We have a document signing service that runs in the cloud. The idea is that user uploads a document that he would like to sign, and the document is then signed on the backend using the user's private key that is kept on an HSM. However, in order to protect the privacy of the document, we are sending only the hash of the document, we do the same thing for verification. We have successfully done that for PaDES and CaDES documents, but are unable to do that for the XaDES documents.
This is the problem we face with verirication. Here is a signed XaDES document:
<?xml version="1.0" encoding="UTF-8" standalone="no"?><note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#" Id="id-448b15cfb37f10f659949fe53afb3bcc"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/><ds:Reference Id="r-id-448b15cfb37f10f659949fe53afb3bcc-1" URI=""><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/TR/1999/REC-xpath-19991116"><ds:XPath>not(ancestor-or-self::ds:Signature)</ds:XPath></ds:Transform><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>VkPkiQYDbE3NZ2fQv7pwDInIY0YjQAbVJvulFHITSoI=</ds:DigestValue></ds:Reference><ds:Reference Type="http://uri.etsi.org/01903#SignedProperties" URI="#xades-id-448b15cfb37f10f659949fe53afb3bcc"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>04YiTp2wqxQpL0DlG0NvJcnnVwdacoykFMBbsfZhajU=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue Id="value-id-448b15cfb37f10f659949fe53afb3bcc">v4fKeQwUI0XYAsTJPti3GYDUCsdyCvUJV0RUXAd9vqyuij7pqaVNK/6/uSnGViokCB8w5w3/T1NPNJTXZ5ahY183Fo86j7MHf2BYjy0K+jSbflG0GGOnVPtpQ05qjVgfKRTAo/xjjKZWgBEAR2hQGSm4eF79I302i9SPDSqy6BuKMCa0d32lyzsmJRSN64ySCbAGx3qxtLjUskhQf73rZnYS8t5TLz5h6wA6hPMLTAIHp5J/LVcznuCSjcP14dll/ZqPvJI5pMp+J3dGU3XjYkylGAX8fx2gO52d1/IRJGubVPM2Sc60xV+iwk3ufS4PwOHZwu7svQwU8Ei8LZ+gCQ==</ds:SignatureValue><ds:KeyInfo><ds:X509Data><ds:X509Certificate>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</ds:X509Certificate><ds:X509Certificate>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</ds:X509Certificate></ds:X509Data></ds:KeyInfo><ds:Object><xades:QualifyingProperties xmlns:xades="http://uri.etsi.org/01903/v1.3.2#" Target="#id-448b15cfb37f10f659949fe53afb3bcc"><xades:SignedProperties Id="xades-id-448b15cfb37f10f659949fe53afb3bcc"><xades:SignedSignatureProperties><xades:SigningTime>2020-07-19T12:46:29Z</xades:SigningTime><xades:SigningCertificateV2><xades:Cert><xades:CertDigest><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha512"/><ds:DigestValue>3oKjV/svZGkzE8RfAtPDgk7+CFifLKrTwDKlAJKlUr1uKyC4HP6IkOdkOjWb8/QY8W8E1TPl0FKFadiMof0mpQ==</ds:DigestValue></xades:CertDigest><xades:IssuerSerialV2>MFswTqRMMEoxCzAJBgNVBAYTAlJTMRAwDgYDVQQHDAdCZW9ncmFkMQ8wDQYDVQQKDAZOZXRTZVQxGDAWBgNVBAMMD0Nsb3VkIENBIE5ldFNlVAIJROVSTMAL7eJg</xades:IssuerSerialV2></xades:Cert></xades:SigningCertificateV2></xades:SignedSignatureProperties><xades:SignedDataObjectProperties><xades:DataObjectFormat ObjectReference="#r-id-448b15cfb37f10f659949fe53afb3bcc-1"><xades:MimeType>application/octet-stream</xades:MimeType></xades:DataObjectFormat></xades:SignedDataObjectProperties></xades:SignedProperties></xades:QualifyingProperties></ds:Object></ds:Signature></note>
This is the hash that needs to be sent to the backend VkPkiQYDbE3NZ2fQv7pwDInIY0YjQAbVJvulFHITSoI=, it is located in the first reference. However notice the URI='' attribute inside that reference tag. That basically means that digest is calculated over the whole tag that is enclosing the <ds:Signature> tag, meaning the content when you apply the transform to exclude the signature tag itself.
However, when you sign the same xml using detached signature it looks like this:
<?xml version="1.0" encoding="UTF-8" standalone="no"?><ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#" Id="id-3308f896f915e9c437bb321d11d1a5d6"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#rsa-sha256"/><ds:Reference Id="r-id-3308f896f915e9c437bb321d11d1a5d6-1"><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>B7hb7YDP0m9/CN8itVMNfjSfLjfDJu3fXiQb2mj/sek=</ds:DigestValue></ds:Reference><ds:Reference Type="http://uri.etsi.org/01903#SignedProperties" URI="#xades-id-3308f896f915e9c437bb321d11d1a5d6"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256"/><ds:DigestValue>6ZjTKKM8F/1ekj/ZtytQo5LmGrDHAxZPu/AO8OLjb5Y=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue Id="value-id-3308f896f915e9c437bb321d11d1a5d6">uiuUlQ03c+1K5hi5Zaca0nVLXYXsxaWynr/NdJJxGxJo6aJ2F6bNvkEm0z7CC4a/vW4drm/VwP7h163QbhlbKcHsoU902I7DIpQy1krzQjbcECVeL+ORnpgE2BjNUGePvlw5EnrqjuhFqooQ3w4TIBgQwGuc40+2uTmtcQCO3hxU/35Fy9tGK441SzNXPW0u0oLkwA+hBWDjj/NdLEHDMOjutiRqOhnAANvV7FY9en6nLQONdVoSk9Q/bH0SlFuDeDn9oa9/cpJjCVnuoAza6KmVcBmYDABr/RBMrUZkZ0aYjb1LvGYs/4AHsCRkmNixJqzW99uEPLPEY87Ja1VP8A==</ds:SignatureValue><ds:KeyInfo><ds:X509Data><ds:X509Certificate>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</ds:X509Certificate><ds:X509Certificate>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</ds:X509Certificate></ds:X509Data></ds:KeyInfo><ds:Object><xades:QualifyingProperties xmlns:xades="http://uri.etsi.org/01903/v1.3.2#" Target="#id-3308f896f915e9c437bb321d11d1a5d6"><xades:SignedProperties Id="xades-id-3308f896f915e9c437bb321d11d1a5d6"><xades:SignedSignatureProperties><xades:SigningTime>2020-07-19T12:47:36Z</xades:SigningTime><xades:SigningCertificateV2><xades:Cert><xades:CertDigest><ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha512"/><ds:DigestValue>3oKjV/svZGkzE8RfAtPDgk7+CFifLKrTwDKlAJKlUr1uKyC4HP6IkOdkOjWb8/QY8W8E1TPl0FKFadiMof0mpQ==</ds:DigestValue></xades:CertDigest><xades:IssuerSerialV2>MFswTqRMMEoxCzAJBgNVBAYTAlJTMRAwDgYDVQQHDAdCZW9ncmFkMQ8wDQYDVQQKDAZOZXRTZVQxGDAWBgNVBAMMD0Nsb3VkIENBIE5ldFNlVAIJROVSTMAL7eJg</xades:IssuerSerialV2></xades:Cert></xades:SigningCertificateV2></xades:SignedSignatureProperties><xades:SignedDataObjectProperties><xades:DataObjectFormat ObjectReference="#r-id-3308f896f915e9c437bb321d11d1a5d6-1"><xades:MimeType>application/octet-stream</xades:MimeType></xades:DataObjectFormat></xades:SignedDataObjectProperties></xades:SignedProperties></xades:QualifyingProperties></ds:Object></ds:Signature>
Notice that the digest value is different, and the URI="" is missing.
So, the problem is that the library that is doing the verefication (DSS) is ignoring the hash that we send to it because of the URI="" and verification fails.
And we cannot remove the URI="" because than the SignedData value will change and the verification will also fail.
So, it seems that we have to construct the real detached signature from enveloped, and we don't see how. Is there any solution to this?
I'm afraid there is no solution to this. When validating the signature, the validation system/library will parse the XML and reconstruct the signed hashes based on the URIs specified in the references. If the original XML is missing, the parsing will fail. End of story.
In the case of detached XAdES signatures, or Manifest-based signatures, the URI of the signed reference points to an external resource - in that case, hash-based validation works because no XML processing is needed on the original document.