add service

pkg/crypto/crypto.go

@@ -0,0 +1,125 @@
+package crypto
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/hmac"
+	"crypto/rand"
+	"crypto/sha256"
+	"crypto/sha512"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"strings"
+)
+
+type Crypto struct {
+	secret string
+}
+
+func NewCrypto(secret string) *Crypto {
+	return &Crypto{secret: secret}
+}
+
+func (c *Crypto) EmailHash(email string) string {
+	if email == "" {
+		return email
+	}
+	normalized := strings.TrimSpace(strings.ToLower(email))
+	h := hmac.New(sha256.New, []byte(c.secret))
+	h.Write([]byte(normalized))
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+func PasswordHash(password string) string {
+	h := sha512.New()
+	h.Write([]byte(password))
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+func (c *Crypto) getKey() []byte {
+	h := sha256.New()
+	h.Write([]byte(c.secret))
+	return h.Sum(nil)
+}
+
+func (c *Crypto) Encrypt(plaintext string) (string, error) {
+	if plaintext == "" {
+		return plaintext, nil
+	}
+
+	key := c.getKey()
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return "", fmt.Errorf("failed to create cipher: %w", err)
+	}
+
+	aesGCM, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", fmt.Errorf("failed to create GCM: %w", err)
+	}
+
+	iv := make([]byte, aesGCM.NonceSize())
+	if _, err := rand.Read(iv); err != nil {
+		return "", fmt.Errorf("failed to generate IV: %w", err)
+	}
+
+	ciphertext := aesGCM.Seal(nil, iv, []byte(plaintext), nil)
+
+	tag := ciphertext[len(ciphertext)-aesGCM.Overhead():]
+	cipherOnly := ciphertext[:len(ciphertext)-aesGCM.Overhead()]
+
+	return fmt.Sprintf("%s:%s:%s",
+		hex.EncodeToString(iv),
+		hex.EncodeToString(tag),
+		hex.EncodeToString(cipherOnly),
+	), nil
+}
+
+func (c *Crypto) Decrypt(ciphertext string) (string, error) {
+	if ciphertext == "" {
+		return ciphertext, nil
+	}
+
+	parts := strings.Split(ciphertext, ":")
+	if len(parts) != 3 {
+		return "", errors.New("invalid encrypted value format")
+	}
+
+	ivHex, tagHex, cipherHex := parts[0], parts[1], parts[2]
+
+	iv, err := hex.DecodeString(ivHex)
+	if err != nil {
+		return "", fmt.Errorf("failed to decode IV: %w", err)
+	}
+
+	tag, err := hex.DecodeString(tagHex)
+	if err != nil {
+		return "", fmt.Errorf("failed to decode tag: %w", err)
+	}
+
+	cipherOnly, err := hex.DecodeString(cipherHex)
+	if err != nil {
+		return "", fmt.Errorf("failed to decode ciphertext: %w", err)
+	}
+
+	key := c.getKey()
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return "", fmt.Errorf("failed to create cipher: %w", err)
+	}
+
+	aesGCM, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", fmt.Errorf("failed to create GCM: %w", err)
+	}
+
+	ciphertextWithTag := append(cipherOnly, tag...)
+
+	plaintext, err := aesGCM.Open(nil, iv, ciphertextWithTag, nil)
+	if err != nil {
+		return "", fmt.Errorf("failed to decrypt: %w", err)
+	}
+
+	return string(plaintext), nil
+}