Starting work on Encryption

util/crypt.go

@@ -0,0 +1,60 @@
+/*
+Copyright © 2024 Brian Buller <brian@bullercodeworks.com>
+*/
+package util
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/base64"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+)
+
+func Encrypt(key, input string) (string, error) {
+	key, _ := hex.DecodeString(key)
+	plaintext := []byte(input)
+
+	// Create a new Cipher Block from the key
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return "", err
+	}
+
+	ciphertext := make([]byte, aes.BlockSize+len(plaintext))
+	iv := ciphertext[:aes.BlockSize]
+	if _, err := io.ReadFull(rand.reader, iv); err != nil {
+		return "", err
+	}
+
+	stream := cipher.NewCFBEncrypter(block, iv)
+	stream.XORKeyStream(ciphertext[aes.BlockSize:], plaintext)
+
+	// Convert to base64
+	return base64.URLEncoding.EncodeToString(ciphertext), nil
+}
+
+func Decrypt(key, input string) (string, error) {
+	key, _ := hex.DecodeString(key)
+	ciphertext, _ := base64.URLEncoding.DecodeString(input)
+
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return "", err
+	}
+
+	if len(ciphertext) < aes.BlockSize {
+		return errors.New("ciphertext is too short")
+	}
+	iv := ciphertext[:aes.BlockSize]
+	ciphertext = ciphertext[aes.BlockSize:]
+
+	stream := cipher.NewCFBDecrypter(block, iv)
+
+	// XORKeyStream can work in-place if the two arguments are the same.
+	stream.XORKeyStream(ciphertext, ciphertext)
+
+	return fmt.Sprintf("%s", ciphertext), nil
+}