Mega Code Archive
Message without tampering with MAC (DES), encryption AES in CTR mode
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import java.security.Key;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.SecureRandom;
import java.security.Security;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.Mac;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
/**
* Message without tampering with MAC (DES), encryption AES in CTR mode
*/
public class MainClass {
public static void main(String[] args) throws Exception {
Security.addProvider(new BouncyCastleProvider());
SecureRandom random = new SecureRandom();
IvParameterSpec ivSpec = createCtrIvForAES(1, random);
Key key = createKeyForAES(256, random);
Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding", "BC");
String input = "www.rntsoft.com";
Mac mac = Mac.getInstance("DES", "BC");
byte[] macKeyBytes = "12345678".getBytes();
Key macKey = new SecretKeySpec(macKeyBytes, "DES");
System.out.println("input : " + input);
// encryption step
cipher.init(Cipher.ENCRYPT_MODE, key, ivSpec);
byte[] cipherText = new byte[cipher.getOutputSize(input.length() + mac.getMacLength())];
int ctLength = cipher.update(input.getBytes(), 0, input.length(), cipherText, 0);
mac.init(macKey);
mac.update(input.getBytes());
ctLength += cipher.doFinal(mac.doFinal(), 0, mac.getMacLength(), cipherText, ctLength);
System.out.println("cipherText : " + new String(cipherText));
// decryption step
cipher.init(Cipher.DECRYPT_MODE, key, ivSpec);
byte[] plainText = cipher.doFinal(cipherText, 0, ctLength);
int messageLength = plainText.length - mac.getMacLength();
mac.init(macKey);
mac.update(plainText, 0, messageLength);
byte[] messageHash = new byte[mac.getMacLength()];
System.arraycopy(plainText, messageLength, messageHash, 0, messageHash.length);
System.out.println("plain : " + new String(plainText) + " verified: "
+ MessageDigest.isEqual(mac.doFinal(), messageHash));
}
static SecretKey createKeyForAES(int bitLength, SecureRandom random)
throws NoSuchAlgorithmException, NoSuchProviderException {
KeyGenerator generator = KeyGenerator.getInstance("AES", "BC");
generator.init(256, random);
return generator.generateKey();
}
public static IvParameterSpec createCtrIvForAES(int messageNumber, SecureRandom random) {
byte[] ivBytes = new byte[16];
random.nextBytes(ivBytes);
ivBytes[0] = (byte) (messageNumber >> 24);
ivBytes[1] = (byte) (messageNumber >> 16);
ivBytes[2] = (byte) (messageNumber >> 8);
ivBytes[3] = (byte) (messageNumber >> 0);
for (int i = 0; i != 7; i++) {
ivBytes[8 + i] = 0;
}
ivBytes[15] = 1;
return new IvParameterSpec(ivBytes);
}
}
MessageWithoutTamperingwithMAC(DES)EncryptionAESinCTRmode.zip( 1,199 k)
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