initial go implementation

internal/utils/crypto/encrypt.go

@@ -0,0 +1,41 @@
+package crypto
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/base64"
+	"fmt"
+)
+
+func Encrypt(plaintext, key, iv string) (string, error) {
+	padded := pkcs7Pad([]byte(plaintext))
+
+	block, err := aes.NewCipher([]byte(key))
+	if err != nil {
+		return "", fmt.Errorf("AES init failed: %v", err)
+	}
+
+	if len(iv) != aes.BlockSize {
+		return "", fmt.Errorf("IV must be %d bytes", aes.BlockSize)
+	}
+
+	mode := cipher.NewCBCEncrypter(block, []byte(iv))
+	ciphertext := make([]byte, len(padded))
+
+	mode.CryptBlocks(ciphertext, padded)
+
+	ciphertextB64 := base64.StdEncoding.EncodeToString(ciphertext)
+
+	return ciphertextB64, nil
+}
+
+func pkcs7Pad(buf []byte) []byte {
+	bufLen := len(buf)
+	padLen := aes.BlockSize - bufLen%aes.BlockSize
+	padded := make([]byte, bufLen+padLen)
+	copy(padded, buf)
+	for i := range padLen {
+		padded[bufLen+i] = byte(padLen)
+	}
+	return padded
+}