Botan 2.19.1
Crypto and TLS for C&
Public Member Functions | List of all members
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 24 of file blinding.h.

Constructor & Destructor Documentation

◆ 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
modulusthe modulus
rngthe RNG to use for generating the nonce
fwd_funca function that calculates the modular exponentiation of the public exponent and the given value (the nonce)
inv_funca 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(fwd),
19 m_inv_fn(inv),
20 m_modulus_bits(modulus.bits()),
21 m_e{},
22 m_d{},
23 m_counter{}
24 {
25 const BigInt k = blinding_nonce();
26 m_e = m_fwd_fn(k);
27 m_d = m_inv_fn(k);
28 }
RandomNumberGenerator & rng() const
Definition: blinding.h:63

◆ Blinder() [2/2]

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

Member Function Documentation

◆ 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
xvalue to blind
Returns
blinded value

Definition at line 35 of file blinding.cpp.

36 {
37 if(!m_reducer.initialized())
38 throw Invalid_State("Blinder not initialized, cannot blind");
39
40 ++m_counter;
41
42 if((BOTAN_BLINDING_REINIT_INTERVAL > 0) && (m_counter > BOTAN_BLINDING_REINIT_INTERVAL))
43 {
44 const BigInt k = blinding_nonce();
45 m_e = m_fwd_fn(k);
46 m_d = m_inv_fn(k);
47 m_counter = 0;
48 }
49 else
50 {
51 m_e = m_reducer.square(m_e);
52 m_d = m_reducer.square(m_d);
53 }
54
55 return m_reducer.multiply(i, m_e);
56 }
BigInt square(const BigInt &x) const
Definition: reducer.h:39
BigInt multiply(const BigInt &x, const BigInt &y) const
Definition: reducer.h:31
bool initialized() const
Definition: reducer.h:58

References Botan::Modular_Reducer::initialized(), Botan::Modular_Reducer::multiply(), and Botan::Modular_Reducer::square().

◆ operator=()

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

◆ rng()

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

Definition at line 63 of file blinding.h.

63{ return m_rng; }

◆ unblind()

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

Unblind a value.

Parameters
xvalue to unblind
Returns
unblinded value

Definition at line 58 of file blinding.cpp.

59 {
60 if(!m_reducer.initialized())
61 throw Invalid_State("Blinder not initialized, cannot unblind");
62
63 return m_reducer.multiply(i, m_d);
64 }

References Botan::Modular_Reducer::initialized(), and Botan::Modular_Reducer::multiply().


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