Swag Docs

internal/helpers/cipher/cipher.go

@@ -0,0 +1,86 @@
+package cipher
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/base64"
+	"strings"
+)
+
+type Crypto interface {
+	Encrypt(plainText string) (string, error)
+	Decrypt(cipherIvKey string) (string, error)
+}
+
+type niceCrypto struct {
+	cipherKey   string
+	cipherIvKey string
+}
+
+func (c niceCrypto) Encrypt(plainText string) (string, error) {
+	if strings.TrimSpace(plainText) == "" {
+		return plainText, nil
+	}
+
+	block, err := aes.NewCipher([]byte(c.cipherKey))
+	if err != nil {
+		return "", err
+	}
+
+	encrypter := cipher.NewCBCEncrypter(block, []byte(c.cipherIvKey))
+	paddedPlainText := padPKCS7([]byte(plainText), encrypter.BlockSize())
+
+	cipherText := make([]byte, len(paddedPlainText))
+	// CryptBlocks 함수에 데이터(paddedPlainText)와 암호화 될 데이터를 저장할 슬라이스(cipherText)를 넣으면 암호화가 된다.
+	encrypter.CryptBlocks(cipherText, paddedPlainText)
+
+	return base64.StdEncoding.EncodeToString(cipherText), nil
+}
+
+func (c niceCrypto) Decrypt(cipherText string) (string, error) {
+	if strings.TrimSpace(cipherText) == "" {
+		return cipherText, nil
+	}
+
+	decodedCipherText, err := base64.StdEncoding.DecodeString(cipherText)
+	if err != nil {
+		return "", err
+	}
+
+	block, err := aes.NewCipher([]byte(c.cipherKey))
+	if err != nil {
+		return "", err
+	}
+
+	decrypter := cipher.NewCBCDecrypter(block, []byte(c.cipherIvKey))
+	plainText := make([]byte, len(decodedCipherText))
+
+	decrypter.CryptBlocks(plainText, decodedCipherText)
+	trimmedPlainText := trimPKCS5(plainText)
+
+	return string(trimmedPlainText), nil
+}
+
+func NewNiceCrypto(cipherKey, cipherIvKey string) (Crypto, error) {
+	if ck := len(cipherKey); ck != 32 {
+		return nil, aes.KeySizeError(ck)
+	}
+
+	if cik := len(cipherIvKey); cik != 16 {
+		return nil, aes.KeySizeError(cik)
+	}
+
+	return &niceCrypto{cipherKey, cipherIvKey}, nil
+}
+
+func padPKCS7(plainText []byte, blockSize int) []byte {
+	padding := blockSize - len(plainText)%blockSize
+	padText := bytes.Repeat([]byte{byte(padding)}, padding)
+	return append(plainText, padText...)
+}
+
+func trimPKCS5(text []byte) []byte {
+	padding := text[len(text)-1]
+	return text[:len(text)-int(padding)]
+}