Encrypted transmission in android

Find two encryption algorithms, one MD5 encryption, which is applicable to password encryption, because this algorithm is irreversible; the other is RSA encryption, Which is reversible:
 
1. MD5 Encryption
 

Import java. security. MessageDigest;

 
Public class MD5 {

Private final static String [] hexDigits = {"0", "1", "2", "3", "4", "5 ",

"6", "7", "8", "9", "a", "B", "c", "d", "e ", "f "};

 
/**
 
* Convert the byte array to a hexadecimal string.
 
*
* @ Param B
 
* Byte array
 
* @ Return hexadecimal string
 
*/

Public static String byteArrayToHexString (byte [] B ){

StringBuffer resultSb = new StringBuffer ();

For (int I = 0; I <B. length; I ++ ){

ResultSb. append (byteToHexString (B [I]);

}

Return resultSb. toString ();

}

 
Private static String byteToHexString (byte B ){

Int n = B;

If (n <0)

N = 256 + n;

Int d1 = n/16;

Int d2 = n % 16;

Return hexDigits [d1] + hexDigits [d2];

}

 
Public static String MD5Encode (String origin ){

String resultString = null;

 
Try {

ResultString = new String (origin );

MessageDigest md = MessageDigest. getInstance ("MD5 ");

ResultString = byteArrayToHexString (md. digest (resultString

. GetBytes ()));

} Catch (Exception ex ){

 
}

Return resultString;

}

}
 
 
Ii. RSA Encryption
 

Import java. security. KeyPair;

Import java. security. KeyPairGenerator;

Import java. security. interfaces. rsw.vatekey;

Import java. security. interfaces. RSAPublicKey;

 
Import javax. crypto. Cipher;

 
/**
 
* RSAEncrypt
 
*
 
* @ Author chen
 
* @ See
 
*/

Public class Rsaencrype {

 
/**
 
* Main method for RSAEncrypt.
 
* @ Param args
 
*/

Public static void main (String [] args ){

Try {

Rsaencrype encrypt = new Rsaencrype ();



String encryptText = "encryptText ";

KeyPairGenerator keyPairGen = KeyPairGenerator. getInstance ("RSA ");

KeyPairGen. initialize (1024 );

KeyPair keyPair = keyPairGen. generateKeyPair ();

// Generate keys

Rsw.vatekey privateKey = (rsw.vatekey) keyPair. getPrivate ();

RSAPublicKey publicKey = (RSAPublicKey) keyPair. getPublic ();



Byte [] e = encrypt. encrypt (publicKey, encryptText. getBytes ());

Byte [] de = encrypt. decrypt (privateKey, e );

System. out. println (encrypt. bytesToString (e ));

System. out. println (encrypt. bytesToString (de ));

} Catch (Exception e ){

E. printStackTrace ();

}

}


/**
 
* Change byte array to String.
 
* @ Return byte []
 
*/

Protected String bytesToString (byte [] encrytpByte ){

String result = "";

For (Byte bytes: encrytpByte ){

Result + = (char) bytes. intValue ();

}

Return result;

}


/**
 
* Encrypt String.
 
* @ Return byte []
 
*/

Protected byte [] encrypt (RSAPublicKey publicKey, byte [] obj ){

If (publicKey! = Null ){

Try {

Cipher cipher = Cipher. getInstance ("RSA ");

Cipher. init (Cipher. ENCRYPT_MODE, publicKey );

Return cipher. doFinal (obj );

} Catch (Exception e ){

E. printStackTrace ();

}

}

Return null;

}

 
/**
 
* Basic decrypt method
 
* @ Return byte []
 
*/

Protected byte [] decrypt (rsw.vatekey privateKey, byte [] obj ){

If (privateKey! = Null ){

Try {

Cipher cipher = Cipher. getInstance ("RSA ");

Cipher. init (Cipher. DECRYPT_MODE, privateKey );

Return cipher. doFinal (obj );

} Catch (Exception e ){

E. printStackTrace ();

}

}


Return null;

}

}