feat: crypto/aesutil/aesecb: add DecryptBase64(), EncryptBase64()

Author: grokify

crypto/aesutil/aesecb/aesecb.go

@@ -0,0 +1,87 @@
+package aesecb
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/base64"
+	"errors"
+)
+
+func DecryptBase64(v, key string) (string, error) {
+	if decoded, err := base64.StdEncoding.DecodeString(v); err != nil {
+		return "", err
+	} else if block, err := aes.NewCipher([]byte(key)); err != nil {
+		return "", err
+	} else if len(decoded)%aes.BlockSize != 0 {
+		return "", errors.New("ciphertext is not a multiple of the block size")
+	} else {
+		decrypted := make([]byte, len(decoded))
+		decryptECB(block, decrypted, decoded)
+
+		decrypted, err = removePKCS7Padding(decrypted, aes.BlockSize)
+		if err != nil {
+			return "", err
+		} else {
+			return string(decrypted), nil
+		}
+	}
+}
+
+// decryptECB performs the ECB mode decryption
+func decryptECB(block cipher.Block, dst, src []byte) {
+	bs := block.BlockSize()
+	for len(src) > 0 {
+		block.Decrypt(dst, src[:bs])
+		src = src[bs:]
+		dst = dst[bs:]
+	}
+}
+
+// removePKCS7Padding removes padding from the decrypted data.
+func removePKCS7Padding(data []byte, blockSize int) ([]byte, error) {
+	if len(data) == 0 || len(data)%blockSize != 0 {
+		return nil, errors.New("invalid padding size")
+	}
+
+	paddingLen := int(data[len(data)-1])
+	if paddingLen == 0 || paddingLen > blockSize {
+		return nil, errors.New("invalid padding")
+	}
+
+	for _, padByte := range data[len(data)-paddingLen:] {
+		if int(padByte) != paddingLen {
+			return nil, errors.New("invalid padding")
+		}
+	}
+
+	return data[:len(data)-paddingLen], nil
+}
+
+func EncryptBase64(v, key string) (string, error) {
+	paddedInput := addPKCS5Padding([]byte(v), aes.BlockSize)
+
+	if block, err := aes.NewCipher([]byte(key)); err != nil {
+		return "", err
+	} else {
+		encrypted := make([]byte, len(paddedInput))
+		encryptECB(block, encrypted, paddedInput)
+		return base64.StdEncoding.EncodeToString(encrypted), nil
+	}
+}
+
+// encryptECB performs the ECB mode encryption.
+func encryptECB(block cipher.Block, dst, src []byte) {
+	bs := block.BlockSize()
+	for len(src) > 0 {
+		block.Encrypt(dst, src[:bs])
+		src = src[bs:]
+		dst = dst[bs:]
+	}
+}
+
+func addPKCS5Padding(data []byte, blockSize int) []byte {
+	padding := blockSize - len(data)%blockSize
+	padText := bytes.Repeat([]byte{byte(padding)}, padding)
+	return append(data, padText...)
+}

crypto/aesutil/aesecb/aesecb_test.go

@@ -0,0 +1,32 @@
+package aesecb
+
+import (
+	"fmt"
+	"testing"
+)
+
+var aesecbTests = []struct {
+	plaintext string
+	key       string
+}{
+	{"My Secret Password", "0123456789abcdef"},
+	{"My Secret Password", "1234567890123456"},
+}
+
+func TestEncryptDecrypt(t *testing.T) {
+	for _, tt := range aesecbTests {
+		enc, err := EncryptBase64(tt.plaintext, tt.key)
+		if err != nil {
+			t.Errorf("aesecb.EncryptBase64 error(%s)", err.Error())
+		}
+		dec, err := DecryptBase64(enc, tt.key)
+		if err != nil {
+			t.Errorf("aesecb.DecryptBase64 error(%s)", err.Error())
+		}
+		if dec != tt.plaintext {
+			fmt.Printf("[%v]\n", []byte(dec))
+			fmt.Printf("[%v]\n", []byte(tt.plaintext))
+			t.Errorf("encrypt/decrypt AES ECB error: want decrypted (%s), got (%s)", tt.plaintext, dec)
+		}
+	}
+}