Botan  2.13.0
Crypto and TLS for C++11
blinding.h
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1 /*
2 * Blinding for public key operations
3 * (C) 1999-2010,2015 Jack Lloyd
4 *
5 * Botan is released under the Simplified BSD License (see license.txt)
6 */
7 
8 #ifndef BOTAN_BLINDER_H_
9 #define BOTAN_BLINDER_H_
10 
11 #include <botan/bigint.h>
12 #include <botan/reducer.h>
13 #include <functional>
14 
16 
17 namespace Botan {
18 
19 class RandomNumberGenerator;
20 
21 /**
22 * Blinding Function Object.
23 */
25  {
26  public:
27  /**
28  * Blind a value.
29  * The blinding nonce k is freshly generated after
30  * BOTAN_BLINDING_REINIT_INTERVAL calls to blind().
31  * BOTAN_BLINDING_REINIT_INTERVAL = 0 means a fresh
32  * nonce is only generated once. On every other call,
33  * an updated nonce is used for blinding: k' = k*k mod n.
34  * @param x value to blind
35  * @return blinded value
36  */
37  BigInt blind(const BigInt& x) const;
38 
39  /**
40  * Unblind a value.
41  * @param x value to unblind
42  * @return unblinded value
43  */
44  BigInt unblind(const BigInt& x) const;
45 
46  /**
47  * @param modulus the modulus
48  * @param rng the RNG to use for generating the nonce
49  * @param fwd_func a function that calculates the modular
50  * exponentiation of the public exponent and the given value (the nonce)
51  * @param inv_func a function that calculates the modular inverse
52  * of the given value (the nonce)
53  */
54  Blinder(const BigInt& modulus,
56  std::function<BigInt (const BigInt&)> fwd_func,
57  std::function<BigInt (const BigInt&)> inv_func);
58 
59  Blinder(const Blinder&) = delete;
60 
61  Blinder& operator=(const Blinder&) = delete;
62 
63  RandomNumberGenerator& rng() const { return m_rng; }
64 
65  private:
66  BigInt blinding_nonce() const;
67 
68  Modular_Reducer m_reducer;
69  RandomNumberGenerator& m_rng;
70  std::function<BigInt (const BigInt&)> m_fwd_fn;
71  std::function<BigInt (const BigInt&)> m_inv_fn;
72  size_t m_modulus_bits = 0;
73 
74  mutable BigInt m_e, m_d;
75  mutable size_t m_counter = 0;
76  };
77 
78 }
79 
80 #endif
int(* final)(unsigned char *, CTX *)
#define BOTAN_PUBLIC_API(maj, min)
Definition: compiler.h:31
RandomNumberGenerator & rng() const
Definition: blinding.h:63
Definition: alg_id.cpp:13
#define BOTAN_FUTURE_INTERNAL_HEADER(hdr)
Definition: compiler.h:139