XML Signature of SOAP Body

Question

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>

Implement XMLSignature from scratch really requires great effort. The signature value is calculated over the digest of the node after applying transforms and canonicalization. The node also includes the digest of the XML document. After this you have to fight with a lot of SOAP request parameters regarding security token. I do not know 'Go', but I suggest you use a framework for soap — pedrofb, Jun 15 '16 at 06:09

score 2 · Accepted Answer · answered Jun 15 '16 at 11:16

Finally, I found how to get all values.

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.
Calculate hash from a string representation of canonicalized <soap:Body> as it will be sent in a request.
Add calculated digest into <DigestValue> of corresponding <Reference>.
Canonicalize <SignedInfo> and calculate hash of it.
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.

Joerg Veigel · Answer 2 · 2016-09-02T15:04:09.003

Referring to the XML example CZ00000019.valid.v3.xml (of the Czech Fiscal Authority EET) the canonicized SignedInfo is:

var signedinfoCanon 
= '<ds:SignedInfo xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">'
+ '<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"></ec:InclusiveNamespaces>'
+ '</ds:CanonicalizationMethod>'
+ '<ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"></ds:SignatureMethod>'
+ '<ds:Reference URI="#id-A72D6FD4C41B1F545F14700558808234">'
+ '<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=""></ec:InclusiveNamespaces>'
+ '</ds:Transform>'
+ '</ds:Transforms>'
+ '<ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"></ds:DigestMethod>'
+ '<ds:DigestValue>4hn06sSS2yurIiUmWaV36JQJZrwbWf36sG9bOHH/ycM=</ds:DigestValue>'
+ '</ds:Reference>'
+ '</ds:SignedInfo>'

score -1 · Answer 3 · answered Jun 14 '16 at 20:50

-1

calculate sha256 like this

import (
"crypto/sha256"

)

var slice = []byte("test")

return sha256.Sum256(slice)

answered Jun 14 '16 at 20:50

goerr

1
1

1

Well, that doesn't answers my question. – chatoooo Jun 14 '16 at 20:56

XML Signature of SOAP Body

3 Answers3