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
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
|
using System;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Utilities;
namespace Org.BouncyCastle.Crypto.Macs
{
/// <summary>
/// Implementation of SipHash as specified in "SipHash: a fast short-input PRF", by Jean-Philippe
/// Aumasson and Daniel J. Bernstein (https://131002.net/siphash/siphash.pdf).
/// </summary>
/// <remarks>
/// "SipHash is a family of PRFs SipHash-c-d where the integer parameters c and d are the number of
/// compression rounds and the number of finalization rounds. A compression round is identical to a
/// finalization round and this round function is called SipRound. Given a 128-bit key k and a
/// (possibly empty) byte string m, SipHash-c-d returns a 64-bit value..."
/// </remarks>
public class SipHash
: IMac
{
protected readonly int c, d;
protected long k0, k1;
protected long v0, v1, v2, v3, v4;
protected byte[] buf = new byte[8];
protected int bufPos = 0;
protected int wordCount = 0;
/// <summary>SipHash-2-4</summary>
public SipHash()
: this(2, 4)
{
}
/// <summary>SipHash-c-d</summary>
/// <param name="c">the number of compression rounds</param>
/// <param name="d">the number of finalization rounds</param>
public SipHash(int c, int d)
{
this.c = c;
this.d = d;
}
public virtual string AlgorithmName
{
get { return "SipHash-" + c + "-" + d; }
}
public virtual int GetMacSize()
{
return 8;
}
public virtual void Init(ICipherParameters parameters)
{
KeyParameter keyParameter = parameters as KeyParameter;
if (keyParameter == null)
throw new ArgumentException("must be an instance of KeyParameter", "parameters");
byte[] key = keyParameter.GetKey();
if (key.Length != 16)
throw new ArgumentException("must be a 128-bit key", "parameters");
this.k0 = (long)Pack.LE_To_UInt64(key, 0);
this.k1 = (long)Pack.LE_To_UInt64(key, 8);
Reset();
}
public virtual void Update(byte input)
{
buf[bufPos] = input;
if (++bufPos == buf.Length)
{
ProcessMessageWord();
bufPos = 0;
}
}
public virtual void BlockUpdate(byte[] input, int offset, int length)
{
for (int i = 0; i < length; ++i)
{
buf[bufPos] = input[offset + i];
if (++bufPos == buf.Length)
{
ProcessMessageWord();
bufPos = 0;
}
}
}
public virtual long DoFinal()
{
buf[7] = (byte)((wordCount << 3) + bufPos);
while (bufPos < 7)
{
buf[bufPos++] = 0;
}
ProcessMessageWord();
v2 ^= 0xffL;
ApplySipRounds(d);
long result = v0 ^ v1 ^ v2 ^ v3;
Reset();
return result;
}
public virtual int DoFinal(byte[] output, int outOff)
{
long result = DoFinal();
Pack.UInt64_To_LE((ulong)result, output, outOff);
return 8;
}
public virtual void Reset()
{
v0 = k0 ^ 0x736f6d6570736575L;
v1 = k1 ^ 0x646f72616e646f6dL;
v2 = k0 ^ 0x6c7967656e657261L;
v3 = k1 ^ 0x7465646279746573L;
Array.Clear(buf, 0, buf.Length);
bufPos = 0;
wordCount = 0;
}
protected virtual void ProcessMessageWord()
{
++wordCount;
long m = (long)Pack.LE_To_UInt64(buf, 0);
v3 ^= m;
ApplySipRounds(c);
v0 ^= m;
}
protected virtual void ApplySipRounds(int n)
{
for (int r = 0; r < n; ++r)
{
v0 += v1;
v2 += v3;
v1 = RotateLeft(v1, 13);
v3 = RotateLeft(v3, 16);
v1 ^= v0;
v3 ^= v2;
v0 = RotateLeft(v0, 32);
v2 += v1;
v0 += v3;
v1 = RotateLeft(v1, 17);
v3 = RotateLeft(v3, 21);
v1 ^= v2;
v3 ^= v0;
v2 = RotateLeft(v2, 32);
}
}
protected static long RotateLeft(long x, int n)
{
ulong ux = (ulong)x;
ux = (ux << n) | (ux >> (64 - n));
return (long)ux;
}
}
}
|
