working commit

pkg/cm509/aes256.go

@@ -0,0 +1,103 @@
+package cm509
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+	"io"
+)
+
+func EncryptAES256(b64data string, key string) (string, error) {
+	var res string
+	var err error
+
+	const aes256KeyLen = 32
+
+	bKey := []byte(key)
+	keyLen := len(bKey)
+	switch {
+	case keyLen > aes256KeyLen:
+		bKey = bKey[:aes256KeyLen]
+	case keyLen < aes256KeyLen:
+		padding := make([]byte, aes256KeyLen-keyLen)
+		bKey = append(bKey, padding...)
+	case keyLen == 0:
+		return res, fmt.Errorf("Zero lenght key")
+	}
+
+	data, err := base64.StdEncoding.DecodeString(b64data)
+	if err != nil {
+		return res, err
+	}
+
+	block, err := aes.NewCipher(bKey)
+	if err != nil {
+		return res, err
+	}
+
+	nonce := make([]byte, 12)
+	_, err = io.ReadFull(rand.Reader, nonce)
+	if err != nil {
+		return res, err
+	}
+
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return res, err
+	}
+
+	ciphertext := aesgcm.Seal(nil, nonce, data, nil)
+	ciphertext = append(nonce, ciphertext...)
+
+	res = base64.StdEncoding.EncodeToString(ciphertext)
+
+	return res, err
+
+}
+
+func DecryptAES256(b64ciphertext string, key string) (string, error) {
+	var res string
+	var err error
+
+	const aes256KeyLen = 32
+
+	bKey := []byte(key)
+	keyLen := len(bKey)
+	switch {
+	case keyLen > aes256KeyLen:
+		bKey = bKey[:aes256KeyLen]
+	case keyLen < aes256KeyLen:
+		padding := make([]byte, aes256KeyLen-keyLen)
+		bKey = append(bKey, padding...)
+	case keyLen == 0:
+		return res, fmt.Errorf("Zero lenght key")
+	}
+
+	ciphertext, err := base64.StdEncoding.DecodeString(b64ciphertext)
+	if err != nil {
+		return res, err
+	}
+
+	block, err := aes.NewCipher(bKey)
+	if err != nil {
+		return res, err
+	}
+
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return res, err
+	}
+
+	nonceSize := aesgcm.NonceSize()
+	nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
+
+	plaintext, err := aesgcm.Open(nil, nonce, ciphertext, nil)
+	if err != nil {
+		return res, err
+	}
+
+	res = base64.StdEncoding.EncodeToString(plaintext)
+	return res, err
+}