The encryption is currently two: private key and public key encryption, also known as symmetry and non-symmetry encryption. The private key encryption only uses a key to add recolve, because the same key is used for encryption and for decryption, Therefore, the private key is encrypted very fast (compared to the public key algorithm), it is especially suitable for encrypting the larger data stream. There are too many things to be introduced, so this time only the private key encryption, private key encryption, only for a block of encryption, that is, convert N-byte encryption to encrypted byte output, since It is encryption. Of course, a key, Right is needed to use a chain pattern called "Password Block Chain (CBC)" in .NET, it requires a key and an IV initialization vector, it is division Blocks are encrypted, and you must use IV vector to encrypt the first block, (everything must be a starting) Next, use the previous block to encrypt the next block until the reading is completed. In addition, send and receive the message, must be The value of the key and IV is conveyed and the key cannot be known for unauthorized users.
The advantages of private key encryption: fast. Disadvantages: patient friends can use the exhaustion method, huh, I can don't be patient. Usage: Usually use the public key encryption, encrypted in public key encryption, first pair public key encryption Then send the public key to the other party. Give the public key plus algorithm a aid. Once, look at the code below: (First build a text file in the execution file directory)
//
------------------------------ file encryption process
FILESTREAM FIN
=
New
FILESTREAM
"
INPUT.TXT
"
FileMode.Open, FileAccess.read; FileStream Fout
=
New
FILESTREAM
"
OUTPUT.TXT
"
Filemode.openorcreate, FileAccess.write;
//
Create an encrypted class
DES DES
=
New
DescryptoServiceProvider (); des.generateKey ();
//
Get randomly generated keys, and IV
DES.GENERATEIV ();
Byte
Keys
=
des.Key;
Byte
Ivs
=
DES.IV;
Long
Leng
=
FIN.LENGTH;
//
Get the length of the file
Long
Temp
=
0
;
//
Temporary variables
Byte
[] Buffer
=
New
Byte
[
400
];
//
Used to store file content in cache
CryptostReam CSTREAM
=
New
CryptostReam (Fout, Des.createEncryptor (Keys, IVS), CRYPTOSTREAMMODE.WRITE);
//
Create an add-on and write to the "Output.txt" file
While
(Temp
<
Leng)
{INT WLENG = FIN.READ (Buffer, 0,400); // Write buffer CSTREAM.WRITE (Buffer, 0, WLENG); // Write file Temp = Temp Leng; console.writeLine ("Encryption success"); Console.readline ();
CStream.close (); fout.close (); fin.close ();
Decryption:
//
----------------------------- Document decryption process
FILESTREAM FIN1
=
New
FILESTREAM
"
OUTPUT.TXT
"
FileMode.open, FileAccess.read; FileStream Fout1
=
New
FILESTREAM
"
Decryption .txt
"
Filemode.openorcreate, FileAccess.write;
//
Des Des1 = New DescryptoServiceProvider ();
//
DES1.GenerateKey ();
//
Get randomly generated keys, and IV
//
DES1.GENERATEIV ();
//
BYTE [] Keys1 = des1.key;
//
IVS1 = des1.IV;
Long
Leng1
=
Fin1.Length;
//
Get the length of the file
Long
Temp1
=
0
;
//
Temporary variables
Byte
[] Buffer1
=
New
Byte
[
400
];
//
Used to store file content in cache
CryptostReam CSTREAM1
=
New
CryptostReam (Fout1, Des.createdEcryptor (Keys, IVS), CRYPTOSTREAMMODE.WRITE);
//
Create an add-on and write to the "Output.txt" file
While
(TEMP1
<
Leng1)
{INT WLENG1 = FIN1.READ (Buffer1,0,400); // Write buffer cstractReam1.write (buffer1, 0, wleng1); // Write file temp1 = temp1 leng1; console.writeline ("Decryption success"); Console.readline ();
CStream.close (); fout.close (); fin.close ();
//
-------------------------- OVER
Encryption process with regard to the DES algorithm reference: http://www.vchome.net/tech/datastruct/datasf25.htm
