上一篇：SQL SERVER中一些常见性能问...

.NET下对二进制文件进行加密解密（C#）

下面的类实现了文件的加密和解密操作，试验了几种文件类型均没有问题，现在和大家共享一下。namespace mycryptohelp
{
/// <summary>
/// 异常处理类
/// </summary>
public class cryptohelpexception : applicationexception
{
public cryptohelpexception(string msg):base(msg){}
}

/// <summary>
/// crypthelp
/// </summary>
public class cryptohelp
{
private const ulong fc_tag = 0xfc010203040506cf;

private const int buffer_size = 128*1024;

/// <summary>
/// 检验两个byte数组是否相同
/// </summary>
/// <param name="b1">byte数组</param>
/// <param name="b2">byte数组</param>
/// <returns>true－相等</returns>
private static bool checkbytearrays(byte[] b1, byte[] b2)
{
   if(b1.length == b2.length)
   {
    for(int i = 0; i < b1.length; ++i)
    {
     if(b1[i] != b2[i])
      return false;
    }
    return true;
   }
   return false;
}

/// <summary>
/// 创建rijndael symmetricalgorithm
/// </summary>
/// <param name="password">密码</param>
/// <param name="salt"></param>
/// <returns>加密对象</returns>
private static symmetricalgorithm createrijndael(string password, byte[] salt)
{
   passwordderivebytes pdb = new passwordderivebytes(password,salt,"sha256",1000);

   symmetricalgorithm sma = rijndael.create();
   sma.keysize = 256;
   sma.key = pdb.getbytes(32);
   sma.padding = paddingmode.pkcs7;
   return sma;
}

/// <summary>
/// 加密文件随机数生成
/// </summary>
private static randomnumbergenerator rand = new rngcryptoserviceprovider();

/// <summary>
/// 生成指定长度的随机byte数组
/// </summary>
/// <param name="count">byte数组长度</param>
/// <returns>随机byte数组</returns>
private static byte[] generaterandombytes(int count)
{
   byte[] bytes = new byte[count];
   rand.getbytes(bytes);
   return bytes;
}

/// <summary>
/// 加密文件
/// </summary>
/// <param name="infile">待加密文件</param>
/// <param name="outfile">加密后输入文件</param>
/// <param name="password">加密密码</param>
public static void encryptfile(string infile, string outfile, string password)
{
   using(filestream fin = file.openread(infile),
       fout = file.openwrite(outfile))
   {
    long lsize = fin.length; // 输入文件长度
    int size = (int)lsize;
    byte[] bytes = new byte[buffer_size]; // 缓存
    int read = -1; // 输入文件读取数量
    int value = 0;

    // 获取iv和salt
    byte[] iv = generaterandombytes(16);
    byte[] salt = generaterandombytes(16);

    // 创建加密对象
    symmetricalgorithm sma = cryptohelp.createrijndael(password, salt);
    sma.iv = iv;

    // 在输出文件开始部分写入iv和salt
    fout.write(iv,0,iv.length);
    fout.write(salt,0,salt.length);

    // 创建散列加密
    hashalgorithm hasher = sha256.create();
    using(cryptostream cout = new cryptostream(fout,sma.createencryptor(),cryptostreammode.write),
        chash = new cryptostream(stream.null,hasher,cryptostreammode.write))
    {
     binarywriter bw = new binarywriter(cout);
     bw.write(lsize);

     bw.write(fc_tag);

     // 读写字节块到加密流缓冲区
     while( (read = fin.read(bytes,0,bytes.length)) != 0 )
     {
      cout.write(bytes,0,read);
      chash.write(bytes,0,read);
      value += read;
     }
     // 关闭加密流
     chash.flush();
     chash.close();

     // 读取散列
     byte[] hash = hasher.hash;

     // 输入文件写入散列
     cout.write(hash,0,hash.length);

     // 关闭文件流
     cout.flush();
     cout.close();
    }
   }
}

/// <summary>
/// 解密文件
/// </summary>
/// <param name="infile">待解密文件</param>
/// <param name="outfile">解密后输出文件</param>
/// <param name="password">解密密码</param>
public static void decryptfile(string infile, string outfile, string password)
{
   // 创建打开文件流
   using(filestream fin = file.openread(infile),
       fout = file.openwrite(outfile))
   {
    int size = (int)fin.length;
    byte[] bytes = new byte[buffer_size];
    int read = -1;
    int value = 0;
    int outvalue = 0;

    byte[] iv = new byte[16];
    fin.read(iv,0,16);
    byte[] salt = new byte[16];
    fin.read(salt,0,16);

    symmetricalgorithm sma = cryptohelp.createrijndael(password,salt);
    sma.iv = iv;

    value = 32;
    long lsize = -1;

    // 创建散列对象, 校验文件
    hashalgorithm hasher = sha256.create();

    using(cryptostream cin = new cryptostream(fin,sma.createdecryptor(),cryptostreammode.read),
        chash = new cryptostream(stream.null,hasher,cryptostreammode.write))
    {
     // 读取文件长度
     binaryreader br = new binaryreader(cin);
     lsize = br.readint64();
     ulong tag = br.readuint64();

     if(fc_tag != tag)
      throw new cryptohelpexception("文件被破坏");

     long numreads = lsize / buffer_size;

     long slack = (long)lsize % buffer_size;

     for(int i = 0; i < numreads; ++i)
     {
      read = cin.read(bytes,0,bytes.length);
      fout.write(bytes,0,read);
      chash.write(bytes,0,read);
      value += read;
      outvalue += read;
     }

     if(slack > 0)
     {
      read = cin.read(bytes,0,(int)slack);
      fout.write(bytes,0,read);
      chash.write(bytes,0,read);
      value += read;
      outvalue += read;
     }

chash.flush();
chash.close();

fout.flush();
fout.close();

byte[] curhash = hasher.hash;

     // 获取比较和旧的散列对象
     byte[] oldhash = new byte[hasher.hashsize / 8];
     read = cin.read(oldhash,0,oldhash.length);
     if((oldhash.length != read) (!checkbytearrays(oldhash,curhash)))
      throw new cryptohelpexception("文件被破坏");
    }

    if(outvalue != lsize)
     throw new cryptohelpexception("文件大小不匹配");
   }
}
}
}

// 调用

public class testclass
{
    string mypassword = "test_password_~!@#";
    string myplainfile = "test.txt";
    string myencryptedfile = "test.encrypted";
    string mydecryptedfile = "test.decrypted";

    [stathread]
    static void main()
    {
        cryptohelp.encryptfile(myplainfile, myencryptedfile, mypassword);
        cryptohelp.decryptfile(myencryptedfile,mydecryptedfile, mypassword);
    }
}

（）

下一篇：利用.NET的File控件上传文件的最终解决方案(个人版)

↓相关文章：