Upstream sync

shared/encryption.go

@@ -0,0 +1,88 @@
+package shared
+
+import (
+	"bytes"
+	"compress/flate"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/base64"
+	"fmt"
+	"io"
+)
+
+type EncryptionClient interface {
+	Encrypt(string) (string, error)
+	Decrypt(string) (string, error)
+}
+
+type encryptionClient struct {
+	Secret string
+}
+
+func NewEncryptionClient(secret string) EncryptionClient {
+	return &encryptionClient{Secret: secret}
+}
+
+func compress(text string) ([]byte, error) {
+	var compressedBytes bytes.Buffer
+	w, err := flate.NewWriter(&compressedBytes, flate.BestCompression)
+	w.Write([]byte(text))
+	w.Close()
+	return compressedBytes.Bytes(), err
+}
+
+func decompress(compressedBytes []byte) (string, error) {
+	reader := flate.NewReader(bytes.NewReader(compressedBytes))
+	defer reader.Close()
+	textBytes := new(bytes.Buffer)
+	_, err := textBytes.ReadFrom(reader)
+	return textBytes.String(), err
+}
+
+// Encrypt method is to encrypt or hide any classified text
+func (e encryptionClient) Encrypt(text string) (string, error) {
+	block, err := aes.NewCipher([]byte(e.Secret))
+	if err != nil {
+		return "", err
+	}
+	compressedText, err := compress(text)
+	if err != nil {
+		return "", err
+	}
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", err
+	}
+	bytes := make([]byte, gcm.NonceSize())
+	if _, err = io.ReadFull(rand.Reader, bytes); err != nil {
+		return "", err
+	}
+	encodedText := gcm.Seal(bytes, bytes, compressedText, nil)
+	return base64.StdEncoding.EncodeToString(encodedText), nil
+}
+
+// Decrypt method is to extract back the encrypted text
+func (e encryptionClient) Decrypt(text string) (string, error) {
+	block, err := aes.NewCipher([]byte(e.Secret))
+	if err != nil {
+		return "", err
+	}
+	cipherText, err := base64.StdEncoding.DecodeString(text)
+	if err != nil {
+		return "", err
+	}
+	gcm, err := cipher.NewGCM(block)
+	if err != nil {
+		return "", err
+	}
+	if len(cipherText) < gcm.NonceSize() {
+		return "", fmt.Errorf("text is too small")
+	}
+	bytes, cipherText := cipherText[:gcm.NonceSize()], cipherText[gcm.NonceSize():]
+	compressedTextBytes, err := gcm.Open(nil, bytes, cipherText, nil)
+	if err != nil {
+		return "", err
+	}
+	return decompress(compressedTextBytes)
+}