refactor: simplify codebase (-209 lines)

internal/crypto/blowfish.go

@@ -3,7 +3,7 @@ package crypto
 import (
 	"crypto/cipher"
 	"crypto/md5"
-	"fmt"
+	"encoding/hex"
 
 	"golang.org/x/crypto/blowfish"
 )
@@ -12,7 +12,7 @@ var iv = []byte{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07}
 
 func GetKey(secretKey, songID string) []byte {
 	hash := md5.Sum([]byte(songID))
-	hashHex := fmt.Sprintf("%x", hash)
+	hashHex := hex.EncodeToString(hash[:])
 
 	key := []byte(secretKey)
 	for i := 0; i < len(hash); i++ {
@@ -28,9 +28,8 @@ func Decrypt(data, key []byte) ([]byte, error) {
 		return nil, err
 	}
 
-	mode := cipher.NewCBCDecrypter(block, iv)
 	decrypted := make([]byte, len(data))
-	mode.CryptBlocks(decrypted, data)
+	cipher.NewCBCDecrypter(block, iv).CryptBlocks(decrypted, data)
 
 	return decrypted, nil
 }