Add KGM Decoder

algo/kgm/kgm.go

@@ -0,0 +1,91 @@
+package kgm
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"github.com/umlock-music/cli/algo/common"
+	"github.com/umlock-music/cli/internal/logging"
+)
+
+var (
+	vprHeader = []byte{
+		0x05, 0x28, 0xBC, 0x96, 0xE9, 0xE4, 0x5A, 0x43,
+		0x91, 0xAA, 0xBD, 0xD0, 0x7A, 0xF5, 0x36, 0x31}
+	kgmHeader = []byte{
+		0x7C, 0xD5, 0x32, 0xEB, 0x86, 0x02, 0x7F, 0x4B,
+		0xA8, 0xAF, 0xA6, 0x8E, 0x0F, 0xFF, 0x99, 0x14}
+	ErrKgmMagicHeader = errors.New("kgm/vpr magic header not matched")
+)
+
+type Decoder struct {
+	file  []byte
+	key   []byte
+	isVpr bool
+	audio []byte
+}
+
+func NewDecoder(file []byte) *Decoder {
+	return &Decoder{
+		file: file,
+	}
+}
+
+func (d Decoder) GetCoverImage() []byte {
+	return nil
+}
+
+func (d Decoder) GetAudioData() []byte {
+	return d.audio
+}
+
+func (d Decoder) GetAudioExt() string {
+	return ""
+}
+
+func (d Decoder) GetMeta() common.Meta {
+	return nil
+}
+
+func (d *Decoder) Validate() error {
+	if bytes.Equal(kgmHeader, d.file[:len(kgmHeader)]) {
+		d.isVpr = false
+	} else if bytes.Equal(vprHeader, d.file[:len(vprHeader)]) {
+		d.isVpr = true
+	} else {
+		return ErrKgmMagicHeader
+	}
+
+	d.key = d.file[0x1c:0x2c]
+	d.key = append(d.key, 0x00)
+	_ = d.file[0x2c:0x3c] //key2
+	return nil
+
+}
+
+func (d *Decoder) Decode() error {
+	headerLen := binary.LittleEndian.Uint32(d.file[0x10:0x14])
+	dataEncrypted := d.file[headerLen:]
+	lenData := len(dataEncrypted)
+	initMask()
+	if fullMaskLen < lenData {
+		logging.Log().Warn("文件过大，处理后的音频不完整,请向我们报告此文件的信息")
+		lenData = fullMaskLen
+	}
+	d.audio = make([]byte, lenData)
+
+	for i := 0; i < lenData; i++ {
+		med8 := d.key[i%17] ^ dataEncrypted[i]
+		med8 ^= (med8 & 0xf) << 4
+
+		msk8 := maskV2PreDef[i%272] ^ maskV2[i>>4]
+		msk8 ^= (msk8 & 0xf) << 4
+		d.audio[i] = med8 ^ msk8
+	}
+	if d.isVpr {
+		for i := 0; i < lenData; i++ {
+			d.audio[i] ^= maskDiffVpr[i%17]
+		}
+	}
+	return nil
+}

algo/kgm/mask.go

@@ -0,0 +1,59 @@
+package kgm
+
+import (
+	"bytes"
+	_ "embed"
+	"github.com/ulikunitz/xz"
+	"github.com/umlock-music/cli/internal/logging"
+	"go.uber.org/zap"
+	"io/ioutil"
+)
+
+var maskDiffVpr = []byte{
+	0x25, 0xDF, 0xE8, 0xA6, 0x75, 0x1E, 0x75, 0x0E,
+	0x2F, 0x80, 0xF3, 0x2D, 0xB8, 0xB6, 0xE3, 0x11,
+	0x00}
+
+var maskV2PreDef = []byte{
+	0xB8, 0xD5, 0x3D, 0xB2, 0xE9, 0xAF, 0x78, 0x8C, 0x83, 0x33, 0x71, 0x51, 0x76, 0xA0, 0xCD, 0x37,
+	0x2F, 0x3E, 0x35, 0x8D, 0xA9, 0xBE, 0x98, 0xB7, 0xE7, 0x8C, 0x22, 0xCE, 0x5A, 0x61, 0xDF, 0x68,
+	0x69, 0x89, 0xFE, 0xA5, 0xB6, 0xDE, 0xA9, 0x77, 0xFC, 0xC8, 0xBD, 0xBD, 0xE5, 0x6D, 0x3E, 0x5A,
+	0x36, 0xEF, 0x69, 0x4E, 0xBE, 0xE1, 0xE9, 0x66, 0x1C, 0xF3, 0xD9, 0x02, 0xB6, 0xF2, 0x12, 0x9B,
+	0x44, 0xD0, 0x6F, 0xB9, 0x35, 0x89, 0xB6, 0x46, 0x6D, 0x73, 0x82, 0x06, 0x69, 0xC1, 0xED, 0xD7,
+	0x85, 0xC2, 0x30, 0xDF, 0xA2, 0x62, 0xBE, 0x79, 0x2D, 0x62, 0x62, 0x3D, 0x0D, 0x7E, 0xBE, 0x48,
+	0x89, 0x23, 0x02, 0xA0, 0xE4, 0xD5, 0x75, 0x51, 0x32, 0x02, 0x53, 0xFD, 0x16, 0x3A, 0x21, 0x3B,
+	0x16, 0x0F, 0xC3, 0xB2, 0xBB, 0xB3, 0xE2, 0xBA, 0x3A, 0x3D, 0x13, 0xEC, 0xF6, 0x01, 0x45, 0x84,
+	0xA5, 0x70, 0x0F, 0x93, 0x49, 0x0C, 0x64, 0xCD, 0x31, 0xD5, 0xCC, 0x4C, 0x07, 0x01, 0x9E, 0x00,
+	0x1A, 0x23, 0x90, 0xBF, 0x88, 0x1E, 0x3B, 0xAB, 0xA6, 0x3E, 0xC4, 0x73, 0x47, 0x10, 0x7E, 0x3B,
+	0x5E, 0xBC, 0xE3, 0x00, 0x84, 0xFF, 0x09, 0xD4, 0xE0, 0x89, 0x0F, 0x5B, 0x58, 0x70, 0x4F, 0xFB,
+	0x65, 0xD8, 0x5C, 0x53, 0x1B, 0xD3, 0xC8, 0xC6, 0xBF, 0xEF, 0x98, 0xB0, 0x50, 0x4F, 0x0F, 0xEA,
+	0xE5, 0x83, 0x58, 0x8C, 0x28, 0x2C, 0x84, 0x67, 0xCD, 0xD0, 0x9E, 0x47, 0xDB, 0x27, 0x50, 0xCA,
+	0xF4, 0x63, 0x63, 0xE8, 0x97, 0x7F, 0x1B, 0x4B, 0x0C, 0xC2, 0xC1, 0x21, 0x4C, 0xCC, 0x58, 0xF5,
+	0x94, 0x52, 0xA3, 0xF3, 0xD3, 0xE0, 0x68, 0xF4, 0x00, 0x23, 0xF3, 0x5E, 0x0A, 0x7B, 0x93, 0xDD,
+	0xAB, 0x12, 0xB2, 0x13, 0xE8, 0x84, 0xD7, 0xA7, 0x9F, 0x0F, 0x32, 0x4C, 0x55, 0x1D, 0x04, 0x36,
+	0x52, 0xDC, 0x03, 0xF3, 0xF9, 0x4E, 0x42, 0xE9, 0x3D, 0x61, 0xEF, 0x7C, 0xB6, 0xB3, 0x93, 0x50,
+}
+
+//go:embed kgm.v2.mask
+var maskV2Xz []byte
+
+var maskV2 []byte
+var fullMaskLen int
+var initMaskOK = false
+
+//todo: 根据需求解压Mask大小
+func initMask() {
+	if initMaskOK {
+		return
+	}
+	maskReader, err := xz.NewReader(bytes.NewReader(maskV2Xz))
+	if err != nil {
+		logging.Log().Fatal("load kgm mask failed", zap.Error(err))
+	}
+	maskV2, err = ioutil.ReadAll(maskReader)
+	if err != nil {
+		logging.Log().Fatal("load kgm mask failed", zap.Error(err))
+	}
+	fullMaskLen = len(maskV2) * 16
+	initMaskOK = true
+}