From e50b1ceaf9c28256c972788ef6990175a4f5d715 Mon Sep 17 00:00:00 2001 From: Stephen Curran Date: Thu, 21 Dec 2023 19:38:29 +0000 Subject: [PATCH 1/5] Finalize - pending review - the terminolgy for the specification Signed-off-by: Stephen Curran --- spec/terminology.md | 236 +++++++++++++++++++++++++++----------------- 1 file changed, 148 insertions(+), 88 deletions(-) diff --git a/spec/terminology.md b/spec/terminology.md index 3c870ac..f28d0c4 100644 --- a/spec/terminology.md +++ b/spec/terminology.md @@ -1,137 +1,197 @@ ## Terminology -[[def: blinding factor]] -~ A blinding factor is a random 3152 bit selected from the set of integers up to the order of the RSA group, `n`. It is generated by the [[ref:holder]] to blind the their [[ref:link secret]] during credential issuance. The blinding factor can then be removed from the signature the [[ref:issuer]] produces to retrieve a valid signature over the unblinded [[ref:link secret]]. A blinding factor is similarly generated for each non-disclosed attribute during credential presentation, such that a [[ref: holder]] can prove they know these values without revealing them to the [[ref: verifier]]. +[[def: Accumulator, accumulator]] +~ A [cryptographic accumulator] is used space- and time-efficient method of proving a value membership is in a set of values without revealing the individual members of the set. In AnonCreds v1, an accumulator is a core element of the [[ref: verifiable credential]] revocation mechanism. -[[def: claim, claims]] -~ A claim is a part of digital identity related to a [[ref: subject]]. A claim can be attested by the identity subject itself, or it can be asserted by another entity. +[[def: AnonCreds Method, AnonCreds method, AnonCreds Methods, AnonCreds methods]] -[[def: Credential Key Correctness Proof]] -~ This is produced during the creation of the [[ref: Credential Definition]] and is included in the [[ref: Credential Offer]] so that the [[ref:holder]] can verify that the [[ref: Public Credential Definition]] used in the blinding process belongs to the [[ref:issuer]]. +~ AnonCreds methods specify how AnonCreds objects are written (registered) and read (resolved) on a given [[ref: verifiable data registry]] implementation. AnonCreds was originally written to use [Hyperledger Indy] as its only [[ref: VDR]] implementation, but the evolution of AnonCreds to enable storing objects on any [[ref: VDR]] implementation means that AnonCreds methods (comparable to [[ref: DID Methods]] from the [DID Core specification]) are necessary. AnonCreds Methods are defined in the [AnonCreds Methods Registry] repository. -[[def: Signature Correctness Proof]] -~ A ZKP based proof to show that a signature to a message is valid, without revealing the message or signature. +[Hyperledger Indy]: https://www.hyperledger.org/projects/hyperledger-indy +[DID Core specification]: https://www.w3.org/TR/did-core/ +[AnonCreds Methods Registry]: https://hyperledger.github.io/anoncreds-methods-registry/ + +[[def: AnonCreds Objects, AnonCreds objects]] + +~ The published and shared data objects used in AnonCreds v1.0 including the published objects [[ref: schema]], [[ref: credential definition]], [[ref: revocation registry definition]], [[ref: revocation registry entry]] and the shared objects [[ref: credential offer]], [[ref: credential request]], and [[ref: presentation request]]. + +[[def: BigNumber, BigNumbers]] + +~ A [BigNumber] is an data object which safely allows mathematical operations on numbers of any magnitude. BigNumbers are commonly used in cryptography schemes, including those underlying AnonCreds v1.0. + +[BigNumber]: https://docs.ethers.org/v5/api/utils/bignumber/ + +[[def: Blinded Secret, Blinded secret, blinded secret, unblinded secret, Unblinded secret]] + +~ A cryptographic technique where a secret value (a number) is blinded before it is shared such that the sender can later prove knowledge ("unblind") of the secret value. The AnonCreds v1.0 [[ref: link secret]] +mechanism is based on the use of a blinded secret. [[def: Blinded Secrets Correctness Proof]] -~ A ZKP based proof to show that some blinded secret was produced correctly from an unblinded secret without exposing the secret to anyone. -[[def: credential, credentials]] +~ A [[ref: ZKP]]-based proof that can be verified to show that a [[ref: blinded secret]] was produced correctly from an [[ref: unblinded secret]] without exposing the secret. + +[[def: Blinding Factor, blinding factor]] + +~ A blinding factor is a random 3152 bit selected from the set of integers up to the order of the RSA group, `n`. It is generated by the [[ref:holder]] to blind the their [[ref:link secret]] during credential issuance. The blinding factor can then be removed from the signature the [[ref:issuer]] produces to retrieve a valid signature over the [[ref: unblinded link secret]]. A blinding factor is similarly generated for each non-disclosed attribute during credential presentation, such that a [[ref: holder]] can prove they know these values without revealing them to the [[ref: verifier]]. + +[[def: Call Home, Call home, call home]] + +~ Call home is a term used when evaluating the privacy characteristics of [[ref: verifiable credential]] deployments. If a [[ref: holder]] presenting data from a verifiable credential must always contact ("call home to") the [[ref: issuer]], [[ref: holder]] actions are open to the actual, or perception of, tracking of the holder by the issuer. [[ref: Verifiable credential]] schemes that do not make possible the tracking of [[ref: holder]] activities by [[ref: issuers]] are preferred. + +[[def: Claim, claim, claims, Claims]] + +~ A claim is a part of digital identity related to a [[ref: subject]]. A claim can be attested by the identity subject itself, or it can be asserted by another entity. + +[[def: Correlatability, correlatability, correlation, Correlation, correlatable, Correlatable]] + +~ When a verifiable credential scheme that has the attribute of [[ref: unlinkability]], the data from the process of sharing a [[ref: verifiable presentations]] with different verifiers cannot be correlated to identify the [[ref: holder]]. + +[[def: Credential, Credentials, credential, credentials, verifiable credential, verifiable credentials, Verifiable Credential, Verifiable Credentials]] + ~ A credential is a set of [[ref: claims]] about an identity [[ref: subject]]. A verifiable credential is a tamper-proof credential whose authorship is cryptographically verifiable. An anonymous credential, also known as AnonCreds, is a verifiable credential that has privacy-preserving properties to enable data minimization and correlation resistance. -[[def: Credential Definition, Credential Definitions, Public Credential Definition, Private Credential Definition]] -~ A Credential Definition (also known as CRED_DEF or CLAIM_DEF) contains data required for [[ref: credential]] issuance (used by the [[ref:issuer]]) as well as [[ref: credential]] validation data (used by the [[ref:holder]] and the [[ref:verifier]]). A Credential Definition is generated by the [[ref:issuer]] before [[ref:credential]] issuance and consists of two distinct but strongly related parts, the **Public Credential Definition** and **Private Credential Definition**. +[[def: Credential Definition, Credential Definitions, Public Credential Definition, Private Credential Definition, CredDef, CredDefs, credential definition, CLAIM_DEF, CRED_DEF]] + +~ A credential definition (also known as CRED_DEF or CLAIM_DEF) contains data required for [[ref: credential]] issuance (used by the [[ref:issuer]]) as well as [[ref: credential]] validation data (used by the [[ref:holder]] and the [[ref:verifier]]). A credential definition is generated by the [[ref:issuer]] before [[ref:credential]] issuance and consists of two distinct but strongly related parts, the **Public Credential Definition** that is published for everyone to use and **Private Credential Definition** that is held as a secret by the issuer and has the private keys necessary to generate signed [[ref: verifiable credentials]]. A credential definition may be generated such that credentials it produces can be revoked. + +[[def: Credential Key Correctness Proof]] -~ A **Public Credential Definition** part of a Credential Definition is a public object (e.g. on a ledger), that references a [[ref: Schema]], references a DID of the [[ref: issuer]] and can be [written](https://hyperledger-indy.readthedocs.io/projects/node/en/latest/requests.html#claim-def) to the ledger by any [[ref: issuer]] who intends to issue [[ref: credentials]] based on that specific [[ref: Schema]] and has the proper permissions in doing so. A Public Credential Definition has to be [accessible](https://hyperledger-indy.readthedocs.io/projects/node/en/latest/requests.html#get-claim-def) to all participants ([[ref:issuers]], [[ref:holders]], and [[ref:verifiers]]). A [[ref: Schema]] is in a 1:n relation with Public Credential Definition, meaning there can be many Public Credential Definition related to the same [[ref: Schema]] while a Credential Definition can only reference one single [[ref: Schema]]. Whenever an AnonCreds credential is issued, it is based on a Credential Definition. That means, the issued credential can only have the attributes listed in the [[ref:Schema]], which is referenced by the Public Credential Definition part. An exception to this is the blinded and signed [[ref:link secret]], an attribute which is part of every AnonCred credential. The [[ref: issuer]]`s public keys for verifying the attributes (one key for one attribute) are within the [[ref:Public Credential Definition]], which allows validation of the credentials by [[ref: verifiers]]. +~ A proof generated during the creation of the [[ref: credential definition]] and included in the [[ref: credential offer]] so that the [[ref:holder]] can verify that the published [[ref: credential definition]] used in the blinding process belongs to the [[ref:issuer]]. -~ The **Private Credential Definition** part of a Credential Definition is stored on the [[ref: issuer]]'s side and is an object that contains the [[ref:issuer]]`s private keys for signing the attributes (one key for one attribute) when issuing an AnonCreds [[ref:Credential]]. These private keys are used to create signature proofs for the issued anonymous credentials, which then can be validated in a derived form by a [[ref: verifier]] by using the published public keys of the Public Credential Definition part. A Private Credential Definition never leaves the [[ref: Issuer]]'s domain and is stored securely. +[[def: Credential Offer, credential offer, Credential offer]] -~ Revokable Verifiable Credentials require (besides) a Credential Definition also a [[ref: REV_REG_DEF]]. +~ A credential offer is a data object sent by an [[ref: issuer]] to a [[ref: holder]] offering to issue a [[ref: credential]]. The credential offer contains the details about the claims the [[ref: issuer]] intends to issue to the [[ref: holder]]. A [[ref: holder]] can reply to the [[ref: issuer]] with a [[ref: credential request]]. A credential offer also includes a [[ref: nonce]] and a [[ref: Credential Key Correctness Proof]]. -[[def: Credential Offer]] -~ A credential offer is an offering from an [[ref: issuer]] towards a [[ref: holder]] to issue a [[ref: credential]]. The credential offer contains the details about the claims the [[ref: issuer]] intends to issue to the [[ref: holder]]. A [[ref: holder]] can reply to the [[ref: issuer]] with a [[ref: Credential Request]]. A credential offer also includes a [[ref: nonce]] and a [[ref: Credential Key Correctness Proof]]. +[[def: Credential Request, credential request, Credential request]] -[[def: Credential Request]] -~ A credential request is a request from an [[ref: holder]] towards a [[ref: issuer]] to get a credential issued by the [[ref: issuer]]. The credential request references a preceding [[ref: Credential offer]] and defines the claims the [[ref: holder]] wants to get issued. A credential request also includes a [[ref: nonce]]. +~ A credential request is a request from an [[ref: holder]] towards a [[ref: issuer]] to get a credential issued by the [[ref: issuer]]. The credential request references a preceding [[ref: credential offer]] and defines the claims the [[ref: holder]] wants to get issued. A credential request also includes a [[ref: nonce]] that is later to use the issuance of the credential. + +[[def: Data Minimization, data minimization, Data minimization]] + +~ An attribute of verifiable data sharing schemes that considers privacy of a scheme based on the amount of data shared in a given interaction. Ideally, the minimum amount of data is shared for the business purpose of the interaction. Techniques such as [[ref: selective disclosure]], [[ref: predicates]], and [[ref: unlinkability]], all available in AnonCreds v1.0 support the goal of privacy-preserving, minimal data sharing. [[def: DID, DIDs]] -~ A Decentralized Identifier (DID), defined by the [W3C DID Core -Specification](https://w3c.github.io/did-core/), is a type of identifier that -enables verifiable, decentralized digital identity. A DID refers to any subject -(e.g., a person, organization, thing, data model, abstract entity, etc.) as -determined by the controller of the DID. DIDs are not used in AnonCreds itself -but there must be an DID-based, enforced relationship between the [[ref: schema -publishers]] and [[ref: issuers]] and the AnonCreds objects they publish. This -is outlined in a note in [this section](anoncreds-setup-data-flow) of this -specification. - -[[def: holder, holders]] -~ A holder, also known as an identity holder, is an entity that is in possession of a [[ref: credential]]. In many use cases, the holder is also the identity [[ref: subject]]. A holder can interact with an issuer to obtain anonymous credentials. It can also derive information from anonymous credentials that can be presented to a [[ref: verifier]] to gain access to goods and services. - -[[def: issuer, issuers]] + +~ A Decentralized Identifier (DID), defined by the [W3C DID Core Specification](https://w3c.github.io/did-core/), is a type of identifier that is useful in enabling verifiable, decentralized digital identity. A DID refers to any subject (e.g., a person, organization, thing, data model, abstract entity, etc.) as determined by the controller of the DID. DIDs are not used in AnonCreds itself but there must be a verifiable identifier (usually a DID) with an enforced relationship between [[ref: schema publishers]] and [[ref: issuers]] and the AnonCreds objects they publish. This is outlined in a note in [this specification section](#anoncreds-setup-data-flow). + +[[def: DID Method, DID method, DID Methods, DID methods]] + +~ DID methods specify how DID documents are written (registered) and read (resolved) on a given [[ref: verifiable data registry]] implementation, allowing DIDs to be registered and resolved in a wide variety of storage containers. The capabilities required by DID Methods are defined in the [DID Core specification], and the (many) DID Methods are defined in the [DID Methods Registry] repository. + +[DID Methods Registry]: https://www.w3.org/TR/did-spec-registries/#did-methods + +[[def: Holder, Holders, holder, holders, prover, Prover]] + +~ A holder, also known as an identity holder and prover, is an entity that is in possession of a [[ref: credential]]. In many use cases, the holder is also the identity [[ref: subject]]. A holder can interact with an issuer to obtain anonymous credentials. It can also derive information from anonymous credentials that can be presented to a [[ref: verifier]] to gain access to goods and services. A prover is a synonym for holder that is often used in a holder-[[ref: verifier]] interaction. In this specification, we only use the term "holder", however the underlying implementations use "prover" in code. + +[[def: Issuer, Issuers, issuer, issuers]] + ~ An issuer is one of the three entities that interact with each other within the domain of digital identities. It can assert [[ref: claims]] about a [[ref: subject]] in the form of a tamper-proof credential whose origins are cryptographically verifiable. -[[def: Issuer Identifier, Issuer Identifiers]] -~ An issuer identifier is a unique identifier for an [[ref: issuer]]. It is used to identify the [[ref: issuer]] of AnonCreds objects published to a [[ref: Verifiable Data Registry]] . See [Issuer Identifiers](#issuer-identifiers) for details. +[[def: Issuer Identifier, Issuer Identifiers, issuer identifier, issuer identifiers]] + +~ An issuer identifier is a unique identifier for an [[ref: issuer]]. It is used to identify the [[ref: issuer]] of AnonCreds objects published to a [[ref: Verifiable Data Registry]]. + +[[def: Link secret, link secret, blinded link secret, unblinded link secret]] + +~ A link secret is a unique identifier known only to the [[ref: holder]] used in AnonCreds to bind credentials issued to a [[ref: holder]] to that [[ref: holder]], and to demonstrate that all of the source verifiable credentials in a presentation are bound to the same link secret that is known to the [[ref: holder]]. During issuance and presentation processes the [[ref: holder]]'s link secret is blinded with a [[ref: blinding factor]] such that it is not correlatable, and a [[ref: Blinded Secrets Correctness Proof]] is provided by the holder to demonstrate they know the link secret without revealing it. + +~ Link secret is also known by the deprecated term `master_secret` in some AnonCreds source code. + +[[def: Nonce, nonce, nonces, Nonces]] -[[def: link secret]] -~ One of the most significant differences between the AnonCreds and W3C [Verifiable Credentials](https://www.w3.org/TR/vc-data-model/) is how a credential is bound to the [[ref: holder]]. With the Verifiable Credential, the holder binding happens without additional interactions between the [[ref: holder]] and [[ref: issuer]]. However, this approach comes with a lack of privacy for the [[ref: holder]]. -The correlatability of credentials due to the necessity of revealing a persistent identifier related to the [[ref: holder]] is one such privacy issue. +~ A nonce is an arbitrary unique number that is often required as an input to the generation of a cryptographic proof to ensure it is uniquely generated and once produced, cannot be replayed. Within AnonCreds, nonces are used during the issuance and presentation processes to prevent replay attacks. -~ AnonCreds are bound to the [[ref: holder]] with a non-correlatable secret only known to the [[ref: holder]] itself called a link secret\*. Instead of a persistent identifier, the link secret as a blind attribute is sent to the [[ref: issuer]] during credential issuance. The issuer signs every claim (including the blinded link secret) individually, enabling [[ref: selective disclosure]] (see below). By removing the [[ref: blinding factor]], the [[ref: holder]] retrieves a credential signature over a set of attributes that include the link secret. This means the [[ref: issuer]] does not know the exact value of the link secret or credential signature. The [[ref: holder]] can prove to a [[ref: verifier]] that the credential was issued to them, and only them, by proving knowledge of the link secret within the credential without disclosing the link secret as a persistent identifier. +[[def: Non-Revocation Proof, NRP, non-revocation proof, Non-revocation proof]] -~ \*) The link secret is known as master secret in the Hyperledger Indy source code. The term "master secret" is deprecated in AnonCreds. +~ A non-revocation proof is a proof provided by a [[ref: holder]] to demonstrate that a revocable credential they are presenting has not been revoked, without revealing a unique, correlatable identifier for the credential. A [[ref: verifier]] verifies a non-revocation proof using information from the [[ref: revocation registry]] to which the [[ref: credential]] belongs. -[[def: nonce]] -~ A nonce is an arbitrary unique number that is used to ensure secure communications. Within AnonCreds, nonces are used during credential issuance e.g. for binding a [[ref: Credential Request]] to a [[ref: Credential Offer]]. +[[def: Predicates, predicates, predicate, Predicate]] -[[def: predicates]] -~ A predicate is a boolean assertion about the value of a [[ref: claim]] without disclosing the value itself. In contrast to any signature suite and algorithm implemented according to the W3C [Verifiable Credentials](https://www.w3.org/TR/vc-data-model/), predicates are fully supported by AnonCreds. +~ A [[ref: zero-knowledge proof]] predicate is a boolean assertion (operators `<=`, `<`, `>`, `>=`) in an presentation about the value of an integer [[ref: claim]] without disclosing the value of the claim. -[[def: NRP]] -~ TODO Non Revocation Proof +[[def: Presentation Request, presentation request, presentation requests, Presentation Requests]] -[[def: Revocation Registry Definition, Revocation Registry]] -~ A Revocation Registry Definition object contains information required for [[ref: verifiers]] in order to enable them to verify whether a revokable verifiable credential has been revoked by the issuer since issuance. +~ An AnonCreds presentation request is an object constructed by the [[ref: verifier]] and sent to the [[ref: holder]] defining the verifiable data that the [[ref: verifier]] wants from the [[ref: holder]] for some business purpose. -~ Revocation Registry Definitions are only needed for revokable verifiable credentials and are most commonly [written](https://hyperledger-indy.readthedocs.io/projects/node/en/latest/requests.html#claim-def) to a public location (e.g. an indy ledger) by the owner of a [[ref: Credential Definition]] immediatly after the [[ref: Credential Definition]] has been written. They can be [read](https://hyperledger-indy.readthedocs.io/projects/node/en/latest/requests.html#get-attrib) from a Hyperledger Indy Node by any client and are updated in case of the revocation of a credential, which is based on the used [[ref: Credential Definition]]. +[[def: Revocation, revocation]] -~ Further details about Hyperledger Indy's revocation process can be found [here](https://hyperledger-indy.readthedocs.io/projects/hipe/en/latest/text/0011-cred-revocation/README.html). +~ A unilateral action by the [[ref: issuer]] of a [[ref: verifiable credential]] issued to a [[ref: holder]] to revoke that credential for some business purpose. Once an issued credential has been revoked, the [[ref: holder]] can no longer produce a [[ref: non-revocation proof]] for the [[ref: credential]]. [[ref: Verifiers]] usually (but not always) are interested if a data is presented from a revoked [[ref: credential]]. -[[def: Revocation Status List]] -~ A Revocation Status List object marks the current status ("revoked" or "not revoked") of all credentials in a [[ref: Revocation Registry Definition]]. A Revocation Status List is written by the owner of a [[ref: Revocation Registry Definition]], respectively the issuer of the credential(s) based on a [[ref: Credential Definition]] and its [[ref: Revocation Registry Definition]]. +[[def: Revocation Registry, Revocation registry, revocation registry, RevReg]] + +~ A Revocation registry is a set of objects related to one another and a [[ref: credential definition]] that holds information about the revocation status of a set of revocable credentials issued from the [[ref: credential definition]]. Each revocation registry consists of a [[ref: revocation registry definition]] and one or more [[ref: revocation registry entries]]. There can be 0 or more revocation registries related to a [[ref: credential definition]], and every issued AnonCreds revocable credential is in a revocation registry. + +[[def: Revocation Registry Definition, revocation registry definition, RevRegDef]] + +~ A revocation registry definition is an object with public and private information about a [[ref: revocation registry]]. The public part is published such that it an be resolved and used by anyone, while the private part is a secret held by the [[ref: issuer]] for use when publishing [[ref: revocation registry entries]] that update the revocation status of one or more credentials. + +[[def: Revocation Registry Entry, Revocation Registry Entries, revocation registry entry, revocation registry entries, RevRegEntry, RevRegEntries]] + +~ A revocation registry entry is an object that is published by the [[ref: issuer]] to set/update the revocation status of one or more issued credentials that are in a [[ref: revocation registry]]. Each revocation registry entry has an identifier (sometimes called a `timestamp`), a cryptographic accumulator that summarizes the revocation state of all the credentials in the [[ref: revocation registry]] and, depending on the [[ref: AnonCreds Method]] being used to publish the object, either the revocation state of all of the credentials in the registry, or the set of credentials whose revocation state has changed ("deltas") since the last revocation registry entry was published. + +[[def: Revocation Status List, revocation status list]] + +~ A Revocation status list is an object that contains the revocation status ("revoked" or "not revoked") of all credentials in a [[ref: Revocation Registry]] at the time of a given [[ref: revocation registry entry]]. For [[AnonCreds Methods]] that store [[ref: revocation registry entries]] as deltas (changes to the revocation state of credentials from the previous [[ref: revocation registry entry]]), the set of deltas from the initial publication of the [[ref: revocation registry]] must be collected and used to calculate the full revocation state of all of the credentials. [[def: Schema, Schemas]] -~ A Schema object is a template that defines a set of attributes (also known as attribute names or [[ref: claims]]) which are going to be used by [[ref: issuers]] for issuance of [Verifiable Credentials](https://www.w3.org/TR/vc-data-model/) within a Hyperledger Indy network. Schemas have a name, version and can be [written](https://hyperledger-indy.readthedocs.io/projects/node/en/latest/transactions.html#schema) to the ledger by any entity with proper permissions. Schemas can be [read](https://hyperledger-indy.readthedocs.io/projects/node/en/latest/requests.html#get-schema) from a Hyperledger Indy Node by any client. -~ In Hyperledger Indy, Credentials are based on a [[ref: Credential Definition]]. Therefore [[ref: Credential Definitions]] reference a Schema in order to define which attribute(names) will be used within the [[ref: Credential Definition]]. +~ A Schema is a object that defines the set of [[ref: claims]] (also known as attributes) that will be populated by [[ref: issuers]] in issuing a give type of AnonCreds [[ref: verifiable credentials]]. Schemas have a name, version, and are published to a [[ref: verifiable data registry]] by a [[ref: schema publisher]] using an [[ref: AnonCreds Method]]. [[ref: Credential definitions]] are generated from a specific schema. + +[[def: Schema Publisher, schema publisher, Schema publisher, Schema Publishers, schema publishers, Schema publishers]] + +~ A Schema publisher is an entity that publishes a [[ref: Schema]] to a [[ref: verifiable data registry]]. The schema publisher could be the one [[ref: issuer]] of a type of credential, but could also be another entity that creates a [[ref: Schema]] to be used by many [[ref: issuer]]s to issue the same type of credential. + +[[def: Selective Disclosure, selective disclosure, Selective disclosure]] + +~ Selective disclosure is the ability to minimize data the shared data from an issued [[ref: credential]] in a [[ref: presentation]] by revealing to a [[ref: verifier]] only a subset of [[ref: claims]] in the [[ref: credential]]. The source credential is still verified by the [[ref: verifier]], but only the revealed values are disclosed. + +[[def: Signature Correctness Proof]] + +~ A [[ref: ZKP]]-based proof that can be verified to show that a signature over a message is valid, without revealing the message or signature. + +[[def: Subject, subject, Credential Subject, credential subject]] + +~ A subject, also known as an identity subject, is the entity about whom the [[ref: claims]] in a credential are asserted. In AnonCreds, the credential subject is not formally defined in [[ref: credential]]. Rather, the issuance of a [[ref: credential]] is always to a specific [[ref: holder]]. The semantics of the credential defines the relationship between the [[ref: holder]] and the subject, with the [[ref: holder]] frequently being the subject. + +[[def: Tails File, Tails file, tails file]] + +~ A tails file is a part of the AnonCreds v1.0 scheme that enables a [[ref: holder]] to produce a [[ref: non-revocation proof]]. A tails file is a static file generated as part of the creation of a [[ref: revocation registry]] by the [[ref: issuer]], published, and retrieved by the [[ref: holder]] of a credential that is in the related [[ref: revocation registry]]. The [[ref: holder]] must have the tails file in order to generate a [[ref: non-revocation proof]] for a source [[ref: credential]] they are providing in a [[ref: presentation]]. + +[[def: Unlinkability, unlinkability, Unlinkable, unlinkable]] + +~ Unlinkability is the attribute of some verifiable credentials schemes (notably AnonCreds) such that no [[ref: correlatable]] identifiers are shared in carrying out verifiable credential issuance and presentation processes. Unlinkability requires that when the processes are repeated with the same or different parties ([[ref: issuers]], [[ref: verifiers]]) no common unique identifiers are shared. Note that unlinkability may be lost if there are unique identifiers shared in the revealed [[ref: claim]] values of [[ref: presentations]]. + +[[def: Verifiable Data Registry, VDR, verifiable data registry]] + +~ [[ref: DIDs]], DID documents and published [[ref: AnonCreds objects]] are stored in a verifiable data registry (VDR) such that an identifier for an object can be resolved (by anyone, in most cases), and the identified object returned. A VDR can be a distributed ledger, a blockchain, a web server, database or any other type of storage system. The process of going from the identifier to discovering and resolving the object is a DID Method (for DIDs) and [[ref: AnonCreds Method]] (for [[ref: AnonCreds objects]]). Resolved objects must adhere to their specified data model, regardless of the discover/resolution method used and the verifiable data registry in which the objects are stored. + +[[def: Verifiable Presentation, verifiable presentation, presentation, Presentation, Verifiable Presentations, verifiable presentations, presentations, Presentations]] -[[def: Schema publisher]] -~ A Schema publisher is an entity that creates a [[ref: Schema]] to the ledger. It can be the [[ref: issuer]], but it can also be another entity that creates a [[ref: Schema]] that can be used by many [[ref: issuer]]s to create [[ref: Credential Definitions]] (see below). +~ An AnonCreds verifiable presentation is a collection of [[ref: claims]] and [[ref: predicates]] derived from one or more [[ref: credentials]] with an added proof that the [[ref; verifier]] can verifier. AnonCreds enable the holder to prove it holds a claim from a VC without revealing the VC itself. Verifying a presentation shows the [[ref: issuer]] of the source [[ref: credentials]], to whom the credentials where issued, that the [[ref: claims]] have not been tampered with, and, if applicable, that the source credentials have not been revoked. AnonCreds presentations are designed to maximize the privacy of the [[ref: holder]] sharing the presentation. -[[def: selective disclosure]] -~ Selective disclosure is the ability to disclose partial information from an issued credential by disclosing only a subset of [[ref: claims]]. +[[def: Verifier, verifier, Verifiers, verifiers]] -[[def: subject]] -~ A subject, also known as an identity subject, is the entity about whom [[ref: claims]] are made. +~ A verifier is an entity that verifies the information from a [[ref: holder]] in a [[ref: presentation]]. -[[def: Tails File]] -~ TODO +[[def: Zero-knowledge proof, zero-knowledge proof, zero-knowledge proofs, ZKP, Zero-knowledge proofs]] -[[def: Verifiable Data Registry, VDR]] -~ [[ref: DIDs]] and DID documents have to be stored on some kind of system, which is available (to the public, in most cases). Such a system can be a distributed ledger, a (decentralized) file system, database and others. Such an anchor for [[ref: DID]s] and DID documents is called Verifiable Data Registry. +~ In cryptography, a zero-knowledge proof is a method by which an entity can prove that they know a certain value without disclosing the value itself. Zero-knowledge proofs in AnonCreds enable a number of privacy-preserving capabilities. -~ In the case of Hyperledger Indy a distributed ledger is used as Verifiable Data Registry. Besides [[ref: DIDs]] and DID documents an instance of a Hyperledger Indy network stores additional data on the ledger, which is required for issuance (e.g. [[ref: Schema]] and [[ref: Credential Definition]]), verification (e.g. [[ref: Revocation Registry Definition]])) and revocation (e.g [[ref: Revocation Status List]]) of credentials. +~ - Prove knowledge of the value of the [[ref: link secret]] related to given a [[ref: blinded link secret]]. -[[def: Verifiable Presentation]] -~ Usually, a VP is a collection of claims obtained from one or more VCs with added proof. Contrary to VCs, VPs are built so that the owner of the data (holder) is cryptographically verifiable.  -More often than not, the data included in a presentation is just about the subject of a VC, although that's not mandatory. -The AnonCreds enable the holder to prove it holds a claim from a VC without revealing the VC itself. The value in the VP has to be derived in such a way that guarantees (in the form of a cryptographic assertion) any given verifier that they can trust the claimed assertion. +~ - Share data from multiple [[ref: credentials]] in a single [[ref: verifiable presentation]] without revealing to the [[ref: verifier]] any correlatable identifiers. -[[def: Verifier]] -~ A verifier is an entity that validates identity information from a [[ref: holder]] to grant access to goods and services. +~ - Use [[ref: selective disclosure]] to reveal only necessary [[ref: claims]] in a [[ref: verifiable presentation]]. -[[def: Witness Delta]] -~ The witness delta is an update by the issuer of the list of revoked -credentials at the time an updated accumulator is published with a [[ref: -Revocation Status List]]. The delta tells [[ref: holders]] generating a Non-Revocation -Proof (NRP) how to adjust their witness (referencing other indexes in the public -tails file) to bring it back into harmony with the current value of the -accumulator, such that the updated witness times the private factor of the credential once again equals the accumulator value. +~ - Use [[ref: predicates]] to minimize the data shared by the [[ref: holder]], such as proving based on a date of birth [[ref: claim]] that they are older than 18 **without** sharing their date of birth. -[[def: zero-knowledge proofs]] -~ In cryptography, the zero-knowledge proof is a method by which an entity can prove that they know a certain value without disclosing the value itself. Zero-knowledge proofs can enable [[ref: holders]] to: -~ _ Combine multiple credentials into a single proof to present to a [[ref: verifier]] without revealing any correlatable identifier. -~ _ [[ref: selective disclosure]] (see below) and disclose only necessary [[ref: claims]] to a [[ref: verifier]]. -~ \* use [[ref: predicates]] (see below) for enclosing logical expressions, such as the [[ref: holder]] being older than 18 without disclosing the value. -~ AnonCreds are capable of all three features mentioned above. +~ - Prove that the source [[ref: credentials]] shared in a presentation have not been revoked without sharing unique identifiers for the [[ref: credentials]]. ### Cryptographic Notations -This specification contains the cryptographic calculations necessary to produce -the data objects exchanged in using Hyperledger AnonCreds, and to verify the various proofs -embedded in those objects. The following is information about the notations used -in displaying the cryptographic calculations: +This specification contains the cryptographic calculations necessary to produce the data objects exchanged in using Hyperledger AnonCreds, and to verify the various proofs embedded in those objects. The following is information about the notations used in displaying the cryptographic calculations: `a || b` : Denotes the concatenation of octet strings `a` and `b`. From df527dca77914d4a098663b03c53d2e51e246424 Mon Sep 17 00:00:00 2001 From: Stephen Curran Date: Thu, 21 Dec 2023 20:45:18 +0000 Subject: [PATCH 2/5] Convert any typo def: links to be ref: in non-terminology files Signed-off-by: Stephen Curran --- spec/data_flow_presentation_create_presentation.md | 6 +++--- spec/data_flow_presentation_verify.md | 2 +- spec/data_flow_setup.md | 2 +- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/spec/data_flow_presentation_create_presentation.md b/spec/data_flow_presentation_create_presentation.md index ce2446d..19a5aad 100644 --- a/spec/data_flow_presentation_create_presentation.md +++ b/spec/data_flow_presentation_create_presentation.md @@ -82,7 +82,7 @@ process to get the necessary additional verifiable credentials may be initiated. If more than one verifiable credential satisfy any of the `restrictions` items, the [[ref: holder]] software might select one to use by default, such as the most recently issued, non-revoked of the credentials, and/or might invoke a user -interface to allow the entity that controls the [[def:holder]] software to +interface to allow the entity that controls the [[ref: holder]] software to select from the set of possible credentials to use. In order to proceed to the presentation generation step, there must be one @@ -540,7 +540,7 @@ The data structure is: The example above is for a source credential that is not revocable. For a revocable source credential, the `rev_reg_id` and `timestamp` (the identifier -for the [[def: Revocation Registry Entry]] used in the non-revocation proof) are +for the [[ref: Revocation Registry Entry]] used in the non-revocation proof) are added. Those are described in the section below on [generation of non-revocation proofs](#generate-non-revocation-proofs) @@ -582,7 +582,7 @@ the presentation request. The `witness` is an integer that is used in the non-revocation zero knowledge proof to demonstrate to the verifier that the holder's credential has -not been revoked. Recall that the `accumulator` of a [[def: Revocation Registry +not been revoked. Recall that the `accumulator` of a [[ref: Revocation Registry State]] is the product of the tails file entries for all of the unrevoked credentials in the registry. For a specific holder, its `witness` is the product of the tails file entries for all of the unrevoked credentials in the registry diff --git a/spec/data_flow_presentation_verify.md b/spec/data_flow_presentation_verify.md index e5364c2..9e7f21e 100644 --- a/spec/data_flow_presentation_verify.md +++ b/spec/data_flow_presentation_verify.md @@ -23,7 +23,7 @@ described below. While in this section we mostly focus on the verification of the proofs in the presentation, there are other data elements included, such as the revealed -attributes, self-attested attributes, and the [[def: Presentation Request]] for +attributes, self-attested attributes, and the [[ref: Presentation Request]] for which the presentation was generated. Some of these values contribute to the verification process, as noted below. Finally, an important part of the verification process is **not** carried out in AnonCreds v1.0 and must be diff --git a/spec/data_flow_setup.md b/spec/data_flow_setup.md index 3300f72..b66b91f 100644 --- a/spec/data_flow_setup.md +++ b/spec/data_flow_setup.md @@ -502,7 +502,7 @@ Detailed process for tails file generation: - Calculate `pow` by doing modular exponentiation of revocation private key(`gamma`) with the finite field element previously calculated. - Multiply `pow` by `g_dash`, which is the generator of elliptic curve group `G2`, and this should be the required point on the curve. - Convert this tail point to an array of bytes(`u8`), and put them into the file as a slice buffer. -- Repeat for all the attributes from index $1$ to $L$, by calculating $([\gamma], [\gamma^2], [\gamma^3], ...[\gamma^L], [\gamma], [\gamma^{L+2}], [\gamma^{L+3}], ..., [\gamma^{2L}])$. Note that Instead of inserting $[\gamma^{L+1}]$ in the sequence, insert the value $[\gamma]$ (the first value in the sequence) in its place, and then continue with $[\gamma^{L+2}]$ and on to $[\gamma^{2L}]$. $[\gamma^{L+1}]$ is not used by holders generating the [[def: Non-Revocation Proof]] and a dummy value is inserted in its place. +- Repeat for all the attributes from index $1$ to $L$, by calculating $([\gamma], [\gamma^2], [\gamma^3], ...[\gamma^L], [\gamma], [\gamma^{L+2}], [\gamma^{L+3}], ..., [\gamma^{2L}])$. Note that Instead of inserting $[\gamma^{L+1}]$ in the sequence, insert the value $[\gamma]$ (the first value in the sequence) in its place, and then continue with $[\gamma^{L+2}]$ and on to $[\gamma^{2L}]$. $[\gamma^{L+1}]$ is not used by holders generating the [[ref: Non-Revocation Proof]] and a dummy value is inserted in its place. - Close the file buffer. Relevant links: [Anoncreds-rs repository](https://github.com/hyperledger/anoncreds-rs/blob/9c915bb77bc4e033cc6d28d45e330ee5bda26211/src/services/tails.rs#LL148C1-L148C37), [Anoncreds-CLSignatures repository](https://github.com/hyperledger/anoncreds-clsignatures-rs/blob/f1ae666656054cd73fe765928c0dada64ef21d87/src/mod.rs#L517) From 7c8d06a0b36a6db4d6931c855d3949aba76bda48 Mon Sep 17 00:00:00 2001 From: Stephen Curran Date: Thu, 21 Dec 2023 21:20:15 +0000 Subject: [PATCH 3/5] Clarified holder as software vs person/org, separated prover def Signed-off-by: Stephen Curran --- spec/terminology.md | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/spec/terminology.md b/spec/terminology.md index f28d0c4..0a51d35 100644 --- a/spec/terminology.md +++ b/spec/terminology.md @@ -83,7 +83,7 @@ mechanism is based on the use of a blinded secret. [[def: Holder, Holders, holder, holders, prover, Prover]] -~ A holder, also known as an identity holder and prover, is an entity that is in possession of a [[ref: credential]]. In many use cases, the holder is also the identity [[ref: subject]]. A holder can interact with an issuer to obtain anonymous credentials. It can also derive information from anonymous credentials that can be presented to a [[ref: verifier]] to gain access to goods and services. A prover is a synonym for holder that is often used in a holder-[[ref: verifier]] interaction. In this specification, we only use the term "holder", however the underlying implementations use "prover" in code. +~ In this specification, the holder is a software component (agent) used by an entity (person, organization, etc.) in possession of [[ref: credentials]] issued to them. Where "holder" is used in the specification we mean the software component. In some places where required, we clearly refer to an entity using holder software as separate from the holder software component. Holders interact with [[ref: issuers]] to obtain [[ref: credentials]], and derive [[ref: presentations]] from the [[ref: credentials]] they hold. [[def: Issuer, Issuers, issuer, issuers]] @@ -115,6 +115,10 @@ mechanism is based on the use of a blinded secret. ~ An AnonCreds presentation request is an object constructed by the [[ref: verifier]] and sent to the [[ref: holder]] defining the verifiable data that the [[ref: verifier]] wants from the [[ref: holder]] for some business purpose. +[[def: Prover, prover]] + +~ A prover is a synonym for holder that is sometimes used in a [[ref: holder]]-[[ref: verifier]] interaction. In this specification, we use the term "holder" in all cases. However the underlying AnonCreds implementations use "prover" in code. + [[def: Revocation, revocation]] ~ A unilateral action by the [[ref: issuer]] of a [[ref: verifiable credential]] issued to a [[ref: holder]] to revoke that credential for some business purpose. Once an issued credential has been revoked, the [[ref: holder]] can no longer produce a [[ref: non-revocation proof]] for the [[ref: credential]]. [[ref: Verifiers]] usually (but not always) are interested if a data is presented from a revoked [[ref: credential]]. From 814d2527aecf1b81d01327ae5ed5d69672f377b6 Mon Sep 17 00:00:00 2001 From: Stephen Curran Date: Tue, 2 Jan 2024 16:51:34 +0000 Subject: [PATCH 4/5] Updated based on comments Signed-off-by: Stephen Curran --- spec/terminology.md | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/spec/terminology.md b/spec/terminology.md index 0a51d35..837dc47 100644 --- a/spec/terminology.md +++ b/spec/terminology.md @@ -2,14 +2,14 @@ [[def: Accumulator, accumulator]] -~ A [cryptographic accumulator] is used space- and time-efficient method of proving a value membership is in a set of values without revealing the individual members of the set. In AnonCreds v1, an accumulator is a core element of the [[ref: verifiable credential]] revocation mechanism. +~ A [cryptographic accumulator] is used in the AnonCreds v1.0 Revocation scheme as a space- and time-efficient method of proving a value membership in a set of values without revealing the individual members of the set. In AnonCreds v1, an accumulator is a core element of the [[ref: verifiable credential]] revocation mechanism. [[def: AnonCreds Method, AnonCreds method, AnonCreds Methods, AnonCreds methods]] -~ AnonCreds methods specify how AnonCreds objects are written (registered) and read (resolved) on a given [[ref: verifiable data registry]] implementation. AnonCreds was originally written to use [Hyperledger Indy] as its only [[ref: VDR]] implementation, but the evolution of AnonCreds to enable storing objects on any [[ref: VDR]] implementation means that AnonCreds methods (comparable to [[ref: DID Methods]] from the [DID Core specification]) are necessary. AnonCreds Methods are defined in the [AnonCreds Methods Registry] repository. +~ AnonCreds methods specify how AnonCreds objects are written (registered) and read (resolved) on a given [[ref: verifiable data registry]] implementation. AnonCreds was originally written to use [Hyperledger Indy] as its only [[ref: VDR]] implementation, but the evolution of AnonCreds to enable storing objects on any [[ref: VDR]] implementation means that AnonCreds methods (comparable to [[ref: DID Methods]] from the [W3C DID Core specification]) are necessary. AnonCreds Methods are defined in the [AnonCreds Methods Registry] repository. [Hyperledger Indy]: https://www.hyperledger.org/projects/hyperledger-indy -[DID Core specification]: https://www.w3.org/TR/did-core/ +[W3C DID Core specification]: https://www.w3.org/TR/did-core/ [AnonCreds Methods Registry]: https://hyperledger.github.io/anoncreds-methods-registry/ [[def: AnonCreds Objects, AnonCreds objects]] @@ -24,7 +24,7 @@ [[def: Blinded Secret, Blinded secret, blinded secret, unblinded secret, Unblinded secret]] -~ A cryptographic technique where a secret value (a number) is blinded before it is shared such that the sender can later prove knowledge ("unblind") of the secret value. The AnonCreds v1.0 [[ref: link secret]] +~ A cryptographic technique where a secret value (a number) is blinded before it is shared such that the sender can later prove knowledge of the secret value without sharing it. The AnonCreds v1.0 [[ref: link secret]] mechanism is based on the use of a blinded secret. [[def: Blinded Secrets Correctness Proof]] @@ -33,7 +33,7 @@ mechanism is based on the use of a blinded secret. [[def: Blinding Factor, blinding factor]] -~ A blinding factor is a random 3152 bit selected from the set of integers up to the order of the RSA group, `n`. It is generated by the [[ref:holder]] to blind the their [[ref:link secret]] during credential issuance. The blinding factor can then be removed from the signature the [[ref:issuer]] produces to retrieve a valid signature over the [[ref: unblinded link secret]]. A blinding factor is similarly generated for each non-disclosed attribute during credential presentation, such that a [[ref: holder]] can prove they know these values without revealing them to the [[ref: verifier]]. +~ A blinding factor is a random [[ref: BigNumber]] selected from the set of integers up to the order of the RSA group, `n`. It is generated by the [[ref:holder]] to blind their [[ref:link secret]] during credential issuance. Knowledge of the blinding factor can be used to create a [[ref: Blinded Secrets Correctness Proof]].The blinding factor can be removed from the signature the [[ref:issuer]] produces to retrieve a valid signature over the [[ref: unblinded link secret]]. A blinding factor and associated [[ref: Blinded Secrets Correctness Proof]] are similarly generated for each non-disclosed attribute during credential presentation, such that a [[ref: holder]] can prove they know these values without revealing them to the [[ref: verifier]]. [[def: Call Home, Call home, call home]] @@ -53,11 +53,11 @@ mechanism is based on the use of a blinded secret. [[def: Credential Definition, Credential Definitions, Public Credential Definition, Private Credential Definition, CredDef, CredDefs, credential definition, CLAIM_DEF, CRED_DEF]] -~ A credential definition (also known as CRED_DEF or CLAIM_DEF) contains data required for [[ref: credential]] issuance (used by the [[ref:issuer]]) as well as [[ref: credential]] validation data (used by the [[ref:holder]] and the [[ref:verifier]]). A credential definition is generated by the [[ref:issuer]] before [[ref:credential]] issuance and consists of two distinct but strongly related parts, the **Public Credential Definition** that is published for everyone to use and **Private Credential Definition** that is held as a secret by the issuer and has the private keys necessary to generate signed [[ref: verifiable credentials]]. A credential definition may be generated such that credentials it produces can be revoked. +~ A credential definition (also known as CRED_DEF or CLAIM_DEF) contains the public data required for [[ref: credential]] issuance (used by the [[ref:issuer]]) as well as [[ref: credential]] validation data (used by the [[ref:holder]] and the [[ref:verifier]]). A credential definition is generated by the [[ref:issuer]] before [[ref:credential]] issuance and published for anyone (primarily [[ref: holders]] and [[ref: verifiers]]) to use. In generating the public credential definition, related private data is also generated and held as a secret by the issuer. The secret data includes the private keys necessary to generate signed [[ref: verifiable credentials]] that can be presented and verified using the published credential definition. A credential definition can optionally be generated such that the credentials it produces can be revoked. [[def: Credential Key Correctness Proof]] -~ A proof generated during the creation of the [[ref: credential definition]] and included in the [[ref: credential offer]] so that the [[ref:holder]] can verify that the published [[ref: credential definition]] used in the blinding process belongs to the [[ref:issuer]]. +~ A proof generated during the creation of the [[ref: credential definition]] and included in the [[ref: credential offer]] so that the [[ref:holder]] can verify that the [[ref: issuer]] is in control of the private data associated with the published [[ref: credential definition]]. [[def: Credential Offer, credential offer, Credential offer]] @@ -65,7 +65,7 @@ mechanism is based on the use of a blinded secret. [[def: Credential Request, credential request, Credential request]] -~ A credential request is a request from an [[ref: holder]] towards a [[ref: issuer]] to get a credential issued by the [[ref: issuer]]. The credential request references a preceding [[ref: credential offer]] and defines the claims the [[ref: holder]] wants to get issued. A credential request also includes a [[ref: nonce]] that is later to use the issuance of the credential. +~ A credential request is a request from an [[ref: holder]] towards a [[ref: issuer]] to get a credential issued by the [[ref: issuer]]. The credential request references a preceding [[ref: credential offer]] and defines the claims the [[ref: holder]] wants to get issued, including a [[ref: Blinded Secret]] and associated [[ref: Blinded Secrets Correctness Proof]]. A credential request also includes a [[ref: nonce]] that is used in issuing the credential. [[def: Data Minimization, data minimization, Data minimization]] @@ -73,11 +73,11 @@ mechanism is based on the use of a blinded secret. [[def: DID, DIDs]] -~ A Decentralized Identifier (DID), defined by the [W3C DID Core Specification](https://w3c.github.io/did-core/), is a type of identifier that is useful in enabling verifiable, decentralized digital identity. A DID refers to any subject (e.g., a person, organization, thing, data model, abstract entity, etc.) as determined by the controller of the DID. DIDs are not used in AnonCreds itself but there must be a verifiable identifier (usually a DID) with an enforced relationship between [[ref: schema publishers]] and [[ref: issuers]] and the AnonCreds objects they publish. This is outlined in a note in [this specification section](#anoncreds-setup-data-flow). +~ A Decentralized Identifier (DID), defined by the [W3C DID Core Specification], is a type of identifier that is useful in enabling verifiable, decentralized digital identity. A DID refers to any subject (e.g., a person, organization, thing, data model, abstract entity, etc.) as determined by the controller of the DID. DIDs are not used in AnonCreds itself but there must be a verifiable identifier (usually a DID) with an enforced relationship between [[ref: schema publishers]] and [[ref: issuers]] and the AnonCreds objects they publish. This is outlined in a note in [this specification section](#anoncreds-setup-data-flow). [[def: DID Method, DID method, DID Methods, DID methods]] -~ DID methods specify how DID documents are written (registered) and read (resolved) on a given [[ref: verifiable data registry]] implementation, allowing DIDs to be registered and resolved in a wide variety of storage containers. The capabilities required by DID Methods are defined in the [DID Core specification], and the (many) DID Methods are defined in the [DID Methods Registry] repository. +~ DID methods specify how DID documents are created and resolved (read) on a given [[ref: verifiable data registry]] implementation, allowing DIDs to be created and resolved in a wide variety of storage containers. The capabilities required by DID Methods are defined in the [DID Core specification], and the (many) DID Methods are defined in the [DID Methods Registry] repository. [DID Methods Registry]: https://www.w3.org/TR/did-spec-registries/#did-methods From 36819f73a9af1084162c4796824b9526c5d13d32 Mon Sep 17 00:00:00 2001 From: Stephen Curran Date: Fri, 5 Jan 2024 15:57:00 +0000 Subject: [PATCH 5/5] Updates based on feedback Signed-off-by: Stephen Curran --- spec/terminology.md | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/spec/terminology.md b/spec/terminology.md index 837dc47..70c79b7 100644 --- a/spec/terminology.md +++ b/spec/terminology.md @@ -53,7 +53,7 @@ mechanism is based on the use of a blinded secret. [[def: Credential Definition, Credential Definitions, Public Credential Definition, Private Credential Definition, CredDef, CredDefs, credential definition, CLAIM_DEF, CRED_DEF]] -~ A credential definition (also known as CRED_DEF or CLAIM_DEF) contains the public data required for [[ref: credential]] issuance (used by the [[ref:issuer]]) as well as [[ref: credential]] validation data (used by the [[ref:holder]] and the [[ref:verifier]]). A credential definition is generated by the [[ref:issuer]] before [[ref:credential]] issuance and published for anyone (primarily [[ref: holders]] and [[ref: verifiers]]) to use. In generating the public credential definition, related private data is also generated and held as a secret by the issuer. The secret data includes the private keys necessary to generate signed [[ref: verifiable credentials]] that can be presented and verified using the published credential definition. A credential definition can optionally be generated such that the credentials it produces can be revoked. +~ A credential definition (also known as CRED_DEF or CLAIM_DEF) contains the public data required for [[ref: credential]] issuances (used by the [[ref:issuer]]) as well as [[ref: credential]] validation data (used by [[ref:holders]] and [[ref:verifiers]]). Any number of credentials can be issued based on a single credential definition. A credential definition is generated by the [[ref:issuer]] before [[ref:credential]] any issuances and published for anyone (primarily [[ref: holders]] and [[ref: verifiers]]) to use. In generating the published credential definition, related private data is also generated and held as a secret by the issuer. The secret data includes the private keys necessary to generate signed [[ref: verifiable credentials]] that can be presented and verified using the published credential definition. A credential definition can optionally be generated such that its generated credentials can be revoked. [[def: Credential Key Correctness Proof]] @@ -69,7 +69,7 @@ mechanism is based on the use of a blinded secret. [[def: Data Minimization, data minimization, Data minimization]] -~ An attribute of verifiable data sharing schemes that considers privacy of a scheme based on the amount of data shared in a given interaction. Ideally, the minimum amount of data is shared for the business purpose of the interaction. Techniques such as [[ref: selective disclosure]], [[ref: predicates]], and [[ref: unlinkability]], all available in AnonCreds v1.0 support the goal of privacy-preserving, minimal data sharing. +~ An attribute of verifiable data sharing schemes that considers privacy of a scheme based on the amount of data shared in a given interaction. Ideally, the minimum amount of data is shared for the purpose of the interaction. Techniques such as [[ref: selective disclosure]], [[ref: predicates]], and [[ref: unlinkability]], all available in AnonCreds v1.0 support the goal of privacy-preserving, minimal data sharing. [[def: DID, DIDs]] @@ -113,7 +113,7 @@ mechanism is based on the use of a blinded secret. [[def: Presentation Request, presentation request, presentation requests, Presentation Requests]] -~ An AnonCreds presentation request is an object constructed by the [[ref: verifier]] and sent to the [[ref: holder]] defining the verifiable data that the [[ref: verifier]] wants from the [[ref: holder]] for some business purpose. +~ An AnonCreds presentation request is an object constructed by the [[ref: verifier]] and sent to the [[ref: holder]] defining the verifiable data that the [[ref: verifier]] wants from the [[ref: holder]] for some purpose. [[def: Prover, prover]] @@ -121,7 +121,7 @@ mechanism is based on the use of a blinded secret. [[def: Revocation, revocation]] -~ A unilateral action by the [[ref: issuer]] of a [[ref: verifiable credential]] issued to a [[ref: holder]] to revoke that credential for some business purpose. Once an issued credential has been revoked, the [[ref: holder]] can no longer produce a [[ref: non-revocation proof]] for the [[ref: credential]]. [[ref: Verifiers]] usually (but not always) are interested if a data is presented from a revoked [[ref: credential]]. +~ A unilateral action by the [[ref: issuer]] of a [[ref: verifiable credential]] issued to a [[ref: holder]] to revoke that credential for some reason. Once an issued credential has been revoked, the [[ref: holder]] can no longer produce a [[ref: non-revocation proof]] for the [[ref: credential]]. [[ref: Verifiers]] usually (but not always) are interested if a data is presented from a revoked [[ref: credential]]. [[def: Revocation Registry, Revocation registry, revocation registry, RevReg]]