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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
{
public class CryptoHelpException : ApplicationException
{
public CryptoHelpException( string msg ):base( msg )
{
}
}
public class CryptoHelp
{
private const ulong FC_TAG = 0xFC010203040506CF;
private const
int BUFFER_SIZE = 128*1024;
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;
}
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;
}
private static RandomNumberGenerator rand = new RNGCryptoServiceProvider( );
private static byte[] GenerateRandomBytes( int count )
{
byte[] bytes = new byte[count];
rand.GetBytes( bytes );
return bytes;
}
public static void EncryptFile( string inFile,
string outFile,
string password )
{
using( FileStream fin = File.OpenRead( inFile ),
fout = File.OpenWrite( outFile ) )
{
long lSize = fin.Length;
int size = ( int )lSize;
byte[] bytes = new byte[BUFFER_SIZE];
int read = -1;
int value = 0;
byte[] IV = GenerateRandomBytes( 16 );
byte[] salt = GenerateRandomBytes( 16 );
SymmetricAlgorithm sma = CryptoHelp.CreateRijndael( password, salt );
sma.IV = IV;
fout.Write( IV,0,IV.Length );
fout.Write( salt,0,salt.Length );
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 );
while(( read = fin.Read( bytes,0,bytes.Length ) ) != 0)
{
cout.Write( bytes,0,read );
chash.Write( bytes,0,read );
value += read;
}
chash.Flush( );
chash.Close( );
byte[] hash = hasher.Hash;
cout.Write( hash,0,hash.Length );
cout.Flush( );
cout.Close( );
}
}
}
public static void DecryptFile( string inFile,
string outFile,
string password )
{
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;
HashAlgorithm hasher = SHA256.Create( );
using( CryptoStream cin = new CryptoStream( fin,sma.CreateDecryptor( ),CryptoStreamMode.Read ),
chash = new CryptoStream( Stream.Null,hasher,CryptoStreamMode.Write ) )
{
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;
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" );
}
}
}
}
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 );
}
}
本文由中国C#技术学习中心整理 如果你对本文有不明之处请到技术论坛讨论!
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