#!/usr/bin/env python3 """ PNG图片分析工具 功能：PNG签名验证、块信息解析、CRC校验、元数据提取、LSB隐写分析 """ import argparse import json import struct import binascii import io import sys from pathlib import Path try: from PIL import Image except ImportError: print("错误：未安装Pillow库，请运行: pip install Pillow") sys.exit(1) def analyze_png(png_path: str, output_json: str = None) -> dict: """ 分析PNG图片 参数: png_path: PNG图片路径 output_json: 输出JSON文件路径（可选） 返回: 分析结果字典 """ result = { 'success': False, 'png_signature': None, 'chunks': [], 'metadata': {}, 'lsb_analysis': {}, 'error': None } try: # 读取文件 with open(png_path, 'rb') as f: data = f.read() # 1. PNG签名验证 png_signature = b'\x89PNG\r\n\x1a\n' if data[:8] != png_signature: result['error'] = '不是有效的PNG文件：签名不匹配' return result result['png_signature'] = binascii.hexlify(data[:8]).decode('ascii') # 2. 块信息解析与CRC校验 pos = 8 srgb = None gamma = None dpi = None while pos + 8 <= len(data): # 解析chunk头部 length = struct.unpack('>I', data[pos:pos+4])[0] chunk_type = data[pos+4:pos+8].decode('ascii', errors='replace') chunk_data = data[pos+8:pos+8+length] # 提取CRC if pos + 12 + length > len(data): result['error'] = f'块 {chunk_type} 数据不完整' break crc_val = struct.unpack('>I', data[pos+8+length:pos+12+length])[0] # 计算CRC crc_calc = binascii.crc32(data[pos+4:pos+8+length]) & 0xffffffff crc_ok = (crc_val == crc_calc) # 构建chunk信息 chunk_info = { 'type': chunk_type, 'length': length, 'crc': binascii.hexlify(struct.pack('>I', crc_val)).decode('ascii'), 'crc_valid': crc_ok } # 提取元数据 if chunk_type == 'sRGB' and length == 1: srgb = chunk_data[0] chunk_info['metadata'] = {'rendering_intent': srgb} if chunk_type == 'gAMA' and length == 4: gamma = round(struct.unpack('>I', chunk_data)[0] / 100000, 5) chunk_info['metadata'] = {'gamma': gamma} if chunk_type == 'pHYs' and length == 9: xdpi = struct.unpack('>I', chunk_data[:4])[0] ydpi = struct.unpack('>I', chunk_data[4:8])[0] unit = chunk_data[8] if unit == 1: dpi = (int(xdpi * 0.0254), int(ydpi * 0.0254)) chunk_info['metadata'] = {'dpi': dpi, 'unit': 'meter'} result['chunks'].append(chunk_info) # 移动到下一个chunk pos += 12 + length # 遇到IEND结束 if chunk_type == 'IEND': break # 保存元数据 if srgb is not None: result['metadata']['srgb'] = srgb if gamma is not None: result['metadata']['gamma'] = gamma if dpi is not None: result['metadata']['dpi'] = dpi # 3. LSB隐写分析 lsb_result = analyze_lsb(data) result['lsb_analysis'] = lsb_result result['success'] = True except FileNotFoundError: result['error'] = f'文件不存在: {png_path}' except Exception as e: result['error'] = f'分析异常: {str(e)}' # 输出到文件 if output_json: with open(output_json, 'w', encoding='utf-8') as f: json.dump(result, f, ensure_ascii=False, indent=2) return result def analyze_lsb(data: bytes) -> dict: """ LSB隐写分析 参数: data: PNG图片二进制数据 返回: LSB分析结果 """ lsb_result = { 'rows': [], 'patterns': [], 'error': None } try: # 使用PIL打开图片 img = Image.open(io.BytesIO(data)) # 转换为RGB或RGBA if img.mode not in ('RGB', 'RGBA'): img = img.convert('RGB') width, height = img.size pixels = img.load() # 提取前8行的LSB lsb_rows = {} for row in range(min(8, height)): R, G, B = [], [], [] for col in range(width): px = pixels[col, row] if isinstance(px, int): px = (px, px, px) r, g, b = px[:3] R.append(str(r & 1)) G.append(str(g & 1)) B.append(str(b & 1)) lsb_rows[row] = {'R': R, 'G': G, 'B': B} lsb_result['rows'] = [{'row': k, 'bits': v} for k, v in lsb_rows.items()] # 定义LSB模式 patterns = [ ('RGB', lambda R, G, B: sum(zip(R, G, B), ())), ('BRG', lambda R, G, B: sum(zip(B, R, G), ())), ('RBG', lambda R, G, B: sum(zip(R, B, G), ())), ('BGR', lambda R, G, B: sum(zip(B, G, R), ())), ('GRB', lambda R, G, B: sum(zip(G, R, B), ())), ('GBR', lambda R, G, B: sum(zip(G, B, R), ())), ('RG0', lambda R, G, B: [R[i] if i % 3 == 0 else G[i] if i % 3 == 1 else '0' for i in range(len(R))]), ('R0B', lambda R, G, B: [R[i] if i % 3 == 0 else '0' if i % 3 == 1 else B[i] for i in range(len(R))]), ('0GB', lambda R, G, B: ['0' if i % 3 == 0 else G[i] if i % 3 == 1 else B[i] for i in range(len(R))]), ('R00', lambda R, G, B: [R[i] if i % 3 == 0 else '0' for i in range(len(R))]), ('0G0', lambda R, G, B: [G[i] if i % 3 == 1 else '0' for i in range(len(R))]), ('00B', lambda R, G, B: [B[i] if i % 3 == 2 else '0' for i in range(len(R))]), ('R', lambda R, G, B: R), ('G', lambda R, G, B: G), ('B', lambda R, G, B: B), ] # 分析每一行 for row, bits in lsb_rows.items(): R, G, B = bits['R'], bits['G'], bits['B'] row_patterns = [] for name, func in patterns: seq = func(R, G, B) binstr = ''.join(seq) # 解码为字符 decs = [] chars = [] for i in range(0, len(binstr), 8): byte = binstr[i:i+8] if len(byte) == 8: dec = int(byte, 2) decs.append(dec) if 32 <= dec <= 126: chars.append(chr(dec)) else: chars.append('.') row_patterns.append({ 'name': name, 'binstr': binstr[:80] + ('...' if len(binstr) > 80 else ''), 'decs': decs[:20], 'chars': ''.join(chars) }) lsb_result['patterns'].append({ 'row': row, 'patterns': row_patterns }) except Exception as e: lsb_result['error'] = str(e) return lsb_result def main(): parser = argparse.ArgumentParser(description='PNG图片分析工具') parser.add_argument('--png', required=True, help='PNG图片路径') parser.add_argument('--output', help='输出JSON文件路径（可选）') args = parser.parse_args() result = analyze_png(args.png, args.output) # 打印结果 if result['success']: print("=" * 60) print("PNG图片分析结果") print("=" * 60) print(f"\n[PNG签名] {result['png_signature']}") print(f"\n[块信息] 共 {len(result['chunks'])} 个块:") for chunk in result['chunks']: status = "✓" if chunk['crc_valid'] else "✗" print(f" {chunk['type']:6s} | 长度: {chunk['length']:8d} | CRC: {chunk['crc']} {status}") if result['metadata']: print(f"\n[元数据]") for key, value in result['metadata'].items(): print(f" {key}: {value}") if result['lsb_analysis'].get('patterns'): print(f"\n[LSB分析] 共 {len(result['lsb_analysis']['patterns'])} 行:") for row_data in result['lsb_analysis']['patterns'][:2]: # 只显示前2行 print(f"\n 第 {row_data['row']} 行:") for pattern in row_data['patterns'][:6]: # 只显示前6个模式 chars = pattern['chars'][:40] if any(c.isalpha() for c in chars): print(f" {pattern['name']:4s}: {chars}") print("\n" + "=" * 60) print("分析完成") else: print(f"错误: {result['error']}") sys.exit(1) if __name__ == '__main__': main()