i], global_pk, nonces[i], global_R) for i in range(N)]
for sig in sigs:
print('Local signature: %s' % to_hex(sig))
print('-----------------')
sig = combine_sig(global_R, sigs)
print('Global sig: %s' % to_hex(sig))
verify(sig, digest, global_pk)
print('Valid Signature!')
if __name__ == '__main__':
if len(sys.argv) > 1:
self_test(digest=sys.argv[1])
else:
self_test(digest='4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b')