updated as per the review comments

pkg/plugin/implementation/signvalidator/cmd/plugin.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"context"
+	"errors"
+
+	"github.com/beckn/beckn-onix/pkg/plugin/definition"
+	"github.com/beckn/beckn-onix/pkg/plugin/implementation/signvalidator"
+)
+
+// provider provides instances of Verifier.
+type provider struct{}
+
+// New initializes a new Verifier instance.
+func (vp provider) New(ctx context.Context, config map[string]string) (definition.SignValidator, func() error, error) {
+	if ctx == nil {
+		return nil, nil, errors.New("context cannot be nil")
+	}
+
+	return signvalidator.New(ctx, &signvalidator.Config{})
+}
+
+// Provider is the exported symbol that the plugin manager will look for.
+var Provider = provider{}

pkg/plugin/implementation/signvalidator/cmd/plugin_test.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"context"
+	"testing"
+)
+
+// TestVerifierProviderSuccess tests successful creation of a verifier.
+func TestVerifierProviderSuccess(t *testing.T) {
+	provider := provider{}
+
+	tests := []struct {
+		name   string
+		ctx    context.Context
+		config map[string]string
+	}{
+		{
+			name:   "Successful creation",
+			ctx:    context.Background(),
+			config: map[string]string{},
+		},
+		{
+			name:   "Nil context",
+			ctx:    context.TODO(),
+			config: map[string]string{},
+		},
+		{
+			name:   "Empty config",
+			ctx:    context.Background(),
+			config: map[string]string{},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			verifier, close, err := provider.New(tt.ctx, tt.config)
+
+			if err != nil {
+				t.Fatalf("Expected no error, but got: %v", err)
+			}
+			if verifier == nil {
+				t.Fatal("Expected verifier instance to be non-nil")
+			}
+			if close != nil {
+				if err := close(); err != nil {
+					t.Fatalf("Test %q failed: cleanup function returned an error: %v", tt.name, err)
+				}
+			}
+		})
+	}
+}
+
+// TestVerifierProviderFailure tests cases where verifier creation should fail.
+func TestVerifierProviderFailure(t *testing.T) {
+	provider := provider{}
+
+	tests := []struct {
+		name    string
+		ctx     context.Context
+		config  map[string]string
+		wantErr bool
+	}{
+		{
+			name:    "Nil context failure",
+			ctx:     nil,
+			config:  map[string]string{},
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			verifierInstance, close, err := provider.New(tt.ctx, tt.config)
+
+			if (err != nil) != tt.wantErr {
+				t.Fatalf("Expected error: %v, but got: %v", tt.wantErr, err)
+			}
+			if verifierInstance != nil {
+				t.Fatal("Expected verifier instance to be nil")
+			}
+			if close != nil {
+				if err := close(); err != nil {
+					t.Fatalf("Test %q failed: cleanup function returned an error: %v", tt.name, err)
+				}
+			}
+
+		})
+	}
+}

pkg/plugin/implementation/signvalidator/signvalidator.go

@@ -0,0 +1,115 @@
+package signvalidator
+
+import (
+	"context"
+	"crypto/ed25519"
+	"encoding/base64"
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+
+	"golang.org/x/crypto/blake2b"
+)
+
+// Config struct for Verifier.
+type Config struct {
+}
+
+// validator implements the validator interface.
+type validator struct {
+	config *Config
+}
+
+// New creates a new Verifier instance.
+func New(ctx context.Context, config *Config) (*validator, func() error, error) {
+	v := &validator{config: config}
+
+	return v, nil, nil
+}
+
+// Verify checks the signature for the given payload and public key.
+func (v *validator) Validate(ctx context.Context, body []byte, header string, publicKeyBase64 string) error {
+	createdTimestamp, expiredTimestamp, signature, err := parseAuthHeader(header)
+	if err != nil {
+		// TODO: Return appropriate error code when Error Code Handling Module is ready
+		return fmt.Errorf("error parsing header: %w", err)
+	}
+
+	signatureBytes, err := base64.StdEncoding.DecodeString(signature)
+	if err != nil {
+		// TODO: Return appropriate error code when Error Code Handling Module is ready
+		return fmt.Errorf("error decoding signature: %w", err)
+	}
+
+	currentTime := time.Now().Unix()
+	if createdTimestamp > currentTime || currentTime > expiredTimestamp {
+		// TODO: Return appropriate error code when Error Code Handling Module is ready
+		return fmt.Errorf("signature is expired or not yet valid")
+	}
+
+	createdTime := time.Unix(createdTimestamp, 0)
+	expiredTime := time.Unix(expiredTimestamp, 0)
+
+	signingString := hash(body, createdTime.Unix(), expiredTime.Unix())
+
+	decodedPublicKey, err := base64.StdEncoding.DecodeString(publicKeyBase64)
+	if err != nil {
+		// TODO: Return appropriate error code when Error Code Handling Module is ready
+		return fmt.Errorf("error decoding public key: %w", err)
+	}
+
+	if !ed25519.Verify(ed25519.PublicKey(decodedPublicKey), []byte(signingString), signatureBytes) {
+		// TODO: Return appropriate error code when Error Code Handling Module is ready
+		return fmt.Errorf("signature verification failed")
+	}
+
+	return nil
+}
+
+// parseAuthHeader extracts signature values from the Authorization header.
+func parseAuthHeader(header string) (int64, int64, string, error) {
+	header = strings.TrimPrefix(header, "Signature ")
+
+	parts := strings.Split(header, ",")
+	signatureMap := make(map[string]string)
+
+	for _, part := range parts {
+		keyValue := strings.SplitN(strings.TrimSpace(part), "=", 2)
+		if len(keyValue) == 2 {
+			key := strings.TrimSpace(keyValue[0])
+			value := strings.Trim(keyValue[1], "\"")
+			signatureMap[key] = value
+		}
+	}
+
+	createdTimestamp, err := strconv.ParseInt(signatureMap["created"], 10, 64)
+	if err != nil {
+		// TODO: Return appropriate error code when Error Code Handling Module is ready
+		return 0, 0, "", fmt.Errorf("invalid created timestamp: %w", err)
+	}
+
+	expiredTimestamp, err := strconv.ParseInt(signatureMap["expires"], 10, 64)
+	if err != nil {
+		// TODO: Return appropriate error code when Error Code Handling Module is ready
+		return 0, 0, "", fmt.Errorf("invalid expires timestamp: %w", err)
+	}
+
+	signature := signatureMap["signature"]
+	if signature == "" {
+		// TODO: Return appropriate error code when Error Code Handling Module is ready
+		return 0, 0, "", fmt.Errorf("signature missing in header")
+	}
+
+	return createdTimestamp, expiredTimestamp, signature, nil
+}
+
+// hash constructs a signing string for verification.
+func hash(payload []byte, createdTimestamp, expiredTimestamp int64) string {
+	hasher, _ := blake2b.New512(nil)
+	hasher.Write(payload)
+	hashSum := hasher.Sum(nil)
+	digestB64 := base64.StdEncoding.EncodeToString(hashSum)
+
+	return fmt.Sprintf("(created): %d\n(expires): %d\ndigest: BLAKE-512=%s", createdTimestamp, expiredTimestamp, digestB64)
+}

pkg/plugin/implementation/signvalidator/signvalidator_test.go

@@ -0,0 +1,147 @@
+package signvalidator
+
+import (
+	"context"
+	"crypto/ed25519"
+	"encoding/base64"
+	"strconv"
+	"testing"
+	"time"
+)
+
+// generateTestKeyPair generates a new ED25519 key pair for testing.
+func generateTestKeyPair() (string, string) {
+	publicKey, privateKey, _ := ed25519.GenerateKey(nil)
+	return base64.StdEncoding.EncodeToString(privateKey), base64.StdEncoding.EncodeToString(publicKey)
+}
+
+// signTestData creates a valid signature for test cases.
+func signTestData(privateKeyBase64 string, body []byte, createdAt, expiresAt int64) string {
+	privateKeyBytes, _ := base64.StdEncoding.DecodeString(privateKeyBase64)
+	privateKey := ed25519.PrivateKey(privateKeyBytes)
+
+	signingString := hash(body, createdAt, expiresAt)
+	signature := ed25519.Sign(privateKey, []byte(signingString))
+
+	return base64.StdEncoding.EncodeToString(signature)
+}
+
+// TestVerifySuccessCases tests all valid signature verification cases.
+func TestVerifySuccess(t *testing.T) {
+	privateKeyBase64, publicKeyBase64 := generateTestKeyPair()
+
+	tests := []struct {
+		name      string
+		body      []byte
+		createdAt int64
+		expiresAt int64
+	}{
+		{
+			name:      "Valid Signature",
+			body:      []byte("Test Payload"),
+			createdAt: time.Now().Unix(),
+			expiresAt: time.Now().Unix() + 3600,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			signature := signTestData(privateKeyBase64, tt.body, tt.createdAt, tt.expiresAt)
+			header := `Signature created="` + strconv.FormatInt(tt.createdAt, 10) +
+				`", expires="` + strconv.FormatInt(tt.expiresAt, 10) +
+				`", signature="` + signature + `"`
+
+			verifier, close, _ := New(context.Background(), &Config{})
+			err := verifier.Validate(context.Background(), tt.body, header, publicKeyBase64)
+
+			if err != nil {
+				t.Fatalf("Expected no error, but got: %v", err)
+			}
+			if close != nil {
+				if err := close(); err != nil {
+					t.Fatalf("Test %q failed: cleanup function returned an error: %v", tt.name, err)
+				}
+			}
+		})
+	}
+}
+
+// TestVerifyFailureCases tests all invalid signature verification cases.
+func TestVerifyFailure(t *testing.T) {
+	privateKeyBase64, publicKeyBase64 := generateTestKeyPair()
+	_, wrongPublicKeyBase64 := generateTestKeyPair()
+
+	tests := []struct {
+		name   string
+		body   []byte
+		header string
+		pubKey string
+	}{
+		{
+			name:   "Missing Authorization Header",
+			body:   []byte("Test Payload"),
+			header: "",
+			pubKey: publicKeyBase64,
+		},
+		{
+			name:   "Malformed Header",
+			body:   []byte("Test Payload"),
+			header: `InvalidSignature created="wrong"`,
+			pubKey: publicKeyBase64,
+		},
+		{
+			name: "Invalid Base64 Signature",
+			body: []byte("Test Payload"),
+			header: `Signature created="` + strconv.FormatInt(time.Now().Unix(), 10) +
+				`", expires="` + strconv.FormatInt(time.Now().Unix()+3600, 10) +
+				`", signature="!!INVALIDBASE64!!"`,
+			pubKey: publicKeyBase64,
+		},
+		{
+			name: "Expired Signature",
+			body: []byte("Test Payload"),
+			header: `Signature created="` + strconv.FormatInt(time.Now().Unix()-7200, 10) +
+				`", expires="` + strconv.FormatInt(time.Now().Unix()-3600, 10) +
+				`", signature="` + signTestData(privateKeyBase64, []byte("Test Payload"), time.Now().Unix()-7200, time.Now().Unix()-3600) + `"`,
+			pubKey: publicKeyBase64,
+		},
+		{
+			name: "Invalid Public Key",
+			body: []byte("Test Payload"),
+			header: `Signature created="` + strconv.FormatInt(time.Now().Unix(), 10) +
+				`", expires="` + strconv.FormatInt(time.Now().Unix()+3600, 10) +
+				`", signature="` + signTestData(privateKeyBase64, []byte("Test Payload"), time.Now().Unix(), time.Now().Unix()+3600) + `"`,
+			pubKey: wrongPublicKeyBase64,
+		},
+		{
+			name: "Invalid Expires Timestamp",
+			body: []byte("Test Payload"),
+			header: `Signature created="` + strconv.FormatInt(time.Now().Unix(), 10) +
+				`", expires="invalid_timestamp"`,
+			pubKey: publicKeyBase64,
+		},
+		{
+			name: "Signature Missing in Headers",
+			body: []byte("Test Payload"),
+			header: `Signature created="` + strconv.FormatInt(time.Now().Unix(), 10) +
+				`", expires="` + strconv.FormatInt(time.Now().Unix()+3600, 10) + `"`,
+			pubKey: publicKeyBase64,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			verifier, close, _ := New(context.Background(), &Config{})
+			err := verifier.Validate(context.Background(), tt.body, tt.header, tt.pubKey)
+
+			if err == nil {
+				t.Fatal("Expected an error but got none")
+			}
+			if close != nil {
+				if err := close(); err != nil {
+					t.Fatalf("Test %q failed: cleanup function returned an error: %v", tt.name, err)
+				}
+			}
+		})
+	}
+}