.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 );

}

}