Update copyright year
[openssl.git] / crypto / ec / curve448 / curve448.c
index e2c57708033f5aed497d8170807f3a7e89c8732f..bed2718ad7a931218711d78b67385394e5a0c119 100644 (file)
@@ -1,8 +1,8 @@
 /*
- * Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2017-2022 The OpenSSL Project Authors. All Rights Reserved.
  * Copyright 2015-2016 Cryptography Research, Inc.
  *
- * Licensed under the OpenSSL license (the "License").  You may not use
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
  * in the file LICENSE in the source distribution or at
  * https://www.openssl.org/source/license.html
 
 #include "point_448.h"
 #include "ed448.h"
-#include "curve448_lcl.h"
+#include "crypto/ecx.h"
+#include "curve448_local.h"
 
 #define COFACTOR 4
 
-/* Comb config: number of combs, n, t, s. */
-#define COMBS_N 5
-#define COMBS_T 5
-#define COMBS_S 18
-#define DECAF_WNAF_FIXED_TABLE_BITS 5
-#define DECAF_WNAF_VAR_TABLE_BITS 3
+#define C448_WNAF_FIXED_TABLE_BITS 5
+#define C448_WNAF_VAR_TABLE_BITS 3
+
+#define EDWARDS_D       (-39081)
 
-static const int EDWARDS_D = -39081;
 static const curve448_scalar_t precomputed_scalarmul_adjustment = {
     {
         {
-            SC_LIMB(0xc873d6d54a7bb0cf), SC_LIMB(0xe933d8d723a70aad),
-            SC_LIMB(0xbb124b65129c96fd), SC_LIMB(0x00000008335dc163)
+            SC_LIMB(0xc873d6d54a7bb0cfULL), SC_LIMB(0xe933d8d723a70aadULL),
+            SC_LIMB(0xbb124b65129c96fdULL), SC_LIMB(0x00000008335dc163ULL)
         }
     }
 };
 
-#define TWISTED_D ((EDWARDS_D)-1)
-
-#define WBITS DECAF_WORD_BITS   /* NB this may be different from ARCH_WORD_BITS */
-
-/* Projective Niels coordinates */
-typedef struct {
-    gf a, b, c;
-} niels_s, niels_t[1];
-typedef struct {
-    niels_t n;
-    gf z;
-} VECTOR_ALIGNED pniels_t[1];
-
-/* Precomputed base */
-struct curve448_precomputed_s {
-    niels_t table[COMBS_N << (COMBS_T - 1)];
-};
+#define TWISTED_D (EDWARDS_D - 1)
 
-extern const gf curve448_precomputed_base_as_fe[];
-const curve448_precomputed_s *curve448_precomputed_base =
-    (const curve448_precomputed_s *)&curve448_precomputed_base_as_fe;
+#define WBITS C448_WORD_BITS   /* NB this may be different from ARCH_WORD_BITS */
 
 /* Inverse. */
 static void gf_invert(gf y, const gf x, int assert_nonzero)
 {
     mask_t ret;
-
     gf t1, t2;
+
     gf_sqr(t1, x);              /* o^2 */
     ret = gf_isr(t2, t1);       /* +-1/sqrt(o^2) = +-1/o */
     (void)ret;
@@ -75,7 +55,7 @@ static void gf_invert(gf y, const gf x, int assert_nonzero)
 }
 
 /** identity = (0,1) */
-const curve448_point_t curve448_point_identity =
+const curve448_point_t ossl_curve448_point_identity =
     { {{{{0}}}, {{{1}}}, {{{1}}}, {{{0}}}} };
 
 static void point_double_internal(curve448_point_t p, const curve448_point_t q,
@@ -102,7 +82,7 @@ static void point_double_internal(curve448_point_t p, const curve448_point_t q,
         gf_mul(p->t, b, d);
 }
 
-void curve448_point_double(curve448_point_t p, const curve448_point_t q)
+void ossl_curve448_point_double(curve448_point_t p, const curve448_point_t q)
 {
     point_double_internal(p, q, 0);
 }
@@ -167,6 +147,7 @@ static void sub_niels_from_pt(curve448_point_t d, const niels_t e,
                               int before_double)
 {
     gf a, b, c;
+
     gf_sub_nr(b, d->y, d->x);   /* 3+e */
     gf_mul(a, e->b, b);
     gf_add_nr(b, d->x, d->y);   /* 2+e */
@@ -203,13 +184,14 @@ static void sub_pniels_from_pt(curve448_point_t p, const pniels_t pn,
     sub_niels_from_pt(p, pn->n, before_double);
 }
 
-decaf_bool_t curve448_point_eq(const curve448_point_t p,
-                               const curve448_point_t q)
+c448_bool_t
+ossl_curve448_point_eq(const curve448_point_t p,
+                       const curve448_point_t q)
 {
     mask_t succ;
+    gf a, b;
 
     /* equality mod 2-torsion compares x/y */
-    gf a, b;
     gf_mul(a, p->y, q->x);
     gf_mul(b, q->y, p->x);
     succ = gf_eq(a, b);
@@ -217,11 +199,12 @@ decaf_bool_t curve448_point_eq(const curve448_point_t p,
     return mask_to_bool(succ);
 }
 
-decaf_bool_t curve448_point_valid(const curve448_point_t p)
+c448_bool_t
+ossl_curve448_point_valid(const curve448_point_t p)
 {
     mask_t out;
-
     gf a, b, c;
+
     gf_mul(a, p->x, p->y);
     gf_mul(b, p->z, p->t);
     out = gf_eq(a, b);
@@ -237,28 +220,28 @@ decaf_bool_t curve448_point_valid(const curve448_point_t p)
     return mask_to_bool(out);
 }
 
-static ossl_inline void constant_time_lookup_niels(niels_s * __restrict__ ni,
+static ossl_inline void constant_time_lookup_niels(niels_s * RESTRICT ni,
                                                    const niels_t * table,
                                                    int nelts, int idx)
 {
     constant_time_lookup(ni, table, sizeof(niels_s), nelts, idx);
 }
 
-void curve448_precomputed_scalarmul(curve448_point_t out,
+void
+ossl_curve448_precomputed_scalarmul(curve448_point_t out,
                                     const curve448_precomputed_s * table,
                                     const curve448_scalar_t scalar)
 {
-    int i;
-    unsigned j, k;
+    unsigned int i, j, k;
     const unsigned int n = COMBS_N, t = COMBS_T, s = COMBS_S;
     niels_t ni;
-
     curve448_scalar_t scalar1x;
-    curve448_scalar_add(scalar1x, scalar, precomputed_scalarmul_adjustment);
-    curve448_scalar_halve(scalar1x, scalar1x);
 
-    for (i = s - 1; i >= 0; i--) {
-        if (i != (int)s - 1)
+    ossl_curve448_scalar_add(scalar1x, scalar, precomputed_scalarmul_adjustment);
+    ossl_curve448_scalar_halve(scalar1x, scalar1x);
+
+    for (i = s; i > 0; i--) {
+        if (i != s)
             point_double_internal(out, out, 0);
 
         for (j = 0; j < n; j++) {
@@ -266,11 +249,11 @@ void curve448_precomputed_scalarmul(curve448_point_t out,
             mask_t invert;
 
             for (k = 0; k < t; k++) {
-                unsigned int bit = i + s * (k + j * t);
-                if (bit < DECAF_448_SCALAR_BITS) {
+                unsigned int bit = (i - 1) + s * (k + j * t);
+
+                if (bit < C448_SCALAR_BITS)
                     tab |=
                         (scalar1x->limb[bit / WBITS] >> (bit % WBITS) & 1) << k;
-                }
             }
 
             invert = (tab >> (t - 1)) - 1;
@@ -281,11 +264,10 @@ void curve448_precomputed_scalarmul(curve448_point_t out,
                                        1 << (t - 1), tab);
 
             cond_neg_niels(ni, invert);
-            if ((i != (int)s - 1) || j) {
-                add_niels_to_pt(out, ni, j == n - 1 && i);
-            } else {
+            if ((i != s) || j != 0)
+                add_niels_to_pt(out, ni, j == n - 1 && i != 1);
+            else
                 niels_to_pt(out, ni);
-            }
         }
     }
 
@@ -293,14 +275,15 @@ void curve448_precomputed_scalarmul(curve448_point_t out,
     OPENSSL_cleanse(scalar1x, sizeof(scalar1x));
 }
 
-void curve448_point_mul_by_ratio_and_encode_like_eddsa(
-                                    uint8_t enc[DECAF_EDDSA_448_PUBLIC_BYTES],
+void
+ossl_curve448_point_mul_by_ratio_and_encode_like_eddsa(
+                                    uint8_t enc[EDDSA_448_PUBLIC_BYTES],
                                     const curve448_point_t p)
 {
-
-    /* The point is now on the twisted curve.  Move it to untwisted. */
     gf x, y, z, t;
     curve448_point_t q;
+
+    /* The point is now on the twisted curve.  Move it to untwisted. */
     curve448_point_copy(q, p);
 
     {
@@ -329,34 +312,33 @@ void curve448_point_mul_by_ratio_and_encode_like_eddsa(
     gf_mul(x, y, z);
 
     /* Encode */
-    enc[DECAF_EDDSA_448_PRIVATE_BYTES - 1] = 0;
+    enc[EDDSA_448_PRIVATE_BYTES - 1] = 0;
     gf_serialize(enc, x, 1);
-    enc[DECAF_EDDSA_448_PRIVATE_BYTES - 1] |= 0x80 & gf_lobit(t);
+    enc[EDDSA_448_PRIVATE_BYTES - 1] |= 0x80 & gf_lobit(t);
 
     OPENSSL_cleanse(x, sizeof(x));
     OPENSSL_cleanse(y, sizeof(y));
     OPENSSL_cleanse(z, sizeof(z));
     OPENSSL_cleanse(t, sizeof(t));
-    curve448_point_destroy(q);
+    ossl_curve448_point_destroy(q);
 }
 
-decaf_error_t curve448_point_decode_like_eddsa_and_mul_by_ratio(
+c448_error_t
+ossl_curve448_point_decode_like_eddsa_and_mul_by_ratio(
                                 curve448_point_t p,
-                                const uint8_t enc[DECAF_EDDSA_448_PUBLIC_BYTES])
+                                const uint8_t enc[EDDSA_448_PUBLIC_BYTES])
 {
-    uint8_t enc2[DECAF_EDDSA_448_PUBLIC_BYTES];
+    uint8_t enc2[EDDSA_448_PUBLIC_BYTES];
     mask_t low;
     mask_t succ;
 
     memcpy(enc2, enc, sizeof(enc2));
 
-    low = ~word_is_zero(enc2[DECAF_EDDSA_448_PRIVATE_BYTES - 1] & 0x80);
-    enc2[DECAF_EDDSA_448_PRIVATE_BYTES - 1] &= ~0x80;
+    low = ~word_is_zero(enc2[EDDSA_448_PRIVATE_BYTES - 1] & 0x80);
+    enc2[EDDSA_448_PRIVATE_BYTES - 1] &= ~0x80;
 
     succ = gf_deserialize(p->y, enc2, 1, 0);
-#if 0 == 0
-    succ &= word_is_zero(enc2[DECAF_EDDSA_448_PRIVATE_BYTES - 1]);
-#endif
+    succ &= word_is_zero(enc2[EDDSA_448_PRIVATE_BYTES - 1]);
 
     gf_sqr(p->x, p->y);
     gf_sub(p->z, ONE, p->x);    /* num = 1-y^2 */
@@ -371,8 +353,9 @@ decaf_error_t curve448_point_decode_like_eddsa_and_mul_by_ratio(
     gf_copy(p->z, ONE);
 
     {
-        /* 4-isogeny 2xy/(y^2-ax^2), (y^2+ax^2)/(2-y^2-ax^2) */
         gf a, b, c, d;
+
+        /* 4-isogeny 2xy/(y^2-ax^2), (y^2+ax^2)/(2-y^2-ax^2) */
         gf_sqr(c, p->x);
         gf_sqr(a, p->y);
         gf_add(d, c, a);
@@ -394,21 +377,22 @@ decaf_error_t curve448_point_decode_like_eddsa_and_mul_by_ratio(
     }
 
     OPENSSL_cleanse(enc2, sizeof(enc2));
-    assert(curve448_point_valid(p) || ~succ);
+    assert(ossl_curve448_point_valid(p) || ~succ);
 
-    return decaf_succeed_if(mask_to_bool(succ));
+    return c448_succeed_if(mask_to_bool(succ));
 }
 
-decaf_error_t decaf_x448(uint8_t out[X_PUBLIC_BYTES],
-                         const uint8_t base[X_PUBLIC_BYTES],
-                         const uint8_t scalar[X_PRIVATE_BYTES])
+c448_error_t
+ossl_x448_int(uint8_t out[X_PUBLIC_BYTES],
+              const uint8_t base[X_PUBLIC_BYTES],
+              const uint8_t scalar[X_PRIVATE_BYTES])
 {
     gf x1, x2, z2, x3, z3, t1, t2;
     int t;
     mask_t swap = 0;
     mask_t nz;
 
-    ignore_result(gf_deserialize(x1, base, 1, 0));
+    (void)gf_deserialize(x1, base, 1, 0);
     gf_copy(x2, ONE);
     gf_copy(z2, ZERO);
     gf_copy(x3, x1);
@@ -425,32 +409,37 @@ decaf_error_t decaf_x448(uint8_t out[X_PUBLIC_BYTES],
             sb = -1;
 
         k_t = (sb >> (t % 8)) & 1;
-        k_t = -k_t;             /* set to all 0s or all 1s */
+        k_t = 0 - k_t;             /* set to all 0s or all 1s */
 
         swap ^= k_t;
         gf_cond_swap(x2, x3, swap);
         gf_cond_swap(z2, z3, swap);
         swap = k_t;
 
-        gf_add_nr(t1, x2, z2);  /* A = x2 + z2 *//* 2+e */
-        gf_sub_nr(t2, x2, z2);  /* B = x2 - z2 *//* 3+e */
-        gf_sub_nr(z2, x3, z3);  /* D = x3 - z3 *//* 3+e */
+        /*
+         * The "_nr" below skips coefficient reduction. In the following
+         * comments, "2+e" is saying that the coefficients are at most 2+epsilon
+         * times the reduction limit.
+         */
+        gf_add_nr(t1, x2, z2);  /* A = x2 + z2 */ /* 2+e */
+        gf_sub_nr(t2, x2, z2);  /* B = x2 - z2 */ /* 3+e */
+        gf_sub_nr(z2, x3, z3);  /* D = x3 - z3 */ /* 3+e */
         gf_mul(x2, t1, z2);     /* DA */
-        gf_add_nr(z2, z3, x3);  /* C = x3 + z3 *//* 2+e */
+        gf_add_nr(z2, z3, x3);  /* C = x3 + z3 */ /* 2+e */
         gf_mul(x3, t2, z2);     /* CB */
-        gf_sub_nr(z3, x2, x3);  /* DA-CB *//* 3+e */
+        gf_sub_nr(z3, x2, x3);  /* DA-CB */ /* 3+e */
         gf_sqr(z2, z3);         /* (DA-CB)^2 */
         gf_mul(z3, x1, z2);     /* z3 = x1(DA-CB)^2 */
-        gf_add_nr(z2, x2, x3);  /* (DA+CB) *//* 2+e */
+        gf_add_nr(z2, x2, x3);  /* (DA+CB) */ /* 2+e */
         gf_sqr(x3, z2);         /* x3 = (DA+CB)^2 */
 
         gf_sqr(z2, t1);         /* AA = A^2 */
         gf_sqr(t1, t2);         /* BB = B^2 */
         gf_mul(x2, z2, t1);     /* x2 = AA*BB */
-        gf_sub_nr(t2, z2, t1);  /* E = AA-BB *//* 3+e */
+        gf_sub_nr(t2, z2, t1);  /* E = AA-BB */ /* 3+e */
 
         gf_mulw(t1, t2, -EDWARDS_D); /* E*-d = a24*E */
-        gf_add_nr(t1, t1, z2);  /* AA + a24*E *//* 2+e */
+        gf_add_nr(t1, t1, z2);  /* AA + a24*E */ /* 2+e */
         gf_mul(z2, t2, t1);     /* z2 = E(AA+a24*E) */
     }
 
@@ -470,24 +459,26 @@ decaf_error_t decaf_x448(uint8_t out[X_PUBLIC_BYTES],
     OPENSSL_cleanse(t1, sizeof(t1));
     OPENSSL_cleanse(t2, sizeof(t2));
 
-    return decaf_succeed_if(mask_to_bool(nz));
+    return c448_succeed_if(mask_to_bool(nz));
 }
 
-void curve448_point_mul_by_ratio_and_encode_like_x448(uint8_t
+void
+ossl_curve448_point_mul_by_ratio_and_encode_like_x448(uint8_t
                                                       out[X_PUBLIC_BYTES],
                                                       const curve448_point_t p)
 {
     curve448_point_t q;
+
     curve448_point_copy(q, p);
     gf_invert(q->t, q->x, 0);   /* 1/x */
     gf_mul(q->z, q->t, q->y);   /* y/x */
     gf_sqr(q->y, q->z);         /* (y/x)^2 */
     gf_serialize(out, q->y, 1);
-    curve448_point_destroy(q);
+    ossl_curve448_point_destroy(q);
 }
 
-void decaf_x448_derive_public_key(uint8_t out[X_PUBLIC_BYTES],
-                                  const uint8_t scalar[X_PRIVATE_BYTES])
+void ossl_x448_derive_public_key(uint8_t out[X_PUBLIC_BYTES],
+                                 const uint8_t scalar[X_PRIVATE_BYTES])
 {
     /* Scalar conditioning */
     uint8_t scalar2[X_PRIVATE_BYTES];
@@ -498,18 +489,19 @@ void decaf_x448_derive_public_key(uint8_t out[X_PUBLIC_BYTES],
     memcpy(scalar2, scalar, sizeof(scalar2));
     scalar2[0] &= -(uint8_t)COFACTOR;
 
-    scalar2[X_PRIVATE_BYTES - 1] &= ~(-1u << ((X_PRIVATE_BITS + 7) % 8));
+    scalar2[X_PRIVATE_BYTES - 1] &= ~((0u - 1u) << ((X_PRIVATE_BITS + 7) % 8));
     scalar2[X_PRIVATE_BYTES - 1] |= 1 << ((X_PRIVATE_BITS + 7) % 8);
 
-    curve448_scalar_decode_long(the_scalar, scalar2, sizeof(scalar2));
+    ossl_curve448_scalar_decode_long(the_scalar, scalar2, sizeof(scalar2));
 
     /* Compensate for the encoding ratio */
-    for (i = 1; i < DECAF_X448_ENCODE_RATIO; i <<= 1) {
-        curve448_scalar_halve(the_scalar, the_scalar);
-    }
-    curve448_precomputed_scalarmul(p, curve448_precomputed_base, the_scalar);
-    curve448_point_mul_by_ratio_and_encode_like_x448(out, p);
-    curve448_point_destroy(p);
+    for (i = 1; i < X448_ENCODE_RATIO; i <<= 1)
+        ossl_curve448_scalar_halve(the_scalar, the_scalar);
+
+    ossl_curve448_precomputed_scalarmul(p, ossl_curve448_precomputed_base,
+                                        the_scalar);
+    ossl_curve448_point_mul_by_ratio_and_encode_like_x448(out, p);
+    ossl_curve448_point_destroy(p);
 }
 
 /* Control for variable-time scalar multiply algorithms. */
@@ -517,12 +509,52 @@ struct smvt_control {
     int power, addend;
 };
 
+#if defined(__GNUC__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ > 3))
+# define NUMTRAILINGZEROS       __builtin_ctz
+#else
+# define NUMTRAILINGZEROS       numtrailingzeros
+static uint32_t numtrailingzeros(uint32_t i)
+{
+    uint32_t tmp;
+    uint32_t num = 31;
+
+    if (i == 0)
+        return 32;
+
+    tmp = i << 16;
+    if (tmp != 0) {
+        i = tmp;
+        num -= 16;
+    }
+    tmp = i << 8;
+    if (tmp != 0) {
+        i = tmp;
+        num -= 8;
+    }
+    tmp = i << 4;
+    if (tmp != 0) {
+        i = tmp;
+        num -= 4;
+    }
+    tmp = i << 2;
+    if (tmp != 0) {
+        i = tmp;
+        num -= 2;
+    }
+    tmp = i << 1;
+    if (tmp != 0)
+        num--;
+
+    return num;
+}
+#endif
+
 static int recode_wnaf(struct smvt_control *control,
                        /* [nbits/(table_bits + 1) + 3] */
                        const curve448_scalar_t scalar,
                        unsigned int table_bits)
 {
-    unsigned int table_size = DECAF_448_SCALAR_BITS / (table_bits + 1) + 3;
+    unsigned int table_size = C448_SCALAR_BITS / (table_bits + 1) + 3;
     int position = table_size - 1; /* at the end */
     uint64_t current = scalar->limb[0] & 0xFFFF;
     uint32_t mask = (1 << (table_bits + 1)) - 1;
@@ -541,22 +573,29 @@ static int recode_wnaf(struct smvt_control *control,
      * 1/5 op. Probably not worth it.
      */
 
-    for (w = 1; w < (DECAF_448_SCALAR_BITS - 1) / 16 + 3; w++) {
-        if (w < (DECAF_448_SCALAR_BITS - 1) / 16 + 1) {
+    for (w = 1; w < (C448_SCALAR_BITS - 1) / 16 + 3; w++) {
+        if (w < (C448_SCALAR_BITS - 1) / 16 + 1) {
             /* Refill the 16 high bits of current */
             current += (uint32_t)((scalar->limb[w / B_OVER_16]
-                       >> (16 * (w %  B_OVER_16))) << 16);
+                       >> (16 * (w % B_OVER_16))) << 16);
         }
 
         while (current & 0xFFFF) {
-            uint32_t pos = __builtin_ctz((uint32_t)current);
+            uint32_t pos = NUMTRAILINGZEROS((uint32_t)current);
             uint32_t odd = (uint32_t)current >> pos;
             int32_t delta = odd & mask;
 
             assert(position >= 0);
-            if (odd & 1 << (table_bits + 1))
+            if (odd & (1 << (table_bits + 1)))
                 delta -= (1 << (table_bits + 1));
-            current -= delta << pos;
+            /*
+             * Coverity gets confused by the value of pos, thinking it might be
+             * 32.  This would require current & 0xFFFF to be zero which isn't
+             * possible.  Suppress this false positive, since adding a check
+             * isn't desirable.
+             */
+            /* coverity[overflow_before_widen] */
+            current -= delta * (1 << pos);
             control[position].power = pos + 16 * (w - 1);
             control[position].addend = delta;
             position--;
@@ -567,9 +606,9 @@ static int recode_wnaf(struct smvt_control *control,
 
     position++;
     n = table_size - position;
-    for (i = 0; i < n; i++) {
+    for (i = 0; i < n; i++)
         control[i] = control[i + position];
-    }
+
     return n - 1;
 }
 
@@ -586,7 +625,7 @@ static void prepare_wnaf_table(pniels_t * output,
     if (tbits == 0)
         return;
 
-    curve448_point_double(tmp, working);
+    ossl_curve448_point_double(tmp, working);
     pt_to_pniels(twop, tmp);
 
     add_pniels_to_pt(tmp, output[0], 0);
@@ -597,83 +636,81 @@ static void prepare_wnaf_table(pniels_t * output,
         pt_to_pniels(output[i], tmp);
     }
 
-    curve448_point_destroy(tmp);
+    ossl_curve448_point_destroy(tmp);
     OPENSSL_cleanse(twop, sizeof(twop));
 }
 
-extern const gf curve448_precomputed_wnaf_as_fe[];
-static const niels_t *curve448_wnaf_base =
-    (const niels_t *)curve448_precomputed_wnaf_as_fe;
-
-void curve448_base_double_scalarmul_non_secret(curve448_point_t combo,
+void
+ossl_curve448_base_double_scalarmul_non_secret(curve448_point_t combo,
                                                const curve448_scalar_t scalar1,
                                                const curve448_point_t base2,
                                                const curve448_scalar_t scalar2)
 {
-    const int table_bits_var = DECAF_WNAF_VAR_TABLE_BITS,
-        table_bits_pre = DECAF_WNAF_FIXED_TABLE_BITS;
-    struct smvt_control control_var[DECAF_448_SCALAR_BITS /
-                                    (DECAF_WNAF_VAR_TABLE_BITS + 1) + 3];
-    struct smvt_control control_pre[DECAF_448_SCALAR_BITS /
-                                    (DECAF_WNAF_FIXED_TABLE_BITS + 1) + 3];
+    const int table_bits_var = C448_WNAF_VAR_TABLE_BITS;
+    const int table_bits_pre = C448_WNAF_FIXED_TABLE_BITS;
+    struct smvt_control control_var[C448_SCALAR_BITS /
+                                    (C448_WNAF_VAR_TABLE_BITS + 1) + 3];
+    struct smvt_control control_pre[C448_SCALAR_BITS /
+                                    (C448_WNAF_FIXED_TABLE_BITS + 1) + 3];
     int ncb_pre = recode_wnaf(control_pre, scalar1, table_bits_pre);
     int ncb_var = recode_wnaf(control_var, scalar2, table_bits_var);
-    pniels_t precmp_var[1 << DECAF_WNAF_VAR_TABLE_BITS];
+    pniels_t precmp_var[1 << C448_WNAF_VAR_TABLE_BITS];
     int contp = 0, contv = 0, i;
 
     prepare_wnaf_table(precmp_var, base2, table_bits_var);
     i = control_var[0].power;
 
     if (i < 0) {
-        curve448_point_copy(combo, curve448_point_identity);
+        curve448_point_copy(combo, ossl_curve448_point_identity);
         return;
-    } else if (i > control_pre[0].power) {
+    }
+    if (i > control_pre[0].power) {
         pniels_to_pt(combo, precmp_var[control_var[0].addend >> 1]);
         contv++;
     } else if (i == control_pre[0].power && i >= 0) {
         pniels_to_pt(combo, precmp_var[control_var[0].addend >> 1]);
-        add_niels_to_pt(combo, curve448_wnaf_base[control_pre[0].addend >> 1],
+        add_niels_to_pt(combo,
+                        ossl_curve448_wnaf_base[control_pre[0].addend >> 1],
                         i);
         contv++;
         contp++;
     } else {
         i = control_pre[0].power;
-        niels_to_pt(combo, curve448_wnaf_base[control_pre[0].addend >> 1]);
+        niels_to_pt(combo, ossl_curve448_wnaf_base[control_pre[0].addend >> 1]);
         contp++;
     }
 
     for (i--; i >= 0; i--) {
-        int cv = (i == control_var[contv].power), cp =
-            (i == control_pre[contp].power);
+        int cv = (i == control_var[contv].power);
+        int cp = (i == control_pre[contp].power);
+
         point_double_internal(combo, combo, i && !(cv || cp));
 
         if (cv) {
             assert(control_var[contv].addend);
 
-            if (control_var[contv].addend > 0) {
+            if (control_var[contv].addend > 0)
                 add_pniels_to_pt(combo,
                                  precmp_var[control_var[contv].addend >> 1],
                                  i && !cp);
-            } else {
+            else
                 sub_pniels_from_pt(combo,
                                    precmp_var[(-control_var[contv].addend)
                                               >> 1], i && !cp);
-            }
             contv++;
         }
 
         if (cp) {
             assert(control_pre[contp].addend);
 
-            if (control_pre[contp].addend > 0) {
+            if (control_pre[contp].addend > 0)
                 add_niels_to_pt(combo,
-                                curve448_wnaf_base[control_pre[contp].addend
+                                ossl_curve448_wnaf_base[control_pre[contp].addend
                                                    >> 1], i);
-            } else {
+            else
                 sub_niels_from_pt(combo,
-                                  curve448_wnaf_base[(-control_pre
+                                  ossl_curve448_wnaf_base[(-control_pre
                                                       [contp].addend) >> 1], i);
-            }
             contp++;
         }
     }
@@ -689,20 +726,20 @@ void curve448_base_double_scalarmul_non_secret(curve448_point_t combo,
     (void)ncb_pre;
 }
 
-void curve448_point_destroy(curve448_point_t point)
+void ossl_curve448_point_destroy(curve448_point_t point)
 {
     OPENSSL_cleanse(point, sizeof(curve448_point_t));
 }
 
-int X448(uint8_t out_shared_key[56], const uint8_t private_key[56],
-         const uint8_t peer_public_value[56])
+int ossl_x448(uint8_t out_shared_key[56], const uint8_t private_key[56],
+              const uint8_t peer_public_value[56])
 {
-    return decaf_x448(out_shared_key, peer_public_value, private_key)
-        == DECAF_SUCCESS;
+    return ossl_x448_int(out_shared_key, peer_public_value, private_key)
+           == C448_SUCCESS;
 }
 
-void X448_public_from_private(uint8_t out_public_value[56],
-                              const uint8_t private_key[56])
+void ossl_x448_public_from_private(uint8_t out_public_value[56],
+                                   const uint8_t private_key[56])
 {
-    decaf_x448_derive_public_key(out_public_value, private_key);
+    ossl_x448_derive_public_key(out_public_value, private_key);
 }