crypto: replace rand<T>()%N idiom with unbiased rand_idx(N)

This commit is contained in:
stoffu 2019-04-03 14:10:24 +09:00
parent b6726aaa6c
commit a2195b9b7f
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GPG key ID: 41DAB8343A9EC012
5 changed files with 36 additions and 12 deletions

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@ -35,6 +35,7 @@
#include <boost/optional.hpp>
#include <type_traits>
#include <vector>
#include <random>
#include "common/pod-class.h"
#include "memwipe.h"
@ -162,6 +163,32 @@ namespace crypto {
return res;
}
/* UniformRandomBitGenerator using crypto::rand<uint64_t>()
*/
struct random_device
{
typedef uint64_t result_type;
static constexpr result_type min() { return 0; }
static constexpr result_type max() { return result_type(-1); }
result_type operator()() const { return crypto::rand<result_type>(); }
};
/* Generate a random value between range_min and range_max
*/
template<typename T>
typename std::enable_if<std::is_integral<T>::value, T>::type rand_range(T range_min, T range_max) {
crypto::random_device rd;
std::uniform_int_distribution<T> dis(range_min, range_max);
return dis(rd);
}
/* Generate a random index between 0 and sz-1
*/
template<typename T>
typename std::enable_if<std::is_unsigned<T>::value, T>::type rand_idx(T sz) {
return crypto::rand_range<T>(0, sz-1);
}
/* Generate a new key pair
*/
inline secret_key generate_keys(public_key &pub, secret_key &sec, const secret_key& recovery_key = secret_key(), bool recover = false) {