Merge branch 'feat/credential-login' into dev

cmd/login.go

@@ -0,0 +1,37 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/mathismqn/godeez/internal/auth"
+	"github.com/spf13/cobra"
+)
+
+var loginCmd = &cobra.Command{
+	Use:   "login",
+	Short: "Log in to Deezer with your email and password",
+	Args:  cobra.NoArgs,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		if err := auth.CheckGatewayEnv(); err != nil {
+			return err
+		}
+
+		email, password, err := auth.PromptCredentials()
+		if err != nil {
+			return err
+		}
+
+		_, username, err := auth.Login(cmd.Context(), email, password)
+		if err != nil {
+			return err
+		}
+
+		fmt.Printf("Successfully logged in as %s.\n", username)
+
+		return nil
+	},
+}
+
+func init() {
+	RootCmd.AddCommand(loginCmd)
+}

cmd/logout.go

@@ -0,0 +1,27 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/mathismqn/godeez/internal/auth"
+	"github.com/spf13/cobra"
+)
+
+var logoutCmd = &cobra.Command{
+	Use:   "logout",
+	Short: "Remove stored Deezer credentials",
+	Args:  cobra.NoArgs,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		if err := auth.Clear(); err != nil {
+			return err
+		}
+
+		fmt.Println("Successfully logged out.")
+
+		return nil
+	},
+}
+
+func init() {
+	RootCmd.AddCommand(logoutCmd)
+}

go.mod

@@ -2,16 +2,21 @@ module github.com/mathismqn/godeez
 
 go 1.25.0
 
-require github.com/spf13/cobra v1.10.2
+require (
+	github.com/spf13/cobra v1.10.2
+	github.com/zalando/go-keyring v0.2.8
+	golang.org/x/term v0.45.0
+)
 
 require (
 	github.com/andybalholm/cascadia v1.3.4 // indirect
+	github.com/danieljoos/wincred v1.2.3 // indirect
 	github.com/fatih/color v1.19.0 // indirect
+	github.com/godbus/dbus/v5 v5.2.2 // indirect
 	github.com/mattn/go-colorable v0.1.15 // indirect
 	github.com/mattn/go-isatty v0.0.24 // indirect
 	golang.org/x/net v0.57.0 // indirect
 	golang.org/x/sys v0.47.0 // indirect
-	golang.org/x/term v0.45.0 // indirect
 	golang.org/x/text v0.40.0 // indirect
 )
 

go.sum

@@ -7,6 +7,8 @@ github.com/bogem/id3v2/v2 v2.1.4/go.mod h1:l+gR8MZ6rc9ryPTPkX77smS5Me/36gxkMgDay
 github.com/briandowns/spinner v1.23.2 h1:Zc6ecUnI+YzLmJniCfDNaMbW0Wid1d5+qcTq4L2FW8w=
 github.com/briandowns/spinner v1.23.2/go.mod h1:LaZeM4wm2Ywy6vO571mvhQNRcWfRUnXOs0RcKV0wYKM=
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
+github.com/danieljoos/wincred v1.2.3 h1:v7dZC2x32Ut3nEfRH+vhoZGvN72+dQ/snVXo/vMFLdQ=
+github.com/danieljoos/wincred v1.2.3/go.mod h1:6qqX0WNrS4RzPZ1tnroDzq9kY3fu1KwE7MRLQK4X0bs=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/fatih/color v1.19.0 h1:Zp3PiM21/9Ld6FzSKyL5c/BULoe/ONr9KlbYVOfG8+w=
@@ -19,6 +21,8 @@ github.com/go-flac/flacvorbis/v2 v2.0.2 h1:xCL3OhxrxWkHrbWUBvGNe+6FQ03yLmBbz0v5z
 github.com/go-flac/flacvorbis/v2 v2.0.2/go.mod h1:SwTB5gs13VaM/N7rstwPoUsPibiMKklgwybYP9dYo2g=
 github.com/go-flac/go-flac/v2 v2.0.4 h1:atf/kFa8U9idtkA//NO22XGr+MzQLeXZecnmP9sYBf0=
 github.com/go-flac/go-flac/v2 v2.0.4/go.mod h1:sYOlTKxutMW0RDYF+KlD6Zn+VOCZlIFQG/r/usPveCs=
+github.com/godbus/dbus/v5 v5.2.2 h1:TUR3TgtSVDmjiXOgAAyaZbYmIeP3DPkld3jgKGV8mXQ=
+github.com/godbus/dbus/v5 v5.2.2/go.mod h1:3AAv2+hPq5rdnr5txxxRwiGjPXamgoIHgz9FPBfOp3c=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/mattn/go-colorable v0.1.15 h1:+u9SLTRGnXv73cEsnsmoZBom+dMU88B2M0aDcWy0/jY=
@@ -33,9 +37,13 @@ github.com/spf13/cobra v1.10.2/go.mod h1:7C1pvHqHw5A4vrJfjNwvOdzYu0Gml16OCs2GRiT
 github.com/spf13/pflag v1.0.9/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/spf13/pflag v1.0.10 h1:4EBh2KAYBwaONj6b2Ye1GiHfwjqyROoF4RwYO+vPwFk=
 github.com/spf13/pflag v1.0.10/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/stretchr/objx v0.5.2 h1:xuMeJ0Sdp5ZMRXx/aWO6RZxdr3beISkG5/G/aIRr3pY=
+github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/8L+MA=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
+github.com/zalando/go-keyring v0.2.8 h1:6sD/Ucpl7jNq10rM2pgqTs0sZ9V3qMrqfIIy5YPccHs=
+github.com/zalando/go-keyring v0.2.8/go.mod h1:tsMo+VpRq5NGyKfxoBVjCuMrG47yj8cmakZDO5QGii0=
 go.etcd.io/bbolt v1.5.0 h1:S7GAl7Fxv12yohbwFfIbQCGDWbQbtDGPET4P/bD4lxU=
 go.etcd.io/bbolt v1.5.0/go.mod h1:mkltfYE5aUHQxUct9N9V+Kp7aSjFqjgrhcXIS70Lrdk=
 go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=

internal/auth/auth.go

@@ -0,0 +1,48 @@
+package auth
+
+import (
+	"context"
+	"fmt"
+)
+
+func Resolve(ctx context.Context, validate func(ctx context.Context, arl string) error) (string, error) {
+	creds, err := Load()
+	if err != nil {
+		return "", err
+	}
+
+	if creds != nil && creds.ARL != "" {
+		if verr := validate(ctx, creds.ARL); verr == nil {
+			return creds.ARL, nil
+		}
+	}
+
+	if creds != nil && creds.Email != "" && creds.Password != "" {
+		arl, _, err := Login(ctx, creds.Email, creds.Password)
+		if err != nil {
+			return "", fmt.Errorf("stored session expired and could not be renewed automatically: %w", err)
+		}
+
+		return arl, nil
+	}
+
+	return "", fmt.Errorf("run 'godeez login' or export DEEZER_ARL environment variable")
+}
+
+func Login(ctx context.Context, email, password string) (string, string, error) {
+	client, err := newMobileClient()
+	if err != nil {
+		return "", "", err
+	}
+
+	creds, username, err := client.Login(ctx, email, password)
+	if err != nil {
+		return "", "", err
+	}
+
+	if err := Save(creds); err != nil {
+		return "", "", err
+	}
+
+	return creds.ARL, username, nil
+}

internal/auth/mobile.go

@@ -0,0 +1,266 @@
+package auth
+
+import (
+	"bytes"
+	"context"
+	"crypto/aes"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io"
+	"math/rand/v2"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/mathismqn/godeez/internal/crypto"
+)
+
+const (
+	gatewayBaseURL   = "https://api.deezer.com/1.0/gateway.php"
+	gatewayUserAgent = "Deezer/6.1.22.49 (Android; 9; Tablet; us) innotek GmbH VirtualBox"
+	nonceAlphabet    = "012345689abdef"
+)
+
+const (
+	deviceOS       = "Android"
+	deviceName     = "VirtualBox"
+	deviceType     = "tablet"
+	deviceModel    = "VirtualBox"
+	devicePlatform = "innotek GmbH_x86_64_9"
+	deviceSerial   = ""
+)
+
+type mobileClient struct {
+	httpClient *http.Client
+	apiKey     string
+	gwKey      []byte
+	sid        string
+}
+
+func CheckGatewayEnv() error {
+	_, _, err := gatewayEnv()
+	return err
+}
+
+func gatewayEnv() (string, string, error) {
+	apiKey := os.Getenv("DEEZER_MOBILE_API_KEY")
+	gwKey := os.Getenv("DEEZER_MOBILE_GW_KEY")
+	if apiKey == "" || gwKey == "" {
+		return "", "", fmt.Errorf("DEEZER_MOBILE_API_KEY and DEEZER_MOBILE_GW_KEY must be set to use email/password login")
+	}
+
+	if len(gwKey) != aes.BlockSize {
+		return "", "", fmt.Errorf("DEEZER_MOBILE_GW_KEY must be exactly %d bytes long", aes.BlockSize)
+	}
+
+	return apiKey, gwKey, nil
+}
+
+func newMobileClient() (*mobileClient, error) {
+	apiKey, gwKey, err := gatewayEnv()
+	if err != nil {
+		return nil, err
+	}
+
+	return &mobileClient{
+		httpClient: &http.Client{Timeout: 20 * time.Second},
+		apiKey:     apiKey,
+		gwKey:      []byte(gwKey),
+	}, nil
+}
+
+func (m *mobileClient) Login(ctx context.Context, email, password string) (*Credentials, string, error) {
+	token, tokenKey, userKey, err := m.authenticate(ctx)
+	if err != nil {
+		return nil, "", err
+	}
+
+	if err := m.checkToken(ctx, token, tokenKey); err != nil {
+		return nil, "", err
+	}
+
+	arl, username, err := m.userAuth(ctx, email, password, userKey)
+	if err != nil {
+		return nil, "", err
+	}
+
+	return &Credentials{Email: email, Password: password, ARL: arl}, username, nil
+}
+
+func (m *mobileClient) authenticate(ctx context.Context) (string, string, string, error) {
+	body, err := m.gatewayRequest(ctx, "mobile_auth", "GET", "uniq_id", genUniqID(), nil)
+	if err != nil {
+		return "", "", "", err
+	}
+
+	var res struct {
+		Results struct {
+			Token string `json:"TOKEN"`
+		} `json:"results"`
+	}
+	if err := json.Unmarshal(body, &res); err != nil {
+		return "", "", "", err
+	}
+
+	if strings.Contains(string(body), "Undefined or invalid API key") {
+		return "", "", "", fmt.Errorf("DEEZER_MOBILE_API_KEY is invalid")
+	}
+	if strings.Contains(string(body), "GATEWAY_ERROR") || res.Results.Token == "" {
+		return "", "", "", fmt.Errorf("unexpected response from gateway")
+	}
+
+	encrypted, err := hex.DecodeString(res.Results.Token)
+	if err != nil {
+		return "", "", "", err
+	}
+
+	decrypted, err := crypto.DecryptECB(m.gwKey, encrypted)
+	if err != nil {
+		return "", "", "", err
+	}
+
+	token := string(decrypted[0:64])
+	tokenKey := string(decrypted[64:80])
+	userKey := string(decrypted[80:96])
+
+	return token, tokenKey, userKey, nil
+}
+
+func (m *mobileClient) checkToken(ctx context.Context, token, tokenKey string) error {
+	encrypted, err := crypto.EncryptECB([]byte(tokenKey), []byte(token))
+	if err != nil {
+		return err
+	}
+	authToken := hex.EncodeToString(encrypted)
+
+	body, err := m.gatewayRequest(ctx, "api_checkToken", "GET", "auth_token", authToken, nil)
+	if err != nil {
+		return err
+	}
+
+	var res struct {
+		Results string `json:"results"`
+	}
+	if err := json.Unmarshal(body, &res); err != nil {
+		return err
+	}
+	if res.Results == "" {
+		return fmt.Errorf("unexpected response from gateway")
+	}
+	m.sid = res.Results
+
+	return nil
+}
+
+func (m *mobileClient) userAuth(ctx context.Context, email, password, userKey string) (string, string, error) {
+	encryptedPassword, err := crypto.EncryptECB([]byte(userKey), crypto.ZeroPad([]byte(password)))
+	if err != nil {
+		return "", "", err
+	}
+
+	payload := map[string]string{
+		"mail":                              email,
+		"password":                          hex.EncodeToString(encryptedPassword),
+		"device_serial":                     deviceSerial,
+		"platform":                          devicePlatform,
+		"custo_version_id":                  "",
+		"custo_partner":                     "",
+		"model":                             deviceModel,
+		"device_name":                       deviceName,
+		"device_os":                         deviceOS,
+		"device_type":                       deviceType,
+		"google_play_services_availability": "1",
+		"consent_string":                    "",
+	}
+
+	jsonBody, err := json.Marshal(payload)
+	if err != nil {
+		return "", "", err
+	}
+
+	body, err := m.gatewayRequest(ctx, "mobile_userAuth", "POST", "", "", jsonBody)
+	if err != nil {
+		return "", "", err
+	}
+
+	if strings.Contains(string(body), "USER_AUTH_ERROR") {
+		return "", "", fmt.Errorf("invalid email or password")
+	}
+
+	var res struct {
+		Results struct {
+			ARL      string `json:"ARL"`
+			UserID   int    `json:"USER_ID"`
+			BlogName string `json:"BLOG_NAME"`
+		} `json:"results"`
+	}
+	if err := json.Unmarshal(body, &res); err != nil {
+		return "", "", err
+	}
+
+	if res.Results.ARL == "" || res.Results.UserID == 0 {
+		return "", "", fmt.Errorf("unexpected response from gateway")
+	}
+
+	return res.Results.ARL, res.Results.BlogName, nil
+}
+
+func (m *mobileClient) gatewayRequest(ctx context.Context, method, httpMethod, paramKey, paramValue string, jsonBody []byte) ([]byte, error) {
+	u, err := url.Parse(gatewayBaseURL)
+	if err != nil {
+		return nil, err
+	}
+
+	q := u.Query()
+	q.Set("method", method)
+	q.Set("api_key", m.apiKey)
+	q.Set("output", "3")
+	if httpMethod == "POST" {
+		q.Set("input", "3")
+	}
+	if m.sid != "" {
+		q.Set("sid", m.sid)
+	}
+	if paramKey != "" {
+		q.Set(paramKey, paramValue)
+	}
+	u.RawQuery = q.Encode()
+
+	var reqBody io.Reader
+	if jsonBody != nil {
+		reqBody = bytes.NewReader(jsonBody)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, httpMethod, u.String(), reqBody)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("User-Agent", gatewayUserAgent)
+	if jsonBody != nil {
+		req.Header.Set("Content-Type", "application/json")
+	}
+
+	resp, err := m.httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	return io.ReadAll(resp.Body)
+}
+
+func genUniqID() string {
+	b := make([]byte, 32)
+	for i := range b {
+		b[i] = nonceAlphabet[rand.IntN(len(nonceAlphabet))]
+	}
+
+	return string(b)
+}

internal/auth/prompt.go

@@ -0,0 +1,28 @@
+package auth
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+
+	"golang.org/x/term"
+)
+
+func PromptCredentials() (string, string, error) {
+	fmt.Print("Email: ")
+	line, err := bufio.NewReader(os.Stdin).ReadString('\n')
+	if err != nil {
+		return "", "", err
+	}
+	email := strings.TrimSpace(line)
+
+	fmt.Print("Password: ")
+	passwordBytes, err := term.ReadPassword(int(os.Stdin.Fd()))
+	fmt.Println()
+	if err != nil {
+		return "", "", err
+	}
+
+	return email, string(passwordBytes), nil
+}

internal/auth/storage.go

@@ -0,0 +1,61 @@
+package auth
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+
+	"github.com/zalando/go-keyring"
+)
+
+const (
+	keyringService = "godeez"
+	keyringUser    = "default"
+)
+
+type Credentials struct {
+	Email    string `json:"email"`
+	Password string `json:"password"`
+	ARL      string `json:"arl,omitempty"`
+}
+
+func Load() (*Credentials, error) {
+	secret, err := keyring.Get(keyringService, keyringUser)
+	if err != nil {
+		if errors.Is(err, keyring.ErrNotFound) {
+			return nil, nil
+		}
+		return nil, fmt.Errorf("system keyring is unavailable: %v", err)
+	}
+
+	var creds Credentials
+	if err := json.Unmarshal([]byte(secret), &creds); err != nil {
+		return nil, err
+	}
+
+	return &creds, nil
+}
+
+func Save(creds *Credentials) error {
+	data, err := json.Marshal(creds)
+	if err != nil {
+		return err
+	}
+
+	if err := keyring.Set(keyringService, keyringUser, string(data)); err != nil {
+		return fmt.Errorf("system keyring is unavailable: %v", err)
+	}
+
+	return nil
+}
+
+func Clear() error {
+	if err := keyring.Delete(keyringService, keyringUser); err != nil {
+		if errors.Is(err, keyring.ErrNotFound) {
+			return nil
+		}
+		return fmt.Errorf("system keyring is unavailable: %v", err)
+	}
+
+	return nil
+}

internal/config/config.go

@@ -10,16 +10,13 @@ import (
 )
 
 type Config struct {
-	ArlCookie string
+	ARLCookie string
 	OutputDir string
 	HomeDir   string
 }
 
 func New() (*Config, error) {
 	arl := os.Getenv("DEEZER_ARL")
-	if arl == "" {
-		return nil, fmt.Errorf("DEEZER_ARL is not set. Export it in your shell: export DEEZER_ARL='your_cookie'")
-	}
 
 	homeDir, err := os.UserHomeDir()
 	if err != nil {
@@ -50,7 +47,7 @@ func New() (*Config, error) {
 	}
 
 	return &Config{
-		ArlCookie: arl,
+		ARLCookie: arl,
 		OutputDir: outputDir,
 		HomeDir:   homeDir,
 	}, nil

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/crypto/ecb.go

@@ -0,0 +1,42 @@
+package crypto
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"fmt"
+)
+
+func ZeroPad(data []byte) []byte {
+	bs := aes.BlockSize
+	padded := make([]byte, len(data)+(bs-len(data)%bs)%bs)
+	copy(padded, data)
+
+	return padded
+}
+
+func EncryptECB(key, data []byte) ([]byte, error) {
+	return ecbTransform(key, data, (cipher.Block).Encrypt)
+}
+
+func DecryptECB(key, data []byte) ([]byte, error) {
+	return ecbTransform(key, data, (cipher.Block).Decrypt)
+}
+
+func ecbTransform(key, data []byte, op func(cipher.Block, []byte, []byte)) ([]byte, error) {
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		return nil, err
+	}
+
+	bs := block.BlockSize()
+	if len(data)%bs != 0 {
+		return nil, fmt.Errorf("data length %d is not a multiple of the AES block size", len(data))
+	}
+
+	out := make([]byte, len(data))
+	for i := 0; i < len(data); i += bs {
+		op(block, out[i:i+bs], data[i:i+bs])
+	}
+
+	return out, nil
+}

internal/deezer/client.go

@@ -9,6 +9,7 @@ import (
 	"net/http"
 	"strings"
 
+	"github.com/mathismqn/godeez/internal/auth"
 	"github.com/mathismqn/godeez/internal/config"
 )
 
@@ -18,7 +19,7 @@ type Client struct {
 }
 
 func NewClient(ctx context.Context, appConfig *config.Config) (*Client, error) {
-	session, err := Authenticate(ctx, appConfig.ArlCookie)
+	session, err := resolveSession(ctx, appConfig)
 	if err != nil {
 		return nil, fmt.Errorf("failed to authenticate: %w", err)
 	}
@@ -29,6 +30,37 @@ func NewClient(ctx context.Context, appConfig *config.Config) (*Client, error) {
 	}, nil
 }
 
+func resolveSession(ctx context.Context, appConfig *config.Config) (*Session, error) {
+	if appConfig.ARLCookie != "" {
+		return Authenticate(ctx, appConfig.ARLCookie)
+	}
+
+	var session *Session
+	validate := func(ctx context.Context, arl string) error {
+		s, err := Authenticate(ctx, arl)
+		if err != nil {
+			return err
+		}
+		session = s
+
+		return nil
+	}
+
+	arl, err := auth.Resolve(ctx, validate)
+	if err != nil {
+		return nil, err
+	}
+
+	if session == nil {
+		session, err = Authenticate(ctx, arl)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return session, nil
+}
+
 func (c *Client) FetchResource(ctx context.Context, resource Resource, id string) error {
 	payload := map[string]interface{}{
 		"nb":     10000,

internal/deezer/session.go

@@ -71,7 +71,7 @@ func Authenticate(ctx context.Context, arlCookie string) (*Session, error) {
 	}
 
 	if res.Results.User.ID == 0 {
-		return nil, fmt.Errorf("invalid arl cookie")
+		return nil, fmt.Errorf("invalid or expired ARL cookie")
 	}
 
 	opts := res.Results.User.Options

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
 			}