Initial commit

internal/utils/sign.go

@@ -0,0 +1,75 @@
+package utils
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/base64"
+	"fmt"
+	"strconv"
+	"time"
+)
+
+const (
+	// DefaultSignKey is the signing key from the Android app
+	DefaultSignKey = "p93jhgh689SBReK6ghtw62"
+	// DesktopSignKey is the signing key from the desktop app
+	DesktopSignKey = "kzqU4XhfCaY6B6JTHODeq5"
+	// DesktopClient is the X-Yandex-Music-Client header value for desktop
+	DesktopClient = "YandexMusicDesktopAppWindows/5.95.0"
+)
+
+// Sign represents a request signature
+type Sign struct {
+	Timestamp int64
+	Value     string
+}
+
+// GetSignRequest creates a signature for a track request
+func GetSignRequest(trackID string, key string) Sign {
+	if key == "" {
+		key = DefaultSignKey
+	}
+
+	timestamp := time.Now().Unix()
+	message := trackID + strconv.FormatInt(timestamp, 10)
+
+	h := hmac.New(sha256.New, []byte(key))
+	h.Write([]byte(message))
+	sign := base64.StdEncoding.EncodeToString(h.Sum(nil))
+
+	return Sign{
+		Timestamp: timestamp,
+		Value:     sign,
+	}
+}
+
+// GetFileInfoSign creates a signature for file info requests
+func GetFileInfoSign(trackID, quality string, codecs []string, transport, key string) Sign {
+	if key == "" {
+		key = DesktopSignKey
+	}
+
+	timestamp := time.Now().Unix()
+	message := fmt.Sprintf("%d%s%s%s%s", timestamp, trackID, quality, joinCodecs(codecs), transport)
+
+	h := hmac.New(sha256.New, []byte(key))
+	h.Write([]byte(message))
+	sign := base64.StdEncoding.EncodeToString(h.Sum(nil))
+	// Remove last character as in Python
+	if len(sign) > 0 {
+		sign = sign[:len(sign)-1]
+	}
+
+	return Sign{
+		Timestamp: timestamp,
+		Value:     sign,
+	}
+}
+
+func joinCodecs(codecs []string) string {
+	result := ""
+	for _, c := range codecs {
+		result += c
+	}
+	return result
+}