/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package com.sun.crypto.provider;
import java.util.Arrays;
import java.io.*;
import java.security.*;
import javax.crypto.*;
import static com.sun.crypto.provider.AESConstants.AES_BLOCK_SIZE;
/**
* This class represents ciphers in GaloisCounter (GCM) mode.
*
* <p>This mode currently should only be used w/ AES cipher.
* Although no checking is done here, caller should only
* pass AES Cipher to the constructor.
*
* <p>NOTE: This class does not deal with buffering or padding.
*
* @since 1.8
*/
final class GaloisCounterMode extends FeedbackCipher {
static int DEFAULT_TAG_LEN = AES_BLOCK_SIZE;
static int DEFAULT_IV_LEN = 12; // in bytes
// buffer for AAD data; if null, meaning update has been called
private ByteArrayOutputStream aadBuffer = new ByteArrayOutputStream();
private int sizeOfAAD = 0;
// in bytes; need to convert to bits (default value 128) when needed
private int tagLenBytes = DEFAULT_TAG_LEN;
// these following 2 fields can only be initialized after init() is
// called, e.g. after cipher key k is set, and STAY UNCHANGED
private byte[] subkeyH = null;
private byte[] preCounterBlock = null;
private GCTR gctrPAndC = null;
private GHASH ghashAllToS = null;
// length of total data, i.e. len(C)
private int processed = 0;
// additional variables for save/restore calls
private byte[] aadBufferSave = null;
private int sizeOfAADSave = 0;
private int processedSave = 0;
// value must be 16-byte long; used by GCTR and GHASH as well
static void increment32(byte[] value) {
if (value.length != AES_BLOCK_SIZE) {
throw new RuntimeException("Unexpected counter block length");
}
// start from last byte and only go over 4 bytes, i.e. total 32 bits
int n = value.length - 1;
while ((n >= value.length - 4) && (++value[n] == 0)) {
n--;
}
}
// ivLen in bits
private static byte[] getLengthBlock(int ivLen) {
byte[] out = new byte[AES_BLOCK_SIZE];
out[12] = (byte)(ivLen >>> 24);
out[13] = (byte)(ivLen >>> 16);
out[14] = (byte)(ivLen >>> 8);
out[15] = (byte)ivLen;
return out;
}
// aLen and cLen both in bits
private static byte[] getLengthBlock(int aLen, int cLen) {
byte[] out = new byte[AES_BLOCK_SIZE];
out[4] = (byte)(aLen >>> 24);
out[5] = (byte)(aLen >>> 16);
out[6] = (byte)(aLen >>> 8);
out[7] = (byte)aLen;
out[12] = (byte)(cLen >>> 24);
out[13] = (byte)(cLen >>> 16);
out[14] = (byte)(cLen >>> 8);
out[15] = (byte)cLen;
return out;
}
private static byte[] expandToOneBlock(byte[] in, int inOfs, int len) {
if (len > AES_BLOCK_SIZE) {
throw new ProviderException("input " + len + " too long");
}
if (len == AES_BLOCK_SIZE && inOfs == 0) {
return in;
} else {
byte[] paddedIn = new byte[AES_BLOCK_SIZE];
System.arraycopy(in, inOfs, paddedIn, 0, len);
return paddedIn;
}
}
private static byte[] getJ0(byte[] iv, byte[] subkeyH) {
byte[] j0;
if (iv.length == 12) { // 96 bits
j0 = expandToOneBlock(iv, 0, iv.length);
j0[AES_BLOCK_SIZE - 1] = 1;
} else {
GHASH g = new GHASH(subkeyH);
int lastLen = iv.length % AES_BLOCK_SIZE;
if (lastLen != 0) {
g.update(iv, 0, iv.length - lastLen);
byte[] padded =
expandToOneBlock(iv, iv.length - lastLen, lastLen);
g.update(padded);
} else {
g.update(iv);
}
byte[] lengthBlock = getLengthBlock(iv.length*8);
g.update(lengthBlock);
j0 = g.digest();
}
return j0;
}
GaloisCounterMode(SymmetricCipher embeddedCipher) {
super(embeddedCipher);
aadBuffer = new ByteArrayOutputStream();
}
/**
* Gets the name of the feedback mechanism
*
* @return the name of the feedback mechanism
*/
String getFeedback() {
return "GCM";
}
/**
* Resets the cipher object to its original state.
* This is used when doFinal is called in the Cipher class, so that the
* cipher can be reused (with its original key and iv).
*/
void reset() {
if (aadBuffer == null) {
aadBuffer = new ByteArrayOutputStream();
} else {
aadBuffer.reset();
}
if (gctrPAndC != null) gctrPAndC.reset();
if (ghashAllToS != null) ghashAllToS.reset();
processed = 0;
sizeOfAAD = 0;
}
/**
* 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();
}
/**
* Restores the content of this cipher to the previous saved one.
*/
void restore() {
processed = processedSave;
sizeOfAAD = sizeOfAADSave;
if (aadBuffer != null) {
aadBuffer.reset();
if (aadBufferSave != null) {
aadBuffer.write(aadBufferSave, 0, aadBufferSave.length);
}
}
if (gctrPAndC != null) gctrPAndC.restore();
if (ghashAllToS != null) ghashAllToS.restore();
}
/**
* Initializes the cipher in the specified mode with the given key
* and iv.
*
* @param decrypting flag indicating encryption or decryption
* @param algorithm the algorithm name
* @param key the key
* @param iv the iv
* @param tagLenBytes the length of tag in bytes
*
* @exception InvalidKeyException if the given key is inappropriate for
* initializing this cipher
*/
void init(boolean decrypting, String algorithm, byte[] key, byte[] iv)
throws InvalidKeyException {
init(decrypting, algorithm, key, iv, DEFAULT_TAG_LEN);
}
/**
* Initializes the cipher in the specified mode with the given key
* and iv.
*
* @param decrypting flag indicating encryption or decryption
* @param algorithm the algorithm name
* @param key the key
* @param iv the iv
* @param tagLenBytes the length of tag in bytes
*
* @exception InvalidKeyException if the given key is inappropriate for
* initializing this cipher
*/
void init(boolean decrypting, String algorithm, byte[] keyValue,
byte[] ivValue, int tagLenBytes)
throws InvalidKeyException {
if (keyValue == null || ivValue == null) {
throw new InvalidKeyException("Internal error");
}
// always encrypt mode for embedded cipher
this.embeddedCipher.init(false, algorithm, keyValue);
this.subkeyH = new byte[AES_BLOCK_SIZE];
this.embeddedCipher.encryptBlock(new byte[AES_BLOCK_SIZE], 0,
this.subkeyH, 0);
this.iv = ivValue.clone();
preCounterBlock = getJ0(iv, subkeyH);
byte[] j0Plus1 = preCounterBlock.clone();
increment32(j0Plus1);
gctrPAndC = new GCTR(embeddedCipher, j0Plus1);
ghashAllToS = new GHASH(subkeyH);
this.tagLenBytes = tagLenBytes;
if (aadBuffer == null) {
aadBuffer = new ByteArrayOutputStream();
} else {
aadBuffer.reset();
}
processed = 0;
sizeOfAAD = 0;
}
/**
* Continues a multi-part update of the Additional Authentication
* Data (AAD), using a subset of the provided buffer. If this
* cipher is operating in either GCM or CCM mode, all AAD must be
* supplied before beginning operations on the ciphertext (via the
* {@code update} and {@code doFinal} methods).
* <p>
* NOTE: Given most modes do not accept AAD, default impl for this
* method throws IllegalStateException.
*
* @param src the buffer containing the AAD
* @param offset the offset in {@code src} where the AAD input starts
* @param len the number of AAD bytes
*
* @throws IllegalStateException if this cipher is in a wrong state
* (e.g., has not been initialized), does not accept AAD, or if
* operating in either GCM or CCM mode and one of the {@code update}
* methods has already been called for the active
* encryption/decryption operation
* @throws UnsupportedOperationException if this method
* has not been overridden by an implementation
*
* @since 1.8
*/
void updateAAD(byte[] src, int offset, int len) {
if (aadBuffer != null) {
aadBuffer.write(src, offset, len);
} else {
// update has already been called
throw new IllegalStateException
("Update has been called; no more AAD data");
}
}
// Feed the AAD data to GHASH, pad if necessary
void processAAD() {
if (aadBuffer != null) {
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);
}
}
}
// Utility to process the last block; used by encryptFinal and decryptFinal
void doLastBlock(byte[] in, int inOfs, int len, byte[] out, int outOfs,
boolean isEncrypt) throws IllegalBlockSizeException {
// process data in 'in'
gctrPAndC.doFinal(in, inOfs, len, out, outOfs);
processed += len;
byte[] ct;
int ctOfs;
if (isEncrypt) {
ct = out;
ctOfs = outOfs;
} else {
ct = in;
ctOfs = inOfs;
}
int lastLen = len % AES_BLOCK_SIZE;
if (lastLen != 0) {
ghashAllToS.update(ct, ctOfs, len - lastLen);
byte[] padded =
expandToOneBlock(ct, (ctOfs + len - lastLen), lastLen);
ghashAllToS.update(padded);
} else {
ghashAllToS.update(ct, ctOfs, len);
}
}
/**
* Performs encryption operation.
*
* <p>The input plain text <code>in</code>, starting at <code>inOff</code>
* and ending at <code>(inOff + len - 1)</code>, is encrypted. The result
* is stored in <code>out</code>, starting at <code>outOfs</code>.
*
* <p>It is the application's responsibility to make sure that
* <code>len</code> is a multiple of the embedded cipher's block size,
* otherwise, a ProviderException will be thrown.
*
* <p>It is also the application's responsibility to make sure that
* <code>init</code> has been called before this method is called.
* (This check is omitted here, to avoid double checking.)
*
* @param in the buffer with the input data to be encrypted
* @param inOfs the offset in <code>in</code>
* @param len the length of the input data
* @param out the buffer for the result
* @param outOfs the offset in <code>out</code>
*/
void encrypt(byte[] in, int inOfs, int len, byte[] out, int outOfs) {
processAAD();
if (len > 0) {
gctrPAndC.update(in, inOfs, len, out, outOfs);
processed += len;
ghashAllToS.update(out, outOfs, len);
}
}
/**
* Performs encryption operation for the last time.
*
* <p>NOTE: <code>len</code> may not be multiple of the embedded
* cipher's block size for this call.
*
* @param in the input buffer with the data to be encrypted
* @param inOfs the offset in <code>in</code>
* @param len the length of the input data
* @param out the buffer for the encryption result
* @param outOfs the offset in <code>out</code>
* @return the number of bytes placed into the <code>out</code> buffer
*/
int encryptFinal(byte[] in, int inOfs, int len, byte[] out, int outOfs)
throws IllegalBlockSizeException {
if (out.length - outOfs < (len + tagLenBytes)) {
throw new RuntimeException("Output buffer too small");
}
processAAD();
if (len > 0) {
//ByteUtil.dumpArray(Arrays.copyOfRange(in, inOfs, inOfs + len));
doLastBlock(in, inOfs, len, out, outOfs, true);
}
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);
System.arraycopy(sOut, 0, out, (outOfs + len), tagLenBytes);
return (len + tagLenBytes);
}
/**
* Performs decryption operation.
*
* <p>The input cipher text <code>in</code>, starting at
* <code>inOfs</code> and ending at <code>(inOfs + len - 1)</code>,
* is decrypted. The result is stored in <code>out</code>, starting at
* <code>outOfs</code>.
*
* <p>It is the application's responsibility to make sure that
* <code>len</code> is a multiple of the embedded cipher's block
* size, as any excess bytes are ignored.
*
* <p>It is also the application's responsibility to make sure that
* <code>init</code> has been called before this method is called.
* (This check is omitted here, to avoid double checking.)
*
* @param in the buffer with the input data to be decrypted
* @param inOfs the offset in <code>in</code>
* @param len the length of the input data
* @param out the buffer for the result
* @param outOfs the offset in <code>out</code>
*/
void decrypt(byte[] in, int inOfs, int len, byte[] out, int outOfs) {
processAAD();
if (len > 0) { // must be at least AES_BLOCK_SIZE bytes long
gctrPAndC.update(in, inOfs, len, out, outOfs);
processed += len;
ghashAllToS.update(in, inOfs, len);
}
}
/**
* 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 {
if (len < tagLenBytes) {
throw new RuntimeException("Input buffer too short - need tag");
}
if (out.length - outOfs < (len - tagLenBytes)) {
throw new RuntimeException("Output buffer too small");
}
processAAD();
int processedOld = processed;
byte[] tag = new byte[tagLenBytes];
// get the trailing tag bytes from 'in'
System.arraycopy(in, inOfs + 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;
}
// return tag length in bytes
int getTagLen() {
return this.tagLenBytes;
}
}