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1
2 package ch.ethz.ssh2.crypto;
3
4
5 import ch.ethz.ssh2.crypto.digest.HashForSSH2Types;
6 import java.math.BigInteger  ;
7
8
14 public class KeyMaterial
15 {
16 public byte[] initial_iv_client_to_server;
17 public byte[] initial_iv_server_to_client;
18 public byte[] enc_key_client_to_server;
19 public byte[] enc_key_server_to_client;
20 public byte[] integrity_key_client_to_server;
21 public byte[] integrity_key_server_to_client;
22
23 private static byte[] calculateKey(HashForSSH2Types sh, BigInteger K, byte[] H, byte type, byte[] SessionID,
24 int keyLength)
25 {
26 byte[] res = new byte[keyLength];
27
28 int dglen = sh.getDigestLength();
29 int numRounds = (keyLength + dglen - 1) / dglen;
30
31 byte[][] tmp = new byte[numRounds][];
32
33 sh.reset();
34 sh.updateBigInt(K);
35 sh.updateBytes(H);
36 sh.updateByte(type);
37 sh.updateBytes(SessionID);
38
39 tmp[0] = sh.getDigest();
40
41 int off = 0;
42 int produced = Math.min(dglen, keyLength);
43
44 System.arraycopy(tmp[0], 0, res, off, produced);
45
46 keyLength -= produced;
47 off += produced;
48
49 for (int i = 1; i < numRounds; i++)
50 {
51 sh.updateBigInt(K);
52 sh.updateBytes(H);
53
54 for (int j = 0; j < i; j++)
55 sh.updateBytes(tmp[j]);
56
57 tmp[i] = sh.getDigest();
58
59 produced = Math.min(dglen, keyLength);
60 System.arraycopy(tmp[i], 0, res, off, produced);
61 keyLength -= produced;
62 off += produced;
63 }
64
65 return res;
66 }
67
68 public static KeyMaterial create(String hashType, byte[] H, BigInteger K, byte[] SessionID, int keyLengthCS,
69 int blockSizeCS, int macLengthCS, int keyLengthSC, int blockSizeSC, int macLengthSC)
70 throws IllegalArgumentException
71 {
72 KeyMaterial km = new KeyMaterial();
73
74 HashForSSH2Types sh = new HashForSSH2Types(hashType);
75
76 km.initial_iv_client_to_server = calculateKey(sh, K, H, (byte) 'A', SessionID, blockSizeCS);
77
78 km.initial_iv_server_to_client = calculateKey(sh, K, H, (byte) 'B', SessionID, blockSizeSC);
79
80 km.enc_key_client_to_server = calculateKey(sh, K, H, (byte) 'C', SessionID, keyLengthCS);
81
82 km.enc_key_server_to_client = calculateKey(sh, K, H, (byte) 'D', SessionID, keyLengthSC);
83
84 km.integrity_key_client_to_server = calculateKey(sh, K, H, (byte) 'E', SessionID, macLengthCS);
85
86 km.integrity_key_server_to_client = calculateKey(sh, K, H, (byte) 'F', SessionID, macLengthSC);
87
88 return km;
89 }
90 }
91 |
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