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This commit is contained in:
Shen Junzheng
2025-04-19 18:21:02 +08:00
parent a745519451
commit 977194b5cf
7 changed files with 126 additions and 37 deletions
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26
pkg/util/dat2img/dat2img.go
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@@ -17,6 +17,7 @@ import (
// Format defines the header and extension for different image types
type Format struct {
Header []byte
AesKey []byte
Ext string
}
@@ -29,10 +30,13 @@ var (
BMP = Format{Header: []byte{0x42, 0x4D}, Ext: "bmp"}
Formats = []Format{JPG, PNG, GIF, TIFF, BMP}
V4Format1 = Format{Header: []byte{0x07, 0x08, 0x56, 0x31}, AesKey: []byte("cfcd208495d565ef")}
V4Format2 = Format{Header: []byte{0x07, 0x08, 0x56, 0x32}, AesKey: []byte("0000000000000000")} // FIXME
V4Formats = []Format{V4Format1, V4Format2}
// WeChat v4 related constants
V4XorKey byte = 0x37 // Default XOR key for WeChat v4 dat files
V4DatHeader = []byte{0x07, 0x08, 0x56, 0x31} // WeChat v4 dat file header
JpgTail = []byte{0xFF, 0xD9} // JPG file tail marker
V4XorKey byte = 0x37 // Default XOR key for WeChat v4 dat files
JpgTail = []byte{0xFF, 0xD9} // JPG file tail marker
)
// Dat2Image converts WeChat dat file data to image data
@@ -43,8 +47,12 @@ func Dat2Image(data []byte) ([]byte, string, error) {
}
// Check if this is a WeChat v4 dat file
if len(data) >= 6 && bytes.Equal(data[:4], V4DatHeader) {
return Dat2ImageV4(data)
if len(data) >= 6 {
for _, format := range V4Formats {
if bytes.Equal(data[:4], format.Header) {
return Dat2ImageV4(data, format.AesKey)
}
}
}
// For older WeChat versions, use XOR decryption
@@ -134,7 +142,7 @@ func ScanAndSetXorKey(dirPath string) (byte, error) {
}
// Check if it's a WeChat v4 dat file
if len(data) < 6 || !bytes.Equal(data[:4], V4DatHeader) {
if len(data) < 6 || (!bytes.Equal(data[:4], V4Format1.Header) && !bytes.Equal(data[:4], V4Format2.Header)) {
return nil
}
@@ -179,13 +187,13 @@ func ScanAndSetXorKey(dirPath string) (byte, error) {
// Dat2ImageV4 processes WeChat v4 dat image files
// WeChat v4 uses a combination of AES-ECB and XOR encryption
func Dat2ImageV4(data []byte) ([]byte, string, error) {
func Dat2ImageV4(data []byte, aeskey []byte) ([]byte, string, error) {
if len(data) < 15 {
return nil, "", fmt.Errorf("data length is too short for WeChat v4 format: %d", len(data))
}
// Parse dat file header:
// - 6 bytes: 0x07085631 (dat file identifier)
// - 6 bytes: 0x07085631 or 0x07085632 (dat file identifier)
// - 4 bytes: int (little-endian) AES-ECB128 encryption length
// - 4 bytes: int (little-endian) XOR encryption length
// - 1 byte: 0x01 (unknown)
@@ -206,7 +214,7 @@ func Dat2ImageV4(data []byte) ([]byte, string, error) {
}
// Decrypt AES part
aesDecryptedData, err := decryptAESECB(fileData[:aesEncryptLen0], []byte("cfcd208495d565ef"))
aesDecryptedData, err := decryptAESECB(fileData[:aesEncryptLen0], aeskey)
if err != nil {
return nil, "", fmt.Errorf("AES decrypt error: %v", err)
}