XML Signature Validation Token

2.1. Notation

3.1. SignatureValidationToken Signature Property

The <svt:SignatureValidationToken> element MUST be placed in a <ds:SignatureProperty> element in accordance with [XMLDSIG11]. The <ds:SignatureProperty> element MUST be placed inside a <ds:SignatureProperties> element inside a <ds:Object> element inside a <ds:Signature> element.¶

Note: [XMLDSIG11] requires the Target attribute to be present in <ds:SignatureProperty>, referencing the signature targeted by this signature property. If an SVT is added to a signature that do not have an Id attribute, implementations SHOULD add an Id attribute to the <ds:Signature> element and reference that Id in the Target attribute. This Id attribute and Target attribute value matching is required by the [XMLDSIG11] standard, but it is redundant in the context of SVT validation as the SVT already contains information that uniquely identifies the target signature. Validation applications SHOULD not reject an SVT token because of Id and Target attribute mismatch, and MUST rely on matching against signature using signed information in the SVT itself.¶

The <svt:SignatureValidationToken> element is defined by the following XML Schema:¶

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
    elementFormDefault="qualified"
    targetNamespace="http://id.swedenconnect.se/svt/1.0/sig-prop/ns"
    xmlns:svt="http://id.swedenconnect.se/svt/1.0/sig-prop/ns">

  <xs:element name="SignatureValidationToken"
      type="svt:SignatureValidationTokenType" />

  <xs:complexType name="SignatureValidationTokenType">
    <xs:simpleContent>
      <xs:extension base="xs:string">
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>

</xs:schema>

The SVT token MUST be included as a string representation of the SVT JWT. Note that this is the string representation of the JWT without further encoding. The SVT MUST NOT be represented by the Base64 encoded bytes of the JWT string.¶

Example:¶

<ds:Signature Id="MySignatureId">
  ...
  <ds:Object>
    <ds:SignatureProperties>
      <ds:SignatureProperty Target="#MySignatureId">
        <svt:SignatureValidationToken>
              eyJ0eXAiOiJKV1QiLCJhb...2aNZ
        </svt:SignatureValidationToken>
      </ds:SignatureProperty>
    </ds:SignatureProperties>
  </ds:Object>
</ds:Signature>

3.2. Multiple SVT in a signature

If a new SVT is stored in a signature which already contains a previously issued SVT, implementations can choose to either replace the existing SVT or to store the new SVT in addition to the existing SVT.¶

If the new SVT is stored in addition to the old SVT, it SHOULD be stored in a new <ds:SignatureProperty> element inside the existing <ds:SignatureProperties> element where the old SVT is located.¶

For interoperability robustness, signature validation applications MUST be able to handle signatures where the new SVT is located in a new <ds:Object> element.¶

4.1. Profile Identifer

When this profile is used the SigValidation object MUST contain a "profile" claim with the value "XML".¶

4.2. Signature Reference Data

The SVT Signature object MUST contain a "sig_ref" claim (SigReference object) with the following elements:¶

• "id" -- The Id-attribute of the XML signature, if present.¶
• "sig_hash" -- The hash over the signature value bytes.¶
• "sb_hash" -- The hash over the canonicalized <ds:SignedInfo> element (the bytes the XML signature algorithm has signed to generated the signature value).¶

4.3. Signed Data Reference Data

The SVT Signature object MUST contain one instance of the "sig_data" claim (SignedData object) for each <ds:Reference> element in the <ds:SignedInfo> element. The "sig_data" claim MUST contain the following elements:¶

• "ref" -- The value of the URI attribute of the corresponding <ds:Reference> element.¶
• "hash" -- The hash of all bytes identified corresponding <ds:Reference> element after applying all identified canonicalization and transformation algorithms. These are the same bytes that is hashed by the hash value in the <ds:DigestValue> element inside the <ds:Reference> element.¶

4.4. Signer Certificate References

The SVT Signature object MUST contain a "signer_cert_ref" claim (CertReference object). The "type" parameter of the "signer_cert_ref" claim MUST be either "chain" or "chain_hash".¶

• The "chain" type MUST be used when signature validation was performed using one or more certificates where some or all of the certificates in the chain are not present in the target signature.¶
• The "chain_hash" type MUST be used when signature validation was performed using one or more certificates where all of the certificates are present in the target signature.¶

5.1. SVT Signing Key Reference

The SVT JOSE header must contain one of the following header parameters in accordance with [RFC7515], for storing a reference to the public key used to verify the signature on the SVT:¶

• "x5c" -- Holds an X.509 certificate [RFC5280] or a chain of certificates. The certificate holding the public key that verifies the signature on the SVT MUST be the first certificate in the chain.¶
• "kid" -- A key identifier holding the Base64 encoded hash value of the certificate that can verify the signature on the SVT. The hash algorithm MUST be the same hash algorithm used when signing the SVT as specified by the alg header parameter.¶