diff options
Diffstat (limited to 'fe25519.c')
| -rw-r--r-- | fe25519.c | 337 |
1 files changed, 337 insertions, 0 deletions
diff --git a/fe25519.c b/fe25519.c new file mode 100644 index 0000000..e54fd15 --- /dev/null +++ b/fe25519.c @@ -0,0 +1,337 @@ +/* $OpenBSD: fe25519.c,v 1.3 2013/12/09 11:03:45 markus Exp $ */ + +/* + * Public Domain, Authors: Daniel J. Bernstein, Niels Duif, Tanja Lange, + * Peter Schwabe, Bo-Yin Yang. + * Copied from supercop-20130419/crypto_sign/ed25519/ref/fe25519.c + */ + +#include "includes.h" + +#define WINDOWSIZE 1 /* Should be 1,2, or 4 */ +#define WINDOWMASK ((1<<WINDOWSIZE)-1) + +#include "fe25519.h" + +static crypto_uint32 equal(crypto_uint32 a,crypto_uint32 b) /* 16-bit inputs */ +{ + crypto_uint32 x = a ^ b; /* 0: yes; 1..65535: no */ + x -= 1; /* 4294967295: yes; 0..65534: no */ + x >>= 31; /* 1: yes; 0: no */ + return x; +} + +static crypto_uint32 ge(crypto_uint32 a,crypto_uint32 b) /* 16-bit inputs */ +{ + unsigned int x = a; + x -= (unsigned int) b; /* 0..65535: yes; 4294901761..4294967295: no */ + x >>= 31; /* 0: yes; 1: no */ + x ^= 1; /* 1: yes; 0: no */ + return x; +} + +static crypto_uint32 times19(crypto_uint32 a) +{ + return (a << 4) + (a << 1) + a; +} + +static crypto_uint32 times38(crypto_uint32 a) +{ + return (a << 5) + (a << 2) + (a << 1); +} + +static void reduce_add_sub(fe25519 *r) +{ + crypto_uint32 t; + int i,rep; + + for(rep=0;rep<4;rep++) + { + t = r->v[31] >> 7; + r->v[31] &= 127; + t = times19(t); + r->v[0] += t; + for(i=0;i<31;i++) + { + t = r->v[i] >> 8; + r->v[i+1] += t; + r->v[i] &= 255; + } + } +} + +static void reduce_mul(fe25519 *r) +{ + crypto_uint32 t; + int i,rep; + + for(rep=0;rep<2;rep++) + { + t = r->v[31] >> 7; + r->v[31] &= 127; + t = times19(t); + r->v[0] += t; + for(i=0;i<31;i++) + { + t = r->v[i] >> 8; + r->v[i+1] += t; + r->v[i] &= 255; + } + } +} + +/* reduction modulo 2^255-19 */ +void fe25519_freeze(fe25519 *r) +{ + int i; + crypto_uint32 m = equal(r->v[31],127); + for(i=30;i>0;i--) + m &= equal(r->v[i],255); + m &= ge(r->v[0],237); + + m = -m; + + r->v[31] -= m&127; + for(i=30;i>0;i--) + r->v[i] -= m&255; + r->v[0] -= m&237; +} + +void fe25519_unpack(fe25519 *r, const unsigned char x[32]) +{ + int i; + for(i=0;i<32;i++) r->v[i] = x[i]; + r->v[31] &= 127; +} + +/* Assumes input x being reduced below 2^255 */ +void fe25519_pack(unsigned char r[32], const fe25519 *x) +{ + int i; + fe25519 y = *x; + fe25519_freeze(&y); + for(i=0;i<32;i++) + r[i] = y.v[i]; +} + +int fe25519_iszero(const fe25519 *x) +{ + int i; + int r; + fe25519 t = *x; + fe25519_freeze(&t); + r = equal(t.v[0],0); + for(i=1;i<32;i++) + r &= equal(t.v[i],0); + return r; +} + +int fe25519_iseq_vartime(const fe25519 *x, const fe25519 *y) +{ + int i; + fe25519 t1 = *x; + fe25519 t2 = *y; + fe25519_freeze(&t1); + fe25519_freeze(&t2); + for(i=0;i<32;i++) + if(t1.v[i] != t2.v[i]) return 0; + return 1; +} + +void fe25519_cmov(fe25519 *r, const fe25519 *x, unsigned char b) +{ + int i; + crypto_uint32 mask = b; + mask = -mask; + for(i=0;i<32;i++) r->v[i] ^= mask & (x->v[i] ^ r->v[i]); +} + +unsigned char fe25519_getparity(const fe25519 *x) +{ + fe25519 t = *x; + fe25519_freeze(&t); + return t.v[0] & 1; +} + +void fe25519_setone(fe25519 *r) +{ + int i; + r->v[0] = 1; + for(i=1;i<32;i++) r->v[i]=0; +} + +void fe25519_setzero(fe25519 *r) +{ + int i; + for(i=0;i<32;i++) r->v[i]=0; +} + +void fe25519_neg(fe25519 *r, const fe25519 *x) +{ + fe25519 t; + int i; + for(i=0;i<32;i++) t.v[i]=x->v[i]; + fe25519_setzero(r); + fe25519_sub(r, r, &t); +} + +void fe25519_add(fe25519 *r, const fe25519 *x, const fe25519 *y) +{ + int i; + for(i=0;i<32;i++) r->v[i] = x->v[i] + y->v[i]; + reduce_add_sub(r); +} + +void fe25519_sub(fe25519 *r, const fe25519 *x, const fe25519 *y) +{ + int i; + crypto_uint32 t[32]; + t[0] = x->v[0] + 0x1da; + t[31] = x->v[31] + 0xfe; + for(i=1;i<31;i++) t[i] = x->v[i] + 0x1fe; + for(i=0;i<32;i++) r->v[i] = t[i] - y->v[i]; + reduce_add_sub(r); +} + +void fe25519_mul(fe25519 *r, const fe25519 *x, const fe25519 *y) +{ + int i,j; + crypto_uint32 t[63]; + for(i=0;i<63;i++)t[i] = 0; + + for(i=0;i<32;i++) + for(j=0;j<32;j++) + t[i+j] += x->v[i] * y->v[j]; + + for(i=32;i<63;i++) + r->v[i-32] = t[i-32] + times38(t[i]); + r->v[31] = t[31]; /* result now in r[0]...r[31] */ + + reduce_mul(r); +} + +void fe25519_square(fe25519 *r, const fe25519 *x) +{ + fe25519_mul(r, x, x); +} + +void fe25519_invert(fe25519 *r, const fe25519 *x) +{ + fe25519 z2; + fe25519 z9; + fe25519 z11; + fe25519 z2_5_0; + fe25519 z2_10_0; + fe25519 z2_20_0; + fe25519 z2_50_0; + fe25519 z2_100_0; + fe25519 t0; + fe25519 t1; + int i; + + /* 2 */ fe25519_square(&z2,x); + /* 4 */ fe25519_square(&t1,&z2); + /* 8 */ fe25519_square(&t0,&t1); + /* 9 */ fe25519_mul(&z9,&t0,x); + /* 11 */ fe25519_mul(&z11,&z9,&z2); + /* 22 */ fe25519_square(&t0,&z11); + /* 2^5 - 2^0 = 31 */ fe25519_mul(&z2_5_0,&t0,&z9); + + /* 2^6 - 2^1 */ fe25519_square(&t0,&z2_5_0); + /* 2^7 - 2^2 */ fe25519_square(&t1,&t0); + /* 2^8 - 2^3 */ fe25519_square(&t0,&t1); + /* 2^9 - 2^4 */ fe25519_square(&t1,&t0); + /* 2^10 - 2^5 */ fe25519_square(&t0,&t1); + /* 2^10 - 2^0 */ fe25519_mul(&z2_10_0,&t0,&z2_5_0); + + /* 2^11 - 2^1 */ fe25519_square(&t0,&z2_10_0); + /* 2^12 - 2^2 */ fe25519_square(&t1,&t0); + /* 2^20 - 2^10 */ for (i = 2;i < 10;i += 2) { fe25519_square(&t0,&t1); fe25519_square(&t1,&t0); } + /* 2^20 - 2^0 */ fe25519_mul(&z2_20_0,&t1,&z2_10_0); + + /* 2^21 - 2^1 */ fe25519_square(&t0,&z2_20_0); + /* 2^22 - 2^2 */ fe25519_square(&t1,&t0); + /* 2^40 - 2^20 */ for (i = 2;i < 20;i += 2) { fe25519_square(&t0,&t1); fe25519_square(&t1,&t0); } + /* 2^40 - 2^0 */ fe25519_mul(&t0,&t1,&z2_20_0); + + /* 2^41 - 2^1 */ fe25519_square(&t1,&t0); + /* 2^42 - 2^2 */ fe25519_square(&t0,&t1); + /* 2^50 - 2^10 */ for (i = 2;i < 10;i += 2) { fe25519_square(&t1,&t0); fe25519_square(&t0,&t1); } + /* 2^50 - 2^0 */ fe25519_mul(&z2_50_0,&t0,&z2_10_0); + + /* 2^51 - 2^1 */ fe25519_square(&t0,&z2_50_0); + /* 2^52 - 2^2 */ fe25519_square(&t1,&t0); + /* 2^100 - 2^50 */ for (i = 2;i < 50;i += 2) { fe25519_square(&t0,&t1); fe25519_square(&t1,&t0); } + /* 2^100 - 2^0 */ fe25519_mul(&z2_100_0,&t1,&z2_50_0); + + /* 2^101 - 2^1 */ fe25519_square(&t1,&z2_100_0); + /* 2^102 - 2^2 */ fe25519_square(&t0,&t1); + /* 2^200 - 2^100 */ for (i = 2;i < 100;i += 2) { fe25519_square(&t1,&t0); fe25519_square(&t0,&t1); } + /* 2^200 - 2^0 */ fe25519_mul(&t1,&t0,&z2_100_0); + + /* 2^201 - 2^1 */ fe25519_square(&t0,&t1); + /* 2^202 - 2^2 */ fe25519_square(&t1,&t0); + /* 2^250 - 2^50 */ for (i = 2;i < 50;i += 2) { fe25519_square(&t0,&t1); fe25519_square(&t1,&t0); } + /* 2^250 - 2^0 */ fe25519_mul(&t0,&t1,&z2_50_0); + + /* 2^251 - 2^1 */ fe25519_square(&t1,&t0); + /* 2^252 - 2^2 */ fe25519_square(&t0,&t1); + /* 2^253 - 2^3 */ fe25519_square(&t1,&t0); + /* 2^254 - 2^4 */ fe25519_square(&t0,&t1); + /* 2^255 - 2^5 */ fe25519_square(&t1,&t0); + /* 2^255 - 21 */ fe25519_mul(r,&t1,&z11); +} + +void fe25519_pow2523(fe25519 *r, const fe25519 *x) +{ + fe25519 z2; + fe25519 z9; + fe25519 z11; + fe25519 z2_5_0; + fe25519 z2_10_0; + fe25519 z2_20_0; + fe25519 z2_50_0; + fe25519 z2_100_0; + fe25519 t; + int i; + + /* 2 */ fe25519_square(&z2,x); + /* 4 */ fe25519_square(&t,&z2); + /* 8 */ fe25519_square(&t,&t); + /* 9 */ fe25519_mul(&z9,&t,x); + /* 11 */ fe25519_mul(&z11,&z9,&z2); + /* 22 */ fe25519_square(&t,&z11); + /* 2^5 - 2^0 = 31 */ fe25519_mul(&z2_5_0,&t,&z9); + + /* 2^6 - 2^1 */ fe25519_square(&t,&z2_5_0); + /* 2^10 - 2^5 */ for (i = 1;i < 5;i++) { fe25519_square(&t,&t); } + /* 2^10 - 2^0 */ fe25519_mul(&z2_10_0,&t,&z2_5_0); + + /* 2^11 - 2^1 */ fe25519_square(&t,&z2_10_0); + /* 2^20 - 2^10 */ for (i = 1;i < 10;i++) { fe25519_square(&t,&t); } + /* 2^20 - 2^0 */ fe25519_mul(&z2_20_0,&t,&z2_10_0); + + /* 2^21 - 2^1 */ fe25519_square(&t,&z2_20_0); + /* 2^40 - 2^20 */ for (i = 1;i < 20;i++) { fe25519_square(&t,&t); } + /* 2^40 - 2^0 */ fe25519_mul(&t,&t,&z2_20_0); + + /* 2^41 - 2^1 */ fe25519_square(&t,&t); + /* 2^50 - 2^10 */ for (i = 1;i < 10;i++) { fe25519_square(&t,&t); } + /* 2^50 - 2^0 */ fe25519_mul(&z2_50_0,&t,&z2_10_0); + + /* 2^51 - 2^1 */ fe25519_square(&t,&z2_50_0); + /* 2^100 - 2^50 */ for (i = 1;i < 50;i++) { fe25519_square(&t,&t); } + /* 2^100 - 2^0 */ fe25519_mul(&z2_100_0,&t,&z2_50_0); + + /* 2^101 - 2^1 */ fe25519_square(&t,&z2_100_0); + /* 2^200 - 2^100 */ for (i = 1;i < 100;i++) { fe25519_square(&t,&t); } + /* 2^200 - 2^0 */ fe25519_mul(&t,&t,&z2_100_0); + + /* 2^201 - 2^1 */ fe25519_square(&t,&t); + /* 2^250 - 2^50 */ for (i = 1;i < 50;i++) { fe25519_square(&t,&t); } + /* 2^250 - 2^0 */ fe25519_mul(&t,&t,&z2_50_0); + + /* 2^251 - 2^1 */ fe25519_square(&t,&t); + /* 2^252 - 2^2 */ fe25519_square(&t,&t); + /* 2^252 - 3 */ fe25519_mul(r,&t,x); +} |