refactor(crypto): use IV as a constant

.example-config

@@ -1,4 +1,2 @@
 arl_cookie = '1d9e90abb452a61b1b7463f0953e1b303c4e2e7e5fd404fde9b385f4de01c340ac0f62f1c8c1550405b0b9beded0e28c481e96a6148e8f4548351add5d7db746b2785ecf83b1768e5dd8cc73b1ad30c18d07c9cb37f5c6b9cd7a78a4de2aff11'
-license_token = 'AAAAA1bcDFgHJKLmnOPqrsTUvwXYZ12o3lmNOjR2xWiQRT3v5zxL4mKoWjxL82jD7sWx93KfYGsN2IkdPxsUw9PTas7oFbgR3nY9qpZmVyHFJKLPxT7sWmqErXyTn5iKoNpRtV7bPdQZ8qLmWoJpU2nKrXz6vW'
 secret_key = 'hTv1IAw19qWy9i3f'
-iv = '0001020304050607'

internal/config/config.go

@@ -11,7 +11,6 @@ import (
 type Config struct {
 	ArlCookie string `mapstructure:"arl_cookie"`
 	SecretKey string `mapstructure:"secret_key"`
-	IV        string `mapstructure:"iv"`
 }
 
 func New(cfgPath, cfgDir string) (*Config, error) {
@@ -22,7 +21,7 @@ func New(cfgPath, cfgDir string) (*Config, error) {
 		if _, err := os.Stat(cfgPath); os.IsNotExist(err) {
 			fmt.Printf("Config file not found, creating one at %s\n", cfgPath)
 
-			content := []byte("arl_cookie = ''\nsecret_key = ''\niv = '0001020304050607'\n")
+			content := []byte("arl_cookie = ''\nsecret_key = ''\n")
 			if err := os.WriteFile(cfgPath, content, 0644); err != nil {
 				return nil, fmt.Errorf("failed to create config file: %w", err)
 			}
@@ -52,12 +51,6 @@ func New(cfgPath, cfgDir string) (*Config, error) {
 	if len(cfg.SecretKey) != 16 {
 		return nil, fmt.Errorf("secret_key must be 16 bytes long")
 	}
-	if cfg.IV == "" {
-		return nil, fmt.Errorf("iv is not set in config file")
-	}
-	if len(cfg.IV) != 16 {
-		return nil, fmt.Errorf("iv must be 16 bytes long")
-	}
 
 	return cfg, nil
 }

internal/crypto/blowfish.go

@@ -8,6 +8,8 @@ import (
 	"golang.org/x/crypto/blowfish"
 )
 
+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)
@@ -20,7 +22,7 @@ func GetKey(secretKey, songID string) []byte {
 	return key
 }
 
-func Decrypt(data, key, iv []byte) ([]byte, error) {
+func Decrypt(data, key []byte) ([]byte, error) {
 	block, err := blowfish.NewCipher(key)
 	if err != nil {
 		return nil, err

internal/downloader/client.go

@@ -2,7 +2,6 @@ package downloader
 
 import (
 	"context"
-	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
@@ -20,7 +19,7 @@ import (
 	"github.com/mathismqn/godeez/internal/tags"
 )
 
-const ChunkSize = 2048
+const chunkSize = 2048
 
 type Client struct {
 	appCtx       *app.Context
@@ -135,7 +134,8 @@ func (c *Client) downloadSong(ctx context.Context, resource deezer.Resource, son
 	dlCtx, cancel := context.WithTimeout(ctx, opts.Timeout)
 	defer cancel()
 
-	if err := c.streamToFile(dlCtx, stream, outputPath, song.ID); err != nil {
+	key := crypto.GetKey(c.appCtx.Config.SecretKey, song.ID)
+	if err := c.streamToFile(dlCtx, stream, outputPath, key); err != nil {
 		fileutil.DeleteFile(outputPath)
 
 		return fmt.Errorf("unable to write to file: %w", err)
@@ -180,7 +180,7 @@ func (c *Client) shouldSkipDownload(ctx context.Context, songID, mediaFormat str
 	return "", false
 }
 
-func (c *Client) streamToFile(ctx context.Context, stream io.ReadCloser, outputPath, songID string) error {
+func (c *Client) streamToFile(ctx context.Context, stream io.ReadCloser, outputPath string, key []byte) error {
 	defer stream.Close()
 
 	file, err := os.Create(outputPath)
@@ -189,13 +189,7 @@ func (c *Client) streamToFile(ctx context.Context, stream io.ReadCloser, outputP
 	}
 	defer file.Close()
 
-	key := crypto.GetKey(c.appCtx.Config.SecretKey, songID)
-	iv, err := hex.DecodeString(c.appCtx.Config.IV)
-	if err != nil {
-		return err
-	}
-
-	buffer := make([]byte, ChunkSize)
+	buffer := make([]byte, chunkSize)
 	for chunk := 0; ; chunk++ {
 		select {
 		case <-ctx.Done():
@@ -205,7 +199,7 @@ func (c *Client) streamToFile(ctx context.Context, stream io.ReadCloser, outputP
 		}
 
 		totalRead := 0
-		for totalRead < ChunkSize {
+		for totalRead < chunkSize {
 			n, err := stream.Read(buffer[totalRead:])
 			if err != nil {
 				if errors.Is(err, io.EOF) {
@@ -223,8 +217,8 @@ func (c *Client) streamToFile(ctx context.Context, stream io.ReadCloser, outputP
 			break
 		}
 
-		if chunk%3 == 0 && totalRead == ChunkSize {
-			buffer, err = crypto.Decrypt(buffer, key, iv)
+		if chunk%3 == 0 && totalRead == chunkSize {
+			buffer, err = crypto.Decrypt(buffer, key)
 			if err != nil {
 				return err
 			}
@@ -235,7 +229,7 @@ func (c *Client) streamToFile(ctx context.Context, stream io.ReadCloser, outputP
 			return err
 		}
 
-		if totalRead < ChunkSize {
+		if totalRead < chunkSize {
 			break
 		}
 	}