Your IP : 3.145.40.61
#!/usr/bin/python
# -*- coding: utf-8 -*-
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation; either version 3, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
# for more details.
"""Pythonic XML Security Library implementation"""
import base64
import hashlib
import os
from cStringIO import StringIO
from M2Crypto import BIO, EVP, RSA, X509, m2
# if lxml is not installed, use c14n.py native implementation
try:
import lxml.etree
except ImportError:
lxml = None
# Features:
# * Uses M2Crypto and lxml (libxml2) but it is independent from libxmlsec1
# * Sign, Verify, Encrypt & Decrypt XML documents
# Enveloping templates ("by reference": signature is parent):
SIGN_REF_TMPL = """
<SignedInfo xmlns="http://www.w3.org/2000/09/xmldsig#">
<CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#" />
<SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1" />
<Reference URI="%(ref_uri)s">
<Transforms>
<Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#" />
</Transforms>
<DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" />
<DigestValue>%(digest_value)s</DigestValue>
</Reference>
</SignedInfo>
"""
SIGNED_TMPL = """
<?xml version="1.0" encoding="UTF-8"?>
<Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
%(signed_info)s
<SignatureValue>%(signature_value)s</SignatureValue>
%(key_info)s
%(ref_xml)s
</Signature>
"""
# Enveloped templates (signature is child, the reference is the root object):
SIGN_ENV_TMPL = """
<SignedInfo xmlns="http://www.w3.org/2000/09/xmldsig#">
<CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
<SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
<Reference URI="">
<Transforms>
<Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
<Transform Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
</Transforms>
<DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
<DigestValue>%(digest_value)s</DigestValue>
</Reference>
</SignedInfo>
"""
SIGNATURE_TMPL = """<Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
%(signed_info)s
<SignatureValue>%(signature_value)s</SignatureValue>
%(key_info)s
</Signature>"""
KEY_INFO_RSA_TMPL = """
<KeyInfo>
<KeyValue>
<RSAKeyValue>
<Modulus>%(modulus)s</Modulus>
<Exponent>%(exponent)s</Exponent>
</RSAKeyValue>
</KeyValue>
</KeyInfo>
"""
KEY_INFO_X509_TMPL = """
<KeyInfo>
<X509Data>
<X509IssuerSerial>
<X509IssuerName>%(issuer_name)s</X509IssuerName>
<X509SerialNumber>%(serial_number)s</X509SerialNumber>
</X509IssuerSerial>
</X509Data>
</KeyInfo>
"""
def canonicalize(xml, c14n_exc=True):
"Return the canonical (c14n) form of the xml document for hashing"
# UTF8, normalization of line feeds/spaces, quoting, attribute ordering...
output = StringIO()
if lxml is not None:
# use faster libxml2 / lxml canonicalization function if available
et = lxml.etree.parse(StringIO(xml))
et.write_c14n(output, exclusive=c14n_exc)
else:
# use pure-python implementation: c14n.py (avoid recursive import)
from .simplexml import SimpleXMLElement
SimpleXMLElement(xml).write_c14n(output, exclusive=c14n_exc)
return output.getvalue()
def sha1_hash_digest(payload):
"Create a SHA1 hash and return the base64 string"
return base64.b64encode(hashlib.sha1(payload).digest())
def rsa_sign(xml, ref_uri, private_key, password=None, cert=None, c14n_exc=True,
sign_template=SIGN_REF_TMPL, key_info_template=KEY_INFO_RSA_TMPL):
"Sign an XML document usign RSA (templates: enveloped -ref- or enveloping)"
# normalize the referenced xml (to compute the SHA1 hash)
ref_xml = canonicalize(xml, c14n_exc)
# create the signed xml normalized (with the referenced uri and hash value)
signed_info = sign_template % {'ref_uri': ref_uri,
'digest_value': sha1_hash_digest(ref_xml)}
signed_info = canonicalize(signed_info, c14n_exc)
# Sign the SHA1 digest of the signed xml using RSA cipher
pkey = RSA.load_key(private_key, lambda *args, **kwargs: password)
signature = pkey.sign(hashlib.sha1(signed_info).digest())
# build the mapping (placeholders) to create the final xml signed message
return {
'ref_xml': ref_xml, 'ref_uri': ref_uri,
'signed_info': signed_info,
'signature_value': base64.b64encode(signature),
'key_info': key_info(pkey, cert, key_info_template),
}
def rsa_verify(xml, signature, key, c14n_exc=True):
"Verify a XML document signature usign RSA-SHA1, return True if valid"
# load the public key (from buffer or filename)
if key.startswith("-----BEGIN PUBLIC KEY-----"):
bio = BIO.MemoryBuffer(key)
rsa = RSA.load_pub_key_bio(bio)
else:
rsa = RSA.load_pub_key(certificate)
# create the digital envelope
pubkey = EVP.PKey()
pubkey.assign_rsa(rsa)
# do the cryptographic validation (using the default sha1 hash digest)
pubkey.reset_context(md='sha1')
pubkey.verify_init()
# normalize and feed the signed xml to be verified
pubkey.verify_update(canonicalize(xml, c14n_exc))
ret = pubkey.verify_final(base64.b64decode(signature))
return ret == 1
def key_info(pkey, cert, key_info_template):
"Convert private key (PEM) to XML Signature format (RSAKeyValue/X509Data)"
exponent = base64.b64encode(pkey.e[4:])
modulus = m2.bn_to_hex(m2.mpi_to_bn(pkey.n)).decode("hex").encode("base64")
x509 = x509_parse_cert(cert) if cert else None
return key_info_template % {
'modulus': modulus,
'exponent': exponent,
'issuer_name': x509.get_issuer().as_text() if x509 else "",
'serial_number': x509.get_serial_number() if x509 else "",
}
# Miscellaneous certificate utility functions:
def x509_parse_cert(cert, binary=False):
"Create a X509 certificate from binary DER, plain text PEM or filename"
if binary:
bio = BIO.MemoryBuffer(cert)
x509 = X509.load_cert_bio(bio, X509.FORMAT_DER)
elif cert.startswith("-----BEGIN CERTIFICATE-----"):
bio = BIO.MemoryBuffer(cert)
x509 = X509.load_cert_bio(bio, X509.FORMAT_PEM)
else:
x509 = X509.load_cert(cert, 1)
return x509
def x509_extract_rsa_public_key(cert, binary=False):
"Return the public key (PEM format) from a X509 certificate"
x509 = x509_parse_cert(cert, binary)
return x509.get_pubkey().get_rsa().as_pem()
def x509_verify(cacert, cert, binary=False):
"Validate the certificate's authenticity using a certification authority"
ca = x509_parse_cert(cacert)
crt = x509_parse_cert(cert, binary)
return crt.verify(ca.get_pubkey())
if __name__ == "__main__":
# basic test of enveloping signature (the reference is a part of the xml)
sample_xml = """<Object xmlns="http://www.w3.org/2000/09/xmldsig#" Id="object">data</Object>"""
output = canonicalize(sample_xml)
print (output)
vars = rsa_sign(sample_xml, '#object', "no_encriptada.key", "password")
print (SIGNED_TMPL % vars)
# basic test of enveloped signature (the reference is the document itself)
sample_xml = """<?xml version="1.0" encoding="UTF-8"?><Object>data%s</Object>"""
vars = rsa_sign(sample_xml % "", '', "no_encriptada.key", "password",
sign_template=SIGN_ENV_TMPL, c14n_exc=False)
print (sample_xml % (SIGNATURE_TMPL % vars))
# basic signature verification:
public_key = x509_extract_rsa_public_key(open("zunimercado.crt").read())
assert rsa_verify(vars['signed_info'], vars['signature_value'], public_key,
c14n_exc=False)