refactor: disambiguate blowfish crypto helper names

internal/crypto/blowfish.go

@@ -9,31 +9,31 @@ import (
 )
 
 var (
-	iv        = []byte{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07}
+	blowfishIV        = []byte{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07}
-	secretKey = []byte("g4el58wc0zvf9na1")
+	blowfishSecretKey = []byte("g4el58wc0zvf9na1")
 )
 
-func GetKey(songID string) []byte {
+func GetBlowfishKey(songID string) []byte {
 	hash := md5.Sum([]byte(songID))
 	hashHex := hex.EncodeToString(hash[:])
 
-	key := make([]byte, len(secretKey))
+	key := make([]byte, len(blowfishSecretKey))
-	copy(key, secretKey)
+	copy(key, blowfishSecretKey)
-	for i := 0; i < len(hash); i++ {
+	for i := range len(hash) {
 		key[i] = key[i] ^ hashHex[i] ^ hashHex[i+16]
 	}
 
 	return key
 }
 
-func Decrypt(data, key []byte) ([]byte, error) {
+func DecryptBlowfish(data, key []byte) ([]byte, error) {
 	block, err := blowfish.NewCipher(key)
 	if err != nil {
 		return nil, err
 	}
 
 	decrypted := make([]byte, len(data))
-	cipher.NewCBCDecrypter(block, iv).CryptBlocks(decrypted, data)
+	cipher.NewCBCDecrypter(block, blowfishIV).CryptBlocks(decrypted, data)
 
 	return decrypted, nil
 }

internal/downloader/client.go

@@ -175,7 +175,7 @@ func (c *Client) downloadSong(ctx context.Context, resource deezer.Resource, son
 	fileName := song.GetFileName(c.resourceType, mediaFormat)
 	outputPath := path.Join(outputDir, fileName)
 
-	key := crypto.GetKey(song.ID)
+	key := crypto.GetBlowfishKey(song.ID)
 	if err := c.streamToFile(dlCtx, stream, outputPath, key); err != nil {
 		fileutil.DeleteFile(outputPath)
 		return downloadResult{err: fmt.Errorf("failed to stream to file: %w", err)}
@@ -233,7 +233,7 @@ func (c *Client) streamToFile(ctx context.Context, stream io.ReadCloser, outputP
 		}
 
 		if chunk%3 == 0 && totalRead == chunkSize {
-			buffer, err = crypto.Decrypt(buffer, key)
+			buffer, err = crypto.DecryptBlowfish(buffer, key)
 			if err != nil {
 				return err
 			}