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Diffstat (limited to 'curve25519-sandy2x.c')
| -rw-r--r-- | curve25519-sandy2x.c | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/curve25519-sandy2x.c b/curve25519-sandy2x.c new file mode 100644 index 0000000..e8d5d2b --- /dev/null +++ b/curve25519-sandy2x.c @@ -0,0 +1,139 @@ +/* SPDX-License-Identifier: GPL-2.0 + * + * Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. + * + * Original author: Tung Chou <blueprint@crypto.tw> + */ + +#include <linux/kernel.h> +#include <linux/string.h> + +enum { CURVE25519_POINT_SIZE = 32 }; + +static __always_inline void normalize_secret(u8 secret[CURVE25519_POINT_SIZE]) +{ + secret[0] &= 248; + secret[31] &= 127; + secret[31] |= 64; +} + +typedef u64 fe[10]; +typedef u64 fe51[5]; +asmlinkage void curve25519_sandy2x_ladder(fe *, const u8 *); +asmlinkage void curve25519_sandy2x_ladder_base(fe *, const u8 *); +asmlinkage void curve25519_sandy2x_fe51_pack(u8 *, const fe51 *); +asmlinkage void curve25519_sandy2x_fe51_mul(fe51 *, const fe51 *, const fe51 *); +asmlinkage void curve25519_sandy2x_fe51_nsquare(fe51 *, const fe51 *, int); + +static inline u32 le24_to_cpupv(const u8 *in) +{ + return le16_to_cpup((__le16 *)in) | ((u32)in[2]) << 16; +} + +static inline void fe_frombytes(fe h, const u8 *s) +{ + u64 h0 = le32_to_cpup((__le32 *)s); + u64 h1 = le24_to_cpupv(s + 4) << 6; + u64 h2 = le24_to_cpupv(s + 7) << 5; + u64 h3 = le24_to_cpupv(s + 10) << 3; + u64 h4 = le24_to_cpupv(s + 13) << 2; + u64 h5 = le32_to_cpup((__le32 *)(s + 16)); + u64 h6 = le24_to_cpupv(s + 20) << 7; + u64 h7 = le24_to_cpupv(s + 23) << 5; + u64 h8 = le24_to_cpupv(s + 26) << 4; + u64 h9 = (le24_to_cpupv(s + 29) & 8388607) << 2; + u64 carry0, carry1, carry2, carry3, carry4, carry5, carry6, carry7, carry8, carry9; + + carry9 = h9 >> 25; h0 += carry9 * 19; h9 &= 0x1FFFFFF; + carry1 = h1 >> 25; h2 += carry1; h1 &= 0x1FFFFFF; + carry3 = h3 >> 25; h4 += carry3; h3 &= 0x1FFFFFF; + carry5 = h5 >> 25; h6 += carry5; h5 &= 0x1FFFFFF; + carry7 = h7 >> 25; h8 += carry7; h7 &= 0x1FFFFFF; + + carry0 = h0 >> 26; h1 += carry0; h0 &= 0x3FFFFFF; + carry2 = h2 >> 26; h3 += carry2; h2 &= 0x3FFFFFF; + carry4 = h4 >> 26; h5 += carry4; h4 &= 0x3FFFFFF; + carry6 = h6 >> 26; h7 += carry6; h6 &= 0x3FFFFFF; + carry8 = h8 >> 26; h9 += carry8; h8 &= 0x3FFFFFF; + + h[0] = h0; + h[1] = h1; + h[2] = h2; + h[3] = h3; + h[4] = h4; + h[5] = h5; + h[6] = h6; + h[7] = h7; + h[8] = h8; + h[9] = h9; +} + +static inline void fe51_invert(fe51 *r, const fe51 *x) +{ + fe51 z2, z9, z11, z2_5_0, z2_10_0, z2_20_0, z2_50_0, z2_100_0, t; + + /* 2 */ curve25519_sandy2x_fe51_nsquare(&z2, x, 1); + /* 4 */ curve25519_sandy2x_fe51_nsquare(&t, (const fe51 *)&z2, 1); + /* 8 */ curve25519_sandy2x_fe51_nsquare(&t, (const fe51 *)&t, 1); + /* 9 */ curve25519_sandy2x_fe51_mul(&z9, (const fe51 *)&t, x); + /* 11 */ curve25519_sandy2x_fe51_mul(&z11, (const fe51 *)&z9, (const fe51 *)&z2); + /* 22 */ curve25519_sandy2x_fe51_nsquare(&t, (const fe51 *)&z11, 1); + /* 2^5 - 2^0 = 31 */ curve25519_sandy2x_fe51_mul(&z2_5_0, (const fe51 *)&t, (const fe51 *)&z9); + + /* 2^10 - 2^5 */ curve25519_sandy2x_fe51_nsquare(&t, (const fe51 *)&z2_5_0, 5); + /* 2^10 - 2^0 */ curve25519_sandy2x_fe51_mul(&z2_10_0, (const fe51 *)&t, (const fe51 *)&z2_5_0); + + /* 2^20 - 2^10 */ curve25519_sandy2x_fe51_nsquare(&t, (const fe51 *)&z2_10_0, 10); + /* 2^20 - 2^0 */ curve25519_sandy2x_fe51_mul(&z2_20_0, (const fe51 *)&t, (const fe51 *)&z2_10_0); + + /* 2^40 - 2^20 */ curve25519_sandy2x_fe51_nsquare(&t, (const fe51 *)&z2_20_0, 20); + /* 2^40 - 2^0 */ curve25519_sandy2x_fe51_mul(&t, (const fe51 *)&t, (const fe51 *)&z2_20_0); + + /* 2^50 - 2^10 */ curve25519_sandy2x_fe51_nsquare(&t, (const fe51 *)&t, 10); + /* 2^50 - 2^0 */ curve25519_sandy2x_fe51_mul(&z2_50_0, (const fe51 *)&t, (const fe51 *)&z2_10_0); + + /* 2^100 - 2^50 */ curve25519_sandy2x_fe51_nsquare(&t, (const fe51 *)&z2_50_0, 50); + /* 2^100 - 2^0 */ curve25519_sandy2x_fe51_mul(&z2_100_0, (const fe51 *)&t, (const fe51 *)&z2_50_0); + + /* 2^200 - 2^100 */ curve25519_sandy2x_fe51_nsquare(&t, (const fe51 *)&z2_100_0, 100); + /* 2^200 - 2^0 */ curve25519_sandy2x_fe51_mul(&t, (const fe51 *)&t, (const fe51 *)&z2_100_0); + + /* 2^250 - 2^50 */ curve25519_sandy2x_fe51_nsquare(&t, (const fe51 *)&t, 50); + /* 2^250 - 2^0 */ curve25519_sandy2x_fe51_mul(&t, (const fe51 *)&t, (const fe51 *)&z2_50_0); + + /* 2^255 - 2^5 */ curve25519_sandy2x_fe51_nsquare(&t, (const fe51 *)&t, 5); + /* 2^255 - 21 */ curve25519_sandy2x_fe51_mul(r, (const fe51 *)t, (const fe51 *)&z11); +} + +bool curve25519_sandy2x(u8 mypublic[CURVE25519_POINT_SIZE], const u8 secret[CURVE25519_POINT_SIZE], const u8 basepoint[CURVE25519_POINT_SIZE]) +{ + u8 e[32]; + fe var[3]; + fe51 x_51, z_51; + + memcpy(e, secret, 32); + normalize_secret(e); +#define x1 var[0] +#define x2 var[1] +#define z2 var[2] + fe_frombytes(x1, basepoint); + curve25519_sandy2x_ladder(var, e); + z_51[0] = (z2[1] << 26) + z2[0]; + z_51[1] = (z2[3] << 26) + z2[2]; + z_51[2] = (z2[5] << 26) + z2[4]; + z_51[3] = (z2[7] << 26) + z2[6]; + z_51[4] = (z2[9] << 26) + z2[8]; + x_51[0] = (x2[1] << 26) + x2[0]; + x_51[1] = (x2[3] << 26) + x2[2]; + x_51[2] = (x2[5] << 26) + x2[4]; + x_51[3] = (x2[7] << 26) + x2[6]; + x_51[4] = (x2[9] << 26) + x2[8]; +#undef x1 +#undef x2 +#undef z2 + fe51_invert(&z_51, (const fe51 *)&z_51); + curve25519_sandy2x_fe51_mul(&x_51, (const fe51 *)&x_51, (const fe51 *)&z_51); + curve25519_sandy2x_fe51_pack(mypublic, (const fe51 *)&x_51); + + return true; +} |