Enum DTGCredentialError 

#[non_exhaustive]
pub enum DTGCredentialError {
    UnknownCredential,
    DataIntegrity(DataIntegrityError),
    NotSigned,
    UnknownVCVersion,
    EmptyAuthorityActions,
    NotAnAuthorityCredential,
    AttenuationParentHasNoId,
    InvalidDigest(String),
    UnsupportedDigestAlgorithm(u64),
    MalformedDelegation(String),
    NotADelegationGrant(String),
    AttenuationWidens(String),
    MissingTaskContext,
    MissingTaskDigest,
    InvalidContext(String),
    InvalidType(String),
    IssuerScopeTooNarrow {
        declared: IssuerScope,
        minimum: IssuerScope,
    },
    InvalidPredicate(String),
    ProfileViolation(String),
    PredicateNotAccepted(String),
    MalformedAcceptList(String),
    MalformedTaskDocument(String),
    NotAWitnessSession(String),
    Canonicalization(String),
    WrongCredentialType {
        expected: String,
        got: String,
    },
    NotAMembershipGrant(String),
    InvalidValidityWindow {
        valid_from: DateTime<Utc>,
        valid_until: DateTime<Utc>,
    },
    JsonTooDeep {
        max: usize,
    },
    NotTheGrantSubject {
        expected: String,
        found: String,
    },
    OutlivesGrant {
        valid_until: Option<DateTime<Utc>>,
        grant_valid_until: DateTime<Utc>,
    },
    ProofNotFromIssuer {
        issuer: String,
        verification_method: String,
    },
    NotValidAt {
        at: DateTime<Utc>,
    },
    MalformedCredential(String),
}

Errors related to DTG Credentials

New variants may be added in minor releases; match with a wildcard arm.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

UnknownCredential

DataIntegrity(DataIntegrityError)

NotSigned

UnknownVCVersion

EmptyAuthorityActions

An AuthorityCredential (VAC) carried an empty actions list.

Emptiness is never a wildcard: a VAC conferring no actions confers nothing, and is rejected rather than treated as unrestricted.

NotAnAuthorityCredential

DTGCredential::attenuate was called on a credential that is not a VAC.

AttenuationParentHasNoId

👎Deprecated since 0.7.0:

Never returned. authority.parent is a digest as of Working Draft 02, so a parent VAC no longer needs an id to be attenuated. This variant will be removed in a future release.

DTGCredential::attenuate was called on a VAC with no id.

No longer produced. Working Draft 02 makes authority.parent a digest of the parent rather than its id, precisely so that no credential needs a top-level identifier merely in order to be referenced.

InvalidDigest(String)

A digest value was not a well-formed digestMultibase.

Either the multibase envelope or the multihash inside it failed to decode. A sha256:<hex> value produced against Working Draft 01 lands here, which is the intended outcome: it is reported rather than silently compared as unequal.

UnsupportedDigestAlgorithm(u64)

A digest named a hash algorithm this library does not implement.

The specification permits a governing party to require a stronger hash, and carries the algorithm in the value itself. A verifier MUST reject an algorithm it does not accept rather than treating it as a mismatch — hence a distinct error.

MalformedDelegation(String)

A DelegationCredential (VDC) was not a well-formed grant or acceptance.

NotADelegationGrant(String)

A delegation acknowledgement was built against something that is not a delegation grant.

AttenuationWidens(String)

An attenuation attempted to confer more than its parent held.

MissingTaskContext

A StatementCredential under a profile that REQUIRES taskContext — witnessed/1, vetted/1, presented/1, or an accept-list entry saying so — carries none.

MissingTaskDigest

A credential that REQUIRES taskContext carries it without taskDigestMultibase, which DTG Core Credentials makes REQUIRED wherever taskContext is.

InvalidContext(String)

@context does not list the W3C VC context first and DTG_CONTEXT_V1 second.

InvalidType(String)

type is not VerifiableCredential, DTGCredential and exactly one concrete subtype (with PersonhoodCredential permitted as a hint on a VMC only), or names a subtype this specification has retired.

IssuerScopeTooNarrow

issuerScope is narrower than the credential type or predicate profile permits.

A community-issued VMC can only truthfully declare public; witnessed/1, vetted/1 and presented/1 require directed at minimum.

Fields

declared: IssuerScope

minimum: IssuerScope

InvalidPredicate(String)

A VSC predicate is not an absolute IRI in Unicode Normalization Form C.

A compact form (a CURIE such as dtg:witnessed, or a bare JSON-LD term) is malformed rather than unknown: no expansion is ever performed.

ProfileViolation(String)

A VSC does not meet a constraint of its predicate’s profile: an object kind the profile does not permit, a REQUIRED member missing, or a subject–object relationship that does not hold.

PredicateNotAccepted(String)

A verifier’s accept-list does not contain the statement’s predicate.

Rejection is the only conforming outcome for an unrecognized predicate: it is not processed as a generic statement, and no published equivalence is followed.

MalformedAcceptList(String)

A registry accept-list document could not be read.

MalformedTaskDocument(String)

A document a credential was to cite as its taskContext is not a Trust Task document that can be named: it is not a JSON object, or it has no string id.

NotAWitnessSession(String)

DTGCredential::new_witnessed_vsc was given something other than the witness/session document that opened the witness session.

A VWC names the innermost exchange that attests the witnessing (Trust Tasks §4.9.1): the party’s own witness/session, not the witness/session/submit exchanged on its thread and not the relationship exchange that contains it.

Canonicalization(String)

The credential could not be canonicalized (JCS, RFC 8785) for digesting

WrongCredentialType

A credential was not of the type an operation requires

Fields

expected: String

got: String

NotAMembershipGrant(String)

A membership acknowledgement was built against something that is not a community-issued membership grant

InvalidValidityWindow

A credential’s validUntil is not after its validFrom.

A window that closes before, or at the instant, it opens describes a credential that is never valid. It is refused where a credential is built or signed rather than left for every verifier to notice. A validFrom in the past is not refused: backdating is how a re-issued credential keeps the date the original took effect.

Compared at whole seconds, the precision the wire form carries.

Fields

valid_from: DateTime<Utc>

valid_until: DateTime<Utc>

JsonTooDeep

A JSON document was nested more deeply than MAX_JSON_DEPTH allows.

Digesting, signing and verifying all walk a credential recursively, so a value deep enough exhausts the stack and aborts the process. It is refused before any of that work starts.

Fields

max: usize

NotTheGrantSubject

A grant names a different party as its subject from the one answering it.

Returned by DTGCredential::new_member_vmc_for and DTGCredential::new_delegate_vdc_for. A party answers a grant for itself, so a grant naming anyone else is refused rather than answered in that party’s name.

Fields

expected: String

found: String

OutlivesGrant

An acknowledgement or acceptance would remain valid after the grant it answers.

valid_until is None where the answer was open-ended against a grant that expires.

Fields

valid_until: Option<DateTime<Utc>>

grant_valid_until: DateTime<Utc>

ProofNotFromIssuer

A proof verified, but was made with a verification method that does not belong to the credential’s issuer.

Fields

issuer: String

verification_method: String

NotValidAt

A credential was not in force at the instant it was checked against.

Fields

at: DateTime<Utc>

MalformedCredential(String)

A credential in its wire form lacks a member it needs, or carries one that cannot be read.

Trait Implementations

impl Debug for DTGCredentialError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for DTGCredentialError

fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for DTGCredentialError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<DataIntegrityError> for DTGCredentialError

fn from(source: DataIntegrityError) -> Self

Converts to this type from the input type.