botan.pubkey.blinding source code

1 /**
2 * Blinding for public key operations
3 * 
4 * Copyright:
5 * (C) 1999-2010 Jack Lloyd
6 * (C) 2014-2015 Etienne Cimon
7 *
8 * License:
9 * Botan is released under the Simplified BSD License (see LICENSE.md)
10 */
11 module botan.pubkey.blinding;
12 
13 import botan.constants;
14 static if (BOTAN_HAS_PUBLIC_KEY_CRYPTO):
15 
16 import botan.math.bigint.bigint;
17 import botan.math.numbertheory.reducer;
18 import botan.math.numbertheory.numthry;
19 
20 /**
21 * Blinding Function Object
22 */
23 struct Blinder
24 {
25 public:
26     /*
27     * Blind a number
28     */
29     BigInt blind()(auto const ref BigInt i)
30     {
31         if (!m_reducer.initialized()) 
32             return i.clone;
33 
34         m_e = m_reducer.square(&m_e);
35         m_d = m_reducer.square(&m_d);
36         return m_reducer.multiply(&i, &m_e);
37     }
38 
39     /*
40     * Unblind a number
41     */
42     BigInt unblind()(auto const ref BigInt i) const
43     {
44         if (!m_reducer.initialized())
45             return i.clone;
46         return m_reducer.multiply(&i, &m_d);
47     }
48 
49     bool initialized() const { return m_reducer.initialized(); }
50 
51     /**
52     * Construct a blinder
53     * Params:
54     *  e = the forward (blinding) mask
55     *  d = the inverse of mask (depends on algo)
56     *  n = modulus of the group operations are performed in
57     */
58     this()(auto const ref BigInt e, 
59            auto const ref BigInt d, 
60            auto const ref BigInt n)
61     {
62         if (e < 1 || d < 1 || n < 1)
63             throw new InvalidArgument("Blinder: Arguments too small");
64         
65         m_reducer = ModularReducer(n);
66         m_e = e.clone;
67         m_d = d.clone;
68     }
69 
70 private:
71     ModularReducer m_reducer;
72     BigInt m_e, m_d;
73 }