web-servicessoapgoxmlsec

XML Signature of SOAP Body

I'm implementing a client for a WS which requires soap:body to be signed. The application is written in Go so I would prefer to avoid linking to C.

The biggest issue is: how to calculate SHA256? What should be the input of digest algorithm? I assume that "/CJj9686ARgbV/YmDrr+1yhcaJuXu022cADK/M8efQs=" is a SHA256 result that is later signed. I tried many variations of canonicalized XML but none of them results in this hash.

Here is an example of correct SOAP message

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
    <SOAP-ENV:Header xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
        <wsse:Security 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"
                       soap:mustUnderstand="1">
            <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="X509-16FE2A6FC1AFE42BE9146412186273511">
                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
            </wsse:BinarySecurityToken>
            <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#" Id="SIG-16FE2A6FC1AFE42BE9146412186273615">
                <ds:SignedInfo>
                    <ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#">
                        <ec:InclusiveNamespaces xmlns:ec="http://www.w3.org/2001/10/xml-exc-c14n#" PrefixList="soap"/>
                    </ds:CanonicalizationMethod>
                    <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/>
                    <ds:Reference URI="#id-16FE2A6FC1AFE42BE9146412186273614">
                        <ds:Transforms>
                            <ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#">
                                <ec:InclusiveNamespaces xmlns:ec="http://www.w3.org/2001/10/xml-exc-c14n#"
                                                        PrefixList=""/>
                            </ds:Transform>
                        </ds:Transforms>
                        <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/>
                        <ds:DigestValue>/CJj9686ARgbV/YmDrr+1yhcaJuXu022cADK/M8efQs=</ds:DigestValue>
                    </ds:Reference>
                </ds:SignedInfo>
                <ds:SignatureValue>
                    Ii+W0EB2V6GJo4jMGwK1HCRdt6+r9TkgfhXyAuY8FNCXhPOtfoUi/Bw31U4Hm7SLscM/8klrQI3Z2vSfdNe3oDi1cm2Qouv1sOBK17VSg/IgKN92BC8kUaoF5W5ZBEcZr0WHjDWasSYEerZQ3Q+ZIJzt6cbS+cLZfQkLFg1UDOi5qLUkWE1pQ9AVYCvwrOFj/hFQx5koQTpigyG/DPlyoh2xOh/DAh6U/P5p+IiQwwCMdo1Rh2czUVpRCr3Cnz97AlQ8G6IGAtWNykXorVYZ1tGnXEaRngzjsn5RE/zCcRkqRpFaiEQuYly1I6YtFOEYIPXskE5oMZkCLINebu1Law==
                </ds:SignatureValue>
                <ds:KeyInfo Id="KI-16FE2A6FC1AFE42BE9146412186273512">
                    <wsse:SecurityTokenReference
                            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"
                            wsu:Id="STR-16FE2A6FC1AFE42BE9146412186273513">
                        <wsse:Reference URI="#X509-16FE2A6FC1AFE42BE9146412186273511"
                                        ValueType="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-x509-token-profile-1.0#X509v3"/>
                    </wsse:SecurityTokenReference>
                </ds:KeyInfo>
            </ds:Signature>
        </wsse:Security>
    </SOAP-ENV:Header>
    <soap:Body xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"
               wsu:Id="id-16FE2A6FC1AFE42BE9146412186273614">
        <Trzba xmlns="http://fs.mfcr.cz/eet/schema/v2">
            <Hlavicka dat_odesl="2016-09-19T19:06:37+01:00" prvni_zaslani="false"
                      uuid_zpravy="9edeb22b-4234-4047-869c-3a76f86c20d3"/>
            <Data celk_trzba="34113.00" cerp_zuct="679.00" cest_sluz="5460.00" dan1="-172.39" dan2="-530.73"
                  dan3="975.65" dat_trzby="2016-01-05T00:30:12+01:00" dic_popl="CZ00000019" id_pokl="/5546/RO24"
                  id_provoz="273" porad_cis="0/6460/ZQ42" pouzit_zboz1="784.00" pouzit_zboz2="967.00"
                  pouzit_zboz3="189.00" rezim="0" urceno_cerp_zuct="324.00" zakl_dan1="-820.92" zakl_dan2="-3538.20"
                  zakl_dan3="9756.46" zakl_nepodl_dph="3036.00"/>
            <KontrolniKody>
                <pkp cipher="RSA2048" digest="SHA256" encoding="base64">
                    W7UlA4hXNsDLvCj/eeRAYeOAsNsgMSdltcJNIW98KQRsfspTMW0Lr/OGQgRHZfO5KjolZgzN3k9mgzrVoX2+N90fCNEnOri2kjrW5vzTgMK6OZ9IryAEg0xFZjjjCQ0qKsQsVi8OLQOn3ZnN/BUGG2SIduER+iIOrhfOmes7OXaa5/2jQSfPTHZHZ/Bxhqld3gL4PHvd7sevZYUupHpE1fM7Uw1+lu8i1YOdghZoMyOfKw7FcqvRJpHrW/JZL5Dr5iCgu5ClmhZrb3hZavsxlDG7P2cUhSQgmEVTxJ2n38q/Cf91KE8e52SODN4Q8BfncXpmtkQ7Go3KsRsY3xN7xg==
                </pkp>
                <bkp digest="SHA1" encoding="base16">1F1A2D90-4EAD34A8-411CFB0B-EB17616E-B2CE8114</bkp>
            </KontrolniKody>
        </Trzba>
    </soap:Body>
</soap:Envelope>
Solution

  • Finally, I found how to get all values.

    1. Canonicalize XML element defined in <SignedInfo><Reference>. In this case it's the <soap:Body> element. Canonicalization adds just soap namespace and adds closing tags. I'm generating these in Go and Go never generates self-closing tags.
    2. Calculate hash from a string representation of canonicalized <soap:Body> as it will be sent in a request.
    3. Add calculated digest into <DigestValue> of corresponding <Reference>.
    4. Canonicalize <SignedInfo> and calculate hash of it.
    5. Sign this hash and add value to <SignedValue>.

    I know that this is not a general approach but it should work for me. C14N is not necessary because Go can produce the same result if you pay attention to attributes order and manually add namespaces.