def sign(self, data):
ecdsa_sig = None
try:
# Hash and apply ECDSA
hashBuf = bytesToC(Digest.SHA256(data))
ecdsa_sig = o.ECDSA_do_sign(hashBuf, 32, self.ec_key)
# Encode the signature into 64 bytes
rBuf = bytesToC(bytearray(32))
sBuf = bytesToC(bytearray(32))
rLen = o.BN_bn2bin(ecdsa_sig.contents.r, rBuf)
sLen = o.BN_bn2bin(ecdsa_sig.contents.s, sBuf)
rBytes = bytearray(32 - rLen) + cToBytes(rBuf)[:rLen]
sBytes = bytearray(32 - sLen) + cToBytes(sBuf)[:sLen]
sigBytes = rBytes + sBytes
assert (len(sigBytes) == 64)
finally:
if ecdsa_sig:
o.ECDSA_SIG_free(ecdsa_sig)
# Double-check the signature before returning
assert (OpenSSL_ECPublicKey(self.rawPublicKey).verify(data, sigBytes))
return sigBytes
def sign(self, data):
privateKeyNum = bytesToNumber(self.rawPrivateKey)
hash = Digest.SHA256(data)
g = generator_256
n = g.order()
x = bytesToNumber(self.rawPublicKey[:32])
y = bytesToNumber(self.rawPublicKey[32:])
pubkey = Public_key(g, Point(g.curve(), x, y))
privkey = Private_key(pubkey, privateKeyNum)
# Generating random nonce k per FIPS 186-3 B.5.1:
# (except we use 32 extra bytes instead of 8 before reduction)
# Random bytes taken from os.urandom as well as HMAC(privkey,hash)
# REVIEW THIS CAREFULLY!!! CHANGE AT YOUR PERIL!!!
# 64 random bytes and HMAC(rawPrivateKey,hash) are used as key for an
# HMAC PRF to generate a 64-byte value which is reduced modulo
# n to produce the nonce
#
# The use of HMAC(rawPrivateKey,hash) means this construction
# will be secure even if os.urandom fails, however we include
# os.urandom anyways out of an excess of caution
randBytes0 = bytearray(os.urandom(64))
randBytes0 += Digest.HMAC_SHA256(self.rawPrivateKey, hash)
randBytes = Digest.HMAC_SHA256(randBytes0, bytearray([1]))
randBytes += Digest.HMAC_SHA256(randBytes0, bytearray([2]))
c = bytesToNumber(randBytes)
k = (c % (n - 1)) + 1
hashNum = bytesToNumber(hash)
sig = privkey.sign(hashNum, k)
sigBytes = numberToBytes(sig.r, 32) + numberToBytes(sig.s, 32)
# Double-check the signature before returning
assert (Python_ECPublicKey(self.rawPublicKey).verify(data, sigBytes))
return sigBytes
def verify(self, data, signature):
assert(len(signature) == 64)
hashNum = bytesToNumber(Digest.SHA256(data))
g = generator_256
x = bytesToNumber(self.rawPublicKey[ : 32])
y = bytesToNumber(self.rawPublicKey[32 : ])
pubkey = Public_key(g, Point(g.curve(), x,y))
sig = Signature(bytesToNumber(signature[:32]),
bytesToNumber(signature[32:]))
return pubkey.verifies(hashNum, sig)
def getSignature(self, data):
# Produce ASN.1 signature
hash = Digest.SHA256(data)
asn1SigBytes = self.ec.sign_dsa_asn1(hash)
# Convert stupid ASN.1 signature into 64-byte signature
# Double-check before returning
sigBytes = self._convertToRawSignature(asn1SigBytes)
assert (ECPublicKey(self.rawPublicKey, self.ec).verify(data, sigBytes))
return sigBytes
def verify(self, data, signature):
assert (len(signature) == 64)
ecdsa_sig = None
try:
# Create ECDSA_SIG
ecdsa_sig = o.ECDSA_SIG_new()
rBuf = bytesToC(signature[:32])
sBuf = bytesToC(signature[32:])
o.BN_bin2bn(rBuf, 32, ecdsa_sig.contents.r)
o.BN_bin2bn(sBuf, 32, ecdsa_sig.contents.s)
# Hash and verify ECDSA
hashBuf = bytesToC(Digest.SHA256(data))
retval = o.ECDSA_do_verify(hashBuf, 32, ecdsa_sig, self.ec_key)
if retval == 1:
return True
elif retval == 0:
return False
else:
assert (False)
finally:
if ecdsa_sig:
o.ECDSA_SIG_free(ecdsa_sig)
def getFingerprint(self):
digest = Digest.SHA256(self.rawPublicKey)
assert (len(digest) == 32)
s = b2a_base32(digest).lower()[:25]
return "%s.%s.%s.%s.%s" % (s[:5], s[5:10], s[10:15], s[15:20],
s[20:25])
def __init__(self, data=None):
if data is None:
return
#self.key_sha256 = bytearray(32)
#self.cert_sha256 = bytearray(32)
self.notAfter = 0
# Below values are populated for TACK certs
self.tackExt = None
# Below values hold cert contents excluding TACK stuff
self.preExtBytes = None
self.extBytes = None
self.postExtBytes = None
p = ASN1Parser(data)
#Get the tbsCertificate
tbsCertificateP = p.getChild(0)
#Is the optional version field present?
#This determines which index the key is at
if tbsCertificateP.value[0] == 0xA0:
subjectPublicKeyInfoIndex = 6
validityIndex = 4
else:
subjectPublicKeyInfoIndex = 5
validityIndex = 3
#Get the subjectPublicKeyInfo
spkiP = tbsCertificateP.getChild(subjectPublicKeyInfoIndex)
#Parse the notAfter time
validityP = tbsCertificateP.getChild(validityIndex)
notAfterP = validityP.getChild(1)
if notAfterP.type == 0x17: # UTCTime
self.notAfter = Time.parseASN1UTCTime(notAfterP.value)
elif notAfterP.type == 0x18: # GeneralizedTime
self.notAfter = Time.parseASN1GeneralizedTime(notAfterP.value)
else:
raise SyntaxError()
# Get the hash values
self.cert_sha256 = Digest.SHA256(data)
self.key_sha256 = Digest.SHA256(spkiP.getTotalBytes())
# Check if this is a TACK certificate:
#Get the tbsCertificate
versionP = tbsCertificateP.getChild(0)
if versionP.type != 0xA0: # i.e. tag of [0], version
return # X.509 version field not present
versionPP = versionP.getTagged()
if versionPP.value != bytearray([0x02]):
return # X.509 version field does not equal v3
# Find extensions element
x = 0
while 1:
certFieldP = tbsCertificateP.getChild(x)
if not certFieldP:
raise SyntaxError("X.509 extensions not present")
if certFieldP.type == 0xA3: # i.e. tag of [3], extensions
break
x += 1
self.preExtBytes = data[versionP.offset:certFieldP.offset]
self.extBytes = bytearray()
# Iterate through extensions
x = 0
certFieldPP = certFieldP.getTagged()
while 1:
extFieldP = certFieldPP.getChild(x)
if not extFieldP:
break
# Check the extnID and parse out TACK if present
extnIDP = extFieldP.getChild(0)
if extnIDP.value == TlsCertificate.OID_TACK:
if self.tackExt:
raise SyntaxError("More than one TACK Extension")
# OK! We found a TACK, parse it..
self.tackExt = TackExtension(extFieldP.getChild(1).value)
else:
# Collect all non-TACK extensions:
self.extBytes += data[extFieldP.offset :\
extFieldP.offset + extFieldP.getTotalLength()]
x += 1
# Finish copying the tail of the certificate
self.postExtBytes = data[certFieldP.offset +
certFieldP.getTotalLength():]
def verify(self, data, signature):
# Convert 64-byte signature into a stupid ASN.1 signature
asn1SigBytes = self._convertToAsn1Signature(signature)
hash = Digest.SHA256(data)
return self.ec.verify_dsa_asn1(hash, asn1SigBytes)