...
In the context of today's Internet traffic, transaction are mostly untrusted which has led to digital identity theft, spoofing, man in the middle attacks and ransomware. The advent of verifiable credentials brings the promise of a more trustworthy infrastructure for reliable transactions. When that infrastructure is combined with other trust assurance elements, verifiable credentials can be highly trustworthy and relied upon for a myriad of transformative digital applications.
The concept of classes for credentials is far from new. Back in late 1990's the US Office of Management and Budget had issued guidance, OMB M-04-04, which defined four levels of assurance, Levels 1 to 4, in terms of the consequences of authentication errors and misuse of identification credentials:
- Level 1 - Little or no confidence in the asserted identity’s validity;
- Level 2 - Some confidence in the asserted identity’s validity;
- Level 3 - High confidence in the asserted identity’s validity; and
- Level 4 - Very high confidence in the asserted identity’s validity.
The OMB guidance defined the required level of authentication assurance in terms of the likely consequences of an authentication error. As the consequences of an authentication error become more serious, the required level of assurance increases. The OMB guidance provided US Federal agencies with the criteria for determining the level of authentication assurance required for specific applications and transactions, based on the risks and their likelihood of occurrence of each application or transaction.
An example of assigning class levels to digital credentials exist for SSL/TLS certificates that encrypt traffic from clients to web servers to protect web traffic. Classes of server authentication certificates have ben established as follows:
- Class 1 Certificates are considered to be low assurance, as the verification method simply confirms that the Subscriber controls the asserted email address. No verification checks of the Subscriber’s identity are performed. This level of validation is referred to as Domain Validation (DV).
- Class 2 Certificates are considered to be medium assurance. They provide a greater level of assurance over Class 1 Certificates, because in addition to email address control, basic verification steps are performed to confirm the identity of the Subscriber. This level of validation is referred to as Organization Validation (OV). The following Certificate types qualify as Class 2 Certificates:
- Standard SSL
- Wildcard SSL
- Code Signing
- Document Signing
- Class 3 Certificates provide a high level of assurance. They are issued only after rigorous validation of the identity of the Subscriber. This level of validation is referred to as Extended Validation (EV). The following Entrust Certificate types qualify as Class 3 Certificates:
- EV SSL
- EV Code Signing
The US National Institute of Standards (NIST) has NIST has more recently published (https://pages.nist.gov/800-63-3/sp800-63-3.html) generally accepted associated classes as it relates to identity credentials. Digital identity as a legal identity further complicates the definition and ability to use digital identities across a range of social and economic use cases. Digital identity is hard. Proving someone is who they say they are — especially remotely, via a digital service — is fraught with opportunities for an attacker to successfully impersonate someone. The standards associated with identity assurance create a solid model for other claims made in a verifiable credential
...
In order to define discrete class classes of verifiable transactions, it is key to identify the variables that make a credential more trustable. The following are factors embodied in the class definitions:
- Credential defined in a Governance Framework at a stated level of assurance
- The degree of assurance that the public key of the signer in a verifiable credential is matched to the possessor of the private key
- The degree of authentication of data that is performed on the contents of a verifiable credential
- The security and protection of the wallet containing the credential
- The security and availability of a registry containing in the credential (if not held in a wallet)
- The security and availability of the public key in a credential for verification purposes
- The trustworthiness of the personnel and infrastructure of the Issuer of a verifiable credential
- The asserted policies of the Issuer
- The degree that practices that meet the Issuer policies are part of a trust assurance scheme
- The rigor of a trust assurance scheme of the ecosystem that governs the credential
Proposed Classes of Verifiable Credentials
The next sections on this page present the proposed classes of credentials under Trust over IP guidance
Class 1 – Untrusted Credentials
Attribute of class: Credentials that are not under standard or ToIP guidance
...
- Credential defined in a Governance Framework at a stated level of assurance: No
- The degree of commensurate assurance that the public key of the signer in a verifiable credential is matched to the possessor of the private key : No assurance(early OMB guidance): Level 1
- The degree of authentication of data that is performed on the contents of a verifiable credential: None
- The security and protection of the wallet containing the credential: None
- The security and availability of a registry containing in the credential (if not held in a wallet): No controls
- The security and availability of the public key in a credential for verification purposes: No requirements
- The trustworthiness of the personnel and infrastructure of the Issuer of a verifiable credential: No requirements
- The asserted policies of the Issuer: No requirements
- The degree that practices that meet the Issuer policies are part of a trust assurance scheme: No trust assurance scheme
- The rigor of a trust assurance scheme of the ecosystem that governs the credential: No trust assurance scheme
- Mapped Level to other Standards:
- NIST 800-63-3: IAL1, AAL1, FAL1
- PCTF: Level 1
- eIDAS: Low
- Vectors of Trust: P0, C0 Ma, Aa
Class 2 – Minimum Internet Grade Credentials
Examples: College transcripts, professional credentials, loyalty credentials
- Attributes of Class:
- Credentials covered under minimum guidance of the ToIP Foundation : Includes most unregulated verifiable claims
- Example credentials: College degree credentials, non-title provenance claims
- Credential defined in a Governance Framework at a stated level of assurance: Yes at Class 2
- The degree of commensurate assurance that the public key of the signer in a verifiable credential is matched to the possessor of the private key : Moderate Assurance(early OMB guidance): Level 2
- The degree of authentication of data that is performed on the contents of a verifiable credential: Authentication Procedures are in place and self-asserted
- The security and protection of the wallet containing the credential: ToIP Compliant Wallet Optional
- The security and availability of a registry containing in the credential (if not held in a wallet): Moderate controls identified in Class 2 Credential Policy
- The security and availability of the public key in a credential for verification purposes: Moderate controls identified in Class 2 Credential Policy
- The trustworthiness of the personnel and infrastructure of the Issuer of a verifiable credential: Moderate controls identified in Class 2 Credential Policy
- The asserted policies of the Issuer: Class 2 Credential Policy
- The degree that practices that meet the Issuer policies are part of a trust assurance scheme: A Defined Trust Assurance Framework
- The rigor of a trust assurance scheme of the ecosystem that governs the credential: Self-Assertion by ecosystem roles
- US Federal PKI equivalence: Basic Assurance
- Mapped Level to other Standards:
- NIST 800-63-3: IAL2, AAL1, FAL1
- PCTF: Level 2
- eIDAS: Between low and substantial
- Vectors of Trust: P2, Ce, Mb, Ab?
Class 3 – Asset Value Grade Credentials
Examples: Digital driver's license, bank transfer credentials. Title claims
- Attributes of Class:
- Identity Credential Used for Asset Transfer such as digital driver's license, passport or bank identity credential, title claims
- Credential defined in a Governance Framework at a stated level of assurance: Yes at Class 3
- The degree of commensurate assurance that the public key of the signer in a verifiable credential is matched to the possessor of the private key : Medium Assurance(early OMB guidance): Level 3
- The degree of authentication of data that is performed on the contents of a verifiable credential: Authentication Procedures are in place, asserted and attested by a third party
- The security and protection of the wallet containing the credential: ToIP Compliant Wallet Required (Layer2)
- The security and availability of a registry containing in the credential (if not held in a wallet): Medium level controls identified in Class 3 Credential Policy
- The security and availability of the public key in a credential for verification purposes: Medium level controls identified in Class 3 Credential Policy
- The trustworthiness of the personnel and infrastructure of the Issuer of a verifiable credential: Medium level controls identified in Class 3 Credential Policy
- The asserted policies of the Issuer: Class 3 Credential Policy
- The degree that practices that meet the Issuer policies are part of a trust assurance scheme: A Defined Trust Assurance Framework
- The rigor of a trust assurance scheme of the ecosystem that governs the credential: Assertion by ecosystem roles and attestation by independent third party
- Mapped Level to other Standards:
- NIST 800-63-3: IAL2, AAL2, FAL2
- PCTF: Level 3
- eIDAS: Substantial
- Vectors of Trust: P2, Cf, Mc, Ac?
Class 4 – High Assurance Grade Credentials
Examples: Clearance credentials, Military operations, access to Coke recipe.
- Attributes of Class:
- Identity Credential Used for High Assurance, High Value, Sensitive Purposes
- Credential defined in a Governance Framework at a stated level of assurance: Yes at Class 4
- The degree of commensurate assurance that the public key of the signer in a verifiable credential is matched to the possessor of the private key : High Assurance(early OMB guidance): Level 4
- The degree of authentication of data that is performed on the contents of a verifiable credential: Authentication Procedures are in place, asserted and attested by a third party and certified by a recognized certification body
- The security and protection of the wallet containing the credential: ToIP Compliant Wallet Required (Layer2) that is FIPS 140-2 3 compliant
- The security and availability of a registry containing in the credential (if not held in a wallet): High level controls identified in Class 4 Credential Policy
- The security and availability of the public key in a credential for verification purposes: High level controls identified in Class 4 Credential Policy
- The trustworthiness of the personnel and infrastructure of the Issuer of a verifiable credential: High level controls identified in Class 4 Credential Policy
- The asserted policies of the Issuer: Class 4 Credential Policy
- The degree that practices that meet the Issuer policies are part of a trust assurance scheme: A Defined Trust Assurance Framework
- The rigor of a trust assurance scheme of the ecosystem that governs the credential: Assertion by ecosystem roles and attestation by independent third party and certified by a recognized certification body
- Mapped Level to other Standards:
- NIST 800-63-3: IAL3, AAL3, FAL3
- PCTF: Level 4
- eIDAS: High
- Vectors of Trust: P3, Cf, Mc, Ad?
...