4f86c39515
* Update Dilithium * Alternative montgomery reduce to avoid i386 functest errors * Explicit casts for msvc * More casts; bump upstream version; fix metadata * another cast
70 lines
2.0 KiB
C
70 lines
2.0 KiB
C
#include "params.h"
|
|
#include "reduce.h"
|
|
#include <stdint.h>
|
|
|
|
/*************************************************
|
|
* Name: PQCLEAN_DILITHIUM2AES_CLEAN_montgomery_reduce
|
|
*
|
|
* Description: For finite field element a with -2^{31}Q <= a <= Q*2^31,
|
|
* compute r \equiv a*2^{-32} (mod Q) such that -Q < r < Q.
|
|
*
|
|
* Arguments: - int64_t: finite field element a
|
|
*
|
|
* Returns r.
|
|
**************************************************/
|
|
int32_t PQCLEAN_DILITHIUM2AES_CLEAN_montgomery_reduce(int64_t a) {
|
|
int32_t t;
|
|
|
|
t = (int32_t)((uint64_t)a * (uint64_t)QINV);
|
|
t = (a - (int64_t)t * Q) >> 32;
|
|
return t;
|
|
}
|
|
|
|
/*************************************************
|
|
* Name: PQCLEAN_DILITHIUM2AES_CLEAN_reduce32
|
|
*
|
|
* Description: For finite field element a with a <= 2^{31} - 2^{22} - 1,
|
|
* compute r \equiv a (mod Q) such that -6283009 <= r <= 6283007.
|
|
*
|
|
* Arguments: - int32_t: finite field element a
|
|
*
|
|
* Returns r.
|
|
**************************************************/
|
|
int32_t PQCLEAN_DILITHIUM2AES_CLEAN_reduce32(int32_t a) {
|
|
int32_t t;
|
|
|
|
t = (a + (1 << 22)) >> 23;
|
|
t = a - t * Q;
|
|
return t;
|
|
}
|
|
|
|
/*************************************************
|
|
* Name: PQCLEAN_DILITHIUM2AES_CLEAN_caddq
|
|
*
|
|
* Description: Add Q if input coefficient is negative.
|
|
*
|
|
* Arguments: - int32_t: finite field element a
|
|
*
|
|
* Returns r.
|
|
**************************************************/
|
|
int32_t PQCLEAN_DILITHIUM2AES_CLEAN_caddq(int32_t a) {
|
|
a += (a >> 31) & Q;
|
|
return a;
|
|
}
|
|
|
|
/*************************************************
|
|
* Name: PQCLEAN_DILITHIUM2AES_CLEAN_freeze
|
|
*
|
|
* Description: For finite field element a, compute standard
|
|
* representative r = a mod^+ Q.
|
|
*
|
|
* Arguments: - int32_t: finite field element a
|
|
*
|
|
* Returns r.
|
|
**************************************************/
|
|
int32_t PQCLEAN_DILITHIUM2AES_CLEAN_freeze(int32_t a) {
|
|
a = PQCLEAN_DILITHIUM2AES_CLEAN_reduce32(a);
|
|
a = PQCLEAN_DILITHIUM2AES_CLEAN_caddq(a);
|
|
return a;
|
|
}
|