int getBufferedLength() {
if (ibuffer == null) {
return 0;
} else {
return ibuffer.size();
}
}
/** Save the current content of this cipher. */
void save() {
processedSave = processed;
sizeOfAADSave = sizeOfAAD;
aadBufferSave = ((aadBuffer == null || aadBuffer.size() == 0) ? null : aadBuffer.toByteArray());
if (gctrPAndC != null) gctrPAndC.save();
if (ghashAllToS != null) ghashAllToS.save();
if (ibuffer != null) {
ibufferSave = ibuffer.toByteArray();
}
}
// Feed the AAD data to GHASH, pad if necessary
void processAAD() {
if (aadBuffer != null && aadBuffer.size() > 0) {
byte[] aad = aadBuffer.toByteArray();
sizeOfAAD = aad.length;
aadBuffer = null;
int lastLen = aad.length % AES_BLOCK_SIZE;
if (lastLen != 0) {
ghashAllToS.update(aad, 0, aad.length - lastLen);
byte[] padded = expandToOneBlock(aad, aad.length - lastLen, lastLen);
ghashAllToS.update(padded);
} else {
ghashAllToS.update(aad);
}
}
}
/**
* Performs decryption operation for the last time.
*
* <p>NOTE: For cipher feedback modes which does not perform special handling for the last few
* blocks, this is essentially the same as <code>encrypt(...)</code>. Given most modes do not do
* special handling, the default impl for this method is to simply call <code>decrypt(...)</code>.
*
* @param in the input buffer with the data to be decrypted
* @param inOfs the offset in <code>cipher</code>
* @param len the length of the input data
* @param out the buffer for the decryption result
* @param outOfs the offset in <code>plain</code>
* @return the number of bytes placed into the <code>out</code> buffer
*/
int decryptFinal(byte[] in, int inOfs, int len, byte[] out, int outOfs)
throws IllegalBlockSizeException, AEADBadTagException, ShortBufferException {
if (len < tagLenBytes) {
throw new AEADBadTagException("Input too short - need tag");
}
if (out.length - outOfs < ((ibuffer.size() + len) - tagLenBytes)) {
throw new ShortBufferException("Output buffer too small");
}
processAAD();
if (len != 0) {
ibuffer.write(in, inOfs, len);
}
// refresh 'in' to all buffered-up bytes
in = ibuffer.toByteArray();
inOfs = 0;
len = in.length;
ibuffer.reset();
byte[] tag = new byte[tagLenBytes];
// get the trailing tag bytes from 'in'
System.arraycopy(in, len - tagLenBytes, tag, 0, tagLenBytes);
len -= tagLenBytes;
if (len > 0) {
doLastBlock(in, inOfs, len, out, outOfs, false);
}
byte[] lengthBlock = getLengthBlock(sizeOfAAD * 8, processed * 8);
ghashAllToS.update(lengthBlock);
byte[] s = ghashAllToS.digest();
byte[] sOut = new byte[s.length];
GCTR gctrForSToTag = new GCTR(embeddedCipher, this.preCounterBlock);
gctrForSToTag.doFinal(s, 0, s.length, sOut, 0);
for (int i = 0; i < tagLenBytes; i++) {
if (tag[i] != sOut[i]) {
throw new AEADBadTagException("Tag mismatch!");
}
}
return len;
}
