1

pkg/cryptohelper/aeshelper/aes256.go

@@ -0,0 +1,88 @@
+package aeshelper
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/md5"
+	"crypto/rand"
+	"encoding/base64"
+	"io"
+)
+
+// Encrypt text with the passphrase
+func Encrypt(text string, passphrase string) string {
+	salt := make([]byte, 8)
+	if _, err := io.ReadFull(rand.Reader, salt); err != nil {
+		panic(err.Error())
+	}
+
+	key, iv := DeriveKeyAndIv(passphrase, string(salt))
+
+	block, err := aes.NewCipher([]byte(key))
+	if err != nil {
+		panic(err)
+	}
+
+	pad := PKCS7Padding([]byte(text), block.BlockSize())
+	ecb := cipher.NewCBCEncrypter(block, []byte(iv))
+	encrypted := make([]byte, len(pad))
+	ecb.CryptBlocks(encrypted, pad)
+
+	return base64.StdEncoding.EncodeToString([]byte("Salted__" + string(salt) + string(encrypted)))
+}
+
+// Decrypt encrypted text with the passphrase
+func Decrypt(encrypted string, passphrase string) string {
+	ct, _ := base64.StdEncoding.DecodeString(encrypted)
+	if len(ct) < 16 || string(ct[:8]) != "Salted__" {
+		return ""
+	}
+
+	salt := ct[8:16]
+	ct = ct[16:]
+	key, iv := DeriveKeyAndIv(passphrase, string(salt))
+
+	block, err := aes.NewCipher([]byte(key))
+	if err != nil {
+		panic(err)
+	}
+
+	cbc := cipher.NewCBCDecrypter(block, []byte(iv))
+	dst := make([]byte, len(ct))
+	cbc.CryptBlocks(dst, ct)
+
+	return string(PKCS7Trimming(dst))
+}
+
+// PKCS7Padding PKCS7Padding
+func PKCS7Padding(ciphertext []byte, blockSize int) []byte {
+	padding := blockSize - len(ciphertext)%blockSize
+	padtext := bytes.Repeat([]byte{byte(padding)}, padding)
+	return append(ciphertext, padtext...)
+}
+
+// PKCS7Trimming PKCS7Trimming
+func PKCS7Trimming(encrypt []byte) []byte {
+	padding := encrypt[len(encrypt)-1]
+	return encrypt[:len(encrypt)-int(padding)]
+}
+
+// DeriveKeyAndIv DeriveKeyAndIv
+func DeriveKeyAndIv(passphrase string, salt string) (string, string) {
+	salted := ""
+	dI := ""
+
+	for len(salted) < 48 {
+		md := md5.New()
+		md.Write([]byte(dI + passphrase + salt))
+		dM := md.Sum(nil)
+		dI = string(dM[:16])
+		salted = salted + dI
+	}
+
+	key := salted[0:32]
+	iv := salted[32:48]
+
+	return key, iv
+}