Botan::RFC6979_Nonce_Generator Class Reference

#include <rfc6979.h>

Public Member Functions
BigInt	nonce_for (const BigInt &group_order, const BigInt &m)
	RFC6979_Nonce_Generator (std::string_view hash, size_t order_bits, const BigInt &x)
	~RFC6979_Nonce_Generator ()

Detailed Description

Definition at line 24 of file rfc6979.h.

Constructor & Destructor Documentation

RFC6979_Nonce_Generator()

Botan::RFC6979_Nonce_Generator::RFC6979_Nonce_Generator	(	std::string_view	hash,
		size_t	order_bits,
		const BigInt &	x )

Definition at line 18 of file rfc6979.cpp.

                                                                                                        :
      m_qlen(order_bits), m_rlen((m_qlen + 7) / 8), m_rng_in(m_rlen * 2), m_rng_out(m_rlen) {
   m_hmac_drbg = std::make_unique<HMAC_DRBG>(MessageAuthenticationCode::create_or_throw(fmt("HMAC({})", hash)));
 
   x.serialize_to(std::span{m_rng_in}.first(m_rlen));
}

References Botan::MessageAuthenticationCode::create_or_throw(), Botan::fmt(), and Botan::BigInt::serialize_to().

~RFC6979_Nonce_Generator()

Botan::RFC6979_Nonce_Generator::~RFC6979_Nonce_Generator ( )

default

Member Function Documentation

nonce_for()

BigInt Botan::RFC6979_Nonce_Generator::nonce_for	(	const BigInt &	group_order,
		const BigInt &	m )

Definition at line 25 of file rfc6979.cpp.

                                                                              {
   BOTAN_DEBUG_ASSERT(order.bits() == m_qlen);
 
   m.serialize_to(std::span{m_rng_in}.last(m_rlen));
 
   m_hmac_drbg->initialize_with(m_rng_in);
 
   const size_t shift = 8 * m_rlen - m_qlen;
   BOTAN_ASSERT_NOMSG(shift < 8);
 
   BigInt k;
 
   do {
      m_hmac_drbg->randomize(m_rng_out);
      k._assign_from_bytes(m_rng_out);
 
      if(shift > 0) {
         k >>= shift;
      }
   } while(k == 0 || k >= order);
 
   return k;
}

References Botan::BigInt::_assign_from_bytes(), Botan::BigInt::bits(), BOTAN_ASSERT_NOMSG, BOTAN_DEBUG_ASSERT, and Botan::BigInt::serialize_to().

Referenced by Botan::generate_rfc6979_nonce().

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

• src/lib/pubkey/rfc6979/rfc6979.h
• src/lib/pubkey/rfc6979/rfc6979.cpp