CODEWITHSUNDEEP
pythonsoappyopensslwssexmlsec
Kent Wong
Kent Wong

Reputation: 581

Why can't I decrypt this xmlsec encrypted WSSE enhanced soap message?

I have used py-wsse from PIP but it seems broken. I've refactored/fixed it up to

  1. Add X509 standards : Signature block with signing, and public/private key usage via a certificate

  2. I was able to encrypt/decrypt this using plain old XMLSEC, after adding the WSSE components I am not able to.

  3. The underlying imports are xmlsec (1.35), and OpenSSL. Encrypt/Decrypt is performed by xmlsec, the key/certificate generation are done by openssl. Signing using these certificates/keyfiles are done by xmlsec.

  4. I do pre/post processing on the xmlsec signed document to create the wsse document. Likewise when I decrypt, I process the document to move the key information back into the EncryptedData block

Here is my Signed and Encrypted Document, as far as I can tell, the encrypteddata block looks the same as my vanilla XMLSEC document asides from a few additional tags. This cannot be decrypted.

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
                   xmlns:ns0="http://schemas.xmlsoap.org/soap/envelope/"
                   xmlns:ns1="http://hcv.health.ontario.ca/"
                   xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"
                   xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"
                   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <SOAP-ENV:Header>
        <wsse:Security mustUnderstand="true">
            <wsse:BinarySecurityToken
                    EncodingType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-soap-message-security-1.0#Base64Binary"
                    ValueType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-x509-token-profile-1.0#X509v3"
                    wsu:Id="id-12e0aebc-9024-476f-a43a-5666e9ea2838">
                __cipher__text__here__
            </wsse:BinarySecurityToken>
            <Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
                <SignedInfo>
                    <CanonicalizationMethod
                            Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
                    <SignatureMethod
                            Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
                    <Reference URI="#id-f147f091-fef5-4f6a-a8fc-50cd1199280a">
                        <Transforms>
                            <Transform
                                    Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
                        </Transforms>
                        <DigestMethod
                                Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
                        <DigestValue>qW0RXziKgv89NQN1Jh3r6GiE68k=</DigestValue>
                    </Reference>
                    <Reference URI="#id-392912e7-0b10-4243-86ea-836e13e445f0">
                        <Transforms>
                            <Transform
                                    Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
                        </Transforms>
                        <DigestMethod
                                Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
                        <DigestValue>2RT70EVr3SxEQIsYFRTlCv+E/VQ=</DigestValue>
                    </Reference>
                </SignedInfo>
                <SignatureValue>
                    __cipher__text__here__
                </SignatureValue>
                <KeyInfo>
                    <wsse:SecurityTokenReference>
                        <X509Data>
                            <X509IssuerSerial>
                                <X509IssuerName>
                                    CN=example.com
                                </X509IssuerName>
                                <X509SerialNumber>1000</X509SerialNumber>
                            </X509IssuerSerial>
                            <X509Certificate>
                            __cipher__text__here__
                            </X509Certificate>
                        </X509Data>
                    </wsse:SecurityTokenReference>
                </KeyInfo>
            </Signature>
            <wsu:Timestamp wsu:Id="id-392912e7-0b10-4243-86ea-836e13e445f0">
                <wsu:Created>2017-07-18T01:32:47.577170+00:00</wsu:Created>
                <wsu:Expires>2017-07-18T01:34:17.577170+00:00</wsu:Expires>
            </wsu:Timestamp>
        </wsse:Security>
    </SOAP-ENV:Header>
    <ns0:Body wsu:Id="id-f147f091-fef5-4f6a-a8fc-50cd1199280a">
        <xenc:EncryptedData xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
                            Type="http://www.w3.org/2001/04/xmlenc#Element"
                            wsu:Id="id-2ba0c3b4-7784-415d-aeca-08a45d504660">
            <xenc:EncryptionMethod
                    Algorithm="http://www.w3.org/2001/04/xmlenc#tripledes-cbc"/>

            <ds:KeyInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
                <xenc:EncryptedKey>
                    <xenc:EncryptionMethod
                            Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p"/>
                    <xenc:CipherData>
                        <xenc:CipherValue>
                            __cipher__text__here__
                        </xenc:CipherValue>
                    </xenc:CipherData>
                    <xenc:ReferenceList>
                        <xenc:DataReference
                                URI="#id-2ba0c3b4-7784-415d-aeca-08a45d504660"/>
                    </xenc:ReferenceList>
                </xenc:EncryptedKey>
            </ds:KeyInfo>

            <xenc:CipherData>
                <xenc:CipherValue>
                    __cipher__text__here__
                </xenc:CipherValue>
            </xenc:CipherData>

        </xenc:EncryptedData>
    </ns0:Body>
</SOAP-ENV:Envelope>

Here is "vanilla XMLSEC" signed and encrypted document, this can be decrypted:

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
                   xmlns:ns0="http://schemas.xmlsoap.org/soap/envelope/"
                   xmlns:ns1="http://example.com/"
                   xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"
                   xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"
                   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <SOAP-ENV:Header>
        <wsse:Security mustUnderstand="true">
            <Signature xmlns="http://www.w3.org/2000/09/xmldsig#">
                <SignedInfo>
                    <CanonicalizationMethod
                            Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
                    <SignatureMethod
                            Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
                    <Reference URI="#id-61b880d6-e56b-4cfc-bec6-471121c72547">
                        <Transforms>
                            <Transform
                                    Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
                        </Transforms>
                        <DigestMethod
                                Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
                        <DigestValue>NvKgiRH+6Q/xMSJxx/7qtkc+IFY=</DigestValue>
                    </Reference>
                    <Reference URI="#id-6b86d1cc-0d2b-42a8-ad1e-78e9448f9983">
                        <Transforms>
                            <Transform
                                    Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/>
                        </Transforms>
                        <DigestMethod
                                Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
                        <DigestValue>5IoUfViIk5hJTt3Whl7I/jFq+Ww=</DigestValue>
                    </Reference>
                </SignedInfo>
                <SignatureValue>
                    RmbXCTcji8c0ZWuRrCYdBL57FtGiwmX5HlZIol1k/d7d8PIdj0YR/41qP7DlSTD2
                    fspVNXLYc9kEh+YbTbodRsGvHQ/ZUWhXC6dX3/1BjdxrycPcQI37REIO+btla5wR
                    Icn5FvXMHPPJfln9y3ulj/RAjHU44nDKE4m0zWJ8lUo=
                </SignatureValue>
                <KeyInfo>
                    <X509Data>
                        <X509IssuerSerial>
                            <X509IssuerName>
                                CN=example.com
                            </X509IssuerName>
                            <X509SerialNumber>1000</X509SerialNumber>
                        </X509IssuerSerial>
                        <X509Certificate>
                            MIICOjCCAaMCAgPoMA0GCSqGSIb3DQEBBQUAMGUxCzAJBgNVBAYTAlVTMRAwDgYD
                        </X509Certificate>
                    </X509Data>
                </KeyInfo>
            </Signature>
            <wsse:UsernameToken>
                <wsse:Username>test_user</wsse:Username>
                <wsse:Password>test_pass</wsse:Password>
            </wsse:UsernameToken>
            <wsu:Timestamp wsu:Id="id-6b86d1cc-0d2b-42a8-ad1e-78e9448f9983">
                <wsu:Created>2017-07-18T01:32:47.577170+00:00</wsu:Created>
                <wsu:Expires>2017-07-18T01:34:17.577170+00:00</wsu:Expires>
            </wsu:Timestamp>
        </wsse:Security>
    </SOAP-ENV:Header>



    <ns0:Body wsu:Id="id-61b880d6-e56b-4cfc-bec6-471121c72547">
        <xenc:EncryptedData xmlns:xenc="http://www.w3.org/2001/04/xmlenc#"
                            Type="http://www.w3.org/2001/04/xmlenc#Element">
            <xenc:EncryptionMethod
                Algorithm="http://www.w3.org/2001/04/xmlenc#tripledes-cbc"/>

            <dsig:KeyInfo xmlns:dsig="http://www.w3.org/2000/09/xmldsig#">
                    <xenc:EncryptedKey>
                        <xenc:EncryptionMethod
                        Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p"/>
                        <xenc:CipherData>
                            <xenc:CipherValue>
                            KViKBt8yTp/ELA/vWWRhrGl86c/cCBORsmg5aYKctmFMfLMx8thU7acMC5TqpGzB
                            </xenc:CipherValue>
                        </xenc:CipherData>
                </xenc:EncryptedKey>
            </dsig:KeyInfo>

            <xenc:CipherData>
                <xenc:CipherValue>
                GPkZpozkWMISAkMJ8OuBuKE6wNLmsftEmK6tt5+0/EpY+TpWI8ffh7KWoxjHTGL6
                </xenc:CipherValue>
            </xenc:CipherData>
        </xenc:EncryptedData>

    </ns0:Body>
</SOAP-ENV:Envelope>

Upvotes: 0

Views: 940

Answers (1)

Kent Wong
Kent Wong

Reputation: 581

Through "debugging" (manually splicing the Signed+Encrypted+Processed document), I managed to decrypt it.

Normal assumption is that order is irrelevant in XML docs, however XMLSEC seems to explicitly expect to expect KeyInfo immediately after Encryption Method within EncryptionData. A simple Swapping of the Encrypted Data CipherData and KeyInfo fixed it.

It would appear XMLSEC is not truly parsing XML, instead it's most likely behaving like the following:

  1. Find 'EncryptedData'

  2. Find 'EncryptionMethod'

  3. Find 'KeyInfo'

  4. Within this KeyInfo, Find it's nested 'CipherData' block, find the 'CipherValue'

  5. Get out of KeyInfo

  6. Then proceed to the Encrypted Data's CipherData Block which is outside of KeyInfo.

Upvotes: 0

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