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Assertion schema

Blockcerts 2.1 Assertion schema. Extends Open Badges v2.0 schema: https://w3id.org/openbadges#Assertion

The schema defines the following properties:

id (string, required)

Defined by id property in https://w3id.org/openbadges#Assertion. This may be an HTTP IRI, but only if the issuer plans to host the assertions on a long-term basis, or (at least) until their expiration. Otherwise it is recommended to use a urn:uuid:<UUID>-formatted IRI.

type (JsonLdType, required)

Defined by type property of https://w3id.org/openbadges#Assertion

recipient (IdentityObject, required)

Defined by recipient property of https://w3id.org/openbadges#Assertion, with Blockcerts extensions for recipient proof of ownership.

badge (BadgeClass, required)

Defined by badge property of https://w3id.org/openbadges#Assertion, with Blockcerts extensions for (display) signature images.

verification (VerificationObject, required)

Defined by verification property of https://w3id.org/openbadges#Assertion, with Blockcerts extensions for verification of badges on a blockchain.

issuedOn (DateTime, required)

Defined by issuedOn property of https://w3id.org/openbadges#Assertion

image (ImageUri)

Defined by image property of https://w3id.org/openbadges#Assertion

evidence (string)

Defined by evidence property of https://w3id.org/openbadges#Assertion

narrative (string)

Defined by narrative property of https://w3id.org/openbadges#Assertion

expires (DateTime)

Defined by expires property of https://w3id.org/openbadges#Assertion

recipientProfile (RecipientProfile)

signature (MerkleProof2017)

Sub Schemas

The schema defines the following additional types:

JsonLdContext (undefined)

A link to a valid JSON-LD context, or array of JSON-LD contexts

This property must be one of the following types:

  • string
  • array

JsonLdType (undefined)

A type or an array of types defined in a referenced JSON-LD context.

This property must be one of the following types:

  • string
  • array

DateTime (string)

Open Badges must express timestamps as strings compatible with ISO 8601 guidelines, including the time and a time zone indicator. It is recommended to publish all timestamps in UTC. Previous versions of Open Badges allowed Unix timestamps as integers. Open Badges v2.0 requires string ISO 8601 values with time zone indicators. For example, 2016-12-31T23:59:59+00:00 is a valid ISO 8601 timestamp. It contains the year, month, day, T separator, hour number 0-23, minute, optional seconds and decimal microsecond, and a time zone indicator (+/- an offset from UTC or the Z designator for UTC).

HashString (string)

Open Badges SHA-256 Hash

IdentityObject (object)

From https://w3id.org/openbadges#IdentityObject.

Properties of the IdentityObject object:

identity (, required)

Defined by identity property of https://w3id.org/openbadges#IdentityObject

The object must be one of the following types:

  • HashString
  • undefined

type (string, enum, required)

Defined by type property of https://w3id.org/openbadges#IdentityObject

This element must be one of the following enum values:

  • email

hashed (boolean, required)

Defined by hashed property of https://w3id.org/openbadges#IdentityObject

salt

Defined by salt property of https://w3id.org/openbadges#IdentityObject

VerificationObject (object)

From https://w3id.org/openbadges#VerificationObject, with extensions for Blockcerts verification

Properties of the VerificationObject object:

type (JsonLdType, required)

Defined by type property of https://w3id.org/openbadges#VerificationObject. Blockcerts extension: this should contain the entry MerkleProofVerification2017

publicKey (string)

Blockcerts extension: the expected blockchain address for the signer of the transaction containing the merkle proof. In Blockcerts publicKeys are typically represented with a <scheme>: prefix. For Bitcoin transactions, this would be the issuer public Bitcoin address prefixed with ecdsa-koblitz-pubkey:; e.g. ecdsa-koblitz-pubkey:14RZvYazz9H2DC2skBfpPVxax54g4yabxe

ImageUri (string)

An image representative of the entity. In Blockcerts this is typically a data URI (https://en.wikipedia.org/wiki/Data_URI_scheme) embedded as a base-64 encoded PNG image, but it may also be a URI where the image may be found.

AlignmentObject (object)

From https://w3id.org/openbadges#AlignmentObject

Properties of the AlignmentObject object:

targetName (string, required)

Defined by targetName property of https://w3id.org/openbadges#AlignmentObject

targetUrl (string, required)

Defined by targetUrl property of https://w3id.org/openbadges#AlignmentObject

targetDescription (string)

Defined by targetDescription property of https://w3id.org/openbadges#AlignmentObject

AlignmentArray (array)

List of objects describing which objectives or educational standards this badge aligns to, if any.

TagsArray (array)

List of tags that describe the type of achievement.

SignatureLine (undefined)

RecipientProfile (undefined)

MerkleProof2017 (undefined)

BadgeClass (object)

From https://w3id.org/openbadges#BadgeClass

Properties of the BadgeClass object:

id (string, required)

Defined by id property of https://w3id.org/openbadges#BadgeClass. This field is now required in V2. This may be an HTTP IRI, but only if the issuer plans to host the BadgeClass definitions on a long-term basis, or (at least) until expiration of certificates referencing this BadgeClass. Otherwise it is recommended to use a urn:uuid:<UUID>-formatted IRI.

type (JsonLdType)

Defined by type property of https://w3id.org/openbadges#BadgeClass

name (string, required)

Defined by name property of https://w3id.org/openbadges#BadgeClass

subtitle (string)

Blockcerts extension: optional subtitle of the certificate

description (string, required)

Defined by description property of https://w3id.org/openbadges#BadgeClass

image (ImageUri, required)

Defined by image property of https://w3id.org/openbadges#BadgeClass

criteria (object, required)

Defined by criteria property of https://w3id.org/openbadges#BadgeClass. This field is required in Open Badges. If migrating from an earlier version, a quick change is to reuse the description field

issuer (Profile, required)

Defined by issuer property of https://w3id.org/openbadges#BadgeClass, with Blockcerts extensions for blockchain verification of badges.

alignment (AlignmentArray)

Defined by alignment property of https://w3id.org/openbadges#BadgeClass

tags (TagsArray)

Defined by tags property of https://w3id.org/openbadges#BadgeClass

signatureLines

Blockcerts extension: array of signature lines for display.

Profile (undefined)

Defined by https://w3id.org/openbadges#Profile. This type is used in certificates, and in the issuer-hosted identification page. The minimal set of properties required in the certificate are id and type. In this case, additional issuer-identification properties are assumed to be available at the issuer-hosted identification page.

id (string, required)

Defined by id property of https://w3id.org/openbadges#Profile

type (JsonLdType, required)

Defined by type property of https://w3id.org/openbadges#Profile

name (string)

Defined by name property of https://w3id.org/openbadges#Profile

url (string)

Defined by url property of https://w3id.org/openbadges#Profile

telephone (string)

Defined by telephone property of https://w3id.org/openbadges#Profile

description (string)

Defined by description property of https://w3id.org/openbadges#Profile

image (ImageUri)

Defined by image property of https://w3id.org/openbadges#Profile

email (string)

Defined by email property of https://w3id.org/openbadges#Profile

revocationList

Defined by revocationList property of https://w3id.org/openbadges#Profile. If embedded in a Blockcert and the issuer-hosted Profile, the value in the Blockcert should take preference.

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