import javax.crypto.Cipher; 
import javax.crypto.KeyGenerator; 
import javax.crypto.SecretKey; 
import javax.crypto.spec.GCMParameterSpec; 

public class GCMError { 

public static void main (String[] args) throws Exception { 
byte[] plainText = null; 
byte[] sunFinalCipherText = null; 
byte[] sunUpdateCipherText = null; 
byte[] aad = null; 

Cipher sunFinal = null; 
Cipher sunUpdate = null; 

Cipher[] ciphers = new Cipher[2]; 

String trans = "AES/GCM/NOPADDING"; 
String sunProvider = "SunJCE"; 
String cipherName = "AES"; 

int keySize = 192; 
int numBytes = 1024; 

SecretKey secretKey = null; 

KeyGenerator keygen = null; 

// Create ciphers 
sunFinal = Cipher.getInstance(trans, sunProvider); 
sunUpdate = Cipher.getInstance(trans, sunProvider); 

ciphers[0] = sunFinal; 
ciphers[1] = sunUpdate; 

// Generate a key 
keygen = KeyGenerator.getInstance(cipherName); 
keygen.init(keySize); 
secretKey = keygen.generateKey(); 

// Generate IV 
byte[] iv = new byte[sunFinal.getBlockSize()]; 
for (int i = 0; i < iv.length; i++) { 
iv[i] = (byte) (i*2); 
} 

// Generate some AAD data 
aad = new byte[100]; 
for (int i = 0; i < aad.length; i++) { 
aad[i] = (byte) (i*2); 
} 

// Generate some plaintext 
plainText = new byte[numBytes]; 
for (int i = 0; i < plainText.length; i++) { 
plainText[i] = (byte)(i+1); 
} 

// Create the paramspec 
GCMParameterSpec paramSpec = new GCMParameterSpec(sunFinal.getBlockSize() 
* Byte.SIZE, iv); 

// Initialize the ciphers; 
for (Cipher cipher : ciphers) { 
cipher.init(Cipher.ENCRYPT_MODE, secretKey, paramSpec); 
} 

// Set up some default data for the ciphertexts 
sunFinalCipherText = new byte[sunFinal.getOutputSize(numBytes)]; 
for (int i = 0; i < numBytes; i++) { 
sunFinalCipherText[i] = (byte) i; 
} 
sunUpdateCipherText = sunFinalCipherText.clone(); 

// Pass the AAD to ciphers 
for (Cipher cipher : ciphers) { 
cipher.updateAAD(aad, 0, aad.length); 
} 

// Do updates 
sunUpdate.update(plainText, 0, plainText.length, sunUpdateCipherText); 

// Do finals 
sunFinal.doFinal(plainText, 0, plainText.length, sunFinalCipherText); 
sunUpdate.doFinal(plainText, 0, 0, sunUpdateCipherText); 

System.out.print("Ciphertexts:"); 
for (int a=0; a<sunFinalCipherText.length; a++) { 
System.out.printf(" %02x", a); 
} 
System.out.println(); 
for (int i=0; i<ciphers.length; i++) { 
switch(i) { 
case 0: 
System.out.print("sunFinal: "); 
break; 
case 1: 
System.out.print("sunUpdate: "); 
break; 
case 2: 
System.out.print("ciscoFinal: "); 
break; 
case 3: 
System.out.print("ciscoUpdate:"); 
break; 
} 
for (int a=0; a<sunFinalCipherText.length; a++) { 
switch(i) { 
case 0: 
System.out.printf(" %02x", sunFinalCipherText[a]); 
break; 
case 1: 
System.out.printf(" %02x", sunUpdateCipherText[a]); 
break; 
} 
} 
System.out.println(); 
} 

for (int i=0; i<sunFinalCipherText.length; i++) { 
if (sunFinalCipherText[i] != sunUpdateCipherText[i]) { 
throw new Exception(String.format("Cipher texts do not match (starting at byte %d).", i)); 
} 
} 

System.out.println("Cipher texts match!"); 
} 

}