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1
2 package ch.ethz.ssh2.crypto.digest;
3
4
10 public final class HMAC implements Digest
11 {
12 Digest md;
13 byte[] k_xor_ipad;
14 byte[] k_xor_opad;
15
16 byte[] tmp;
17
18 int size;
19
20 public HMAC(Digest md, byte[] key, int size)
21 {
22 this.md = md;
23 this.size = size;
24
25 tmp = new byte[md.getDigestLength()];
26
27 final int BLOCKSIZE = 64;
28
29 k_xor_ipad = new byte[BLOCKSIZE];
30 k_xor_opad = new byte[BLOCKSIZE];
31
32 if (key.length > BLOCKSIZE)
33 {
34 md.reset();
35 md.update(key);
36 md.digest(tmp);
37 key = tmp;
38 }
39
40 System.arraycopy(key, 0, k_xor_ipad, 0, key.length);
41 System.arraycopy(key, 0, k_xor_opad, 0, key.length);
42
43 for (int i = 0; i < BLOCKSIZE; i++)
44 {
45 k_xor_ipad[i] ^= 0x36;
46 k_xor_opad[i] ^= 0x5C;
47 }
48 md.update(k_xor_ipad);
49 }
50
51 public final int getDigestLength()
52 {
53 return size;
54 }
55
56 public final void update(byte b)
57 {
58 md.update(b);
59 }
60
61 public final void update(byte[] b)
62 {
63 md.update(b);
64 }
65
66 public final void update(byte[] b, int off, int len)
67 {
68 md.update(b, off, len);
69 }
70
71 public final void reset()
72 {
73 md.reset();
74 md.update(k_xor_ipad);
75 }
76
77 public final void digest(byte[] out)
78 {
79 digest(out, 0);
80 }
81
82 public final void digest(byte[] out, int off)
83 {
84 md.digest(tmp);
85
86 md.update(k_xor_opad);
87 md.update(tmp);
88
89 md.digest(tmp);
90
91 System.arraycopy(tmp, 0, out, off, size);
92
93 md.update(k_xor_ipad);
94 }
95 }
96 |
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