blob: b8809487e00204ae91e1b9fa2d48a535ea64fc77 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
|
package org.bouncycastle.crypto.tls;
/**
* RFC 4347 4.1.2.5 Anti-replay
*
* Support fast rejection of duplicate records by maintaining a sliding receive window
*/
class DTLSReplayWindow {
private static final long VALID_SEQ_MASK = 0x0000FFFFFFFFFFFFL;
private static final long WINDOW_SIZE = 64L;
private long latestConfirmedSeq = -1;
private long bitmap = 0;
/**
* Check whether a received record with the given sequence number should be rejected as a duplicate.
*
* @param seq the 48-bit DTLSPlainText.sequence_number field of a received record.
* @return true if the record should be discarded without further processing.
*/
boolean shouldDiscard(long seq)
{
if ((seq & VALID_SEQ_MASK) != seq)
return true;
if (seq <= latestConfirmedSeq)
{
long diff = latestConfirmedSeq - seq;
if (diff >= WINDOW_SIZE)
return true;
if ((bitmap & (1L << diff)) != 0)
return true;
}
return false;
}
/**
* Report that a received record with the given sequence number passed authentication checks.
*
* @param seq the 48-bit DTLSPlainText.sequence_number field of an authenticated record.
*/
void reportAuthenticated(long seq)
{
if ((seq & VALID_SEQ_MASK) != seq)
throw new IllegalArgumentException("'seq' out of range");
if (seq <= latestConfirmedSeq)
{
long diff = latestConfirmedSeq - seq;
if (diff < WINDOW_SIZE) {
bitmap |= (1L << diff);
}
}
else
{
long diff = seq - latestConfirmedSeq;
if (diff >= WINDOW_SIZE) {
bitmap = 1;
}
else {
bitmap <<= diff;
bitmap |= 1;
}
latestConfirmedSeq = seq;
}
}
/**
* When a new epoch begins, sequence numbers begin again at 0
*/
void reset()
{
latestConfirmedSeq = -1;
bitmap = 0;
}
}
|