fix: logging module

pkg/plugin/implementation/decrypter/decrypter.go

@@ -0,0 +1,85 @@
+package decryption
+
+import (
+	"context"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/ecdh"
+	"encoding/base64"
+	"fmt"
+
+	"github.com/zenazn/pkcs7pad"
+)
+
+// decrypter implements the Decrypter interface and handles the decryption process.
+type decrypter struct {
+}
+
+// New creates a new decrypter instance with the given configuration.
+func New(ctx context.Context) (*decrypter, func() error, error) {
+	return &decrypter{}, nil, nil
+}
+
+// Decrypt decrypts the given encryptedData using the provided privateKeyBase64 and publicKeyBase64.
+func (d *decrypter) Decrypt(ctx context.Context, encryptedData, privateKeyBase64, publicKeyBase64 string) (string, error) {
+	privateKeyBytes, err := base64.StdEncoding.DecodeString(privateKeyBase64)
+	if err != nil {
+		return "", fmt.Errorf("invalid private key: %w", err)
+	}
+
+	publicKeyBytes, err := base64.StdEncoding.DecodeString(publicKeyBase64)
+	if err != nil {
+		return "", fmt.Errorf("invalid public key: %w", err)
+	}
+
+	// Decode the Base64 encoded encrypted data.
+	messageByte, err := base64.StdEncoding.DecodeString(encryptedData)
+	if err != nil {
+		return "", fmt.Errorf("failed to decode encrypted data: %w", err)
+	}
+
+	aesCipher, err := createAESCipher(privateKeyBytes, publicKeyBytes)
+	if err != nil {
+		return "", fmt.Errorf("failed to create AES cipher: %w", err)
+	}
+
+	blocksize := aesCipher.BlockSize()
+	if len(messageByte)%blocksize != 0 {
+		return "", fmt.Errorf("ciphertext is not a multiple of the blocksize")
+	}
+
+	for i := 0; i < len(messageByte); i += aesCipher.BlockSize() {
+		executionSlice := messageByte[i : i+aesCipher.BlockSize()]
+		aesCipher.Decrypt(executionSlice, executionSlice)
+	}
+
+	messageByte, err = pkcs7pad.Unpad(messageByte)
+	if err != nil {
+		return "", fmt.Errorf("failed to unpad data: %w", err)
+	}
+
+	return string(messageByte), nil
+}
+
+func createAESCipher(privateKey, publicKey []byte) (cipher.Block, error) {
+	x25519Curve := ecdh.X25519()
+	x25519PrivateKey, err := x25519Curve.NewPrivateKey(privateKey)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create private key: %w", err)
+	}
+	x25519PublicKey, err := x25519Curve.NewPublicKey(publicKey)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create public key: %w", err)
+	}
+	sharedSecret, err := x25519PrivateKey.ECDH(x25519PublicKey)
+	if err != nil {
+		return nil, fmt.Errorf("failed to derive shared secret: %w", err)
+	}
+
+	aesCipher, err := aes.NewCipher(sharedSecret)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create AES cipher: %w", err)
+	}
+
+	return aesCipher, nil
+}