presentation example

examples/presentation/presentation.go

@@ -0,0 +1,118 @@
+// A simple example of making a presentation request
+// and a presentation definition with various comments.
+// Please see the acutal source code documentation
+// for more detialed information and specifications for the specific
+// methods. This is intended to give an overview and basic
+// idea of how things work.
+
+//
+// |------------|       |----------------------|        |------------|
+// |  Verifier  | ----> | Presentation Request | -----> |   Holder   |
+// |            |       |      \Definition     |        |            |
+// |------------|       |----------------------|        |------------|
+//
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"github.com/TBD54566975/ssi-sdk/credential/exchange"
+	"github.com/TBD54566975/ssi-sdk/crypto"
+	"github.com/TBD54566975/ssi-sdk/cryptosuite"
+	"github.com/TBD54566975/ssi-sdk/util"
+)
+
+// Makes a dummy presentation definition. These are
+// eventually transported via Presentation Request.
+// For more information on presentation definitions go
+// https://identity.foundation/presentation-exchange/#term:presentation-definition
+func makePresentationData() exchange.PresentationDefinition {
+	// Input Descriptors: Describe the information the verifier requires of the holder
+	// https://identity.foundation/presentation-exchange/#input-descriptor
+	// Required fields: ID and Input Descriptors
+	return exchange.PresentationDefinition{
+		ID: "test-id",
+		InputDescriptors: []exchange.InputDescriptor{
+			{
+				ID:      "test-input-descriptor-id",
+				Name:    "test-input-descriptor",
+				Purpose: "because!",
+			},
+		},
+		Name: "test-def",
+		Format: &exchange.ClaimFormat{ // Optional property
+			JWTVC: &exchange.JWTType{Alg: []crypto.SignatureAlgorithm{crypto.EdDSA}},
+		},
+	}
+}
+
+// Build a presentation request (PR)
+// A PR is sent by a verifier to a holder
+// It can be sent over multiple mechanisms
+// For more information, please go to here:
+// https://identity.foundation/presentation-exchange/#presentation-request
+// and for the source code with the sdk,
+// https://github.com/TBD54566975/ssi-sdk/blob/main/credential/exchange/request.go
+// is appropriate to start off with.
+func makePresentationRequest(presentationData exchange.PresentationDefinition) (pr []byte, err error) {
+
+	// Generate JSON Web Key
+	// The JSONWebKey2020 type specifies a number of key type and curve pairs to enable JOSE conformance
+	// https://w3c-ccg.github.io/lds-jws2020/#dfn-jsonwebkey2020
+	jwk, err := cryptosuite.GenerateJSONWebKey2020(cryptosuite.OKP, cryptosuite.Ed25519)
+	if err != nil {
+		return
+	}
+
+	// Signer:
+	// https://github.com/TBD54566975/ssi-sdk/blob/main/cryptosuite/jsonwebkey2020.go#L350
+	// Implements: https://github.com/TBD54566975/ssi-sdk/blob/main/cryptosuite/jwt.go#L12
+	signer, err := cryptosuite.NewJSONWebKeySigner(jwk.ID, jwk.PrivateKeyJWK, cryptosuite.Authentication)
+	if err != nil {
+		return
+	}
+
+	// Builds a presentation request
+	// Requires a signeer, the presentation data, and the target
+	// Target is the Audience Key
+	requestJWTBytes, err := exchange.BuildJWTPresentationRequest(*signer, presentationData, "did:test")
+	if err != nil {
+		return
+	}
+
+	// TODO: Add better documentation on the verification prcoess
+	// Seems like needed to know more of: https://github.com/lestrrat-go/jwx/tree/develop/v2/jwt
+	verifier, err := cryptosuite.NewJSONWebKeyVerifier(jwk.ID, jwk.PublicKeyJWK)
+	if err != nil {
+		return
+	}
+
+	parsed, err := verifier.VerifyAndParseJWT(string(requestJWTBytes))
+	if err != nil {
+		return
+	}
+
+	if dat, err := util.PrettyJSON(parsed); err == nil {
+		fmt.Printf("Parsed Response:%s\n", string(dat))
+	}
+
+	return requestJWTBytes, err
+}
+
+func handleError(err error, msg string) {
+	if err != nil {
+		os.Stderr.WriteString(fmt.Sprintf("%s: %v", msg, err))
+		os.Exit(1)
+	}
+}
+
+func main() {
+	data := makePresentationData()
+	pr, err := makePresentationRequest(data)
+	handleError(err, "faild to make presentation request")
+	dat, err := json.Marshal(pr)
+	handleError(err, "failed to marshal presentation request")
+	fmt.Printf("Presentation Request:\n%s", string(dat))
+}