Coverage Summary for Class: MGF1BytesGeneratorExt (org.ethereum.crypto)
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Method, %
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Line, %
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MGF1BytesGeneratorExt |
0%
(0/1)
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(0/5)
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1 /*
2 * This file is part of RskJ
3 * Copyright (C) 2017 RSK Labs Ltd.
4 * (derived from ethereumJ library, Copyright (c) 2016 <ether.camp>)
5 *
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU Lesser General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 */
19
20 package org.ethereum.crypto;
21
22 import org.bouncycastle.crypto.DataLengthException;
23 import org.bouncycastle.crypto.DerivationFunction;
24 import org.bouncycastle.crypto.DerivationParameters;
25 import org.bouncycastle.crypto.Digest;
26 import org.bouncycastle.crypto.params.MGFParameters;
27
28 /**
29 * This class is borrowed from spongycastle project
30 * The only change made is addition of 'counterStart' parameter to
31 * conform to Crypto++ capabilities
32 */
33 public class MGF1BytesGeneratorExt implements DerivationFunction {
34 private Digest digest;
35 private byte[] seed;
36 private int hLen;
37 private int counterStart;
38
39 public MGF1BytesGeneratorExt(Digest digest, int counterStart) {
40 this.digest = digest;
41 this.hLen = digest.getDigestSize();
42 this.counterStart = counterStart;
43 }
44
45 public void init(DerivationParameters param) {
46 if(!(param instanceof MGFParameters)) {
47 throw new IllegalArgumentException("MGF parameters required for MGF1Generator");
48 } else {
49 MGFParameters p = (MGFParameters)param;
50 this.seed = p.getSeed();
51 }
52 }
53
54 public Digest getDigest() {
55 return this.digest;
56 }
57
58 private void itoosp(int i, byte[] sp) {
59 sp[0] = (byte)(i >>> 24);
60 sp[1] = (byte)(i >>> 16);
61 sp[2] = (byte)(i >>> 8);
62 sp[3] = (byte)(i >>> 0);
63 }
64
65 public int generateBytes(byte[] out, int outOff, int len) throws DataLengthException, IllegalArgumentException {
66 if(out.length - len < outOff) {
67 throw new DataLengthException("output buffer too small");
68 } else {
69 byte[] hashBuf = new byte[this.hLen];
70 byte[] c = new byte[4];
71 int counter = 0;
72 int hashCounter = counterStart;
73 this.digest.reset();
74 if(len > this.hLen) {
75 do {
76 this.itoosp(hashCounter++, c);
77 this.digest.update(this.seed, 0, this.seed.length);
78 this.digest.update(c, 0, c.length);
79 this.digest.doFinal(hashBuf, 0);
80 System.arraycopy(hashBuf, 0, out, outOff + counter * this.hLen, this.hLen);
81 ++counter;
82 } while(counter < len / this.hLen);
83 }
84
85 if(counter * this.hLen < len) {
86 this.itoosp(hashCounter, c);
87 this.digest.update(this.seed, 0, this.seed.length);
88 this.digest.update(c, 0, c.length);
89 this.digest.doFinal(hashBuf, 0);
90 System.arraycopy(hashBuf, 0, out, outOff + counter * this.hLen, len - counter * this.hLen);
91 }
92
93 return len;
94 }
95 }
96 }