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import _ed25519
BadSignatureError = _ed25519.BadSignatureError
class SigningKey(object):
# this is how all keys are created
def __init__(self, sk_bytes):
if not isinstance(sk_bytes, type("")):
raise TypeError("must be bytes, not %s" % type(sk_bytes))
if len(sk_bytes) != 32:
raise ValueError("must be exactly 32 bytes")
vk_bytes, sk_and_vk = _ed25519.publickey(sk_bytes)
assert sk_and_vk[:32] == sk_bytes
assert vk_bytes == sk_and_vk[32:]
self.vk_bytes = vk_bytes
self.sk_and_vk = sk_and_vk
def __eq__(self, them):
if not isinstance(them, object): return False
return (them.__class__ == self.__class__
and them.sk_and_vk == self.sk_and_vk)
def get_verifying_key_bytes(self):
return self.vk_bytes
def sign(self, msg):
sig_and_msg = _ed25519.sign(msg, self.sk_and_vk)
# the response is R+S+msg
sig_R = sig_and_msg[0:32]
sig_S = sig_and_msg[32:64]
msg_out = sig_and_msg[64:]
sig_out = sig_R + sig_S
assert msg_out == msg
return sig_out
class VerifyingKey(object):
def __init__(self, vk_bytes):
if not isinstance(vk_bytes, type("")):
raise TypeError("must be bytes, not %s" % type(vk_bytes))
if len(vk_bytes) != 32:
raise ValueError("must be exactly 32 bytes")
self.vk_bytes = vk_bytes
def __eq__(self, them):
if not isinstance(them, object): return False
return (them.__class__ == self.__class__
and them.vk_bytes == self.vk_bytes)
def verify(self, sig, msg):
assert isinstance(sig, type("")) # string, really bytes
assert len(sig) == 64
sig_R = sig[:32]
sig_S = sig[32:]
sig_and_msg = sig_R + sig_S + msg
# this might raise BadSignatureError
msg2 = _ed25519.open(sig_and_msg, self.vk_bytes)
assert msg2 == msg
def selftest():
from binascii import unhexlify
message = "crypto libraries should always test themselves at powerup"
sk_bytes = unhexlify("548b1f9f938519ad3d527d8c47a1e6ec1439fbec61710b245363865c6f234899")
sk = SigningKey(sk_bytes)
vk_bytes = unhexlify("787162d9ad1ad571237681560c1ad653fb7df9e09e637e6a8072e4520fd288ca")
vk = VerifyingKey(vk_bytes)
assert sk.get_verifying_key_bytes() == vk_bytes
sig = sk.sign(message)
assert sig == "13f42bc2d485e76c7cfaad25e1a840ede25b44a73befb0a528d836d7b434cf87e260c09d980388fab4cb564885857ea4dc3fb04107ca74960cc5a4d415fbf50d".decode('hex'), sig
vk.verify(sig, message)
selftest()
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