functions: en/decrypt with chacha20poly1305

Author: pilinux

chaCha20.go

@@ -0,0 +1,56 @@
+package crypt
+
+import (
+	"crypto/rand"
+	"fmt"
+
+	"golang.org/x/crypto/chacha20poly1305"
+)
+
+// EncryptChacha20poly1305 encrypts and authenticates the given message with
+// ChaCha20-Poly1305 AEAD using the given 256-bit key.
+func EncryptChacha20poly1305(key []byte, text string) (ciphertext []byte, nonce []byte, err error) {
+	// create a new ChaCha20-Poly1305 AEAD using the given 256-bit key
+	aead, err := chacha20poly1305.New(key)
+	if err != nil {
+		err = fmt.Errorf("error creating AEAD: %v", err)
+		return
+	}
+
+	// generate a 96-bit random nonce
+	nonce = make([]byte, aead.NonceSize())
+	_, err = rand.Read(nonce)
+	if err != nil {
+		err = fmt.Errorf("error generating nonce: %v", err)
+		return
+	}
+
+	// data to be encrypted
+	data := []byte(text)
+
+	// encrypt the data
+	ciphertext = aead.Seal(nil, nonce, data, nil)
+
+	return
+}
+
+// DecryptChacha20poly1305 decrypts and authenticates the given message with
+// ChaCha20-Poly1305 AEAD using the given 256-bit key and 96-bit nonce.
+func DecryptChacha20poly1305(key, nonce, ciphertext []byte) (text string, err error) {
+	// create a new ChaCha20-Poly1305 AEAD using the given 256-bit key
+	aead, err := chacha20poly1305.New(key)
+	if err != nil {
+		err = fmt.Errorf("error creating AEAD: %v", err)
+		return
+	}
+
+	// decrypt the data
+	plaintext, err := aead.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		err = fmt.Errorf("error decrypting data: %v", err)
+		return
+	}
+	text = string(plaintext)
+
+	return
+}