remove duplication

src/kem/kyber/common/reduce.c

@@ -3,7 +3,7 @@
 #include <stdint.h>
 
 /*************************************************
-* Name:        PQCLEAN_KYBER768_CLEAN_montgomery_reduce
+* Name:        kyber_montgomery_reduce
 *
 * Description: Montgomery reduction; given a 32-bit integer a, computes
 *              16-bit integer congruent to a * R^-1 mod q, where R=2^16
@@ -13,7 +13,7 @@
 *
 * Returns:     integer in {-q+1,...,q-1} congruent to a * R^-1 modulo q.
 **************************************************/
-int16_t PQCLEAN_KYBER768_CLEAN_montgomery_reduce(int32_t a) {
+int16_t kyber_montgomery_reduce(int32_t a) {
     int32_t t;
     int16_t u;
 
@@ -25,20 +25,19 @@ int16_t PQCLEAN_KYBER768_CLEAN_montgomery_reduce(int32_t a) {
 }
 
 /*************************************************
-* Name:        PQCLEAN_KYBER768_CLEAN_barrett_reduce
+* Name:        kyber_barrett_reduce
 *
 * Description: Barrett reduction; given a 16-bit integer a, computes
-*              centered representative congruent to a mod q in {-(q-1)/2,...,(q-1)/2}
+*              centered representative congruent to a mod q in {0,q}
 *
 * Arguments:   - int16_t a: input integer to be reduced
 *
-* Returns:     integer in {-(q-1)/2,...,(q-1)/2} congruent to a modulo q.
+* Returns:     integer in {0,q} congruent to a modulo q.
 **************************************************/
-int16_t PQCLEAN_KYBER768_CLEAN_barrett_reduce(int16_t a) {
-    int16_t t;
-    const int16_t v = ((1U << 26) + KYBER_Q / 2) / KYBER_Q;
-
-    t  = ((int32_t)v * a + (1 << 25)) >> 26;
-    t *= KYBER_Q;
-    return a - t;
+int16_t kyber_barrett_reduce(int16_t a) {
+    static const int32_t v = 20159;
+    int32_t t;
+    t = v*a;
+    t >>= 26;
+    return a - ((int16_t)t)*KYBER_Q;
 }

src/kem/kyber/kyber1024/clean/CMakeLists.txt

@@ -6,7 +6,7 @@ set(
   ntt.c
   poly.c
   polyvec.c
-  reduce.c
+  ../../common/reduce.c
   symmetric-shake.c
   verify.c
 )

src/kem/kyber/kyber1024/clean/ntt.c

@@ -1,6 +1,6 @@
 #include "ntt.h"
 #include "params.h"
-#include "reduce.h"
+#include "../../common/reduce.h"
 #include <stdint.h>
 
 /* Code to generate PQCLEAN_KYBER1024_CLEAN_zetas and zetas_inv used in the number-theoretic transform:

src/kem/kyber/kyber1024/clean/poly.c

@@ -2,7 +2,7 @@
 #include "ntt.h"
 #include "params.h"
 #include "poly.h"
-#include "reduce.h"
+#include "../../common/reduce.h"
 #include "symmetric.h"
 #include <stdint.h>
 

src/kem/kyber/kyber1024/clean/reduce.c

@@ -1,44 +0,0 @@
-#include "params.h"
-#include "reduce.h"
-#include <stdint.h>
-
-/*************************************************
-* Name:        PQCLEAN_KYBER1024_CLEAN_montgomery_reduce
-*
-* Description: Montgomery reduction; given a 32-bit integer a, computes
-*              16-bit integer congruent to a * R^-1 mod q, where R=2^16
-*
-* Arguments:   - int32_t a: input integer to be reduced;
-*                           has to be in {-q2^15,...,q2^15-1}
-*
-* Returns:     integer in {-q+1,...,q-1} congruent to a * R^-1 modulo q.
-**************************************************/
-int16_t PQCLEAN_KYBER1024_CLEAN_montgomery_reduce(int32_t a) {
-    int32_t t;
-    int16_t u;
-
-    u = (int16_t)(a * (int64_t)QINV);
-    t = (int32_t)u * KYBER_Q;
-    t = a - t;
-    t >>= 16;
-    return (int16_t)t;
-}
-
-/*************************************************
-* Name:        PQCLEAN_KYBER1024_CLEAN_barrett_reduce
-*
-* Description: Barrett reduction; given a 16-bit integer a, computes
-*              centered representative congruent to a mod q in {-(q-1)/2,...,(q-1)/2}
-*
-* Arguments:   - int16_t a: input integer to be reduced
-*
-* Returns:     integer in {-(q-1)/2,...,(q-1)/2} congruent to a modulo q.
-**************************************************/
-int16_t PQCLEAN_KYBER1024_CLEAN_barrett_reduce(int16_t a) {
-    int16_t t;
-    const int16_t v = ((1U << 26) + KYBER_Q / 2) / KYBER_Q;
-
-    t  = ((int32_t)v * a + (1 << 25)) >> 26;
-    t *= KYBER_Q;
-    return a - t;
-}

src/kem/kyber/kyber1024/clean/reduce.h

@@ -1,13 +0,0 @@
-#ifndef PQCLEAN_KYBER1024_CLEAN_REDUCE_H
-#define PQCLEAN_KYBER1024_CLEAN_REDUCE_H
-#include "params.h"
-#include <stdint.h>
-
-#define MONT 2285 // 2^16 mod q
-#define QINV 62209 // q^-1 mod 2^16
-
-int16_t PQCLEAN_KYBER1024_CLEAN_montgomery_reduce(int32_t a);
-
-int16_t PQCLEAN_KYBER1024_CLEAN_barrett_reduce(int16_t a);
-
-#endif

src/kem/kyber/kyber512/clean/CMakeLists.txt

@@ -6,7 +6,6 @@ set(
   ntt.c
   poly.c
   polyvec.c
-  reduce.c
   symmetric-shake.c
   verify.c
 )

src/kem/kyber/kyber512/clean/ntt.c

@@ -1,6 +1,6 @@
 #include "ntt.h"
 #include "params.h"
-#include "reduce.h"
+#include "../../common/reduce.h"
 #include <stdint.h>
 
 /* Code to generate PQCLEAN_KYBER512_CLEAN_zetas and zetas_inv used in the number-theoretic transform:

src/kem/kyber/kyber512/clean/poly.c

@@ -2,7 +2,7 @@
 #include "ntt.h"
 #include "params.h"
 #include "poly.h"
-#include "reduce.h"
+#include "../../common/reduce.h"
 #include "symmetric.h"
 #include <stdint.h>
 

src/kem/kyber/kyber512/clean/reduce.c

@@ -1,44 +0,0 @@
-#include "params.h"
-#include "reduce.h"
-#include <stdint.h>
-
-/*************************************************
-* Name:        PQCLEAN_KYBER512_CLEAN_montgomery_reduce
-*
-* Description: Montgomery reduction; given a 32-bit integer a, computes
-*              16-bit integer congruent to a * R^-1 mod q, where R=2^16
-*
-* Arguments:   - int32_t a: input integer to be reduced;
-*                           has to be in {-q2^15,...,q2^15-1}
-*
-* Returns:     integer in {-q+1,...,q-1} congruent to a * R^-1 modulo q.
-**************************************************/
-int16_t PQCLEAN_KYBER512_CLEAN_montgomery_reduce(int32_t a) {
-    int32_t t;
-    int16_t u;
-
-    u = (int16_t)(a * (int64_t)QINV);
-    t = (int32_t)u * KYBER_Q;
-    t = a - t;
-    t >>= 16;
-    return (int16_t)t;
-}
-
-/*************************************************
-* Name:        PQCLEAN_KYBER512_CLEAN_barrett_reduce
-*
-* Description: Barrett reduction; given a 16-bit integer a, computes
-*              centered representative congruent to a mod q in {-(q-1)/2,...,(q-1)/2}
-*
-* Arguments:   - int16_t a: input integer to be reduced
-*
-* Returns:     integer in {-(q-1)/2,...,(q-1)/2} congruent to a modulo q.
-**************************************************/
-int16_t PQCLEAN_KYBER512_CLEAN_barrett_reduce(int16_t a) {
-    int16_t t;
-    const int16_t v = ((1U << 26) + KYBER_Q / 2) / KYBER_Q;
-
-    t  = ((int32_t)v * a + (1 << 25)) >> 26;
-    t *= KYBER_Q;
-    return a - t;
-}

src/kem/kyber/kyber512/clean/reduce.h

@@ -1,13 +0,0 @@
-#ifndef PQCLEAN_KYBER512_CLEAN_REDUCE_H
-#define PQCLEAN_KYBER512_CLEAN_REDUCE_H
-#include "params.h"
-#include <stdint.h>
-
-#define MONT 2285 // 2^16 mod q
-#define QINV 62209 // q^-1 mod 2^16
-
-int16_t PQCLEAN_KYBER512_CLEAN_montgomery_reduce(int32_t a);
-
-int16_t PQCLEAN_KYBER512_CLEAN_barrett_reduce(int16_t a);
-
-#endif

src/kem/kyber/kyber768/clean/CMakeLists.txt

@@ -6,7 +6,6 @@ set(
   ntt.c
   poly.c
   polyvec.c
-  reduce.c
   symmetric-shake.c
   verify.c
 )

src/kem/kyber/kyber768/clean/ntt.c

@@ -1,6 +1,6 @@
 #include "ntt.h"
 #include "params.h"
-#include "reduce.h"
+#include "../../common/reduce.h"
 #include <stdint.h>
 
 /* Code to generate PQCLEAN_KYBER768_CLEAN_zetas and zetas_inv used in the number-theoretic transform:

src/kem/kyber/kyber768/clean/poly.c

@@ -2,7 +2,7 @@
 #include "ntt.h"
 #include "params.h"
 #include "poly.h"
-#include "reduce.h"
+#include "../../common/reduce.h"
 #include "symmetric.h"
 #include <stdint.h>
 

src/kem/kyber/kyber768/clean/reduce.h

@@ -1,13 +0,0 @@
-#ifndef PQCLEAN_KYBER768_CLEAN_REDUCE_H
-#define PQCLEAN_KYBER768_CLEAN_REDUCE_H
-#include "params.h"
-#include <stdint.h>
-
-#define MONT 2285 // 2^16 mod q
-#define QINV 62209 // q^-1 mod 2^16
-
-int16_t PQCLEAN_KYBER768_CLEAN_montgomery_reduce(int32_t a);
-
-int16_t PQCLEAN_KYBER768_CLEAN_barrett_reduce(int16_t a);
-
-#endif