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Some cleanups (removed unused files, split i15 code into per-function files).

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This commit is contained in:
Thomas Pornin 2017-01-16 20:19:11 +01:00
parent bd3036844b
commit 2f454aad57
22 changed files with 945 additions and 843 deletions
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8
src/ec/ec_curve25519.c
View file

@ -32,10 +32,10 @@ static const unsigned char GEN[] = {
};
static const unsigned char ORDER[] = {
0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x14, 0xDE, 0xF9, 0xDE, 0xA2, 0xF7, 0x9C, 0xD6,
0x58, 0x12, 0x63, 0x1A, 0x5C, 0xF5, 0xD3, 0xED
0x7F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};
/* see inner.h */

28
src/inner.h
View file

@ -1456,30 +1456,14 @@ extern const br_ec_curve_def br_secp256r1;
extern const br_ec_curve_def br_secp384r1;
extern const br_ec_curve_def br_secp521r1;
extern const br_ec_curve_def br_curve25519;
#if 0
/* obsolete */
/*
* Type for the parameters for a "prime curve":
* coordinates are in GF(p), with p prime
* curve equation is Y^2 = X^3 - 3*X + b
* b is in Montgomery representation
* curve order is n and is prime
* base point is G (encoded) and has order n
* For Curve25519, the advertised "order" really is 2^255-1, since the
* point multipliction function really works over arbitrary 255-bit
* scalars. This value is only meant as a hint for ECDH key generation;
* only ECDSA uses the exact curve order, and ECDSA is not used with
* that specific curve.
*/
typedef struct {
const uint32_t *p;
const uint32_t *b;
const uint32_t p0i;
} br_ec_prime_i31_curve;
extern const br_ec_prime_i31_curve br_ec_prime_i31_secp256r1;
extern const br_ec_prime_i31_curve br_ec_prime_i31_secp384r1;
extern const br_ec_prime_i31_curve br_ec_prime_i31_secp521r1;
#define BR_EC_I31_LEN ((BR_MAX_EC_SIZE + 61) / 31)
#endif
extern const br_ec_curve_def br_curve25519;
/*
* Decode some bytes as an i31 integer, with truncation (corresponding

40
src/ec/ec_prime_i31_secp256r1.c → src/int/i15_add.c
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
@ -24,23 +24,23 @@
#include "inner.h"
static const uint32_t P256_P[] = {
0x00000108,
0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF, 0x00000007,
0x00000000, 0x00000000, 0x00000040, 0x7FFFFF80,
0x000000FF
};
static const uint32_t P256_B[] = {
0x00000108,
0x6FEE1803, 0x6229C4BD, 0x21B139BE, 0x327150AA,
0x3567802E, 0x3F7212ED, 0x012E4355, 0x782DD38D,
0x0000000E
};
/* see inner.h */
const br_ec_prime_i31_curve br_ec_prime_i31_secp256r1 = {
P256_P,
P256_B,
0x00000001
};
uint32_t
br_i15_add(uint16_t *a, const uint16_t *b, uint32_t ctl)
{
uint32_t cc;
size_t u, m;
cc = 0;
m = (a[0] + 31) >> 4;
for (u = 1; u < m; u ++) {
uint32_t aw, bw, naw;
aw = a[u];
bw = b[u];
naw = aw + bw + cc;
cc = naw >> 15;
a[u] = MUX(ctl, naw & 0x7FFF, aw);
}
return cc;
}

40
src/ec/ec_prime_i31_secp384r1.c → src/int/i15_bitlen.c
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
@ -24,25 +24,21 @@
#include "inner.h"
static const uint32_t P384_P[] = {
0x0000018C,
0x7FFFFFFF, 0x00000001, 0x00000000, 0x7FFFFFF8,
0x7FFFFFEF, 0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF,
0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF,
0x00000FFF
};
static const uint32_t P384_B[] = {
0x0000018C,
0x6E666840, 0x070D0392, 0x5D810231, 0x7651D50C,
0x17E218D6, 0x1B192002, 0x44EFE441, 0x3A524E2B,
0x2719BA5F, 0x41F02209, 0x36C5643E, 0x5813EFFE,
0x000008A5
};
/* see inner.h */
const br_ec_prime_i31_curve br_ec_prime_i31_secp384r1 = {
P384_P,
P384_B,
0x00000001
};
uint32_t
br_i15_bit_length(uint16_t *x, size_t xlen)
{
uint32_t tw, twk;
tw = 0;
twk = 0;
while (xlen -- > 0) {
uint32_t w, c;
c = EQ(tw, 0);
w = x[xlen];
tw = MUX(c, w, tw);
twk = MUX(c, (uint32_t)xlen, twk);
}
return (twk << 4) + BIT_LENGTH(tw);
}

480
src/int/i15_core.c
View file

@ -1,480 +0,0 @@
/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/*
* This file contains the core "big integer" functions for the i15
* implementation, that represents integers as sequences of 15-bit
* words.
*/
/* see inner.h */
uint32_t
br_i15_iszero(const uint16_t *x)
{
uint32_t z;
size_t u;
z = 0;
for (u = (x[0] + 15) >> 4; u > 0; u --) {
z |= x[u];
}
return ~(z | -z) >> 31;
}
/* see inner.h */
uint16_t
br_i15_ninv15(uint16_t x)
{
uint32_t y;
y = 2 - x;
y = MUL15(y, 2 - MUL15(x, y));
y = MUL15(y, 2 - MUL15(x, y));
y = MUL15(y, 2 - MUL15(x, y));
return MUX(x & 1, -y, 0) & 0x7FFF;
}
/* see inner.h */
uint32_t
br_i15_add(uint16_t *a, const uint16_t *b, uint32_t ctl)
{
uint32_t cc;
size_t u, m;
cc = 0;
m = (a[0] + 31) >> 4;
for (u = 1; u < m; u ++) {
uint32_t aw, bw, naw;
aw = a[u];
bw = b[u];
naw = aw + bw + cc;
cc = naw >> 15;
a[u] = MUX(ctl, naw & 0x7FFF, aw);
}
return cc;
}
/* see inner.h */
uint32_t
br_i15_sub(uint16_t *a, const uint16_t *b, uint32_t ctl)
{
uint32_t cc;
size_t u, m;
cc = 0;
m = (a[0] + 31) >> 4;
for (u = 1; u < m; u ++) {
uint32_t aw, bw, naw;
aw = a[u];
bw = b[u];
naw = aw - bw - cc;
cc = naw >> 31;
a[u] = MUX(ctl, naw & 0x7FFF, aw);
}
return cc;
}
/*
* Constant-time division. The divisor must not be larger than 16 bits,
* and the quotient must fit on 17 bits.
*/
static uint32_t
divrem16(uint32_t x, uint32_t d, uint32_t *r)
{
int i;
uint32_t q;
q = 0;
d <<= 16;
for (i = 16; i >= 0; i --) {
uint32_t ctl;
ctl = LE(d, x);
q |= ctl << i;
x -= (-ctl) & d;
d >>= 1;
}
if (r != NULL) {
*r = x;
}
return q;
}
/* see inner.h */
void
br_i15_muladd_small(uint16_t *x, uint16_t z, const uint16_t *m)
{
/*
* Constant-time: we accept to leak the exact bit length of the
* modulus m.
*/
unsigned m_bitlen, mblr;
size_t u, mlen;
uint32_t hi, a0, a, b, q;
uint32_t cc, tb, over, under;
/*
* Simple case: the modulus fits on one word.
*/
m_bitlen = m[0];
if (m_bitlen == 0) {
return;
}
if (m_bitlen <= 15) {
uint32_t rem;
divrem16(((uint32_t)x[1] << 15) | z, m[1], &rem);
x[1] = rem;
return;
}
mlen = (m_bitlen + 15) >> 4;
mblr = m_bitlen & 15;
/*
* Principle: we estimate the quotient (x*2^15+z)/m by
* doing a 30/15 division with the high words.
*
* Let:
* w = 2^15
* a = (w*a0 + a1) * w^N + a2
* b = b0 * w^N + b2
* such that:
* 0 <= a0 < w
* 0 <= a1 < w
* 0 <= a2 < w^N
* w/2 <= b0 < w
* 0 <= b2 < w^N
* a < w*b
* I.e. the two top words of a are a0:a1, the top word of b is
* b0, we ensured that b0 is "full" (high bit set), and a is
* such that the quotient q = a/b fits on one word (0 <= q < w).
*
* If a = b*q + r (with 0 <= r < q), then we can estimate q by
* using a division on the top words:
* a0*w + a1 = b0*u + v (with 0 <= v < b0)
* Then the following holds:
* 0 <= u <= w
* u-2 <= q <= u
*/
hi = x[mlen];
if (mblr == 0) {
a0 = x[mlen];
memmove(x + 2, x + 1, (mlen - 1) * sizeof *x);
x[1] = z;
a = (a0 << 15) + x[mlen];
b = m[mlen];
} else {
a0 = (x[mlen] << (15 - mblr)) | (x[mlen - 1] >> mblr);
memmove(x + 2, x + 1, (mlen - 1) * sizeof *x);
x[1] = z;
a = (a0 << 15) | (((x[mlen] << (15 - mblr))
| (x[mlen - 1] >> mblr)) & 0x7FFF);
b = (m[mlen] << (15 - mblr)) | (m[mlen - 1] >> mblr);
}
q = divrem16(a, b, NULL);
/*
* We computed an estimate for q, but the real one may be q,
* q-1 or q-2; moreover, the division may have returned a value
* 8000 or even 8001 if the two high words were identical, and
* we want to avoid values beyond 7FFF. We thus adjust q so
* that the "true" multiplier will be q+1, q or q-1, and q is
* in the 0000..7FFF range.
*/
q = MUX(EQ(b, a0), 0x7FFF, q - 1 + ((q - 1) >> 31));
/*
* We subtract q*m from x (x has an extra high word of value 'hi').
* Since q may be off by 1 (in either direction), we may have to
* add or subtract m afterwards.
*
* The 'tb' flag will be true (1) at the end of the loop if the
* result is greater than or equal to the modulus (not counting
* 'hi' or the carry).
*/
cc = 0;
tb = 1;
for (u = 1; u <= mlen; u ++) {
uint32_t mw, zl, xw, nxw;
mw = m[u];
zl = MUL15(mw, q) + cc;
cc = zl >> 15;
zl &= 0x7FFF;
xw = x[u];
nxw = xw - zl;
cc += nxw >> 31;
nxw &= 0x7FFF;
x[u] = nxw;
tb = MUX(EQ(nxw, mw), tb, GT(nxw, mw));
}
/*
* If we underestimated q, then either cc < hi (one extra bit
* beyond the top array word), or cc == hi and tb is true (no
* extra bit, but the result is not lower than the modulus).
*
* If we overestimated q, then cc > hi.
*/
over = GT(cc, hi);
under = ~over & (tb | LT(cc, hi));
br_i15_add(x, m, over);
br_i15_sub(x, m, under);
}
/* see inner.h */
void
br_i15_montymul(uint16_t *d, const uint16_t *x, const uint16_t *y,
const uint16_t *m, uint16_t m0i)
{
size_t len, len4, u, v;
uint32_t dh;
len = (m[0] + 15) >> 4;
len4 = len & ~(size_t)3;
br_i15_zero(d, m[0]);
dh = 0;
for (u = 0; u < len; u ++) {
uint32_t f, xu, r, zh;
xu = x[u + 1];
f = MUL15((d[1] + MUL15(x[u + 1], y[1])) & 0x7FFF, m0i)
& 0x7FFF;
r = 0;
for (v = 0; v < len4; v += 4) {
uint32_t z;
z = d[v + 1] + MUL15(xu, y[v + 1])
+ MUL15(f, m[v + 1]) + r;
r = z >> 15;
d[v + 0] = z & 0x7FFF;
z = d[v + 2] + MUL15(xu, y[v + 2])
+ MUL15(f, m[v + 2]) + r;
r = z >> 15;
d[v + 1] = z & 0x7FFF;
z = d[v + 3] + MUL15(xu, y[v + 3])
+ MUL15(f, m[v + 3]) + r;
r = z >> 15;
d[v + 2] = z & 0x7FFF;
z = d[v + 4] + MUL15(xu, y[v + 4])
+ MUL15(f, m[v + 4]) + r;
r = z >> 15;
d[v + 3] = z & 0x7FFF;
}
for (; v < len; v ++) {
uint32_t z;
z = d[v + 1] + MUL15(xu, y[v + 1])
+ MUL15(f, m[v + 1]) + r;
r = z >> 15;
d[v + 0] = z & 0x7FFF;
}
zh = dh + r;
d[len] = zh & 0x7FFF;
dh = zh >> 15;
}
/*
* Restore the bit length (it was overwritten in the loop above).
*/
d[0] = m[0];
/*
* d[] may be greater than m[], but it is still lower than twice
* the modulus.
*/
br_i15_sub(d, m, NEQ(dh, 0) | NOT(br_i15_sub(d, m, 0)));
}
/* see inner.h */
void
br_i15_to_monty(uint16_t *x, const uint16_t *m)
{
unsigned k;
for (k = (m[0] + 15) >> 4; k > 0; k --) {
br_i15_muladd_small(x, 0, m);
}
}
/* see inner.h */
void
br_i15_modpow(uint16_t *x,
const unsigned char *e, size_t elen,
const uint16_t *m, uint16_t m0i, uint16_t *t1, uint16_t *t2)
{
size_t mlen;
unsigned k;
mlen = ((m[0] + 31) >> 4) * sizeof m[0];
memcpy(t1, x, mlen);
br_i15_to_monty(t1, m);
br_i15_zero(x, m[0]);
x[1] = 1;
for (k = 0; k < ((unsigned)elen << 3); k ++) {
uint32_t ctl;
ctl = (e[elen - 1 - (k >> 3)] >> (k & 7)) & 1;
br_i15_montymul(t2, x, t1, m, m0i);
CCOPY(ctl, x, t2, mlen);
br_i15_montymul(t2, t1, t1, m, m0i);
memcpy(t1, t2, mlen);
}
}
/* see inner.h */
void
br_i15_encode(void *dst, size_t len, const uint16_t *x)
{
unsigned char *buf;
size_t u, xlen;
uint32_t acc;
int acc_len;
xlen = (x[0] + 15) >> 4;
if (xlen == 0) {
memset(dst, 0, len);
return;
}
u = 1;
acc = 0;
acc_len = 0;
buf = dst;
while (len -- > 0) {
if (acc_len < 8) {
if (u <= xlen) {
acc += (uint32_t)x[u ++] << acc_len;
}
acc_len += 15;
}
buf[len] = (unsigned char)acc;
acc >>= 8;
acc_len -= 8;
}
}
/* see inner.h */
uint32_t
br_i15_decode_mod(uint16_t *x, const void *src, size_t len, const uint16_t *m)
{
/*
* Two-pass algorithm: in the first pass, we determine whether the
* value fits; in the second pass, we do the actual write.
*
* During the first pass, 'r' contains the comparison result so
* far:
* 0x00000000 value is equal to the modulus
* 0x00000001 value is greater than the modulus
* 0xFFFFFFFF value is lower than the modulus
*
* Since we iterate starting with the least significant bytes (at
* the end of src[]), each new comparison overrides the previous
* except when the comparison yields 0 (equal).
*
* During the second pass, 'r' is either 0xFFFFFFFF (value fits)
* or 0x00000000 (value does not fit).
*
* We must iterate over all bytes of the source, _and_ possibly
* some extra virutal bytes (with value 0) so as to cover the
* complete modulus as well. We also add 4 such extra bytes beyond
* the modulus length because it then guarantees that no accumulated
* partial word remains to be processed.
*/
const unsigned char *buf;
size_t mlen, tlen;
int pass;
uint32_t r;
buf = src;
mlen = (m[0] + 15) >> 4;
tlen = (mlen << 1);
if (tlen < len) {
tlen = len;
}
tlen += 4;
r = 0;
for (pass = 0; pass < 2; pass ++) {
size_t u, v;
uint32_t acc;
int acc_len;
v = 1;
acc = 0;
acc_len = 0;
for (u = 0; u < tlen; u ++) {
uint32_t b;
if (u < len) {
b = buf[len - 1 - u];
} else {
b = 0;
}
acc |= (b << acc_len);
acc_len += 8;
if (acc_len >= 15) {
uint32_t xw;
xw = acc & (uint32_t)0x7FFF;
acc_len -= 15;
acc = b >> (8 - acc_len);
if (v <= mlen) {
if (pass) {
x[v] = r & xw;
} else {
uint32_t cc;
cc = (uint32_t)CMP(xw, m[v]);
r = MUX(EQ(cc, 0), r, cc);
}
} else {
if (!pass) {
r = MUX(EQ(xw, 0), r, 1);
}
}
v ++;
}
}
/*
* When we reach this point at the end of the first pass:
* r is either 0, 1 or -1; we want to set r to 0 if it
* is equal to 0 or 1, and leave it to -1 otherwise.
*
* When we reach this point at the end of the second pass:
* r is either 0 or -1; we want to leave that value
* untouched. This is a subcase of the previous.
*/
r >>= 1;
r |= (r << 1);
}
x[0] = m[0];
return r & (uint32_t)1;
}

124
src/int/i15_decmod.c Normal file
View file

@ -0,0 +1,124 @@
/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/* see inner.h */
uint32_t
br_i15_decode_mod(uint16_t *x, const void *src, size_t len, const uint16_t *m)
{
/*
* Two-pass algorithm: in the first pass, we determine whether the
* value fits; in the second pass, we do the actual write.
*
* During the first pass, 'r' contains the comparison result so
* far:
* 0x00000000 value is equal to the modulus
* 0x00000001 value is greater than the modulus
* 0xFFFFFFFF value is lower than the modulus
*
* Since we iterate starting with the least significant bytes (at
* the end of src[]), each new comparison overrides the previous
* except when the comparison yields 0 (equal).
*
* During the second pass, 'r' is either 0xFFFFFFFF (value fits)
* or 0x00000000 (value does not fit).
*
* We must iterate over all bytes of the source, _and_ possibly
* some extra virutal bytes (with value 0) so as to cover the
* complete modulus as well. We also add 4 such extra bytes beyond
* the modulus length because it then guarantees that no accumulated
* partial word remains to be processed.
*/
const unsigned char *buf;
size_t mlen, tlen;
int pass;
uint32_t r;
buf = src;
mlen = (m[0] + 15) >> 4;
tlen = (mlen << 1);
if (tlen < len) {
tlen = len;
}
tlen += 4;
r = 0;
for (pass = 0; pass < 2; pass ++) {
size_t u, v;
uint32_t acc;
int acc_len;
v = 1;
acc = 0;
acc_len = 0;
for (u = 0; u < tlen; u ++) {
uint32_t b;
if (u < len) {
b = buf[len - 1 - u];
} else {
b = 0;
}
acc |= (b << acc_len);
acc_len += 8;
if (acc_len >= 15) {
uint32_t xw;
xw = acc & (uint32_t)0x7FFF;
acc_len -= 15;
acc = b >> (8 - acc_len);
if (v <= mlen) {
if (pass) {
x[v] = r & xw;
} else {
uint32_t cc;
cc = (uint32_t)CMP(xw, m[v]);
r = MUX(EQ(cc, 0), r, cc);
}
} else {
if (!pass) {
r = MUX(EQ(xw, 0), r, 1);
}
}
v ++;
}
}
/*
* When we reach this point at the end of the first pass:
* r is either 0, 1 or -1; we want to set r to 0 if it
* is equal to 0 or 1, and leave it to -1 otherwise.
*
* When we reach this point at the end of the second pass:
* r is either 0 or -1; we want to leave that value
* untouched. This is a subcase of the previous.
*/
r >>= 1;
r |= (r << 1);
}
x[0] = m[0];
return r & (uint32_t)1;
}

54
src/ec/ec_prime_i31_secp521r1.c → src/int/i15_decode.c
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
@ -24,27 +24,33 @@
#include "inner.h"
static const uint32_t P521_P[] = {
0x00000219,
0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF,
0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF,
0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF,
0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF, 0x7FFFFFFF,
0x01FFFFFF
};
static const uint32_t P521_B[] = {
0x00000219,
0x540FC00A, 0x228FEA35, 0x2C34F1EF, 0x67BF107A,
0x46FC1CD5, 0x1605E9DD, 0x6937B165, 0x272A3D8F,
0x42785586, 0x44C8C778, 0x15F3B8B4, 0x64B73366,
0x03BA8B69, 0x0D05B42A, 0x21F929A2, 0x2C31C393,
0x00654FAE
};
/* see inner.h */
const br_ec_prime_i31_curve br_ec_prime_i31_secp521r1 = {
P521_P,
P521_B,
0x00000001
};
void
br_i15_decode(uint16_t *x, const void *src, size_t len)
{
const unsigned char *buf;
size_t v;
uint32_t acc;
int acc_len;
buf = src;
v = 1;
acc = 0;
acc_len = 0;
while (len -- > 0) {
uint32_t b;
b = buf[len];
acc |= (b << acc_len);
acc_len += 8;
if (acc_len >= 15) {
x[v ++] = acc & 0x7FFF;
acc_len -= 15;
acc >>= 15;
}
}
if (acc_len != 0) {
x[v ++] = acc;
}
x[0] = br_i15_bit_length(x + 1, v - 1);
}

73
src/int/i15_ext2.c → src/int/i15_decred.c
View file

@ -24,11 +24,6 @@
#include "inner.h"
/*
* This file contains some additional functions for "i15" big integers.
* These functions are needed to support RSA.
*/
/* see inner.h */
void
br_i15_decode_reduce(uint16_t *x,
@ -103,71 +98,3 @@ br_i15_decode_reduce(uint16_t *x,
br_i15_muladd_small(x, acc, m);
}
}
/* see inner.h */
void
br_i15_reduce(uint16_t *x, const uint16_t *a, const uint16_t *m)
{
uint32_t m_bitlen, a_bitlen;
size_t mlen, alen, u;
m_bitlen = m[0];
mlen = (m_bitlen + 15) >> 4;
x[0] = m_bitlen;
if (m_bitlen == 0) {
return;
}
/*
* If the source is shorter, then simply copy all words from a[]
* and zero out the upper words.
*/
a_bitlen = a[0];
alen = (a_bitlen + 15) >> 4;
if (a_bitlen < m_bitlen) {
memcpy(x + 1, a + 1, alen * sizeof *a);
for (u = alen; u < mlen; u ++) {
x[u + 1] = 0;
}
return;
}
/*
* The source length is at least equal to that of the modulus.
* We must thus copy N-1 words, and input the remaining words
* one by one.
*/
memcpy(x + 1, a + 2 + (alen - mlen), (mlen - 1) * sizeof *a);
x[mlen] = 0;
for (u = 1 + alen - mlen; u > 0; u --) {
br_i15_muladd_small(x, a[u], m);
}
}
/* see inner.h */
void
br_i15_mulacc(uint16_t *d, const uint16_t *a, const uint16_t *b)
{
size_t alen, blen, u;
alen = (a[0] + 15) >> 4;
blen = (b[0] + 15) >> 4;
d[0] = a[0] + b[0];
for (u = 0; u < blen; u ++) {
uint32_t f;
size_t v;
uint32_t cc;
f = b[1 + u];
cc = 0;
for (v = 0; v < alen; v ++) {
uint32_t z;
z = (uint32_t)d[1 + u + v] + MUL15(f, a[1 + v]) + cc;
cc = z >> 15;
d[1 + u + v] = z & 0x7FFF;
}
d[1 + u + alen] = cc;
}
}

56
src/int/i15_encode.c Normal file
View file

@ -0,0 +1,56 @@
/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/* see inner.h */
void
br_i15_encode(void *dst, size_t len, const uint16_t *x)
{
unsigned char *buf;
size_t u, xlen;
uint32_t acc;
int acc_len;
xlen = (x[0] + 15) >> 4;
if (xlen == 0) {
memset(dst, 0, len);
return;
}
u = 1;
acc = 0;
acc_len = 0;
buf = dst;
while (len -- > 0) {
if (acc_len < 8) {
if (u <= xlen) {
acc += (uint32_t)x[u ++] << acc_len;
}
acc_len += 15;
}
buf[len] = (unsigned char)acc;
acc >>= 8;
acc_len -= 8;
}
}

77
src/int/i15_ext1.c → src/int/i15_fmont.c
View file

@ -24,83 +24,6 @@
#include "inner.h"
/*
* This file contains some additional functions for "i15" big integers.
* These functions are needed to support ECDSA.
*/
/* see inner.h */
void
br_i15_rshift(uint16_t *x, int count)
{
size_t u, len;
unsigned r;
len = (x[0] + 15) >> 4;
if (len == 0) {
return;
}
r = x[1] >> count;
for (u = 2; u <= len; u ++) {
unsigned w;
w = x[u];
x[u - 1] = ((w << (15 - count)) | r) & 0x7FFF;
r = w >> count;
}
x[len] = r;
}
/* see inner.h */
uint32_t
br_i15_bit_length(uint16_t *x, size_t xlen)
{
uint32_t tw, twk;
tw = 0;
twk = 0;
while (xlen -- > 0) {
uint32_t w, c;
c = EQ(tw, 0);
w = x[xlen];
tw = MUX(c, w, tw);
twk = MUX(c, (uint32_t)xlen, twk);
}
return (twk << 4) + BIT_LENGTH(tw);
}
/* see inner.h */
void
br_i15_decode(uint16_t *x, const void *src, size_t len)
{
const unsigned char *buf;
size_t v;
uint32_t acc;
int acc_len;
buf = src;
v = 1;
acc = 0;
acc_len = 0;
while (len -- > 0) {
uint32_t b;
b = buf[len];
acc |= (b << acc_len);
acc_len += 8;
if (acc_len >= 15) {
x[v ++] = acc & 0x7FFF;
acc_len -= 15;
acc >>= 15;
}
}
if (acc_len != 0) {
x[v ++] = acc;
}
x[0] = br_i15_bit_length(x + 1, v - 1);
}
/* see inner.h */
void
br_i15_from_monty(uint16_t *x, const uint16_t *m, uint16_t m0i)

39
src/int/i15_iszero.c Normal file
View file

@ -0,0 +1,39 @@
/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/* see inner.h */
uint32_t
br_i15_iszero(const uint16_t *x)
{
uint32_t z;
size_t u;
z = 0;
for (u = (x[0] + 15) >> 4; u > 0; u --) {
z |= x[u];
}
return ~(z | -z) >> 31;
}

50
src/int/i15_modpow.c Normal file
View file

@ -0,0 +1,50 @@
/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/* see inner.h */
void
br_i15_modpow(uint16_t *x,
const unsigned char *e, size_t elen,
const uint16_t *m, uint16_t m0i, uint16_t *t1, uint16_t *t2)
{
size_t mlen;
unsigned k;
mlen = ((m[0] + 31) >> 4) * sizeof m[0];
memcpy(t1, x, mlen);
br_i15_to_monty(t1, m);
br_i15_zero(x, m[0]);
x[1] = 1;
for (k = 0; k < ((unsigned)elen << 3); k ++) {
uint32_t ctl;
ctl = (e[elen - 1 - (k >> 3)] >> (k & 7)) & 1;
br_i15_montymul(t2, x, t1, m, m0i);
CCOPY(ctl, x, t2, mlen);
br_i15_montymul(t2, t1, t1, m, m0i);
memcpy(t1, t2, mlen);
}
}

91
src/int/i15_montmul.c Normal file
View file

@ -0,0 +1,91 @@
/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/* see inner.h */
void
br_i15_montymul(uint16_t *d, const uint16_t *x, const uint16_t *y,
const uint16_t *m, uint16_t m0i)
{
size_t len, len4, u, v;
uint32_t dh;
len = (m[0] + 15) >> 4;
len4 = len & ~(size_t)3;
br_i15_zero(d, m[0]);
dh = 0;
for (u = 0; u < len; u ++) {
uint32_t f, xu, r, zh;
xu = x[u + 1];
f = MUL15((d[1] + MUL15(x[u + 1], y[1])) & 0x7FFF, m0i)
& 0x7FFF;
r = 0;
for (v = 0; v < len4; v += 4) {
uint32_t z;
z = d[v + 1] + MUL15(xu, y[v + 1])
+ MUL15(f, m[v + 1]) + r;
r = z >> 15;
d[v + 0] = z & 0x7FFF;
z = d[v + 2] + MUL15(xu, y[v + 2])
+ MUL15(f, m[v + 2]) + r;
r = z >> 15;
d[v + 1] = z & 0x7FFF;
z = d[v + 3] + MUL15(xu, y[v + 3])
+ MUL15(f, m[v + 3]) + r;
r = z >> 15;
d[v + 2] = z & 0x7FFF;
z = d[v + 4] + MUL15(xu, y[v + 4])
+ MUL15(f, m[v + 4]) + r;
r = z >> 15;
d[v + 3] = z & 0x7FFF;
}
for (; v < len; v ++) {
uint32_t z;
z = d[v + 1] + MUL15(xu, y[v + 1])
+ MUL15(f, m[v + 1]) + r;
r = z >> 15;
d[v + 0] = z & 0x7FFF;
}
zh = dh + r;
d[len] = zh & 0x7FFF;
dh = zh >> 15;
}
/*
* Restore the bit length (it was overwritten in the loop above).
*/
d[0] = m[0];
/*
* d[] may be greater than m[], but it is still lower than twice
* the modulus.
*/
br_i15_sub(d, m, NEQ(dh, 0) | NOT(br_i15_sub(d, m, 0)));
}

52
src/int/i15_mulacc.c Normal file
View file

@ -0,0 +1,52 @@
/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/* see inner.h */
void
br_i15_mulacc(uint16_t *d, const uint16_t *a, const uint16_t *b)
{
size_t alen, blen, u;
alen = (a[0] + 15) >> 4;
blen = (b[0] + 15) >> 4;
d[0] = a[0] + b[0];
for (u = 0; u < blen; u ++) {
uint32_t f;
size_t v;
uint32_t cc;
f = b[1 + u];
cc = 0;
for (v = 0; v < alen; v ++) {
uint32_t z;
z = (uint32_t)d[1 + u + v] + MUL15(f, a[1 + v]) + cc;
cc = z >> 15;
d[1 + u + v] = z & 0x7FFF;
}
d[1 + u + alen] = cc;
}
}

173
src/int/i15_muladd.c Normal file
View file

@ -0,0 +1,173 @@
/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/*
* Constant-time division. The divisor must not be larger than 16 bits,
* and the quotient must fit on 17 bits.
*/
static uint32_t
divrem16(uint32_t x, uint32_t d, uint32_t *r)
{
int i;
uint32_t q;
q = 0;
d <<= 16;
for (i = 16; i >= 0; i --) {
uint32_t ctl;
ctl = LE(d, x);
q |= ctl << i;
x -= (-ctl) & d;
d >>= 1;
}
if (r != NULL) {
*r = x;
}
return q;
}
/* see inner.h */
void
br_i15_muladd_small(uint16_t *x, uint16_t z, const uint16_t *m)
{
/*
* Constant-time: we accept to leak the exact bit length of the
* modulus m.
*/
unsigned m_bitlen, mblr;
size_t u, mlen;
uint32_t hi, a0, a, b, q;
uint32_t cc, tb, over, under;
/*
* Simple case: the modulus fits on one word.
*/
m_bitlen = m[0];
if (m_bitlen == 0) {
return;
}
if (m_bitlen <= 15) {
uint32_t rem;
divrem16(((uint32_t)x[1] << 15) | z, m[1], &rem);
x[1] = rem;
return;
}
mlen = (m_bitlen + 15) >> 4;
mblr = m_bitlen & 15;
/*
* Principle: we estimate the quotient (x*2^15+z)/m by
* doing a 30/15 division with the high words.
*
* Let:
* w = 2^15
* a = (w*a0 + a1) * w^N + a2
* b = b0 * w^N + b2
* such that:
* 0 <= a0 < w
* 0 <= a1 < w
* 0 <= a2 < w^N
* w/2 <= b0 < w
* 0 <= b2 < w^N
* a < w*b
* I.e. the two top words of a are a0:a1, the top word of b is
* b0, we ensured that b0 is "full" (high bit set), and a is
* such that the quotient q = a/b fits on one word (0 <= q < w).
*
* If a = b*q + r (with 0 <= r < q), then we can estimate q by
* using a division on the top words:
* a0*w + a1 = b0*u + v (with 0 <= v < b0)
* Then the following holds:
* 0 <= u <= w
* u-2 <= q <= u
*/
hi = x[mlen];
if (mblr == 0) {
a0 = x[mlen];
memmove(x + 2, x + 1, (mlen - 1) * sizeof *x);
x[1] = z;
a = (a0 << 15) + x[mlen];
b = m[mlen];
} else {
a0 = (x[mlen] << (15 - mblr)) | (x[mlen - 1] >> mblr);
memmove(x + 2, x + 1, (mlen - 1) * sizeof *x);
x[1] = z;
a = (a0 << 15) | (((x[mlen] << (15 - mblr))
| (x[mlen - 1] >> mblr)) & 0x7FFF);
b = (m[mlen] << (15 - mblr)) | (m[mlen - 1] >> mblr);
}
q = divrem16(a, b, NULL);
/*
* We computed an estimate for q, but the real one may be q,
* q-1 or q-2; moreover, the division may have returned a value
* 8000 or even 8001 if the two high words were identical, and
* we want to avoid values beyond 7FFF. We thus adjust q so
* that the "true" multiplier will be q+1, q or q-1, and q is
* in the 0000..7FFF range.
*/
q = MUX(EQ(b, a0), 0x7FFF, q - 1 + ((q - 1) >> 31));
/*
* We subtract q*m from x (x has an extra high word of value 'hi').
* Since q may be off by 1 (in either direction), we may have to
* add or subtract m afterwards.
*
* The 'tb' flag will be true (1) at the end of the loop if the
* result is greater than or equal to the modulus (not counting
* 'hi' or the carry).
*/
cc = 0;
tb = 1;
for (u = 1; u <= mlen; u ++) {
uint32_t mw, zl, xw, nxw;
mw = m[u];
zl = MUL15(mw, q) + cc;
cc = zl >> 15;
zl &= 0x7FFF;
xw = x[u];
nxw = xw - zl;
cc += nxw >> 31;
nxw &= 0x7FFF;
x[u] = nxw;
tb = MUX(EQ(nxw, mw), tb, GT(nxw, mw));
}
/*
* If we underestimated q, then either cc < hi (one extra bit
* beyond the top array word), or cc == hi and tb is true (no
* extra bit, but the result is not lower than the modulus).
*
* If we overestimated q, then cc > hi.
*/
over = GT(cc, hi);
under = ~over & (tb | LT(cc, hi));
br_i15_add(x, m, over);
br_i15_sub(x, m, under);
}

38
src/int/i15_ninv15.c Normal file
View file

@ -0,0 +1,38 @@
/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/* see inner.h */
uint16_t
br_i15_ninv15(uint16_t x)
{
uint32_t y;
y = 2 - x;
y = MUL15(y, 2 - MUL15(x, y));
y = MUL15(y, 2 - MUL15(x, y));
y = MUL15(y, 2 - MUL15(x, y));
return MUX(x & 1, -y, 0) & 0x7FFF;
}

66
src/int/i15_reduce.c Normal file
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@ -0,0 +1,66 @@
/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/* see inner.h */
void
br_i15_reduce(uint16_t *x, const uint16_t *a, const uint16_t *m)
{
uint32_t m_bitlen, a_bitlen;
size_t mlen, alen, u;
m_bitlen = m[0];
mlen = (m_bitlen + 15) >> 4;
x[0] = m_bitlen;
if (m_bitlen == 0) {
return;
}
/*
* If the source is shorter, then simply copy all words from a[]
* and zero out the upper words.
*/
a_bitlen = a[0];
alen = (a_bitlen + 15) >> 4;
if (a_bitlen < m_bitlen) {
memcpy(x + 1, a + 1, alen * sizeof *a);
for (u = alen; u < mlen; u ++) {
x[u + 1] = 0;
}
return;
}
/*
* The source length is at least equal to that of the modulus.
* We must thus copy N-1 words, and input the remaining words
* one by one.
*/
memcpy(x + 1, a + 2 + (alen - mlen), (mlen - 1) * sizeof *a);
x[mlen] = 0;
for (u = 1 + alen - mlen; u > 0; u --) {
br_i15_muladd_small(x, a[u], m);
}
}

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/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/* see inner.h */
void
br_i15_rshift(uint16_t *x, int count)
{
size_t u, len;
unsigned r;
len = (x[0] + 15) >> 4;
if (len == 0) {
return;
}
r = x[1] >> count;
for (u = 2; u <= len; u ++) {
unsigned w;
w = x[u];
x[u - 1] = ((w << (15 - count)) | r) & 0x7FFF;
r = w >> count;
}
x[len] = r;
}

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/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/* see inner.h */
uint32_t
br_i15_sub(uint16_t *a, const uint16_t *b, uint32_t ctl)
{
uint32_t cc;
size_t u, m;
cc = 0;
m = (a[0] + 31) >> 4;
for (u = 1; u < m; u ++) {
uint32_t aw, bw, naw;
aw = a[u];
bw = b[u];
naw = aw - bw - cc;
cc = naw >> 31;
a[u] = MUX(ctl, naw & 0x7FFF, aw);
}
return cc;
}

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/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "inner.h"
/* see inner.h */
void
br_i15_to_monty(uint16_t *x, const uint16_t *m)
{
unsigned k;
for (k = (m[0] + 15) >> 4; k > 0; k --) {
br_i15_muladd_small(x, 0, m);
}
}