Botan 3.4.0 Crypto and TLS for C&
Botan::Blinder Class Referencefinal

#include <blinding.h>

## Public Member Functions

BigInt blind (const BigInt &x) const

Blinder (const BigInt &modulus, RandomNumberGenerator &rng, std::function< BigInt(const BigInt &)> fwd_func, std::function< BigInt(const BigInt &)> inv_func)

Blinder (const Blinder &)=delete

Blinderoperator= (const Blinder &)=delete

RandomNumberGeneratorrng () const

BigInt unblind (const BigInt &x) const

## Detailed Description

Blinding Function Object.

Definition at line 22 of file blinding.h.

## ◆ Blinder() [1/2]

 Botan::Blinder::Blinder ( const BigInt & modulus, RandomNumberGenerator & rng, std::function< BigInt(const BigInt &)> fwd_func, std::function< BigInt(const BigInt &)> inv_func )
Parameters
 modulus the modulus rng the RNG to use for generating the nonce fwd_func a function that calculates the modular exponentiation of the public exponent and the given value (the nonce) inv_func a function that calculates the modular inverse of the given value (the nonce)

Definition at line 12 of file blinding.cpp.

15 :
16 m_reducer(modulus),
17 m_rng(rng),
18 m_fwd_fn(std::move(fwd)),
19 m_inv_fn(std::move(inv)),
20 m_modulus_bits(modulus.bits()),
21 m_e{},
22 m_d{},
23 m_counter{} {
24 const BigInt k = blinding_nonce();
25 m_e = m_fwd_fn(k);
26 m_d = m_inv_fn(k);
27}
RandomNumberGenerator & rng() const
Definition blinding.h:60

## ◆ Blinder() [2/2]

 Botan::Blinder::Blinder ( const Blinder & )
delete

## ◆ blind()

 BigInt Botan::Blinder::blind ( const BigInt & x ) const

Blind a value. The blinding nonce k is freshly generated after BOTAN_BLINDING_REINIT_INTERVAL calls to blind(). BOTAN_BLINDING_REINIT_INTERVAL = 0 means a fresh nonce is only generated once. On every other call, an updated nonce is used for blinding: k' = k*k mod n.

Parameters
 x value to blind
Returns
blinded value

Definition at line 33 of file blinding.cpp.

33 {
34 if(!m_reducer.initialized()) {
35 throw Invalid_State("Blinder not initialized, cannot blind");
36 }
37
38 ++m_counter;
39
41 const BigInt k = blinding_nonce();
42 m_e = m_fwd_fn(k);
43 m_d = m_inv_fn(k);
44 m_counter = 0;
45 } else {
46 m_e = m_reducer.square(m_e);
47 m_d = m_reducer.square(m_d);
48 }
49
50 return m_reducer.multiply(i, m_e);
51}
BigInt square(const BigInt &x) const
Definition reducer.h:43
BigInt multiply(const BigInt &x, const BigInt &y) const
Definition reducer.h:30
bool initialized() const
Definition reducer.h:60
#define BOTAN_BLINDING_REINIT_INTERVAL
Definition build.h:427

## ◆ operator=()

 Blinder & Botan::Blinder::operator= ( const Blinder & )
delete

## ◆ rng()

 RandomNumberGenerator & Botan::Blinder::rng ( ) const
inline

Definition at line 60 of file blinding.h.

60{ return m_rng; }

## ◆ unblind()

 BigInt Botan::Blinder::unblind ( const BigInt & x ) const

Unblind a value.

Parameters
 x value to unblind
Returns
unblinded value

Definition at line 53 of file blinding.cpp.

53 {
54 if(!m_reducer.initialized()) {
55 throw Invalid_State("Blinder not initialized, cannot unblind");
56 }
57
58 return m_reducer.multiply(i, m_d);
59}

The documentation for this class was generated from the following files: