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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* 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).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
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*
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package sun.security.provider;
import java.math.BigInteger;
import java.security.DigestException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.SecureRandomParameters;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class HashDrbg extends AbstractHashDrbg {
private static final byte[] ZERO = new byte[1];
private static final byte[] ONE = new byte[]{1};
private MessageDigest digest;
private byte[] v;
private byte[] c;
public HashDrbg(SecureRandomParameters params) {
mechName = "Hash_DRBG";
configure(params);
}
/**
* This call, used by the constructors, instantiates the digest.
*/
@Override
protected void initEngine() {
try {
/*
* Use the local SUN implementation to avoid native
* performance overhead.
*/
digest = MessageDigest.getInstance(algorithm, "SUN");
} catch (NoSuchProviderException | NoSuchAlgorithmException e) {
// Fallback to any available.
try {
digest = MessageDigest.getInstance(algorithm);
} catch (NoSuchAlgorithmException exc) {
throw new InternalError(
"internal error: " + algorithm + " not available.", exc);
}
}
}
private byte[] hashDf(int requested, List<byte[]> inputs) {
return hashDf(digest, outLen, requested, inputs);
}
/**
* A hash-based derivation function defined in NIST SP 800-90Ar1 10.3.1.
* The function is used inside Hash_DRBG, and can also be used as an
* approved conditioning function as described in 800-90B 6.4.2.2.
*
* Note: In each current call, requested is seedLen, therefore small,
* no need to worry about overflow.
*
* @param digest a {@code MessageDigest} object in reset state
* @param outLen {@link MessageDigest#getDigestLength} of {@code digest}
* @param requested requested output length, in bytes
* @param inputs input data
* @return the condensed/expanded output
*/
public static byte[] hashDf(MessageDigest digest, int outLen,
int requested, List<byte[]> inputs) {
// 1. temp = the Null string.
// 2. len = upper_int(no_of_bits_to_return / outLen)
int len = (requested + outLen - 1) / outLen;
byte[] temp = new byte[len * outLen];
// 3. counter = 0x01
int counter = 1;
// 4. For i = 1 to len do
for (int i=0; i<len; i++) {
// 4.1 temp = temp
// || Hash (counter || no_of_bits_to_return || input_string).
digest.update((byte) counter);
digest.update((byte)(requested >> 21)); // requested*8 as int32
digest.update((byte)(requested >> 13));
digest.update((byte)(requested >> 5));
digest.update((byte)(requested << 3));
for (byte[] input : inputs) {
digest.update(input);
}
try {
digest.digest(temp, i * outLen, outLen);
} catch (DigestException e) {
throw new AssertionError("will not happen", e);
}
// 4.2 counter = counter + 1
counter++;
}
// 5. requested_bits = leftmost (temp, no_of_bits_to_return).
return temp.length == requested? temp: Arrays.copyOf(temp, requested);
// 6. Return
}
// This method is used by both instantiation and reseeding.
@Override
protected final synchronized void hashReseedInternal(List<byte[]> inputs) {
// 800-90Ar1 10.1.1.2: Instantiate Process.
// 800-90Ar1 10.1.1.3: Reseed Process.
byte[] seed;
// Step 2: seed = Hash_df (seed_material, seedlen).
if (v != null) {
// Step 1 of 10.1.1.3: Prepend 0x01 || V
inputs.add(0, ONE);
inputs.add(1, v);
seed = hashDf(seedLen, inputs);
} else {
seed = hashDf(seedLen, inputs);
}
// Step 3. V = seed.
v = seed;
// Step 4. C = Hash_df ((0x00 || V), seedlen).
inputs = new ArrayList<>(2);
inputs.add(ZERO);
inputs.add(v);
c = hashDf(seedLen, inputs);
// Step 5. reseed_counter = 1.
reseedCounter = 1;
//status();
// Step 6: Return
}
private void status() {
if (debug != null) {
debug.println(this, "V = " + hex(v));
debug.println(this, "C = " + hex(c));
debug.println(this, "reseed counter = " + reseedCounter);
}
}
/**
* Adds byte arrays into an existing one.
*
* @param out existing array
* @param data more arrays, can be of different length
*/
private static void addBytes(byte[] out, int len, byte[]... data) {
for (byte[] d: data) {
int dlen = d.length;
int carry = 0;
for (int i = 0; i < len; i++) {
int sum = (out[len - i - 1] & 0xff) + carry;
if (i < dlen) {
sum += (d[dlen - i - 1] & 0xff);
}
out[len - i - 1] = (byte) sum;
carry = sum >> 8;
if (i >= dlen - 1 && carry == 0) break;
}
}
}
/**
* Generates a user-specified number of random bytes.
*
* @param result the array to be filled in with random bytes.
*/
@Override
public final synchronized void generateAlgorithm(
byte[] result, byte[] additionalInput) {
if (debug != null) {
debug.println(this, "generateAlgorithm");
}
// 800-90Ar1 10.1.1.4: Hash_DRBG_Generate Process
// Step 1: Check reseed_counter. Will not fail. Already checked in
// AbstractDrbg#engineNextBytes.
// Step 2: additional_input
if (additionalInput != null) {
digest.update((byte)2);
digest.update(v);
digest.update(additionalInput);
addBytes(v, seedLen, digest.digest());
}
// Step 3. Hashgen (requested_number_of_bits, V).
hashGen(result, v);
// Step 4. H = Hash (0x03 || V).
digest.update((byte)3);
digest.update(v);
byte[] h = digest.digest();
// Step 5. V = (V + H + C + reseed_counter) mod 2seedlen.
byte[] rcBytes;
if (reseedCounter < 256) {
rcBytes = new byte[]{(byte)reseedCounter};
} else {
rcBytes = BigInteger.valueOf(reseedCounter).toByteArray();
}
addBytes(v, seedLen, h, c, rcBytes);
// Step 6. reseed_counter = reseed_counter + 1.
reseedCounter++;
//status();
// Step 7: Return.
}
// 800-90Ar1 10.1.1.4: Hashgen
private void hashGen(byte[] output, byte[] v) {
// Step 2. data = V
byte[] data = v;
// Step 3: W is output not filled
// Step 4: For i = 1 to m
int pos = 0;
int len = output.length;
while (len > 0) {
if (len < outLen) {
// Step 4.1 w = Hash (data).
// Step 4.2 W = W || w.
System.arraycopy(digest.digest(data), 0, output, pos,
len);
} else {
try {
// Step 4.1 w = Hash (data).
digest.update(data);
// Step 4.2 digest into right position, no need to cat
digest.digest(output, pos, outLen);
} catch (DigestException e) {
throw new AssertionError("will not happen", e);
}
}
len -= outLen;
if (len <= 0) {
// shortcut, so that data and pos needn't be updated
break;
}
// Step 4.3 data = (data + 1) mod 2^seedlen.
if (data == v) {
data = Arrays.copyOf(v, v.length);
}
addBytes(data, seedLen, ONE);
pos += outLen;
}
// Step 5: No need to truncate
// Step 6: Return
}
}