7.5 Credential Validation and Path Validation
All changes in this version
Title changed
Before · SP 800-116
Credential Validation and Path Validation
After · SP 800-116 Rev. 1
Credential Validation and Path Validation
Control changed
Before · SP 800-116
Credential validation is the process of determining if a presented identity credential is valid, i.e., was legitimately issued and has not expired or been terminated. On-line credential validation is extremely valuable to relying parties because it retrieves the most up-to-date credential status, and can block fraudulent use of a PIV Card that has been terminated as lost or stolen. Credential validation is required by the PKI authentication mechanism, and can be implemented for BIO, BIO-A, CAK, and CHUID authentication mechanisms. FIPS 201 Section 5.4.5 states, “The presence of a valid, unexpired, and unrevoked PIV authentication certificate on a card is proof that the card was issued and is not revoked.” FIPS 201 Section 6.2 further says, “The status of the PIV authentication certificate is directly tied to the status of all other credential elements held by the card.” These statements imply that PIV credential validation may be done by performing path validation (see below) on the PIV Authentication Key certificate or Card Authentication Key certificate. Since the expiration date of a PIV Card is contained in the CHUID, a relying party can determine if a PIV Card has expired by reading the CHUID, verifying the CHUID’s signature, then extracting and comparing the expiration date with the current date received from a trusted source. On-line, on-demand credential validation may not always be practical, due to absence of network connectivity to the PCI, or inadequate response time. In these circumstances, it may be possible for PIV Cards of interest to be registered with a caching status proxy. The caching status proxy can poll the status of all registered cards periodically, and cache the status responses from their issuer(s). Relying parties will see quick query-response service from the caching status proxy. The cache status should be updated at least once every 24 hours. Recommendation: On-line credential validation should be implemented for all of the FIPS 201 authentication mechanisms whenever possible. It is especially important when the one-factor, non-biometric mechanisms (CHUID, CAK) are used, because they could be exploited by simple possession of a misappropriated PIV Card. Caching techniques can be used to implement credential validation when on-line, on-demand credential validation is not possible. It is also recommended that the cached data be protected against tampering. Data objects read from a smart card by a reader should not be fully trusted as authentic (i.e., produced by a PCI) and unmodified until their digital signatures are verified. Most data objects in a PIV card-application have embedded digital signatures (i.e., all certificates, the CHUID, fingerprint template, facial image, and security object). The Printed Information Buffer must be signed by the Security Object, and the Card Capability Container may be signed by the Security Object. Path validation (or trust path validation ) is the process of verifying the binding between the subject identifier and subject public key in a certificate, based on the public key of a trust anchor, through the validation of a chain of certificates that begins with a certificate issued by the trust anchor and ends with the target certificate. The public key of a trust anchor is implicitly trusted by the relying party (generally, this means it was installed into the relying system by means of a trusted process, such as a direct device-to-device copy). Full trust in a PIV authentication mechanism requires that path validation succeed for each PIV data object used by the mechanism. 11
The PKI authentication mechanism requires path validation to be performed on the PIV Authentication Key certificate. FIPS 201 does not require that path validation be performed for the BIO, BIO-A, CHUID, and CAK authentication mechanisms; however, these authentication mechanisms can be fully trusted only if path validation is performed. In the absence of path validation, an impostor could forge a fingerprint template and a CHUID object, for example, with signatures from a phony Certification Authority. BIO authentication would succeed with this counterfeit PIV Card, and the forgery would not be detected. Because credential validation is a special case of path validation, both services can be economically implemented by a single PACS service component. Recommendation: Path validation should be performed on all signed data objects required by the authentication mechanism in use. Path validation should employ on-line credential validation where possible, or cached certificate status where on-line certificate validation is not possible.
After · SP 800-116 Rev. 1
Credential validation is the process of determining if a presented identity credential is valid, i.e., was legitimately issued and has not expired or been terminated. On-line credential validation is extremely valuable to relying parties because it retrieves the most up-to-date credential status, and can block fraudulent use of a PIV Card that has been terminated as lost or stolen. Credential validation is required by the PKI authentication mechanism, and can be implemented for BIO, BIO-A, CAK, and CHUID authentication mechanisms. FIPS 201 Section 5.4.5 states, “The presence of a valid, unexpired, and unrevoked PIV authentication certificate on a card is proof that the card was issued and is not revoked.” FIPS 201 Section 6.2 further says, “The status of the PIV authentication certificate is directly tied to the status of all other credential elements held by the card.” These statements imply that PIV credential validation may be done by performing path validation (see below) on the PIV Authentication Key certificate or Card Authentication Key certificate. Since the expiration date of a PIV Card is contained in the CHUID, a relying party can determine if a PIV Card has expired by reading the CHUID, verifying the CHUID’s signature, then extracting and comparing the expiration date with the current date received from a trusted source. On-line, on-demand credential validation may not always be practical, due to absence of network connectivity to the PCI, or inadequate response time. In these circumstances, it may be possible for PIV Cards of interest to be registered with a caching status proxy. The caching status proxy can poll the status of all registered cards periodically, and cache the status responses from their issuer(s). Relying parties will see quick query-response service from the caching status proxy. The cache status should be updated at least once every 24 hours. Recommendation: On-line credential validation should be implemented for all of the FIPS 201 authentication mechanisms whenever possible. It is especially important when the one-factor, non-biometric mechanisms (CHUID, CAK) are used, because they could be exploited by simple possession of a misappropriated PIV Card. Caching techniques can be used to implement credential validation when on-line, on-demand credential validation is not possible. It is also recommended that the cached data be protected against tampering. Data objects read from a smart card by a reader should not be fully trusted as authentic (i.e., produced by a PCI) and unmodified until their digital signatures are verified. Most data objects in a PIV card-application have embedded digital signatures (i.e., all certificates, the CHUID, fingerprint template, facial image, and security object). The Printed Information Buffer must be signed by the Security Object, and the Card Capability Container may be signed by the Security Object. Path validation (or trust path validation ) is the process of verifying the binding between the subject identifier and subject public key in a certificate, based on the public key of a trust anchor, through the validation of a chain of certificates that begins with a certificate issued by the trust anchor and ends with the target certificate. The public key of a trust anchor is implicitly trusted by the relying party (generally, this means it was installed into the relying system by means of a trusted process, such as a direct device-to-device copy). Full trust in a PIV authentication mechanism requires that path validation succeed for each PIV data object used by the mechanism. 11
The PKI authentication mechanism requires path validation to be performed on the PIV Authentication Key certificate. FIPS 201 does not require that path validation be performed for the BIO, BIO-A, CHUID, and CAK authentication mechanisms; however, these authentication mechanisms can be fully trusted only if path validation is performed. In the absence of path validation, an impostor could forge a fingerprint template and a CHUID object, for example, with signatures from a phony Certification Authority. BIO authentication would succeed with this counterfeit PIV Card, and the forgery would not be detected. Because credential validation is a special case of path validation, both services can be economically implemented by a single PACS service component. Recommendation: Path validation should be performed on all signed data objects required by the authentication mechanism in use. Path validation should employ on-line credential validation where possible, or cached certificate status where on-line certificate validation is not possible.