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Diffstat (limited to 'src/crypto/curve25519-u128.h')
| -rw-r--r-- | src/crypto/curve25519-u128.h | 408 |
1 files changed, 0 insertions, 408 deletions
diff --git a/src/crypto/curve25519-u128.h b/src/crypto/curve25519-u128.h deleted file mode 100644 index 9f9ab20..0000000 --- a/src/crypto/curve25519-u128.h +++ /dev/null @@ -1,408 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 - * - * Copyright (C) 2008 Google Inc. All Rights Reserved. - * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. - * - * Original author: Adam Langley <agl@imperialviolet.org> - */ - -typedef u64 limb; -typedef limb felem[5]; -typedef __uint128_t u128; - -/* Sum two numbers: output += in */ -static __always_inline void fsum(limb *output, const limb *in) -{ - output[0] += in[0]; - output[1] += in[1]; - output[2] += in[2]; - output[3] += in[3]; - output[4] += in[4]; -} - -/* Find the difference of two numbers: output = in - output - * (note the order of the arguments!) - * - * Assumes that out[i] < 2**52 - * On return, out[i] < 2**55 - */ -static __always_inline void fdifference_backwards(felem out, const felem in) -{ - /* 152 is 19 << 3 */ - static const limb two54m152 = (((limb)1) << 54) - 152; - static const limb two54m8 = (((limb)1) << 54) - 8; - - out[0] = in[0] + two54m152 - out[0]; - out[1] = in[1] + two54m8 - out[1]; - out[2] = in[2] + two54m8 - out[2]; - out[3] = in[3] + two54m8 - out[3]; - out[4] = in[4] + two54m8 - out[4]; -} - -/* Multiply a number by a scalar: output = in * scalar */ -static __always_inline void fscalar_product(felem output, const felem in, const limb scalar) -{ - u128 a; - - a = ((u128) in[0]) * scalar; - output[0] = ((limb)a) & 0x7ffffffffffffUL; - - a = ((u128) in[1]) * scalar + ((limb) (a >> 51)); - output[1] = ((limb)a) & 0x7ffffffffffffUL; - - a = ((u128) in[2]) * scalar + ((limb) (a >> 51)); - output[2] = ((limb)a) & 0x7ffffffffffffUL; - - a = ((u128) in[3]) * scalar + ((limb) (a >> 51)); - output[3] = ((limb)a) & 0x7ffffffffffffUL; - - a = ((u128) in[4]) * scalar + ((limb) (a >> 51)); - output[4] = ((limb)a) & 0x7ffffffffffffUL; - - output[0] += (a >> 51) * 19; -} - -/* Multiply two numbers: output = in2 * in - * - * output must be distinct to both inputs. The inputs are reduced coefficient - * form, the output is not. - * - * Assumes that in[i] < 2**55 and likewise for in2. - * On return, output[i] < 2**52 - */ -static __always_inline void fmul(felem output, const felem in2, const felem in) -{ - u128 t[5]; - limb r0, r1, r2, r3, r4, s0, s1, s2, s3, s4, c; - - r0 = in[0]; - r1 = in[1]; - r2 = in[2]; - r3 = in[3]; - r4 = in[4]; - - s0 = in2[0]; - s1 = in2[1]; - s2 = in2[2]; - s3 = in2[3]; - s4 = in2[4]; - - t[0] = ((u128) r0) * s0; - t[1] = ((u128) r0) * s1 + ((u128) r1) * s0; - t[2] = ((u128) r0) * s2 + ((u128) r2) * s0 + ((u128) r1) * s1; - t[3] = ((u128) r0) * s3 + ((u128) r3) * s0 + ((u128) r1) * s2 + ((u128) r2) * s1; - t[4] = ((u128) r0) * s4 + ((u128) r4) * s0 + ((u128) r3) * s1 + ((u128) r1) * s3 + ((u128) r2) * s2; - - r4 *= 19; - r1 *= 19; - r2 *= 19; - r3 *= 19; - - t[0] += ((u128) r4) * s1 + ((u128) r1) * s4 + ((u128) r2) * s3 + ((u128) r3) * s2; - t[1] += ((u128) r4) * s2 + ((u128) r2) * s4 + ((u128) r3) * s3; - t[2] += ((u128) r4) * s3 + ((u128) r3) * s4; - t[3] += ((u128) r4) * s4; - - r0 = (limb)t[0] & 0x7ffffffffffffUL; c = (limb)(t[0] >> 51); - t[1] += c; r1 = (limb)t[1] & 0x7ffffffffffffUL; c = (limb)(t[1] >> 51); - t[2] += c; r2 = (limb)t[2] & 0x7ffffffffffffUL; c = (limb)(t[2] >> 51); - t[3] += c; r3 = (limb)t[3] & 0x7ffffffffffffUL; c = (limb)(t[3] >> 51); - t[4] += c; r4 = (limb)t[4] & 0x7ffffffffffffUL; c = (limb)(t[4] >> 51); - r0 += c * 19; c = r0 >> 51; r0 = r0 & 0x7ffffffffffffUL; - r1 += c; c = r1 >> 51; r1 = r1 & 0x7ffffffffffffUL; - r2 += c; - - output[0] = r0; - output[1] = r1; - output[2] = r2; - output[3] = r3; - output[4] = r4; -} - -static __always_inline void fsquare_times(felem output, const felem in, limb count) -{ - u128 t[5]; - limb r0, r1, r2, r3, r4, c; - limb d0, d1, d2, d4, d419; - - r0 = in[0]; - r1 = in[1]; - r2 = in[2]; - r3 = in[3]; - r4 = in[4]; - - do { - d0 = r0 * 2; - d1 = r1 * 2; - d2 = r2 * 2 * 19; - d419 = r4 * 19; - d4 = d419 * 2; - - t[0] = ((u128) r0) * r0 + ((u128) d4) * r1 + (((u128) d2) * (r3 )); - t[1] = ((u128) d0) * r1 + ((u128) d4) * r2 + (((u128) r3) * (r3 * 19)); - t[2] = ((u128) d0) * r2 + ((u128) r1) * r1 + (((u128) d4) * (r3 )); - t[3] = ((u128) d0) * r3 + ((u128) d1) * r2 + (((u128) r4) * (d419 )); - t[4] = ((u128) d0) * r4 + ((u128) d1) * r3 + (((u128) r2) * (r2 )); - - r0 = (limb)t[0] & 0x7ffffffffffffUL; c = (limb)(t[0] >> 51); - t[1] += c; r1 = (limb)t[1] & 0x7ffffffffffffUL; c = (limb)(t[1] >> 51); - t[2] += c; r2 = (limb)t[2] & 0x7ffffffffffffUL; c = (limb)(t[2] >> 51); - t[3] += c; r3 = (limb)t[3] & 0x7ffffffffffffUL; c = (limb)(t[3] >> 51); - t[4] += c; r4 = (limb)t[4] & 0x7ffffffffffffUL; c = (limb)(t[4] >> 51); - r0 += c * 19; c = r0 >> 51; r0 = r0 & 0x7ffffffffffffUL; - r1 += c; c = r1 >> 51; r1 = r1 & 0x7ffffffffffffUL; - r2 += c; - } while (--count); - - output[0] = r0; - output[1] = r1; - output[2] = r2; - output[3] = r3; - output[4] = r4; -} - -/* Load a little-endian 64-bit number */ -static inline limb load_limb(const u8 *in) -{ - return le64_to_cpu(*(__le64 *)in); -} - -static inline void store_limb(u8 *out, limb in) -{ - *(__le64 *)out = cpu_to_le64(in); -} - -/* Take a little-endian, 32-byte number and expand it into polynomial form */ -static inline void fexpand(limb *output, const u8 *in) -{ - output[0] = load_limb(in) & 0x7ffffffffffffUL; - output[1] = (load_limb(in + 6) >> 3) & 0x7ffffffffffffUL; - output[2] = (load_limb(in + 12) >> 6) & 0x7ffffffffffffUL; - output[3] = (load_limb(in + 19) >> 1) & 0x7ffffffffffffUL; - output[4] = (load_limb(in + 24) >> 12) & 0x7ffffffffffffUL; -} - -/* Take a fully reduced polynomial form number and contract it into a - * little-endian, 32-byte array - */ -static void fcontract(u8 *output, const felem input) -{ - u128 t[5]; - - t[0] = input[0]; - t[1] = input[1]; - t[2] = input[2]; - t[3] = input[3]; - t[4] = input[4]; - - t[1] += t[0] >> 51; t[0] &= 0x7ffffffffffffUL; - t[2] += t[1] >> 51; t[1] &= 0x7ffffffffffffUL; - t[3] += t[2] >> 51; t[2] &= 0x7ffffffffffffUL; - t[4] += t[3] >> 51; t[3] &= 0x7ffffffffffffUL; - t[0] += 19 * (t[4] >> 51); t[4] &= 0x7ffffffffffffUL; - - t[1] += t[0] >> 51; t[0] &= 0x7ffffffffffffUL; - t[2] += t[1] >> 51; t[1] &= 0x7ffffffffffffUL; - t[3] += t[2] >> 51; t[2] &= 0x7ffffffffffffUL; - t[4] += t[3] >> 51; t[3] &= 0x7ffffffffffffUL; - t[0] += 19 * (t[4] >> 51); t[4] &= 0x7ffffffffffffUL; - - /* now t is between 0 and 2^255-1, properly carried. */ - /* case 1: between 0 and 2^255-20. case 2: between 2^255-19 and 2^255-1. */ - - t[0] += 19; - - t[1] += t[0] >> 51; t[0] &= 0x7ffffffffffffUL; - t[2] += t[1] >> 51; t[1] &= 0x7ffffffffffffUL; - t[3] += t[2] >> 51; t[2] &= 0x7ffffffffffffUL; - t[4] += t[3] >> 51; t[3] &= 0x7ffffffffffffUL; - t[0] += 19 * (t[4] >> 51); t[4] &= 0x7ffffffffffffUL; - - /* now between 19 and 2^255-1 in both cases, and offset by 19. */ - - t[0] += 0x8000000000000UL - 19; - t[1] += 0x8000000000000UL - 1; - t[2] += 0x8000000000000UL - 1; - t[3] += 0x8000000000000UL - 1; - t[4] += 0x8000000000000UL - 1; - - /* now between 2^255 and 2^256-20, and offset by 2^255. */ - - t[1] += t[0] >> 51; t[0] &= 0x7ffffffffffffUL; - t[2] += t[1] >> 51; t[1] &= 0x7ffffffffffffUL; - t[3] += t[2] >> 51; t[2] &= 0x7ffffffffffffUL; - t[4] += t[3] >> 51; t[3] &= 0x7ffffffffffffUL; - t[4] &= 0x7ffffffffffffUL; - - store_limb(output, t[0] | (t[1] << 51)); - store_limb(output+8, (t[1] >> 13) | (t[2] << 38)); - store_limb(output+16, (t[2] >> 26) | (t[3] << 25)); - store_limb(output+24, (t[3] >> 39) | (t[4] << 12)); -} - -/* Input: Q, Q', Q-Q' - * Output: 2Q, Q+Q' - * - * x2 z3: long form - * x3 z3: long form - * x z: short form, destroyed - * xprime zprime: short form, destroyed - * qmqp: short form, preserved - */ -static void fmonty(limb *x2, limb *z2, /* output 2Q */ - limb *x3, limb *z3, /* output Q + Q' */ - limb *x, limb *z, /* input Q */ - limb *xprime, limb *zprime, /* input Q' */ - - const limb *qmqp /* input Q - Q' */) -{ - limb origx[5], origxprime[5], zzz[5], xx[5], zz[5], xxprime[5], zzprime[5], zzzprime[5]; - - memcpy(origx, x, 5 * sizeof(limb)); - fsum(x, z); - fdifference_backwards(z, origx); // does x - z - - memcpy(origxprime, xprime, sizeof(limb) * 5); - fsum(xprime, zprime); - fdifference_backwards(zprime, origxprime); - fmul(xxprime, xprime, z); - fmul(zzprime, x, zprime); - memcpy(origxprime, xxprime, sizeof(limb) * 5); - fsum(xxprime, zzprime); - fdifference_backwards(zzprime, origxprime); - fsquare_times(x3, xxprime, 1); - fsquare_times(zzzprime, zzprime, 1); - fmul(z3, zzzprime, qmqp); - - fsquare_times(xx, x, 1); - fsquare_times(zz, z, 1); - fmul(x2, xx, zz); - fdifference_backwards(zz, xx); // does zz = xx - zz - fscalar_product(zzz, zz, 121665); - fsum(zzz, xx); - fmul(z2, zz, zzz); -} - -/* Maybe swap the contents of two limb arrays (@a and @b), each @len elements - * long. Perform the swap iff @swap is non-zero. - * - * This function performs the swap without leaking any side-channel - * information. - */ -static void swap_conditional(limb a[5], limb b[5], limb iswap) -{ - unsigned int i; - const limb swap = -iswap; - - for (i = 0; i < 5; ++i) { - const limb x = swap & (a[i] ^ b[i]); - - a[i] ^= x; - b[i] ^= x; - } -} - -/* 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) - */ -static void cmult(limb *resultx, limb *resultz, const u8 *n, const limb *q) -{ - limb a[5] = {0}, b[5] = {1}, c[5] = {1}, d[5] = {0}; - limb *nqpqx = a, *nqpqz = b, *nqx = c, *nqz = d, *t; - limb e[5] = {0}, f[5] = {1}, g[5] = {0}, h[5] = {1}; - limb *nqpqx2 = e, *nqpqz2 = f, *nqx2 = g, *nqz2 = h; - - unsigned int i, j; - - memcpy(nqpqx, q, sizeof(limb) * 5); - - for (i = 0; i < 32; ++i) { - u8 byte = n[31 - i]; - - for (j = 0; j < 8; ++j) { - const limb bit = byte >> 7; - - swap_conditional(nqx, nqpqx, bit); - swap_conditional(nqz, nqpqz, bit); - fmonty(nqx2, nqz2, - nqpqx2, nqpqz2, - nqx, nqz, - nqpqx, nqpqz, - q); - swap_conditional(nqx2, nqpqx2, bit); - swap_conditional(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; - } - } - - memcpy(resultx, nqx, sizeof(limb) * 5); - memcpy(resultz, nqz, sizeof(limb) * 5); -} - -static void crecip(felem out, const felem z) -{ - felem a, t0, b, c; - - /* 2 */ fsquare_times(a, z, 1); // a = 2 - /* 8 */ fsquare_times(t0, a, 2); - /* 9 */ fmul(b, t0, z); // b = 9 - /* 11 */ fmul(a, b, a); // a = 11 - /* 22 */ fsquare_times(t0, a, 1); - /* 2^5 - 2^0 = 31 */ fmul(b, t0, b); - /* 2^10 - 2^5 */ fsquare_times(t0, b, 5); - /* 2^10 - 2^0 */ fmul(b, t0, b); - /* 2^20 - 2^10 */ fsquare_times(t0, b, 10); - /* 2^20 - 2^0 */ fmul(c, t0, b); - /* 2^40 - 2^20 */ fsquare_times(t0, c, 20); - /* 2^40 - 2^0 */ fmul(t0, t0, c); - /* 2^50 - 2^10 */ fsquare_times(t0, t0, 10); - /* 2^50 - 2^0 */ fmul(b, t0, b); - /* 2^100 - 2^50 */ fsquare_times(t0, b, 50); - /* 2^100 - 2^0 */ fmul(c, t0, b); - /* 2^200 - 2^100 */ fsquare_times(t0, c, 100); - /* 2^200 - 2^0 */ fmul(t0, t0, c); - /* 2^250 - 2^50 */ fsquare_times(t0, t0, 50); - /* 2^250 - 2^0 */ fmul(t0, t0, b); - /* 2^255 - 2^5 */ fsquare_times(t0, t0, 5); - /* 2^255 - 21 */ fmul(out, t0, a); -} - -static bool curve25519_donna(u8 mypublic[CURVE25519_POINT_SIZE], const u8 secret[CURVE25519_POINT_SIZE], const u8 basepoint[CURVE25519_POINT_SIZE]) -{ - limb bp[5], x[5], z[5], zmone[5]; - u8 e[32]; - - memcpy(e, secret, 32); - normalize_secret(e); - - fexpand(bp, basepoint); - cmult(x, z, e, bp); - crecip(zmone, z); - fmul(z, x, zmone); - fcontract(mypublic, z); - - memzero_explicit(e, sizeof(e)); - memzero_explicit(bp, sizeof(bp)); - memzero_explicit(x, sizeof(x)); - memzero_explicit(z, sizeof(z)); - memzero_explicit(zmone, sizeof(zmone)); - - return true; -} |