ref: c8a5f3d79cd198facac5491f20249f6945db62b9
dir: /lib/crypto/curve25519.myr/
/* Copyright 2008, Google Inc.
* Translated to Myrddin by Ori Bernstein in 2018
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* curve25519: Curve25519 elliptic curve, public key function
*
* http://code.google.com/p/curve25519-donna/
*
* Adam Langley <[email protected]>
*
* Derived from public domain C code by Daniel J. Bernstein <[email protected]>
*
* More information about curve25519 can be found here
* http://cr.yp.to/ecdh.html
*
* djb's sample implementation of curve25519 is written in a special assembly
* language called qhasm and uses the floating point registers.
*
* This is, almost, a clean room reimplementation from the curve25519 paper. It
* uses many of the tricks described therein. Only the crecip function is taken
* from the sample implementation.
*/
use std
pkg crypto =
const Nine : byte[:]
const curve25519 : (pub : byte[:/*32*/], secret : byte[:/*32*/], basepoint : byte[:/*32*/] -> void)
;;
const Nine = \
"\x09\x00\x00\x00\x00\x00\x00\x00" \
"\x00\x00\x00\x00\x00\x00\x00\x00" \
"\x00\x00\x00\x00\x00\x00\x00\x00" \
"\x00\x00\x00\x00\x00\x00\x00\x00"
/* Sum two numbers: out += in */
const fsum = {out, in
for var i = 0; i < 10; i += 2
out[0 + i] = out[0 + i] + in[0 + i]
out[1 + i] = out[1 + i] + in[1 + i]
;;
}
/* Find the difference of two numbers: out = in - out
* (note the order of the arguments!)
*/
const fdiff = {out, in
for var i = 0; i < 10; ++i
out[i] = in[i] - out[i]
;;
}
/* Multiply a number my a scalar: out = in * scalar */
const fscalarproduct = {out, in, scalar
for var i = 0; i < 10; ++i
out[i] = in[i] * scalar
;;
}
/* Multiply two numbers: out = in2 * in
*
* out must be distinct to both ins. The ins are reduced coefficient
* form, the out is not.
*/
const fproduct = {output, in2, in
output[0] = in2[0] * in[0]
output[1] = in2[0] * in[1] + \
in2[1] * in[0]
output[2] = 2 * in2[1] * in[1] + \
in2[0] * in[2] + \
in2[2] * in[0]
output[3] = in2[1] * in[2] + \
in2[2] * in[1] + \
in2[0] * in[3] + \
in2[3] * in[0]
output[4] = in2[2] * in[2] + \
2 * (in2[1] * in[3] + \
in2[3] * in[1]) + \
in2[0] * in[4] + \
in2[4] * in[0]
output[5] = in2[2] * in[3] + \
in2[3] * in[2] + \
in2[1] * in[4] + \
in2[4] * in[1] + \
in2[0] * in[5] + \
in2[5] * in[0]
output[6] = 2 * (in2[3] * in[3] + \
in2[1] * in[5] + \
in2[5] * in[1]) + \
in2[2] * in[4] + \
in2[4] * in[2] + \
in2[0] * in[6] + \
in2[6] * in[0]
output[7] = in2[3] * in[4] + \
in2[4] * in[3] + \
in2[2] * in[5] + \
in2[5] * in[2] + \
in2[1] * in[6] + \
in2[6] * in[1] + \
in2[0] * in[7] + \
in2[7] * in[0]
output[8] = in2[4] * in[4] + \
2 * (in2[3] * in[5] + \
in2[5] * in[3] + \
in2[1] * in[7] + \
in2[7] * in[1]) + \
in2[2] * in[6] + \
in2[6] * in[2] + \
in2[0] * in[8] + \
in2[8] * in[0]
output[9] = in2[4] * in[5] + \
in2[5] * in[4] + \
in2[3] * in[6] + \
in2[6] * in[3] + \
in2[2] * in[7] + \
in2[7] * in[2] + \
in2[1] * in[8] + \
in2[8] * in[1] + \
in2[0] * in[9] + \
in2[9] * in[0]
output[10] = 2 * (in2[5] * in[5] + \
in2[3] * in[7] + \
in2[7] * in[3] + \
in2[1] * in[9] + \
in2[9] * in[1]) + \
in2[4] * in[6] + \
in2[6] * in[4] + \
in2[2] * in[8] + \
in2[8] * in[2]
output[11] = in2[5] * in[6] + \
in2[6] * in[5] + \
in2[4] * in[7] + \
in2[7] * in[4] + \
in2[3] * in[8] + \
in2[8] * in[3] + \
in2[2] * in[9] + \
in2[9] * in[2]
output[12] = in2[6] * in[6] + \
2 * (in2[5] * in[7] + \
in2[7] * in[5] + \
in2[3] * in[9] + \
in2[9] * in[3]) + \
in2[4] * in[8] + \
in2[8] * in[4]
output[13] = in2[6] * in[7] + \
in2[7] * in[6] + \
in2[5] * in[8] + \
in2[8] * in[5] + \
in2[4] * in[9] + \
in2[9] * in[4]
output[14] = 2 * (in2[7] * in[7] + \
in2[5] * in[9] + \
in2[9] * in[5]) + \
in2[6] * in[8] + \
in2[8] * in[6]
output[15] = in2[7] * in[8] + \
in2[8] * in[7] + \
in2[6] * in[9] + \
in2[9] * in[6]
output[16] = in2[8] * in[8] + \
2 * (in2[7] * in[9] + \
in2[9] * in[7])
output[17] = in2[8] * in[9] + \
in2[9] * in[8]
output[18] = 2 * in2[9] * in[9]
}
/* Reduce a long form to a short form by taking the input mod 2^255 - 19. */
const freducedegree= {output
output[8] += output[18] << 4;
output[8] += output[18] << 1;
output[8] += output[18];
output[7] += output[17] << 4;
output[7] += output[17] << 1;
output[7] += output[17];
output[6] += output[16] << 4;
output[6] += output[16] << 1;
output[6] += output[16];
output[5] += output[15] << 4;
output[5] += output[15] << 1;
output[5] += output[15];
output[4] += output[14] << 4;
output[4] += output[14] << 1;
output[4] += output[14];
output[3] += output[13] << 4;
output[3] += output[13] << 1;
output[3] += output[13];
output[2] += output[12] << 4;
output[2] += output[12] << 1;
output[2] += output[12];
output[1] += output[11] << 4;
output[1] += output[11] << 1;
output[1] += output[11];
output[0] += output[10] << 4;
output[0] += output[10] << 1;
output[0] += output[10];
}
/* Reduce all coeff of the short form in to be -2**25 <= x <= 2**25
*/
const freducecoeff = {out
var over
var hi, sgn, round
out[10] = 0;
for var i = 0; i < 10; i += 2
/* out[i]/2^26, constant time */
hi = ((out[i] : uint64) >> 32 : uint32)
sgn = (hi : int32) >> 31
round = (sgn : uint32) >> 6;
/* Should return v / (1<<26) */
over = (out[i] + (round : int64)) >> 26
out[i] -= over << 26;
out[i+1] += over;
hi = ((out[i + 1] : uint64) >> 32 : uint32)
sgn = (hi : int32) >> 31
round = (sgn : uint32) >> 7
/* Should return v / (1<<26) */
over = (out[i+1] + (round : int64)) >> 25
out[i+1] -= over << 25;
out[i+2] += over;
;;
/* Now |out[10]| < 2 ^ 38 and all other coefficients are reduced. */
out[0] += out[10] << 4
out[0] += out[10] << 1
out[0] += out[10];
out[10] = 0
/*
* Now out[1..9] are reduced, and |out[0]| < 2^26 + 19 * 2^38
* So |over| will be no more than 77825
*/
/* out[i]/2^26, constant time */
hi = ((out[0] : uint64) >> 32 : uint32)
sgn = (hi : int32) >> 31
round = (sgn : uint32) >> 6;
/* Should return v / (1<<26) */
over = (out[0] + (round : int64)) >> 26
out[0] -= over << 26;
out[1] += over;
/*
* Now out[0,2..9] are reduced, and |out[1]| < 2^25 + 77825
* So |over| will be no more than 1.
* out[1] fits in 32 bits, so we can use div_s32_by_2_25 here.
*/
/*
* Finally, out[0,1,3..9] are reduced, and out[2] is "nearly reduced":
* we have |out[2]| <= 2^26. This is good enough for all of our math,
* but it will require an extra freduce_coefficients before fcontract.
*/
}
/* A helpful wrapper around fproduct: out = in * in2.
*
* out must be distinct to both ins. The out is reduced degree and
* reduced coefficient.
*/
const fmul = {out, in, in2
var t : int64[19]
fproduct(t[:], in, in2)
freducedegree(t[:])
freducecoeff(t[:])
std.slcp(out[:10], t[:10])
}
const fsquareinner = {out, in
var tmp : int64
out[0] = in[0] * in[0]
out[1] = 2 * in[0] * in[1]
out[2] = 2 * (in[1] * in[1] + \
in[0] * in[2])
out[3] = 2 * (in[1] * in[2] + \
in[0] * in[3])
out[4] = in[2] * in[2] + \
4 * in[1] * in[3] + \
2 * in[0] * in[4]
out[5] = 2 * (in[2] * in[3] + \
in[1] * in[4] + \
in[0] * in[5])
out[6] = 2 * (in[3] * in[3] + \
in[2] * in[4] + \
in[0] * in[6] + \
2 * in[1] * in[5])
out[7] = 2 * (in[3] * in[4] + \
in[2] * in[5] + \
in[1] * in[6] + \
in[0] * in[7])
tmp = in[1] * in[7] + in[3] * in[5]
out[8] = in[4] * in[4] + \
2 * (in[2] * in[6] + \
in[0] * in[8] + \
2 * tmp)
out[9] = 2 * (in[4] * in[5] + \
in[3] * in[6] + \
in[2] * in[7] + \
in[1] * in[8] + \
in[0] * in[9])
tmp = in[3] * in[7] + in[1] * in[9]
out[10] = 2 * (in[5] * in[5] + \
in[4] * in[6] + \
in[2] * in[8] + \
2 * tmp)
out[11] = 2 * (in[5] * in[6] + \
in[4] * in[7] + \
in[3] * in[8] + \
in[2] * in[9])
out[12] = in[6] * in[6] + \
2 * (in[4] * in[8] + \
2 * (in[5] * in[7] + \
in[3] * in[9]))
out[13] = 2 * (in[6] * in[7] + \
in[5] * in[8] + \
in[4] * in[9])
out[14] = 2 * (in[7] * in[7] + \
in[6] * in[8] + \
2 * in[5] * in[9])
out[15] = 2 * (in[7] * in[8] + \
in[6] * in[9])
out[16] = in[8] * in[8] + \
4 * in[7] * in[9]
out[17] = 2 * in[8] * in[9]
out[18] = 2 * in[9] * in[9]
}
const fsquare = {out, in
var t : int64[19]
fsquareinner(t[:], in)
freducedegree(t[:])
freducecoeff(t[:])
std.slcp(out[:10], t[:10])
}
/* Take a little-endian, 32-byte number and expand it into polynomial form */
const fexpand = {out, in
/*
* #define F(n,start,shift,mask) \
* out[n] = (((in[start + 0] : int64) | \
* (in[start + 1] : int64) << 8 | \
* (in[start + 2] : int64) << 16 | \
* (in[start + 3] : int64) << 24) >> shift) & mask
* F(0, 0, 0, 0x3ffffff)
* F(1, 3, 2, 0x1ffffff)
* F(2, 6, 3, 0x3ffffff)
* F(3, 9, 5, 0x1ffffff)
* F(4, 12, 6, 0x3ffffff)
* F(5, 16, 0, 0x1ffffff)
* F(6, 19, 1, 0x3ffffff()
* F(7, 22, 3, 0x1ffffff)
* F(8, 25, 4, 0x3ffffff)
* F(9, 28, 6, 0x1ffffff)
* #undef F
*/
out[0] = (((in[0 + 0] : int64) | (in[0 + 1] : int64) << 8 | (in[0 + 2] : int64) << 16 | (in[0 + 3] : int64) << 24) >> 0) & 0x3ffffff
out[1] = (((in[3 + 0] : int64) | (in[3 + 1] : int64) << 8 | (in[3 + 2] : int64) << 16 | (in[3 + 3] : int64) << 24) >> 2) & 0x1ffffff
out[2] = (((in[6 + 0] : int64) | (in[6 + 1] : int64) << 8 | (in[6 + 2] : int64) << 16 | (in[6 + 3] : int64) << 24) >> 3) & 0x3ffffff
out[3] = (((in[9 + 0] : int64) | (in[9 + 1] : int64) << 8 | (in[9 + 2] : int64) << 16 | (in[9 + 3] : int64) << 24) >> 5) & 0x1ffffff
out[4] = (((in[12 + 0] : int64) | (in[12 + 1] : int64) << 8 | (in[12 + 2] : int64) << 16 | (in[12 + 3] : int64) << 24) >> 6) & 0x3ffffff
out[5] = (((in[16 + 0] : int64) | (in[16 + 1] : int64) << 8 | (in[16 + 2] : int64) << 16 | (in[16 + 3] : int64) << 24) >> 0) & 0x1ffffff
out[6] = (((in[19 + 0] : int64) | (in[19 + 1] : int64) << 8 | (in[19 + 2] : int64) << 16 | (in[19 + 3] : int64) << 24) >> 1) & 0x3ffffff
out[7] = (((in[22 + 0] : int64) | (in[22 + 1] : int64) << 8 | (in[22 + 2] : int64) << 16 | (in[22 + 3] : int64) << 24) >> 3) & 0x1ffffff
out[8] = (((in[25 + 0] : int64) | (in[25 + 1] : int64) << 8 | (in[25 + 2] : int64) << 16 | (in[25 + 3] : int64) << 24) >> 4) & 0x3ffffff
out[9] = (((in[28 + 0] : int64) | (in[28 + 1] : int64) << 8 | (in[28 + 2] : int64) << 16 | (in[28 + 3] : int64) << 24) >> 6) & 0x1ffffff
}
/* s32_eq returns 0xffffffff iff a == b and zero otherwise. */
const s32_eq = {a, b
a = ~(a ^ b)
a &= a << 16
a &= a << 8
a &= a << 4
a &= a << 2
a &= a << 1
-> a >> 31
}
/* s32_gte returns 0xffffffff if a >= b and zero otherwise, where a and b are
both non-negative. */
const s32_gte = {a, b
a -= b
/* a >= 0 iff a >= b. */
-> ~(a >> 31)
}
/* Take a fully reduced polynomial form number and contract it into a
* little-endian, 32-byte array
*/
const fcontract = {out : byte[:], in_limbs : int64[:]
var mask, carry
var in : int32[10]
for var i = 0; i < 10; i++
in[i] = (in_limbs[i] : int32)
;;
for var j = 0; j < 2; ++j
for var i = 0; i < 9; ++i
if (i & 1) == 1
/* This calculation is a time-invariant way to make in[i] positive
* by borrowing from the next-larger int64_t.
*/
mask = in[i] >> 31
carry = -((in[i] & mask) >> 25);
in[i+0] = in[i] + (carry << 25)
in[i+1] = in[i+1] - carry
else
mask = in[i] >> 31
carry = -((in[i] & mask) >> 26)
in[i+0] = in[i] + (carry << 26)
in[i+1] = in[i+1] - carry
;;
;;
mask = in[9] >> 31
carry = -((in[9] & mask) >> 25)
in[9] = in[9] + (carry << 25)
in[0] = in[0] - (carry * 19)
;;
/* The first borrow-propagation pass above ended with every int64_t
except (possibly) in[0] non-negative.
Since each in int64_t except in[0] is decreased by at most 1
by a borrow-propagation pass, the second borrow-propagation pass
could only have wrapped around to decrease in[0] again if the
first pass left in[0] negative *and* in[1] through in[9]
were all zero. In that case, in[1] is now 2^25 - 1, and this
last borrow-propagation step will leave in[1] non-negative.
*/
mask = in[0] >> 31
carry = -((in[0] & mask) >> 26)
in[0] = in[0] + (carry << 26)
in[1] = in[1] - carry
for var j = 0; j < 2; j++
for var i = 0; i < 9; i++
if (i & 1) == 1
carry = in[1] >> 25
in[i+0] &= 0x1ffffff
in[i+1] += carry
else
carry = in[i] >> 26
in[i+0] &= 0x3ffffff
in[i+1] += carry
;;
;;
carry = in[9] >> 25
in[9] &= 0x1ffffff
in[0] += (19 * carry)
;;
mask = s32_gte(in[0], 0x3ffffed)
for var i = 1; i < 10; i++
if (i & 1) == 1
mask &= s32_eq(in[i], 0x1ffffff)
else
mask &= s32_eq(in[i], 0x3ffffff)
;;
;;
in[0] -= (mask & 0x3ffffed)
for var i = 1; i < 10; i++
if (i & 1) == 1
in[i] -= (mask & 0x1ffffff)
else
in[i] -= (mask & 0x3ffffff)
;;
;;
/* Both passes through the above loop, plus the last 0-to-1 step, are
necessary: if in[9] is -1 and in[0] through in[8] are 0,
negative values will remain in the array until the end.
*/
in[1] <<= 2
in[2] <<= 3
in[3] <<= 5
in[4] <<= 6
in[6] <<= 1
in[7] <<= 3
in[8] <<= 4
in[9] <<= 6
out[0] = 0
out[16] = 0
out[ 0+0] |= (in[0] & 0xff : byte); out[ 0+1] = ((in[0] >> 8) & 0xff : byte); out[ 0+2] = ((in[0] >> 16) & 0xff : byte); out[ 0+3] = ((in[0] >> 24) & 0xff : byte)
out[ 3+0] |= (in[1] & 0xff : byte); out[ 3+1] = ((in[1] >> 8) & 0xff : byte); out[ 3+2] = ((in[1] >> 16) & 0xff : byte); out[ 3+3] = ((in[1] >> 24) & 0xff : byte)
out[ 6+0] |= (in[2] & 0xff : byte); out[ 6+1] = ((in[2] >> 8) & 0xff : byte); out[ 6+2] = ((in[2] >> 16) & 0xff : byte); out[ 6+3] = ((in[2] >> 24) & 0xff : byte)
out[ 9+0] |= (in[3] & 0xff : byte); out[ 9+1] = ((in[3] >> 8) & 0xff : byte); out[ 9+2] = ((in[3] >> 16) & 0xff : byte); out[ 9+3] = ((in[3] >> 24) & 0xff : byte)
out[12+0] |= (in[4] & 0xff : byte); out[12+1] = ((in[4] >> 8) & 0xff : byte); out[12+2] = ((in[4] >> 16) & 0xff : byte); out[12+3] = ((in[4] >> 24) & 0xff : byte)
out[16+0] |= (in[5] & 0xff : byte); out[16+1] = ((in[5] >> 8) & 0xff : byte); out[16+2] = ((in[5] >> 16) & 0xff : byte); out[16+3] = ((in[5] >> 24) & 0xff : byte)
out[19+0] |= (in[6] & 0xff : byte); out[19+1] = ((in[6] >> 8) & 0xff : byte); out[19+2] = ((in[6] >> 16) & 0xff : byte); out[19+3] = ((in[6] >> 24) & 0xff : byte)
out[22+0] |= (in[7] & 0xff : byte); out[22+1] = ((in[7] >> 8) & 0xff : byte); out[22+2] = ((in[7] >> 16) & 0xff : byte); out[22+3] = ((in[7] >> 24) & 0xff : byte)
out[25+0] |= (in[8] & 0xff : byte); out[25+1] = ((in[8] >> 8) & 0xff : byte); out[25+2] = ((in[8] >> 16) & 0xff : byte); out[25+3] = ((in[8] >> 24) & 0xff : byte)
out[28+0] |= (in[9] & 0xff : byte); out[28+1] = ((in[9] >> 8) & 0xff : byte); out[28+2] = ((in[9] >> 16) & 0xff : byte); out[28+3] = ((in[9] >> 24) & 0xff : byte)
}
/* Input: Q, Q', Q-Q'
* Output: 2Q, Q+Q'
*
* x2 z3: long form, out 2Q
* x3 z3: long form, out Q + Q'
* x z: short form, destroyed, in Q
* xprime zprime: short form, destroyed, in Q'
* qmqp: short form, preserved, in Q - Q'
*/
const fmonty = {x2, z2, x3, z3, x, z, xprime, zprime, qmqp
var origx : int64[10]
var origxprime : int64[10]
var zzz : int64 [19]
var xx : int64[19]
var zz : int64[19]
var xxprime : int64[19]
var zzprime : int64[19]
var zzzprime : int64[19]
var xxxprime : int64[19]
std.clear(&origx);
std.clear(&origxprime);
std.clear(&zzz);
std.clear(&xx);
std.clear(&zz);
std.clear(&xxprime);
std.clear(&zzprime);
std.clear(&zzzprime);
std.clear(&xxxprime);
std.slcp(origx[:10], x[:10])
fsum(x, z)
fdiff(z, origx[:]); // does x - z
std.slcp(origxprime[:10], xprime[:10])
fsum(xprime, zprime)
fdiff(zprime, origxprime[:])
fproduct(xxprime[:], xprime, z)
fproduct(zzprime[:], x, zprime)
freducedegree(xxprime[:])
freducecoeff(xxprime[:])
freducedegree(zzprime[:])
freducecoeff(zzprime[:])
std.slcp(origxprime[:10], xxprime[:10])
fsum(xxprime[:], zzprime[:])
fdiff(zzprime[:], origxprime[:])
fsquare(xxxprime[:], xxprime[:])
fsquare(zzzprime[:], zzprime[:])
fproduct(zzprime[:], zzzprime[:], qmqp)
freducedegree(zzprime[:])
freducecoeff(zzprime[:])
std.slcp(x3[:10], xxxprime[:10])
std.slcp(z3[:10], zzprime[:10])
fsquare(xx[:], x)
fsquare(zz[:], z)
fproduct(x2, xx[:], zz[:])
freducedegree(x2)
freducecoeff(x2)
fdiff(zz[:], xx[:]); // does zz = xx - zz
std.slfill(zzz[10:], 0)
fscalarproduct(zzz[:], zz[:], 121665)
/* No need to call freduce_degree here:
fscalar_product doesn't increase the degree of its input. */
freducecoeff(zzz[:])
fsum(zzz[:], xx[:])
fproduct(z2, zz[:], zzz[:])
freducedegree(z2)
freducecoeff(z2)
}
const cswap = {a, b, swap
var s, x
s = (-swap : int32)
for var i = 0; i < 10; ++i
x = s & ((a[i] : int32) ^ (b[i] : int32))
a[i] = ((a[i] : int32) ^ x : int64)
b[i] = ((b[i] : int32) ^ x : int64)
;;
}
/* Calculates nQ where Q is the x-coordinate of a point on the curve
*
* resultx/resultz: the x coordinate of the resulting curve point (short form)
* n: a little endian, 32-byte number
* q: a point of the curve (short form)
*/
const cmult = {resultx, resultz, n, q
var a : int64[19] = [.[0] = 0, .[18] = 0]
var b : int64[19] = [.[0] = 1, .[18] = 0]
var c : int64[19] = [.[0] = 1, .[18] = 0]
var d : int64[19] = [.[0] = 0, .[18] = 0]
var e : int64[19] = [.[0] = 0, .[18] = 0]
var f : int64[19] = [.[0] = 1, .[18] = 0]
var g : int64[19] = [.[0] = 0, .[18] = 0]
var h : int64[19] = [.[0] = 1, .[18] = 0]
var nqpqx = a[:]
var nqpqz = b[:]
var nqx = c[:]
var nqz = d[:]
var nqpqx2 = e[:]
var nqpqz2 = f[:]
var nqx2 = g[:]
var nqz2 = h[:]
var byte
var t
std.slcp(nqpqx[:10], q[:10])
for var i = 0; i < 32; ++i
byte = n[31 - i]
for var j = 0; j < 8; ++j
var bit = (byte >> 7 : int64)
cswap(nqx, nqpqx, bit)
cswap(nqz, nqpqz, bit)
fmonty(nqx2, nqz2,
nqpqx2, nqpqz2,
nqx, nqz,
nqpqx, nqpqz,
q)
cswap(nqx2, nqpqx2, bit)
cswap(nqz2, nqpqz2, bit)
t = nqx
nqx = nqx2
nqx2 = t
t = nqz
nqz = nqz2
nqz2 = t
t = nqpqx
nqpqx = nqpqx2
nqpqx2 = t
t = nqpqz
nqpqz = nqpqz2
nqpqz2 = t
byte <<= 1
;;
;;
std.slcp(resultx[:10], nqx[:10])
std.slcp(resultz[:10], nqz[:10])
}
// -----------------------------------------------------------------------------
// Shamelessly copied from djb's code
// -----------------------------------------------------------------------------
const crecip = {out, z
var z2 : int64[10]
var z9 : int64[10]
var z11 : int64[10]
var z2_5_0 : int64[10]
var z2_10_0 : int64[10]
var z2_20_0 : int64[10]
var z2_50_0 : int64[10]
var z2_100_0 : int64[10]
var t0 : int64[10]
var t1 : int64[10]
var i
/* 2 */ fsquare(z2[:], z[:])
/* 4 */ fsquare(t1[:], z2[:])
/* 8 */ fsquare(t0[:], t1[:])
/* 9 */ fmul(z9[:] ,t0[:], z[:])
/* 11 */ fmul(z11[:], z9[:], z2[:])
/* 22 */ fsquare(t0[:], z11[:])
/* 2^5 - 2^0 = 31 */ fmul(z2_5_0[:], t0[:], z9[:])
/* 2^6 - 2^1 */ fsquare(t0[:], z2_5_0[:])
/* 2^7 - 2^2 */ fsquare(t1[:], t0[:])
/* 2^8 - 2^3 */ fsquare(t0[:], t1[:])
/* 2^9 - 2^4 */ fsquare(t1[:], t0[:])
/* 2^10 - 2^5 */ fsquare(t0[:],t1[:])
/* 2^10 - 2^0 */ fmul(z2_10_0[:], t0[:], z2_5_0[:])
/* 2^11 - 2^1 */ fsquare(t0[:], z2_10_0[:])
/* 2^12 - 2^2 */ fsquare(t1[:], t0[:])
/* 2^20 - 2^10 */
for i = 2;i < 10;i += 2
fsquare(t0[:],t1[:])
fsquare(t1[:],t0[:])
;;
/* 2^20 - 2^0 */ fmul(z2_20_0[:], t1[:], z2_10_0[:])
/* 2^21 - 2^1 */ fsquare(t0[:], z2_20_0[:])
/* 2^22 - 2^2 */ fsquare(t1[:], t0[:])
/* 2^40 - 2^20 */
for i = 2;i < 20;i += 2
fsquare(t0[:], t1[:])
fsquare(t1[:], t0[:])
;;
/* 2^40 - 2^0 */ fmul(t0[:], t1[:], z2_20_0[:])
/* 2^41 - 2^1 */ fsquare(t1[:],t0[:])
/* 2^42 - 2^2 */ fsquare(t0[:],t1[:])
/* 2^50 - 2^10 */
for i = 2;i < 10;i += 2
fsquare(t1[:],t0[:])
fsquare(t0[:],t1[:])
;;
/* 2^50 - 2^0 */ fmul(z2_50_0[:], t0[:], z2_10_0[:])
/* 2^51 - 2^1 */ fsquare(t0[:], z2_50_0[:])
/* 2^52 - 2^2 */ fsquare(t1[:], t0[:])
/* 2^100 - 2^50 */
for i = 2;i < 50;i += 2
fsquare(t0[:],t1[:])
fsquare(t1[:],t0[:])
;;
/* 2^100 - 2^0 */ fmul(z2_100_0[:], t1[:], z2_50_0[:])
/* 2^101 - 2^1 */ fsquare(t1[:], z2_100_0[:])
/* 2^102 - 2^2 */ fsquare(t0[:], t1[:])
/* 2^200 - 2^100 */
for i = 2;i < 100;i += 2
fsquare(t1[:],t0[:])
fsquare(t0[:],t1[:])
;;
/* 2^200 - 2^0 */ fmul(t1[:],t0[:], z2_100_0[:])
/* 2^201 - 2^1 */ fsquare(t0[:], t1[:])
/* 2^202 - 2^2 */ fsquare(t1[:], t0[:])
/* 2^250 - 2^50 */
for i = 2;i < 50;i += 2
fsquare(t0[:], t1[:])
fsquare(t1[:], t0[:])
;;
/* 2^250 - 2^0 */ fmul(t0[:], t1[:], z2_50_0[:])
/* 2^251 - 2^1 */ fsquare(t1[:], t0[:])
/* 2^252 - 2^2 */ fsquare(t0[:], t1[:])
/* 2^253 - 2^3 */ fsquare(t1[:], t0[:])
/* 2^254 - 2^4 */ fsquare(t0[:], t1[:])
/* 2^255 - 2^5 */ fsquare(t1[:], t0[:])
/* 2^255 - 21 */ fmul(out,t1[:], z11[:])
}
const curve25519 = {pub : byte[:/*32*/], secret : byte[:/*32*/], basepoint : byte[:/*32*/]
var bp : int64[10]
var x : int64[10]
var z : int64[11] /* one extra for reduced coefficients */
var zmone : int64[10]
std.assert(pub.len == 32 , "wrong pubkey size\n")
std.assert(secret.len == 32 , "wrong secret size\n")
std.assert(basepoint.len == 32 , "wrong basepoint size\n")
secret[0] &= 248
secret[31] &= 127
secret[31] |= 64
fexpand(bp[:], basepoint[:])
cmult(x[:], z[:], secret[:], bp[:])
crecip(zmone[:], z[:])
fmul(z[:], x[:], zmone[:])
fcontract(pub[:], z[:])
}