CL Anoncreds Crypto services

* added high-level CL crypto Issuer API
* added high-level CL crypto Prover API
* added high-level CL crypto Verifier API
* added ursa-implementations for the services
* added unit tests for issue credential flow with CL crypto
* added unit tests for present proof flow with CL crypto

Signed-off-by: konstantin.goncharov <konstantin.goncharov@avast.com>

pkg/doc/cl/api.go

@@ -0,0 +1,77 @@
+/*
+Copyright Avast Software. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package cl
+
+import (
+	"github.com/hyperledger/aries-framework-go/pkg/crypto"
+	"github.com/hyperledger/aries-framework-go/pkg/kms"
+)
+
+// Issuer contains all high-level methods to process CL Anoncreds on the issuer's side.
+type Issuer interface {
+	// GetCredentialDefinition returns a public CredDef data - public key, correctness proof and attributes
+	// returns:
+	// 		credDef as *CredentialDefinition
+	//		error in case of errors
+	GetCredentialDefinition() (*CredentialDefinition, error)
+	// OfferCredential generates CredOffer containing valid nonce
+	// returns:
+	// 		offer as *CredentialOffer
+	//		error in case of errors
+	OfferCredential() (*CredentialOffer, error)
+	// IssueCredential issues and signs Credential for values and CredRequest
+	// provided by prover and CredOffer from the previous step
+	// Resulting Credential will contain signature and signature's correctness proof, along with issued attributes
+	// returns:
+	// 		credential as *Credential
+	//		error in case of errors
+	IssueCredential(values map[string]interface{},
+		credentialRequest *CredentialRequest, credOffer *CredentialOffer) (*Credential, error)
+}
+
+// Prover contains all high-level methods to process CL Anoncreds on the prover's side.
+type Prover interface {
+	// RequestCredential generates CredRequest which contains blinded secrets with MS, using issuer's CredDef public data
+	// and CredOffer from the previous step
+	// returns:
+	// 		request as *CredentialRequest
+	//		error in case of errors
+	RequestCredential(credOffer *CredentialOffer,
+		credDef *CredentialDefinition, proverID string) (*CredentialRequest, error)
+	// ProcessCredential updates issued Credential signature for CredDef, using blinding factor from a CredRequest
+	// returns:
+	// 		credential as *Credential
+	//		error in case of errors
+	ProcessCredential(credential *Credential, credRequest *CredentialRequest,
+		credDef *CredentialDefinition) (*Credential, error)
+	// CreateProof composes Proof for the provided Credentials for CredDefs
+	// matching revealead attrs and predicates specified in PresentationRequest
+	// returns:
+	// 		proof as *Proof
+	//		error in case of errors
+	CreateProof(presentationRequest *PresentationRequest, credentials []*Credential,
+		credDefs []*CredentialDefinition) (*Proof, error)
+}
+
+// Verifier contains all high-level methods to process CL Anoncreds on the verifier's side.
+type Verifier interface {
+	// RequestPresentation generates PresentationRequest with unique nonce and provided list of attrs and predicates
+	// returns:
+	// 		request as *PresentationRequest
+	//		error in case of errors
+	RequestPresentation(items []*PresentationRequestItem) (*PresentationRequest, error)
+	// VerifyProof verifies given Proof according to PresentationRequest and CredDefs
+	// returns:
+	//		error in case of errors or nil if proof verification was successful
+	VerifyProof(proof *Proof, presentationRequest *PresentationRequest, credDefs []*CredentialDefinition) error
+}
+
+// Provider for CL services constructors.
+type Provider interface {
+	KMS() kms.KeyManager
+	Crypto() crypto.Crypto
+}

pkg/doc/cl/model.go

@@ -0,0 +1,64 @@
+/*
+Copyright Avast Software. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package cl
+
+// CredentialDefinition contains public data of CL CredDef.
+type CredentialDefinition struct {
+	CredPubKey              []byte
+	CredDefCorrectnessProof []byte
+	Attrs                   []string
+}
+
+// CredentialOffer contains nonce of CL CredOffer.
+type CredentialOffer struct {
+	Nonce []byte
+}
+
+// CredentialRequest contains nonce, proverID and blinded secrets of CL CredRequest.
+type CredentialRequest struct {
+	BlindedCredentialSecrets *BlindedCredentialSecrets
+	Nonce                    []byte
+	ProverID                 string
+}
+
+// BlindedCredentialSecrets contains handle, blinding factor and correctness proof of CL BlindedSecrets.
+type BlindedCredentialSecrets struct {
+	Handle           []byte
+	BlindingFactor   []byte
+	CorrectnessProof []byte
+}
+
+// Credential contains CL Credential's signature, correctness proof for it and related credential's values.
+type Credential struct {
+	Signature []byte
+	Values    map[string]interface{}
+	SigProof  []byte
+}
+
+// PresentationRequest contains items used for CL Proof generation.
+type PresentationRequest struct {
+	Items []*PresentationRequestItem
+	Nonce []byte
+}
+
+// PresentationRequestItem consists of revealed attributes and predicates upon which CL Proof is generated.
+type PresentationRequestItem struct {
+	RevealedAttrs []string
+	Predicates    []*Predicate
+}
+
+// Predicate defines predicate for CL Proof.
+type Predicate struct {
+	Attr  string
+	PType string
+	Value int32
+}
+
+// Proof wraps CL Proof in raw bytes.
+type Proof struct {
+	Proof []byte
+}

pkg/doc/cl/ursa/crypto_test.go

@@ -0,0 +1,228 @@
+//go:build ursa
+// +build ursa
+
+/*
+Copyright SecureKey Technologies Inc. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package ursa
+
+import (
+	"testing"
+
+	"github.com/google/tink/go/keyset"
+	"github.com/stretchr/testify/require"
+
+	"github.com/hyperledger/aries-framework-go/pkg/crypto"
+	"github.com/hyperledger/aries-framework-go/pkg/crypto/tinkcrypto"
+	bld "github.com/hyperledger/aries-framework-go/pkg/crypto/tinkcrypto/primitive/cl/blinder"
+	sgn "github.com/hyperledger/aries-framework-go/pkg/crypto/tinkcrypto/primitive/cl/signer"
+	"github.com/hyperledger/aries-framework-go/pkg/doc/cl"
+	"github.com/hyperledger/aries-framework-go/pkg/kms"
+	mockkms "github.com/hyperledger/aries-framework-go/pkg/mock/kms"
+)
+
+func TestCL(t *testing.T) {
+	km := &mockkms.KeyManager{}
+	c := &tinkcrypto.Crypto{}
+	provider := newProvider(km, c)
+
+	values := map[string]interface{}{"attr1": 5, "attr2": "aaa"}
+	values2 := map[string]interface{}{"attr3": 5, "attr4": "aaa"}
+
+	presentaionItems := []*cl.PresentationRequestItem{{
+		RevealedAttrs: []string{"attr2"},
+		Predicates: []*cl.Predicate{
+			{
+				PType: "GE",
+				Attr:  "attr1",
+				Value: 4,
+			},
+		},
+	}}
+
+	var (
+		issuer   *Issuer
+		prover   *Prover
+		verifier *Verifier
+
+		credDef    *cl.CredentialDefinition
+		offer      *cl.CredentialOffer
+		request    *cl.CredentialRequest
+		credential *cl.Credential
+
+		originalSignature []byte
+
+		presentation *cl.PresentationRequest
+		proof        *cl.Proof
+	)
+
+	t.Run("test CL services creation", func(t *testing.T) {
+		var err error
+
+		issKh, issPubKey := createAndExportSignerKey(t, []string{"attr1", "attr2"})
+		km.GetKeyValue = issKh
+		km.ExportPubKeyBytesValue = issPubKey
+		km.ExportPubKeyTypeValue = kms.CLCredDefType
+
+		issuer, err = NewIssuer(provider, "credDefKID", []string{"attr1", "attr2"})
+		require.NoError(t, err)
+
+		prvKh := createBlinderKey(t)
+		km.GetKeyValue = prvKh
+
+		prover, err = NewProver(provider, "msKID")
+		require.NoError(t, err)
+
+		verifier, err = NewVerifier()
+		require.NoError(t, err)
+	})
+
+	t.Run("test CL issue credential flow", func(t *testing.T) {
+		var err error
+
+		// 0. Issuer expose CredDef
+		credDef, err = issuer.GetCredentialDefinition()
+		require.NoError(t, err)
+		require.NotEmpty(t, credDef.CredPubKey)
+		require.NotEmpty(t, credDef.CredDefCorrectnessProof)
+
+		// 1. Issuer offers credential
+		offer, err = issuer.OfferCredential()
+		require.NoError(t, err)
+		require.NotEmpty(t, offer.Nonce)
+
+		// 2. Prover requests credential
+		request, err = prover.RequestCredential(offer, credDef, "proverDID")
+		require.NoError(t, err)
+		require.NotEmpty(t, request.Nonce)
+		require.NotEmpty(t, request.ProverID)
+		require.NotEmpty(t, request.BlindedCredentialSecrets)
+
+		// 3. Issuer issues credential
+		credential, err = issuer.IssueCredential(values, request, offer)
+		require.NoError(t, err)
+		require.NotEmpty(t, credential.Signature)
+		require.NotEmpty(t, credential.SigProof)
+		require.NotEmpty(t, credential.Values)
+
+		// 4. Prover verifies credential
+		originalSignature = credential.Signature
+
+		err = prover.ProcessCredential(credential, request, credDef)
+		require.NoError(t, err)
+		require.NotEmpty(t, credential.Signature)
+		require.NotEmpty(t, credential.SigProof)
+		require.NotEmpty(t, credential.Values)
+
+		require.NotEqual(t, originalSignature, credential.Signature)
+	})
+
+	t.Run("test CL present proof flow", func(t *testing.T) {
+		var err error
+
+		// 1. Verifier makes presentation request
+		presentation, err = verifier.RequestPresentation(presentaionItems)
+		require.NoError(t, err)
+		require.NotEmpty(t, presentation.Items)
+		require.NotEmpty(t, presentation.Nonce)
+
+		// 2. Prover creates proof accordingly
+		proof, err = prover.CreateProof(presentation, []*cl.Credential{credential}, []*cl.CredentialDefinition{credDef})
+		require.NoError(t, err)
+		require.NotEmpty(t, proof.Proof)
+
+		// 3. Verifier verifies resulting proof
+		err = verifier.VerifyProof(proof, presentation, []*cl.CredentialDefinition{credDef})
+		require.NoError(t, err)
+	})
+
+	t.Run("test CL failures", func(t *testing.T) {
+		var err error
+
+		issKh2, issPubKey2 := createAndExportSignerKey(t, []string{"attr3", "attr4"})
+		km.GetKeyValue = issKh2
+		km.ExportPubKeyBytesValue = issPubKey2
+		km.ExportPubKeyTypeValue = kms.CLCredDefType
+
+		issuer2, err := NewIssuer(provider, "credDefKID2", []string{"attr3", "attr4"})
+		require.NoError(t, err)
+		credDef2, err := issuer2.GetCredentialDefinition()
+		require.NoError(t, err)
+
+		// Issuer fails to issue credential for unknown credDef
+		_, err = issuer2.IssueCredential(values, request, offer)
+		require.Error(t, err)
+
+		// Issuer fails to issue credential for invalid values
+		_, err = issuer.IssueCredential(values2, request, offer)
+		require.Error(t, err)
+
+		// Prover fails to process credential with unmatched credDef
+		err = prover.ProcessCredential(credential, request, credDef2)
+		require.Error(t, err)
+
+		// Prover fails to create proof with unmatched credDefs
+		_, err = prover.CreateProof(presentation, []*cl.Credential{credential}, []*cl.CredentialDefinition{credDef2})
+		require.Error(t, err)
+
+		// Verifier fails to verify proof for unprocessed credential
+		unprocessed := &cl.Credential{
+			Signature: originalSignature,
+			SigProof:  credential.SigProof,
+			Values:    credential.Values,
+		}
+
+		invalid, err := prover.CreateProof(presentation, []*cl.Credential{unprocessed}, []*cl.CredentialDefinition{credDef})
+		require.NoError(t, err)
+
+		err = verifier.VerifyProof(invalid, presentation, []*cl.CredentialDefinition{credDef})
+		require.Error(t, err)
+
+		//  Verifier fails to verify proof for other credDef
+		err = verifier.VerifyProof(proof, presentation, []*cl.CredentialDefinition{credDef2})
+		require.Error(t, err)
+	})
+}
+
+func createAndExportSignerKey(t *testing.T, attrs []string) (*keyset.Handle, []byte) {
+	kh, err := keyset.NewHandle(sgn.CredDefKeyTemplate(attrs))
+	require.NoError(t, err)
+
+	pKh, err := kh.Public()
+	require.NoError(t, err)
+
+	pubKey, err := sgn.ExportCredDefPubKey(pKh)
+	require.NoError(t, err)
+
+	return kh, pubKey
+}
+
+func createBlinderKey(t *testing.T) *keyset.Handle {
+	kh, err := keyset.NewHandle(bld.MasterSecretKeyTemplate())
+	require.NoError(t, err)
+
+	return kh
+}
+
+type mockProvider struct {
+	km kms.KeyManager
+	cr crypto.Crypto
+}
+
+func (p *mockProvider) KMS() kms.KeyManager {
+	return p.km
+}
+
+func (p *mockProvider) Crypto() crypto.Crypto {
+	return p.cr
+}
+
+func newProvider(km kms.KeyManager, cr crypto.Crypto) *mockProvider {
+	return &mockProvider{
+		km: km,
+		cr: cr,
+	}
+}