def buildSignerInfo(self, certificate, pykeyHash, digestValue):
"""Given a pyasn1 certificate, a pykey hash identifier
and a hash value, creates a SignerInfo with the
appropriate values."""
signerInfo = rfc2315.SignerInfo()
signerInfo['version'] = 1
issuerAndSerialNumber = rfc2315.IssuerAndSerialNumber()
issuerAndSerialNumber['issuer'] = self.signer.getIssuer()
issuerAndSerialNumber['serialNumber'] = certificate['tbsCertificate'][
'serialNumber']
signerInfo['issuerAndSerialNumber'] = issuerAndSerialNumber
signerInfo['digestAlgorithm'] = self.pykeyHashToDigestAlgorithm(
pykeyHash)
rsa = rfc2459.AlgorithmIdentifier()
rsa['algorithm'] = rfc2459.rsaEncryption
rsa['parameters'] = univ.Null()
authenticatedAttributes = self.buildAuthenticatedAttributes(
digestValue,
implicitTag=tag.Tag(tag.tagClassContext, tag.tagFormatConstructed,
0))
authenticatedAttributesTBS = self.buildAuthenticatedAttributes(
digestValue)
signerInfo['authenticatedAttributes'] = authenticatedAttributes
signerInfo['digestEncryptionAlgorithm'] = rsa
authenticatedAttributesEncoded = encoder.encode(
authenticatedAttributesTBS)
signature = self.signingKey.sign(authenticatedAttributesEncoded,
pykeyHash)
# signature will be a hexified bit string of the form
# "'<hex bytes>'H". For some reason that's what BitString wants,
# but since this is an OCTET STRING, we have to strip off the
# quotation marks and trailing "H".
signerInfo['encryptedDigest'] = univ.OctetString(
hexValue=signature[1:-2])
return signerInfo
def getSigningTimeAuthenticode(data):
signerInfo, dummy = decode(data, asn1Spec=rfc2315.SignerInfo())
attrs = signerInfo['authenticatedAttributes']
if not attrs:
return
for attr in attrs:
if attr['type'] == univ.ObjectIdentifier('1.2.840.113549.1.9.5'):
signingTime, dummy = decode(attr['values'][0],
asn1Spec=TimeChoice())
return parseTimeChoice(signingTime)
def _create_pkcs7(cert, csr, private_key):
"""Creates the PKCS7 structure and signs it"""
content_info = rfc2315.ContentInfo()
content_info.setComponentByName('contentType', rfc2315.data)
content_info.setComponentByName('content',
encoder.encode(rfc2315.Data(csr)))
issuer_and_serial = rfc2315.IssuerAndSerialNumber()
issuer_and_serial.setComponentByName('issuer',
cert[0]['tbsCertificate']['issuer'])
issuer_and_serial.setComponentByName(
'serialNumber', cert[0]['tbsCertificate']['serialNumber'])
raw_signature, _ = _sign(private_key, csr)
signature = rfc2314.univ.OctetString(
hexValue=binascii.hexlify(raw_signature).decode('ascii'))
# Microsoft adds parameters with ASN.1 NULL encoding here,
# but according to rfc5754 they should be absent:
# "Implementations MUST generate SHA2 AlgorithmIdentifiers with absent parameters."
sha2 = rfc2315.AlgorithmIdentifier()
sha2.setComponentByName('algorithm', (2, 16, 840, 1, 101, 3, 4, 2, 1))
alg_from_cert = cert[0]['tbsCertificate']['subjectPublicKeyInfo'][
'algorithm']['algorithm']
digest_encryption_algorithm = rfc2315.AlgorithmIdentifier()
digest_encryption_algorithm.setComponentByName('algorithm', alg_from_cert)
digest_encryption_algorithm.setComponentByName('parameters', '\x05\x00')
signer_info = rfc2315.SignerInfo()
signer_info.setComponentByName('version', 1)
signer_info.setComponentByName('issuerAndSerialNumber', issuer_and_serial)
signer_info.setComponentByName('digestAlgorithm', sha2)
signer_info.setComponentByName('digestEncryptionAlgorithm',
digest_encryption_algorithm)
signer_info.setComponentByName('encryptedDigest', signature)
signer_infos = rfc2315.SignerInfos().setComponents(signer_info)
digest_algorithms = rfc2315.DigestAlgorithmIdentifiers().setComponents(
sha2)
extended_cert_or_cert = rfc2315.ExtendedCertificateOrCertificate()
extended_cert_or_cert.setComponentByName('certificate', cert[0])
extended_certs_and_cert = rfc2315.ExtendedCertificatesAndCertificates(
).subtype(implicitTag=rfc2315.tag.Tag(rfc2315.tag.tagClassContext,
rfc2315.tag.tagFormatConstructed, 0))
extended_certs_and_cert.setComponents(extended_cert_or_cert)
signed_data = rfc2315.SignedData()
signed_data.setComponentByName('version', 1)
signed_data.setComponentByName('digestAlgorithms', digest_algorithms)
signed_data.setComponentByName('contentInfo', content_info)
signed_data.setComponentByName('certificates', extended_certs_and_cert)
signed_data.setComponentByName('signerInfos', signer_infos)
outer_content_info = rfc2315.ContentInfo()
outer_content_info.setComponentByName('contentType', rfc2315.signedData)
outer_content_info.setComponentByName('content',
encoder.encode(signed_data))
return encoder.encode(outer_content_info)