+++ /dev/null
-/* $OpenBSD: smult_curve25519_ref.c,v 1.1 2014/07/22 00:41:19 deraadt Exp $ */
-/*
-version 20081011
-Matthew Dempsky
-Public domain.
-Derived from public domain code by D. J. Bernstein.
-*/
-
-int crypto_scalarmult_curve25519(unsigned char *, const unsigned char *, const unsigned char *);
-
-static void add(unsigned int out[32],const unsigned int a[32],const unsigned int b[32])
-{
- unsigned int j;
- unsigned int u;
- u = 0;
- for (j = 0;j < 31;++j) { u += a[j] + b[j]; out[j] = u & 255; u >>= 8; }
- u += a[31] + b[31]; out[31] = u;
-}
-
-static void sub(unsigned int out[32],const unsigned int a[32],const unsigned int b[32])
-{
- unsigned int j;
- unsigned int u;
- u = 218;
- for (j = 0;j < 31;++j) {
- u += a[j] + 65280 - b[j];
- out[j] = u & 255;
- u >>= 8;
- }
- u += a[31] - b[31];
- out[31] = u;
-}
-
-static void squeeze(unsigned int a[32])
-{
- unsigned int j;
- unsigned int u;
- u = 0;
- for (j = 0;j < 31;++j) { u += a[j]; a[j] = u & 255; u >>= 8; }
- u += a[31]; a[31] = u & 127;
- u = 19 * (u >> 7);
- for (j = 0;j < 31;++j) { u += a[j]; a[j] = u & 255; u >>= 8; }
- u += a[31]; a[31] = u;
-}
-
-static const unsigned int minusp[32] = {
- 19, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 128
-} ;
-
-static void freeze(unsigned int a[32])
-{
- unsigned int aorig[32];
- unsigned int j;
- unsigned int negative;
-
- for (j = 0;j < 32;++j) aorig[j] = a[j];
- add(a,a,minusp);
- negative = -((a[31] >> 7) & 1);
- for (j = 0;j < 32;++j) a[j] ^= negative & (aorig[j] ^ a[j]);
-}
-
-static void mult(unsigned int out[32],const unsigned int a[32],const unsigned int b[32])
-{
- unsigned int i;
- unsigned int j;
- unsigned int u;
-
- for (i = 0;i < 32;++i) {
- u = 0;
- for (j = 0;j <= i;++j) u += a[j] * b[i - j];
- for (j = i + 1;j < 32;++j) u += 38 * a[j] * b[i + 32 - j];
- out[i] = u;
- }
- squeeze(out);
-}
-
-static void mult121665(unsigned int out[32],const unsigned int a[32])
-{
- unsigned int j;
- unsigned int u;
-
- u = 0;
- for (j = 0;j < 31;++j) { u += 121665 * a[j]; out[j] = u & 255; u >>= 8; }
- u += 121665 * a[31]; out[31] = u & 127;
- u = 19 * (u >> 7);
- for (j = 0;j < 31;++j) { u += out[j]; out[j] = u & 255; u >>= 8; }
- u += out[j]; out[j] = u;
-}
-
-static void square(unsigned int out[32],const unsigned int a[32])
-{
- unsigned int i;
- unsigned int j;
- unsigned int u;
-
- for (i = 0;i < 32;++i) {
- u = 0;
- for (j = 0;j < i - j;++j) u += a[j] * a[i - j];
- for (j = i + 1;j < i + 32 - j;++j) u += 38 * a[j] * a[i + 32 - j];
- u *= 2;
- if ((i & 1) == 0) {
- u += a[i / 2] * a[i / 2];
- u += 38 * a[i / 2 + 16] * a[i / 2 + 16];
- }
- out[i] = u;
- }
- squeeze(out);
-}
-
-static void select(unsigned int p[64],unsigned int q[64],const unsigned int r[64],const unsigned int s[64],unsigned int b)
-{
- unsigned int j;
- unsigned int t;
- unsigned int bminus1;
-
- bminus1 = b - 1;
- for (j = 0;j < 64;++j) {
- t = bminus1 & (r[j] ^ s[j]);
- p[j] = s[j] ^ t;
- q[j] = r[j] ^ t;
- }
-}
-
-static void mainloop(unsigned int work[64],const unsigned char e[32])
-{
- unsigned int xzm1[64];
- unsigned int xzm[64];
- unsigned int xzmb[64];
- unsigned int xzm1b[64];
- unsigned int xznb[64];
- unsigned int xzn1b[64];
- unsigned int a0[64];
- unsigned int a1[64];
- unsigned int b0[64];
- unsigned int b1[64];
- unsigned int c1[64];
- unsigned int r[32];
- unsigned int s[32];
- unsigned int t[32];
- unsigned int u[32];
- unsigned int j;
- unsigned int b;
- int pos;
-
- for (j = 0;j < 32;++j) xzm1[j] = work[j];
- xzm1[32] = 1;
- for (j = 33;j < 64;++j) xzm1[j] = 0;
-
- xzm[0] = 1;
- for (j = 1;j < 64;++j) xzm[j] = 0;
-
- for (pos = 254;pos >= 0;--pos) {
- b = e[pos / 8] >> (pos & 7);
- b &= 1;
- select(xzmb,xzm1b,xzm,xzm1,b);
- add(a0,xzmb,xzmb + 32);
- sub(a0 + 32,xzmb,xzmb + 32);
- add(a1,xzm1b,xzm1b + 32);
- sub(a1 + 32,xzm1b,xzm1b + 32);
- square(b0,a0);
- square(b0 + 32,a0 + 32);
- mult(b1,a1,a0 + 32);
- mult(b1 + 32,a1 + 32,a0);
- add(c1,b1,b1 + 32);
- sub(c1 + 32,b1,b1 + 32);
- square(r,c1 + 32);
- sub(s,b0,b0 + 32);
- mult121665(t,s);
- add(u,t,b0);
- mult(xznb,b0,b0 + 32);
- mult(xznb + 32,s,u);
- square(xzn1b,c1);
- mult(xzn1b + 32,r,work);
- select(xzm,xzm1,xznb,xzn1b,b);
- }
-
- for (j = 0;j < 64;++j) work[j] = xzm[j];
-}
-
-static void recip(unsigned int out[32],const unsigned int z[32])
-{
- unsigned int z2[32];
- unsigned int z9[32];
- unsigned int z11[32];
- unsigned int z2_5_0[32];
- unsigned int z2_10_0[32];
- unsigned int z2_20_0[32];
- unsigned int z2_50_0[32];
- unsigned int z2_100_0[32];
- unsigned int t0[32];
- unsigned int t1[32];
- int i;
-
- /* 2 */ square(z2,z);
- /* 4 */ square(t1,z2);
- /* 8 */ square(t0,t1);
- /* 9 */ mult(z9,t0,z);
- /* 11 */ mult(z11,z9,z2);
- /* 22 */ square(t0,z11);
- /* 2^5 - 2^0 = 31 */ mult(z2_5_0,t0,z9);
-
- /* 2^6 - 2^1 */ square(t0,z2_5_0);
- /* 2^7 - 2^2 */ square(t1,t0);
- /* 2^8 - 2^3 */ square(t0,t1);
- /* 2^9 - 2^4 */ square(t1,t0);
- /* 2^10 - 2^5 */ square(t0,t1);
- /* 2^10 - 2^0 */ mult(z2_10_0,t0,z2_5_0);
-
- /* 2^11 - 2^1 */ square(t0,z2_10_0);
- /* 2^12 - 2^2 */ square(t1,t0);
- /* 2^20 - 2^10 */ for (i = 2;i < 10;i += 2) { square(t0,t1); square(t1,t0); }
- /* 2^20 - 2^0 */ mult(z2_20_0,t1,z2_10_0);
-
- /* 2^21 - 2^1 */ square(t0,z2_20_0);
- /* 2^22 - 2^2 */ square(t1,t0);
- /* 2^40 - 2^20 */ for (i = 2;i < 20;i += 2) { square(t0,t1); square(t1,t0); }
- /* 2^40 - 2^0 */ mult(t0,t1,z2_20_0);
-
- /* 2^41 - 2^1 */ square(t1,t0);
- /* 2^42 - 2^2 */ square(t0,t1);
- /* 2^50 - 2^10 */ for (i = 2;i < 10;i += 2) { square(t1,t0); square(t0,t1); }
- /* 2^50 - 2^0 */ mult(z2_50_0,t0,z2_10_0);
-
- /* 2^51 - 2^1 */ square(t0,z2_50_0);
- /* 2^52 - 2^2 */ square(t1,t0);
- /* 2^100 - 2^50 */ for (i = 2;i < 50;i += 2) { square(t0,t1); square(t1,t0); }
- /* 2^100 - 2^0 */ mult(z2_100_0,t1,z2_50_0);
-
- /* 2^101 - 2^1 */ square(t1,z2_100_0);
- /* 2^102 - 2^2 */ square(t0,t1);
- /* 2^200 - 2^100 */ for (i = 2;i < 100;i += 2) { square(t1,t0); square(t0,t1); }
- /* 2^200 - 2^0 */ mult(t1,t0,z2_100_0);
-
- /* 2^201 - 2^1 */ square(t0,t1);
- /* 2^202 - 2^2 */ square(t1,t0);
- /* 2^250 - 2^50 */ for (i = 2;i < 50;i += 2) { square(t0,t1); square(t1,t0); }
- /* 2^250 - 2^0 */ mult(t0,t1,z2_50_0);
-
- /* 2^251 - 2^1 */ square(t1,t0);
- /* 2^252 - 2^2 */ square(t0,t1);
- /* 2^253 - 2^3 */ square(t1,t0);
- /* 2^254 - 2^4 */ square(t0,t1);
- /* 2^255 - 2^5 */ square(t1,t0);
- /* 2^255 - 21 */ mult(out,t1,z11);
-}
-
-int crypto_scalarmult_curve25519(unsigned char *q,
- const unsigned char *n,
- const unsigned char *p)
-{
- unsigned int work[96];
- unsigned char e[32];
- unsigned int i;
- for (i = 0;i < 32;++i) e[i] = n[i];
- e[0] &= 248;
- e[31] &= 127;
- e[31] |= 64;
- for (i = 0;i < 32;++i) work[i] = p[i];
- mainloop(work,e);
- recip(work + 32,work + 32);
- mult(work + 64,work,work + 32);
- freeze(work + 64);
- for (i = 0;i < 32;++i) q[i] = work[64 + i];
- return 0;
-}