1 files changed, 72 insertions, 0 deletions
diff --git a/pkg/ext/auth.go b/pkg/ext/auth.go
new file mode 100644
index 0000000..d9fbfba
--- /dev/null
+++ b/pkg/ext/auth.go
@@ -0,0 +1,72 @@
+package ext
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/gob"
+	"fmt"
+	"io"
+)
+
+type Token struct {
+	UserID   uint
+	Username string
+}
+
+var nonce []byte
+
+func init() {
+	nonce = make([]byte, 12)
+	if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
+		fmt.Println("Erro while generating nonce " + err.Error())
+		panic(1)
+	}
+}
+
+func ReadToken(data []byte, key []byte) (*Token, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		panic(err.Error())
+	}
+
+	plaintext, err := aesgcm.Open(nil, nonce, data, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	r := bytes.NewReader(plaintext)
+	var token Token
+	dec := gob.NewDecoder(r)
+	if err = dec.Decode(&token); err != nil {
+		return nil, err
+	}
+	return &token, nil
+}
+
+func WriteToken(token *Token, key []byte) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	aesgcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return nil, err
+	}
+
+	var buffer bytes.Buffer
+	enc := gob.NewEncoder(&buffer)
+	if err := enc.Encode(token); err != nil {
+		return nil, err
+	}
+
+	ciphertext := aesgcm.Seal(nil, nonce, buffer.Bytes(), nil)
+	return ciphertext, nil
+}