以下の encrypt メソッドの引数に String でテキスト文字列を渡すと、暗号化されたものがバイト列で返ってくる。復号は decrypt の引数にそのバイト列を渡す。両メソッド共、crypt_spec 引数に AES を指定すれば AES で暗号するし、DES を指定すれば DES で暗号化する。
import java.io.*;
import java.security.*;
import javax.crypto.*;
import javax.crypto.spec.*;
// CHANGE THIS VALUE DEPENDING ON WHAT YOU WANT
public static final int MESSAGE_LENGTH = 1024;
/**
* @param text
* Message to encrypt
* @param secret_key
* Secret Key
* @param crypt_spec
* Crypt algorithm like "AES" or "DES"
* @return Encrypted Byte Strings
*/
public byte[] encrypt(String text, byte[] secret_key, String crypt_spec)
throws InvalidKeyException, IllegalBlockSizeException, IOException,
BadPaddingException {
SecretKeySpec sKey = new SecretKeySpec(secret_key, crypt_spec);
byte[] secret = new byte[MESSAGE_LENGTH];
try {
Cipher cipher = Cipher.getInstance(crypt_spec);
cipher.init(Cipher.ENCRYPT_MODE, sKey);
secret = cipher.doFinal(text.getBytes());
} catch (Exception e) {
System.out.println(this.getClass().getName()
+ ".encrypt: Exception:");
e.printStackTrace();
}
return secret;
}
/**
* @param b
* Encypted Byte Message
* @param crypt_spec
* Crypt Algorithm like "AES" or "DES"
* @return Decrypted String
*/
public String decrypt(byte[] b, byte[] secret_key, String crypt_spec)
throws InvalidKeyException, IllegalBlockSizeException, IOException,
BadPaddingException {
SecretKeySpec sKey = new SecretKeySpec(secret_key, crypt_spec);
byte[] secret = new byte[MESSAGE_LENGTH];
try {
Cipher cipher = Cipher.getInstance(crypt_spec);
cipher.init(Cipher.DECRYPT_MODE, sKey);
secret = cipher.doFinal(b);
} catch (Exception e) {
System.out.println(this.getClass().getName()
+ ".decrypt: Exception:");
e.printStackTrace();
}
return new String(secret);
}
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