import base64
import hashlib
from lxml import etree
from .ds import SignatureValueType, KeyInfoType, CanonicalizationMethodType, SignatureMethodType, ReferenceType, TransformsType, TransformType, \
DigestMethodType, X509DataType, X509IssuerSerialType, SignedInfo, Signature
from .. import Signer
from ... import XElement
def _tobytes(element: etree.Element, exclusive=True) -> bytes:
return etree.tostring(element, method='c14n', exclusive=exclusive)
def _digest(element: etree.Element, exclusive=True) -> str:
element_digest = hashlib.sha1(
_tobytes(element, exclusive)
).digest()
return base64.b64encode(element_digest).decode()
[docs]def signature_c14n_sha1(signer: Signer, element: etree.Element, nsmap=None) -> XElement:
digest = _digest(element, exclusive=False)
signed_info = SignedInfo(
canonicalization_method=CanonicalizationMethodType(
algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315",
),
signature_method=SignatureMethodType(
algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"
),
reference=ReferenceType(
uri="",
transforms=TransformsType(
transform=TransformType(
algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"
)
),
digest_method=DigestMethodType(
algorithm="http://www.w3.org/2000/09/xmldsig#sha1"
),
digest_value=digest
)
)
signed_info["_nsmap"] = nsmap
signature = Signature(
signed_info=signed_info,
signature_value=SignatureValueType(
signer.sign_sha1(
_tobytes(signed_info.to_xml(), exclusive=False)
)
),
key_info=KeyInfoType(
x509data=X509DataType(
x509issuer_serial=X509IssuerSerialType(
x509issuer_name=signer.issuer(),
x509serial_number=signer.serial_number
),
x509certificate=signer.certificate_base64()
)
)
)
signature["_nsmap"] = nsmap
return signature