cdaefa:EFA Policy Assertion SAML2 Binding
Inhaltsverzeichnis
SAML 2.0 Profile for ECR Policy Assertions
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This profile applies to scenarios where the eCR Context Manager requests an Access Policy Assertion from the eCR Policy Provider and thus implements a policy push authorization model. There is no specification in the case that the Authorization Decision Provider requests policies from the eCR Policy Provider. |
| Assertion Element | Opt | Usage Convention | |||
|---|---|---|---|---|---|
| @Version | R | MUST be “2.0” | |||
| @ID | R | URN encoded unique identifier (UUID) of the assertion | |||
| @IssueInstant | R | Time instant of issuance in UTC | |||
| Issuer | R | Address URI that identifies the endpoint of the issuing service | |||
| Subject | R | This element defines the subject confirmation method of the user in order to use the Policy Assertion as a supporting token. Moreover, it defines the subject name identifier that accords with the user identity from an Identity Assertion. | |||
| NameID | R | Identifier of the HP given in the Identity Asstertion encoded as an X.509 subject name, an e-Mail address or as a string value (unspecified format). Only identifiers must be used that can be long-term tracked back to an individual person. | |||
| @Format | R | MUST be urn:oasis:names:tc:SAML:1.1:nameid-format:unspecified or urn:oasis:names:tc:SAML:1.1:nameid-format:X509SubjectName | |||
| SubjectConfirmation | R | ||||
| @Method | R | This element MUST hold a URI reference that identifies a protocol to be used to authenticate the subject.[SAML2.0core] The value of this element MUST be set to | |||
| SubjectConfirmationData | R | ||||
| ds:KeyInfo | R | The XML Signature [XMLSignature] element MUST embed a cryptographic key that is only held by the user. This can be the user’s public key (ds:KeyValue/ds:RSAKeyValue), the complete user’s X.509 certificate (ds:X509Data/ds:X509Certificate), or an encrypted symmetric key (xenc:EncryptedKey [XMLEncryption]). This symmetric key MUST be encrypted by using the public key of the consumer service’s certificate [eFA PKI 1.2]. | |||
| Conditions | R | ||||
| @NotBefore | R | time instant from which the assertion is useable. This condition MUST be assessed by the assertion consumer to proof the validity of the assertion. | |||
| @NotOnOrAfter | R | Time instant at which the assertion expires. This condition MUST be assessed by the assertion consumer to proof the validity of the assertion. The maximum validity timespan for a Policy Assertion MUST NOT be more than 4 hours. | |||
| XACMLPolicyStatement | R | ||||
| PolicySet | R | PolicySet that expresses the given authorization (see section below for details). | |||
| ds:Signature | R | Enveloped XML signature of the issuer of the Policy Assertion (see section below for details). | |||
PolicySet Profile
The ECR 2.0 specification differentiates three kinds of an authorization statement as it is described logically in the security token services section for the Policy Provider. These are:
- Reference without semantics (policyId) to an access policy which contains the valid authorization rules for an eCR Consumer
- Reference with semantics (e.g., as per IHE BPPC)
- Access policy which contains the valid authorization rules for an eCR Consumer
In order to implement such differentiations the <PolicySet> element has different sub-elements.
Policy Assignment
| PolicySet Element | Opt | Usage Convention | |||||
|---|---|---|---|---|---|---|---|
| @PolicySetId | R | URN encoded unique identifier (UUID) of the policy set. | |||||
| @PolicyCombiningAlgId | R | This attribute is REQUIRED. Its value is a predefined identifier of the policy-combining algorithm for this policy set (see Appendix C and section B.10 in [XACML2.0Core]). The urn:oasis:names:tc:xacml:1.0:policy-combining-algorithm:ordered-permit-overrides algorithm has been used. Other algorithms are not allowed. | |||||
| Target | R | This element is used to specify the resource match (i.e., purpose) | |||||
| Subjects | R | This element contains one xacml:Subject element. | |||||
| Subject | R | It contains one xacml:SubjectMatch element. | |||||
| SubjectMatch | R | It defines matches of the subject attributes. | |||||
| @MatchId | R | Its value specifies the matching function. The identifier must refer to the subject nameID format of the Identity Assertion. The following list defines the used identifier for this policy (see A.3.13 in [XACML2.0Core]):
| |||||
| AttributeValue | R | It defines the regular expression for matching. | |||||
| @DataType | R | Its value is either http://www.w3.org/2001/XMLSchema#string, urn:oasis:names:tc:xacml:1.0:data-type:x500Name, or urn:oasis:names:tc:xacml:1.0:data-type:rfc822Name that corresponds to the subject match. | |||||
| SubjectAttributeDesignator | R | It defines the designator of a resource attribute. | |||||
| @AttributeId | R | It specifies the identifier of the attribute that is used for matching. The value of this attribute is set to urn:oasis:names:tc:xacml:1.0:resource:resource-id. | |||||
| @DataType | R | It specifies the type of the values that the resource attribute designator returns. The value of this attribute is set to http://www.w3.org/2001/XMLSchema#anyURI. | |||||
| Resources | R | This element contains one xacml:Resource element. | |||||
| Resource | R | It contains one xacml:ResourceMatch element. | |||||
| ResourceMatch | R | It defines matches of the resource attributes. | |||||
| @MatchId | R | Its value specifies the matching function. The identifier urn:oasis:names:tc:xacml:1.0:function:anyURI-regexp-match is defined to use regular expressions (see A.3.13 in [XACML2.0Core]). | |||||
| AttributeValue | R | It defines the regular expression for matching. | |||||
| @DataType | R | Its value is http://www.w3.org/2001/XMLSchema#string to indicate that the attribute value is of string simple type. | |||||
| ResourceAttributeDesignator | R | It defines the designator of a resource attribute. | |||||
| @AttributeId | R | It specifies the identifier of the attribute that is used for matching. The value of this attribute is set to urn:oasis:names:tc:xacml:1.0:resource:resource-id. | |||||
| @DataType | R | It specifies the type of the values that the resource attribute designator returns. The value of this attribute is set to http://www.w3.org/2001/XMLSchema#anyURI. | |||||
| PolicySetIdReference | R | Its value either references an assigned access policy that is expressed in a separate XACML PolicySet or already expresses the given authorization. | |||||
Policy Attachment
It is implementation-specific how the PolicySet with the authorization rules is defined - there are no restrictions made. However, there MUST NOT be used further PolicyIdReference or PolicySetIdReference elements.
Assertion Signature
Every Policy Assertion MUST be signed by its issuer. The XML signature MUST be applied by using the saml:Assertion/ds:Signature element as defined below.
| Signature Parameter | Usage Convention |
|---|---|
| CanonicalizationMethod | SHOULD be http://www.w3.org/2001/10/xml-exc-c14n# |
| Transformation | Enveloped signature transform acc. to section 6.6.4 of [W3C XMLDSig] SHOULD be used (http://www.w3.org/2000/09/xmldsig#enveloped-signature). In addition, exclusive canonicalization SHOULD be defined as transformation (http://www.w3.org/2001/10/xml-exc-c14n#, acc. [W3C XMLDSig] and [W3C XML-EXC 1.0]). As inclusive namespaces other prefixes than the ones defined in EFA Namespaces MUST NOT be used. |
| SignatureMethod | For signing assertions the signature method http://www.w3.org/2001/04/xmldsig-more#rsa-sha256 or |
| DigestMethod | For signing assertions the digest method http://www.w3.org/2000/09/xmldsig#sha1 or |
| KeyInfo | This element MUST either contain a wsse:SecurityTokenReference element which references the X.509 certificate of the assertion’s issuer by using a subject key identifier OR contain a ds:X509Data element which contains the X.509 certificate of the assertion issuer. |
Example Assertion
<soap12:Envelope … >
<soap12:Header … >
<wsse:Security … >
<saml:Assertion xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
ID="uuid-6dbb391c-20d3-4568-8c04-ff9d91d049c1"
IssueInstant="2013-04-05T08:14:28.788Z" Version="2.0">
<saml:Issuer>urn:de:berlin:hp:pap</saml:Issuer>
<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
<ds:SignedInfo>
<ds:CanonicalizationMethod
Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#" />
<ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1" />
<ds:Reference URI="#urn:uuid:7102AC72154DCFD1F51253534608780">
<ds:Transforms>
<ds:Transform
Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature" />
<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 saml xs" />
</ds:Transform>
</ds:Transforms>
<ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1" />
<ds:DigestValue>A1LyLvFHRrYaOJ28YVFd3MfKGSI=</ds:DigestValue>
</ds:Reference>
</ds:SignedInfo>
<ds:SignatureValue>ggyn … LQ==</ds:SignatureValue>
<ds:KeyInfo>
<ds:X509Data>
<ds:X509Certificate> … </ds:X509Certificate>
</ds:X509Data>
</ds:KeyInfo>
</ds:Signature>
<saml:Subject>
<saml:NameID
Format="urn:oasis:names:tc:SAML:1.1:nameid-format:X509SubjectName">
...
</saml:NameID>
<saml:SubjectConfirmation
Method="urn:oasis:names:tc:SAML:2.0:cm:holder-of-key">
<saml:SubjectConfirmationData>
<ds:KeyInfo>
<ds:X509Data>
<ds:X509Certificate> … </ds:X509Certificate>
</ds:X509Data>
</ds:KeyInfo>
</saml:SubjectConfirmationData/>
</saml:SubjectConfirmation>
</saml:Subject>
<saml:Conditions
NotBefore="2013-04-05T08:14:28.788Z"
NotOnOrAfter="2013-04-05T12:14:28.788Z">
</saml:Conditions>
<xacml-saml:XACMLPolicyStatement>
<xacml:PolicySet>
...
</xacml:PolicySet>
</xacml-saml:XACMLPolicyStatement>
</saml:Assertion>
</wsse:Security>
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