fix: logging module

pkg/plugin/implementation/signer/signer.go

@@ -0,0 +1,77 @@
+package signer
+
+import (
+	"context"
+	"crypto/ed25519"
+	"encoding/base64"
+	"errors"
+	"fmt"
+
+	"golang.org/x/crypto/blake2b"
+)
+
+// Config holds the configuration for the signing process.
+type Config struct {
+}
+
+// Signer implements the Signer interface and handles the signing process.
+type Signer struct {
+	config *Config
+}
+
+// New creates a new Signer instance with the given configuration.
+func New(ctx context.Context, config *Config) (*Signer, func() error, error) {
+	s := &Signer{config: config}
+
+	return s, s.Close, nil
+}
+
+// hash generates a signing string using BLAKE-512 hashing.
+func hash(payload []byte, createdAt, expiresAt int64) (string, error) {
+	hasher, _ := blake2b.New512(nil)
+
+	_, err := hasher.Write(payload)
+	if err != nil {
+		return "", fmt.Errorf("failed to hash payload: %w", err)
+	}
+
+	hashSum := hasher.Sum(nil)
+	digestB64 := base64.StdEncoding.EncodeToString(hashSum)
+
+	return fmt.Sprintf("(created): %d\n(expires): %d\ndigest: BLAKE-512=%s", createdAt, expiresAt, digestB64), nil
+}
+
+// generateSignature signs the given signing string using the provided private key.
+func generateSignature(signingString []byte, privateKeyBase64 string) ([]byte, error) {
+	privateKeyBytes, err := base64.StdEncoding.DecodeString(privateKeyBase64)
+	if err != nil {
+		return nil, fmt.Errorf("error decoding private key: %w", err)
+	}
+
+	if len(privateKeyBytes) != ed25519.PrivateKeySize {
+		return nil, errors.New("invalid private key length")
+	}
+
+	privateKey := ed25519.PrivateKey(privateKeyBytes)
+	return ed25519.Sign(privateKey, signingString), nil
+}
+
+// Sign generates a digital signature for the provided payload.
+func (s *Signer) Sign(ctx context.Context, body []byte, privateKeyBase64 string, createdAt, expiresAt int64) (string, error) {
+	signingString, err := hash(body, createdAt, expiresAt)
+	if err != nil {
+		return "", err
+	}
+
+	signature, err := generateSignature([]byte(signingString), privateKeyBase64)
+	if err != nil {
+		return "", err
+	}
+
+	return base64.StdEncoding.EncodeToString(signature), nil
+}
+
+// Close releases resources (mock implementation returning nil).
+func (s *Signer) Close() error {
+	return nil
+}