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Diffstat (limited to 'security/manager/tools/pycms.py')
| -rwxr-xr-x | security/manager/tools/pycms.py | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/security/manager/tools/pycms.py b/security/manager/tools/pycms.py new file mode 100755 index 0000000000..1717513fdf --- /dev/null +++ b/security/manager/tools/pycms.py @@ -0,0 +1,219 @@ +#!/usr/bin/env python +# +# This Source Code Form is subject to the terms of the Mozilla Public +# License, v. 2.0. If a copy of the MPL was not distributed with this +# file, You can obtain one at http://mozilla.org/MPL/2.0/. + +""" +Reads a specification from stdin and outputs a PKCS7 (CMS) message with +the desired properties. + +The specification format is as follows: + +sha1:<hex string> +sha256:<hex string> +signer: +<pycert specification> + +Eith or both of sha1 and sha256 may be specified. The value of +each hash directive is what will be put in the messageDigest +attribute of the SignerInfo that corresponds to the signature +algorithm defined by the hash algorithm and key type of the +default key. Together, these comprise the signerInfos field of +the SignedData. If neither hash is specified, the signerInfos +will be an empty SET (i.e. there will be no actual signature +information). +The certificate specification must come last. +""" + +import base64 +import sys +from io import StringIO + +import pycert +import pykey +from pyasn1.codec.der import decoder, encoder +from pyasn1.type import tag, univ +from pyasn1_modules import rfc2315, rfc2459 + + +class Error(Exception): + """Base class for exceptions in this module.""" + + pass + + +class UnknownDirectiveError(Error): + """Helper exception type to handle unknown specification + directives.""" + + def __init__(self, directive): + super(UnknownDirectiveError, self).__init__() + self.directive = directive + + def __str__(self): + return "Unknown directive %s" % repr(self.directive) + + +class CMS(object): + """Utility class for reading a CMS specification and + generating a CMS message""" + + def __init__(self, paramStream): + self.sha1 = "" + self.sha256 = "" + signerSpecification = StringIO() + readingSignerSpecification = False + for line in paramStream.readlines(): + if readingSignerSpecification: + print(line.strip(), file=signerSpecification) + elif line.strip() == "signer:": + readingSignerSpecification = True + elif line.startswith("sha1:"): + self.sha1 = line.strip()[len("sha1:") :] + elif line.startswith("sha256:"): + self.sha256 = line.strip()[len("sha256:") :] + else: + raise UnknownDirectiveError(line.strip()) + signerSpecification.seek(0) + self.signer = pycert.Certificate(signerSpecification) + self.signingKey = pykey.keyFromSpecification("default") + + def buildAuthenticatedAttributes(self, value, implicitTag=None): + """Utility function to build a pyasn1 AuthenticatedAttributes + object. Useful because when building a SignerInfo, the + authenticatedAttributes needs to be tagged implicitly, but when + signing an AuthenticatedAttributes, it needs the explicit SET + tag.""" + if implicitTag: + authenticatedAttributes = rfc2315.Attributes().subtype( + implicitTag=implicitTag + ) + else: + authenticatedAttributes = rfc2315.Attributes() + contentTypeAttribute = rfc2315.Attribute() + # PKCS#9 contentType + contentTypeAttribute["type"] = univ.ObjectIdentifier("1.2.840.113549.1.9.3") + contentTypeAttribute["values"] = univ.SetOf(rfc2459.AttributeValue()) + # PKCS#7 data + contentTypeAttribute["values"][0] = univ.ObjectIdentifier( + "1.2.840.113549.1.7.1" + ) + authenticatedAttributes[0] = contentTypeAttribute + hashAttribute = rfc2315.Attribute() + # PKCS#9 messageDigest + hashAttribute["type"] = univ.ObjectIdentifier("1.2.840.113549.1.9.4") + hashAttribute["values"] = univ.SetOf(rfc2459.AttributeValue()) + hashAttribute["values"][0] = univ.OctetString(hexValue=value) + authenticatedAttributes[1] = hashAttribute + return authenticatedAttributes + + def pykeyHashToDigestAlgorithm(self, pykeyHash): + """Given a pykey hash algorithm identifier, builds an + AlgorithmIdentifier for use with pyasn1.""" + if pykeyHash == pykey.HASH_SHA1: + oidString = "1.3.14.3.2.26" + elif pykeyHash == pykey.HASH_SHA256: + oidString = "2.16.840.1.101.3.4.2.1" + else: + raise pykey.UnknownHashAlgorithmError(pykeyHash) + algorithmIdentifier = rfc2459.AlgorithmIdentifier() + algorithmIdentifier["algorithm"] = univ.ObjectIdentifier(oidString) + # Directly setting parameters to univ.Null doesn't currently work. + nullEncapsulated = encoder.encode(univ.Null()) + algorithmIdentifier["parameters"] = univ.Any(nullEncapsulated) + return algorithmIdentifier + + 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 toDER(self): + contentInfo = rfc2315.ContentInfo() + contentInfo["contentType"] = rfc2315.signedData + + signedData = rfc2315.SignedData() + signedData["version"] = rfc2315.Version(1) + + digestAlgorithms = rfc2315.DigestAlgorithmIdentifiers() + digestAlgorithms[0] = self.pykeyHashToDigestAlgorithm(pykey.HASH_SHA1) + signedData["digestAlgorithms"] = digestAlgorithms + + dataContentInfo = rfc2315.ContentInfo() + dataContentInfo["contentType"] = rfc2315.data + signedData["contentInfo"] = dataContentInfo + + certificates = rfc2315.ExtendedCertificatesAndCertificates().subtype( + implicitTag=tag.Tag(tag.tagClassContext, tag.tagFormatConstructed, 0) + ) + extendedCertificateOrCertificate = rfc2315.ExtendedCertificateOrCertificate() + certificate = decoder.decode( + self.signer.toDER(), asn1Spec=rfc2459.Certificate() + )[0] + extendedCertificateOrCertificate["certificate"] = certificate + certificates[0] = extendedCertificateOrCertificate + signedData["certificates"] = certificates + + signerInfos = rfc2315.SignerInfos() + + if len(self.sha1) > 0: + signerInfos[len(signerInfos)] = self.buildSignerInfo( + certificate, pykey.HASH_SHA1, self.sha1 + ) + if len(self.sha256) > 0: + signerInfos[len(signerInfos)] = self.buildSignerInfo( + certificate, pykey.HASH_SHA256, self.sha256 + ) + signedData["signerInfos"] = signerInfos + + encoded = encoder.encode(signedData) + anyTag = univ.Any(encoded).subtype( + explicitTag=tag.Tag(tag.tagClassContext, tag.tagFormatConstructed, 0) + ) + + contentInfo["content"] = anyTag + return encoder.encode(contentInfo) + + def toPEM(self): + output = "-----BEGIN PKCS7-----" + der = self.toDER() + b64 = base64.b64encode(der) + while b64: + output += "\n" + b64[:64] + b64 = b64[64:] + output += "\n-----END PKCS7-----\n" + return output + + +# When run as a standalone program, this will read a specification from +# stdin and output the certificate as PEM to stdout. +if __name__ == "__main__": + print(CMS(sys.stdin).toPEM()) |