def new_keys():
"Generate a public/private keypair for hash-based signatures"
sk = ""
digest1 = ""
digest2 = ""
# First half
for n in range(256):
for b in False, True:
secret = os.urandom(32)
sk += secret
digest1 += sha256(secret)
# First Second
for n in range(256):
for b in False, True:
secret = os.urandom(32)
sk += secret
digest2 += sha256(secret)
pk = sha256(sha256(digest1) + sha256(digest2))
return pk, sk
def verify(msg, sig, pk):
"verify a 256-bit value using hash-bash signatures"
msg = crypturd.fixed_length_key(msg, 32)
checksum = 0
digest = ""
for i in range(32):
c = ord(msg[i])
checksum += c
digest += hash_times(sig[i * 32:i * 32 + 32], 256 - c)
digest += hash_times(sig[-64:-32], checksum // 256)
digest += hash_times(sig[-32:], checksum % 256)
return sha256(digest) == pk
def new_keys(sk=None):
"Generate a public/private keypair for hash-based signatures"
if not sk or len(sk) < 32 * 34:
sk = os.urandom(32 * 34)
pk = ""
# 32 secrets for 32 blocks of 8-bits each
for n in range(32):
pk += hash_times(sk[n * 32:n * 32 + 32], 256)
# 2 checksum blocks
pk += hash_times(sk[-64:-32], 32)
pk += hash_times(sk[-32:], 256)
return sha256(pk), sk
def digest_right(msg2, sig):
"verify 2 256-bit values using hash-bash signatures (second part)"
msg1 = crypturd.fixed_length_key(msg2, 32)
digest2 = ""
M2 = crypturd.bigendian2int(msg2)
for i in range(256):
zero = sig[i * 64 + 16384:i * 64 + 16416]
one = sig[i * 64 + 16416:i * 64 + 16448]
if ((1 << i) & M2) > 0:
one = crypturd.sha256(one)
else:
zero = crypturd.sha256(zero)
digest2 += zero + one
return sha256(digest2)
def digest_left(msg1, sig):
"verify 2 256-bit values using hash-bash signatures (first part)"
msg1 = crypturd.fixed_length_key(msg1, 32)
digest1 = ""
M1 = crypturd.bigendian2int(msg1)
for i in range(256):
zero = sig[i * 64:i * 64 + 32]
one = sig[i * 64 + 32:i * 64 + 64]
if ((1 << i) & M1) > 0:
one = crypturd.sha256(one)
else:
zero = crypturd.sha256(zero)
digest1 += zero + one
return sha256(digest1)
def verify(msg1, msg2, sig, pk):
"verify 2 256-bit values using hash-bash signatures"
return sha256(digest_left(msg1, sig) + digest_right(msg2, sig)) == pk