diff options
Diffstat (limited to 'src/curve25519-donna-32bit.h')
| -rw-r--r-- | src/curve25519-donna-32bit.h | 466 |
1 files changed, 466 insertions, 0 deletions
diff --git a/src/curve25519-donna-32bit.h b/src/curve25519-donna-32bit.h new file mode 100644 index 0000000..5ef91a2 --- /dev/null +++ b/src/curve25519-donna-32bit.h @@ -0,0 +1,466 @@ +typedef uint32_t bignum25519[10]; + +static const uint32_t reduce_mask_26 = (1 << 26) - 1; +static const uint32_t reduce_mask_25 = (1 << 25) - 1; + +/* out = in */ +DONNA_INLINE static void +curve25519_copy(bignum25519 out, const bignum25519 in) { + out[0] = in[0]; + out[1] = in[1]; + out[2] = in[2]; + out[3] = in[3]; + out[4] = in[4]; + out[5] = in[5]; + out[6] = in[6]; + out[7] = in[7]; + out[8] = in[8]; + out[9] = in[9]; +} + +/* out = a + b */ +DONNA_INLINE static void +curve25519_add(bignum25519 out, const bignum25519 a, const bignum25519 b) { + out[0] = a[0] + b[0]; + out[1] = a[1] + b[1]; + out[2] = a[2] + b[2]; + out[3] = a[3] + b[3]; + out[4] = a[4] + b[4]; + out[5] = a[5] + b[5]; + out[6] = a[6] + b[6]; + out[7] = a[7] + b[7]; + out[8] = a[8] + b[8]; + out[9] = a[9] + b[9]; +} + +/* out = a - b */ +DONNA_INLINE static void +curve25519_sub(bignum25519 out, const bignum25519 a, const bignum25519 b) { + uint32_t c; + out[0] = 0x7ffffda + a[0] - b[0] ; c = (out[0] >> 26); out[0] &= reduce_mask_26; + out[1] = 0x3fffffe + a[1] - b[1] + c; c = (out[1] >> 25); out[1] &= reduce_mask_25; + out[2] = 0x7fffffe + a[2] - b[2] + c; c = (out[2] >> 26); out[2] &= reduce_mask_26; + out[3] = 0x3fffffe + a[3] - b[3] + c; c = (out[3] >> 25); out[3] &= reduce_mask_25; + out[4] = 0x7fffffe + a[4] - b[4] + c; c = (out[4] >> 26); out[4] &= reduce_mask_26; + out[5] = 0x3fffffe + a[5] - b[5] + c; c = (out[5] >> 25); out[5] &= reduce_mask_25; + out[6] = 0x7fffffe + a[6] - b[6] + c; c = (out[6] >> 26); out[6] &= reduce_mask_26; + out[7] = 0x3fffffe + a[7] - b[7] + c; c = (out[7] >> 25); out[7] &= reduce_mask_25; + out[8] = 0x7fffffe + a[8] - b[8] + c; c = (out[8] >> 26); out[8] &= reduce_mask_26; + out[9] = 0x3fffffe + a[9] - b[9] + c; c = (out[9] >> 25); out[9] &= reduce_mask_25; + out[0] += 19 * c; +} + +/* out = in * scalar */ +DONNA_INLINE static void +curve25519_scalar_product(bignum25519 out, const bignum25519 in, const uint32_t scalar) { + uint64_t a; + uint32_t c; + a = mul32x32_64(in[0], scalar); out[0] = (uint32_t)a & reduce_mask_26; c = (uint32_t)(a >> 26); + a = mul32x32_64(in[1], scalar) + c; out[1] = (uint32_t)a & reduce_mask_25; c = (uint32_t)(a >> 25); + a = mul32x32_64(in[2], scalar) + c; out[2] = (uint32_t)a & reduce_mask_26; c = (uint32_t)(a >> 26); + a = mul32x32_64(in[3], scalar) + c; out[3] = (uint32_t)a & reduce_mask_25; c = (uint32_t)(a >> 25); + a = mul32x32_64(in[4], scalar) + c; out[4] = (uint32_t)a & reduce_mask_26; c = (uint32_t)(a >> 26); + a = mul32x32_64(in[5], scalar) + c; out[5] = (uint32_t)a & reduce_mask_25; c = (uint32_t)(a >> 25); + a = mul32x32_64(in[6], scalar) + c; out[6] = (uint32_t)a & reduce_mask_26; c = (uint32_t)(a >> 26); + a = mul32x32_64(in[7], scalar) + c; out[7] = (uint32_t)a & reduce_mask_25; c = (uint32_t)(a >> 25); + a = mul32x32_64(in[8], scalar) + c; out[8] = (uint32_t)a & reduce_mask_26; c = (uint32_t)(a >> 26); + a = mul32x32_64(in[9], scalar) + c; out[9] = (uint32_t)a & reduce_mask_25; c = (uint32_t)(a >> 25); + out[0] += c * 19; +} + +/* out = a * b */ +DONNA_INLINE static void +curve25519_mul(bignum25519 out, const bignum25519 a, const bignum25519 b) { + uint32_t r0,r1,r2,r3,r4,r5,r6,r7,r8,r9; + uint32_t s0,s1,s2,s3,s4,s5,s6,s7,s8,s9; + uint64_t m0,m1,m2,m3,m4,m5,m6,m7,m8,m9,c; + uint32_t p; + + r0 = b[0]; + r1 = b[1]; + r2 = b[2]; + r3 = b[3]; + r4 = b[4]; + r5 = b[5]; + r6 = b[6]; + r7 = b[7]; + r8 = b[8]; + r9 = b[9]; + + s0 = a[0]; + s1 = a[1]; + s2 = a[2]; + s3 = a[3]; + s4 = a[4]; + s5 = a[5]; + s6 = a[6]; + s7 = a[7]; + s8 = a[8]; + s9 = a[9]; + + m1 = mul32x32_64(r0, s1) + mul32x32_64(r1, s0); + m3 = mul32x32_64(r0, s3) + mul32x32_64(r1, s2) + mul32x32_64(r2, s1) + mul32x32_64(r3, s0); + m5 = mul32x32_64(r0, s5) + mul32x32_64(r1, s4) + mul32x32_64(r2, s3) + mul32x32_64(r3, s2) + mul32x32_64(r4, s1) + mul32x32_64(r5, s0); + m7 = mul32x32_64(r0, s7) + mul32x32_64(r1, s6) + mul32x32_64(r2, s5) + mul32x32_64(r3, s4) + mul32x32_64(r4, s3) + mul32x32_64(r5, s2) + mul32x32_64(r6, s1) + mul32x32_64(r7, s0); + m9 = mul32x32_64(r0, s9) + mul32x32_64(r1, s8) + mul32x32_64(r2, s7) + mul32x32_64(r3, s6) + mul32x32_64(r4, s5) + mul32x32_64(r5, s4) + mul32x32_64(r6, s3) + mul32x32_64(r7, s2) + mul32x32_64(r8, s1) + mul32x32_64(r9, s0); + + r1 *= 2; + r3 *= 2; + r5 *= 2; + r7 *= 2; + + m0 = mul32x32_64(r0, s0); + m2 = mul32x32_64(r0, s2) + mul32x32_64(r1, s1) + mul32x32_64(r2, s0); + m4 = mul32x32_64(r0, s4) + mul32x32_64(r1, s3) + mul32x32_64(r2, s2) + mul32x32_64(r3, s1) + mul32x32_64(r4, s0); + m6 = mul32x32_64(r0, s6) + mul32x32_64(r1, s5) + mul32x32_64(r2, s4) + mul32x32_64(r3, s3) + mul32x32_64(r4, s2) + mul32x32_64(r5, s1) + mul32x32_64(r6, s0); + m8 = mul32x32_64(r0, s8) + mul32x32_64(r1, s7) + mul32x32_64(r2, s6) + mul32x32_64(r3, s5) + mul32x32_64(r4, s4) + mul32x32_64(r5, s3) + mul32x32_64(r6, s2) + mul32x32_64(r7, s1) + mul32x32_64(r8, s0); + + r1 *= 19; + r2 *= 19; + r3 = (r3 / 2) * 19; + r4 *= 19; + r5 = (r5 / 2) * 19; + r6 *= 19; + r7 = (r7 / 2) * 19; + r8 *= 19; + r9 *= 19; + + m1 += (mul32x32_64(r9, s2) + mul32x32_64(r8, s3) + mul32x32_64(r7, s4) + mul32x32_64(r6, s5) + mul32x32_64(r5, s6) + mul32x32_64(r4, s7) + mul32x32_64(r3, s8) + mul32x32_64(r2, s9)); + m3 += (mul32x32_64(r9, s4) + mul32x32_64(r8, s5) + mul32x32_64(r7, s6) + mul32x32_64(r6, s7) + mul32x32_64(r5, s8) + mul32x32_64(r4, s9)); + m5 += (mul32x32_64(r9, s6) + mul32x32_64(r8, s7) + mul32x32_64(r7, s8) + mul32x32_64(r6, s9)); + m7 += (mul32x32_64(r9, s8) + mul32x32_64(r8, s9)); + + r3 *= 2; + r5 *= 2; + r7 *= 2; + r9 *= 2; + + m0 += (mul32x32_64(r9, s1) + mul32x32_64(r8, s2) + mul32x32_64(r7, s3) + mul32x32_64(r6, s4) + mul32x32_64(r5, s5) + mul32x32_64(r4, s6) + mul32x32_64(r3, s7) + mul32x32_64(r2, s8) + mul32x32_64(r1, s9)); + m2 += (mul32x32_64(r9, s3) + mul32x32_64(r8, s4) + mul32x32_64(r7, s5) + mul32x32_64(r6, s6) + mul32x32_64(r5, s7) + mul32x32_64(r4, s8) + mul32x32_64(r3, s9)); + m4 += (mul32x32_64(r9, s5) + mul32x32_64(r8, s6) + mul32x32_64(r7, s7) + mul32x32_64(r6, s8) + mul32x32_64(r5, s9)); + m6 += (mul32x32_64(r9, s7) + mul32x32_64(r8, s8) + mul32x32_64(r7, s9)); + m8 += (mul32x32_64(r9, s9)); + + r0 = (uint32_t)m0 & reduce_mask_26; c = (m0 >> 26); + m1 += c; r1 = (uint32_t)m1 & reduce_mask_25; c = (m1 >> 25); + m2 += c; r2 = (uint32_t)m2 & reduce_mask_26; c = (m2 >> 26); + m3 += c; r3 = (uint32_t)m3 & reduce_mask_25; c = (m3 >> 25); + m4 += c; r4 = (uint32_t)m4 & reduce_mask_26; c = (m4 >> 26); + m5 += c; r5 = (uint32_t)m5 & reduce_mask_25; c = (m5 >> 25); + m6 += c; r6 = (uint32_t)m6 & reduce_mask_26; c = (m6 >> 26); + m7 += c; r7 = (uint32_t)m7 & reduce_mask_25; c = (m7 >> 25); + m8 += c; r8 = (uint32_t)m8 & reduce_mask_26; c = (m8 >> 26); + m9 += c; r9 = (uint32_t)m9 & reduce_mask_25; p = (uint32_t)(m9 >> 25); + m0 = r0 + mul32x32_64(p,19); r0 = (uint32_t)m0 & reduce_mask_26; p = (uint32_t)(m0 >> 26); + r1 += p; + + out[0] = r0; + out[1] = r1; + out[2] = r2; + out[3] = r3; + out[4] = r4; + out[5] = r5; + out[6] = r6; + out[7] = r7; + out[8] = r8; + out[9] = r9; +} + +/* out = in * in */ +DONNA_INLINE static void +curve25519_square(bignum25519 out, const bignum25519 in) { + uint32_t r0,r1,r2,r3,r4,r5,r6,r7,r8,r9; + uint32_t d6,d7,d8,d9; + uint64_t m0,m1,m2,m3,m4,m5,m6,m7,m8,m9,c; + uint32_t p; + + r0 = in[0]; + r1 = in[1]; + r2 = in[2]; + r3 = in[3]; + r4 = in[4]; + r5 = in[5]; + r6 = in[6]; + r7 = in[7]; + r8 = in[8]; + r9 = in[9]; + + + m0 = mul32x32_64(r0, r0); + r0 *= 2; + m1 = mul32x32_64(r0, r1); + m2 = mul32x32_64(r0, r2) + mul32x32_64(r1, r1 * 2); + r1 *= 2; + m3 = mul32x32_64(r0, r3) + mul32x32_64(r1, r2 ); + m4 = mul32x32_64(r0, r4) + mul32x32_64(r1, r3 * 2) + mul32x32_64(r2, r2); + r2 *= 2; + m5 = mul32x32_64(r0, r5) + mul32x32_64(r1, r4 ) + mul32x32_64(r2, r3); + m6 = mul32x32_64(r0, r6) + mul32x32_64(r1, r5 * 2) + mul32x32_64(r2, r4) + mul32x32_64(r3, r3 * 2); + r3 *= 2; + m7 = mul32x32_64(r0, r7) + mul32x32_64(r1, r6 ) + mul32x32_64(r2, r5) + mul32x32_64(r3, r4 ); + m8 = mul32x32_64(r0, r8) + mul32x32_64(r1, r7 * 2) + mul32x32_64(r2, r6) + mul32x32_64(r3, r5 * 2) + mul32x32_64(r4, r4 ); + m9 = mul32x32_64(r0, r9) + mul32x32_64(r1, r8 ) + mul32x32_64(r2, r7) + mul32x32_64(r3, r6 ) + mul32x32_64(r4, r5 * 2); + + d6 = r6 * 19; + d7 = r7 * 2 * 19; + d8 = r8 * 19; + d9 = r9 * 2 * 19; + + m0 += (mul32x32_64(d9, r1 ) + mul32x32_64(d8, r2 ) + mul32x32_64(d7, r3 ) + mul32x32_64(d6, r4 * 2) + mul32x32_64(r5, r5 * 2 * 19)); + m1 += (mul32x32_64(d9, r2 / 2) + mul32x32_64(d8, r3 ) + mul32x32_64(d7, r4 ) + mul32x32_64(d6, r5 * 2)); + m2 += (mul32x32_64(d9, r3 ) + mul32x32_64(d8, r4 * 2) + mul32x32_64(d7, r5 * 2) + mul32x32_64(d6, r6 )); + m3 += (mul32x32_64(d9, r4 ) + mul32x32_64(d8, r5 * 2) + mul32x32_64(d7, r6 )); + m4 += (mul32x32_64(d9, r5 * 2) + mul32x32_64(d8, r6 * 2) + mul32x32_64(d7, r7 )); + m5 += (mul32x32_64(d9, r6 ) + mul32x32_64(d8, r7 * 2)); + m6 += (mul32x32_64(d9, r7 * 2) + mul32x32_64(d8, r8 )); + m7 += (mul32x32_64(d9, r8 )); + m8 += (mul32x32_64(d9, r9 )); + + r0 = (uint32_t)m0 & reduce_mask_26; c = (m0 >> 26); + m1 += c; r1 = (uint32_t)m1 & reduce_mask_25; c = (m1 >> 25); + m2 += c; r2 = (uint32_t)m2 & reduce_mask_26; c = (m2 >> 26); + m3 += c; r3 = (uint32_t)m3 & reduce_mask_25; c = (m3 >> 25); + m4 += c; r4 = (uint32_t)m4 & reduce_mask_26; c = (m4 >> 26); + m5 += c; r5 = (uint32_t)m5 & reduce_mask_25; c = (m5 >> 25); + m6 += c; r6 = (uint32_t)m6 & reduce_mask_26; c = (m6 >> 26); + m7 += c; r7 = (uint32_t)m7 & reduce_mask_25; c = (m7 >> 25); + m8 += c; r8 = (uint32_t)m8 & reduce_mask_26; c = (m8 >> 26); + m9 += c; r9 = (uint32_t)m9 & reduce_mask_25; p = (uint32_t)(m9 >> 25); + m0 = r0 + mul32x32_64(p,19); r0 = (uint32_t)m0 & reduce_mask_26; p = (uint32_t)(m0 >> 26); + r1 += p; + + out[0] = r0; + out[1] = r1; + out[2] = r2; + out[3] = r3; + out[4] = r4; + out[5] = r5; + out[6] = r6; + out[7] = r7; + out[8] = r8; + out[9] = r9; +} + +/* out = in^(2 * count) */ +static void +curve25519_square_times(bignum25519 out, const bignum25519 in, int count) { + uint32_t r0,r1,r2,r3,r4,r5,r6,r7,r8,r9; + uint32_t d6,d7,d8,d9; + uint64_t m0,m1,m2,m3,m4,m5,m6,m7,m8,m9,c; + uint32_t p; + + r0 = in[0]; + r1 = in[1]; + r2 = in[2]; + r3 = in[3]; + r4 = in[4]; + r5 = in[5]; + r6 = in[6]; + r7 = in[7]; + r8 = in[8]; + r9 = in[9]; + + do { + m0 = mul32x32_64(r0, r0); + r0 *= 2; + m1 = mul32x32_64(r0, r1); + m2 = mul32x32_64(r0, r2) + mul32x32_64(r1, r1 * 2); + r1 *= 2; + m3 = mul32x32_64(r0, r3) + mul32x32_64(r1, r2 ); + m4 = mul32x32_64(r0, r4) + mul32x32_64(r1, r3 * 2) + mul32x32_64(r2, r2); + r2 *= 2; + m5 = mul32x32_64(r0, r5) + mul32x32_64(r1, r4 ) + mul32x32_64(r2, r3); + m6 = mul32x32_64(r0, r6) + mul32x32_64(r1, r5 * 2) + mul32x32_64(r2, r4) + mul32x32_64(r3, r3 * 2); + r3 *= 2; + m7 = mul32x32_64(r0, r7) + mul32x32_64(r1, r6 ) + mul32x32_64(r2, r5) + mul32x32_64(r3, r4 ); + m8 = mul32x32_64(r0, r8) + mul32x32_64(r1, r7 * 2) + mul32x32_64(r2, r6) + mul32x32_64(r3, r5 * 2) + mul32x32_64(r4, r4 ); + m9 = mul32x32_64(r0, r9) + mul32x32_64(r1, r8 ) + mul32x32_64(r2, r7) + mul32x32_64(r3, r6 ) + mul32x32_64(r4, r5 * 2); + + d6 = r6 * 19; + d7 = r7 * 2 * 19; + d8 = r8 * 19; + d9 = r9 * 2 * 19; + + m0 += (mul32x32_64(d9, r1 ) + mul32x32_64(d8, r2 ) + mul32x32_64(d7, r3 ) + mul32x32_64(d6, r4 * 2) + mul32x32_64(r5, r5 * 2 * 19)); + m1 += (mul32x32_64(d9, r2 / 2) + mul32x32_64(d8, r3 ) + mul32x32_64(d7, r4 ) + mul32x32_64(d6, r5 * 2)); + m2 += (mul32x32_64(d9, r3 ) + mul32x32_64(d8, r4 * 2) + mul32x32_64(d7, r5 * 2) + mul32x32_64(d6, r6 )); + m3 += (mul32x32_64(d9, r4 ) + mul32x32_64(d8, r5 * 2) + mul32x32_64(d7, r6 )); + m4 += (mul32x32_64(d9, r5 * 2) + mul32x32_64(d8, r6 * 2) + mul32x32_64(d7, r7 )); + m5 += (mul32x32_64(d9, r6 ) + mul32x32_64(d8, r7 * 2)); + m6 += (mul32x32_64(d9, r7 * 2) + mul32x32_64(d8, r8 )); + m7 += (mul32x32_64(d9, r8 )); + m8 += (mul32x32_64(d9, r9 )); + + r0 = (uint32_t)m0 & reduce_mask_26; c = (m0 >> 26); + m1 += c; r1 = (uint32_t)m1 & reduce_mask_25; c = (m1 >> 25); + m2 += c; r2 = (uint32_t)m2 & reduce_mask_26; c = (m2 >> 26); + m3 += c; r3 = (uint32_t)m3 & reduce_mask_25; c = (m3 >> 25); + m4 += c; r4 = (uint32_t)m4 & reduce_mask_26; c = (m4 >> 26); + m5 += c; r5 = (uint32_t)m5 & reduce_mask_25; c = (m5 >> 25); + m6 += c; r6 = (uint32_t)m6 & reduce_mask_26; c = (m6 >> 26); + m7 += c; r7 = (uint32_t)m7 & reduce_mask_25; c = (m7 >> 25); + m8 += c; r8 = (uint32_t)m8 & reduce_mask_26; c = (m8 >> 26); + m9 += c; r9 = (uint32_t)m9 & reduce_mask_25; p = (uint32_t)(m9 >> 25); + m0 = r0 + mul32x32_64(p,19); r0 = (uint32_t)m0 & reduce_mask_26; p = (uint32_t)(m0 >> 26); + r1 += p; + } while (--count); + + out[0] = r0; + out[1] = r1; + out[2] = r2; + out[3] = r3; + out[4] = r4; + out[5] = r5; + out[6] = r6; + out[7] = r7; + out[8] = r8; + out[9] = r9; +} + + +/* Take a little-endian, 32-byte number and expand it into polynomial form */ +static void +curve25519_expand(bignum25519 out, const unsigned char in[32]) { + static const union { uint8_t b[2]; uint16_t s; } endian_check = {{1,0}}; + uint32_t x0,x1,x2,x3,x4,x5,x6,x7; + + if (endian_check.s == 1) { + x0 = *(uint32_t *)(in + 0); + x1 = *(uint32_t *)(in + 4); + x2 = *(uint32_t *)(in + 8); + x3 = *(uint32_t *)(in + 12); + x4 = *(uint32_t *)(in + 16); + x5 = *(uint32_t *)(in + 20); + x6 = *(uint32_t *)(in + 24); + x7 = *(uint32_t *)(in + 28); + } else { + #define F(s) \ + ((((uint32_t)in[s + 0]) ) | \ + (((uint32_t)in[s + 1]) << 8) | \ + (((uint32_t)in[s + 2]) << 16) | \ + (((uint32_t)in[s + 3]) << 24)) + x0 = F(0); + x1 = F(4); + x2 = F(8); + x3 = F(12); + x4 = F(16); + x5 = F(20); + x6 = F(24); + x7 = F(28); + #undef F + } + + out[0] = ( x0 ) & reduce_mask_26; + out[1] = ((((uint64_t)x1 << 32) | x0) >> 26) & reduce_mask_25; + out[2] = ((((uint64_t)x2 << 32) | x1) >> 19) & reduce_mask_26; + out[3] = ((((uint64_t)x3 << 32) | x2) >> 13) & reduce_mask_25; + out[4] = (( x3) >> 6) & reduce_mask_26; + out[5] = ( x4 ) & reduce_mask_25; + out[6] = ((((uint64_t)x5 << 32) | x4) >> 25) & reduce_mask_26; + out[7] = ((((uint64_t)x6 << 32) | x5) >> 19) & reduce_mask_25; + out[8] = ((((uint64_t)x7 << 32) | x6) >> 12) & reduce_mask_26; + out[9] = (( x7) >> 6) & reduce_mask_25; /* ignore the top bit */ +} + +/* Take a fully reduced polynomial form number and contract it into a little-endian, 32-byte array */ +static void +curve25519_contract(unsigned char out[32], const bignum25519 in) { + bignum25519 f; + curve25519_copy(f, in); + + #define carry_pass() \ + f[1] += f[0] >> 26; f[0] &= reduce_mask_26; \ + f[2] += f[1] >> 25; f[1] &= reduce_mask_25; \ + f[3] += f[2] >> 26; f[2] &= reduce_mask_26; \ + f[4] += f[3] >> 25; f[3] &= reduce_mask_25; \ + f[5] += f[4] >> 26; f[4] &= reduce_mask_26; \ + f[6] += f[5] >> 25; f[5] &= reduce_mask_25; \ + f[7] += f[6] >> 26; f[6] &= reduce_mask_26; \ + f[8] += f[7] >> 25; f[7] &= reduce_mask_25; \ + f[9] += f[8] >> 26; f[8] &= reduce_mask_26; + + #define carry_pass_full() \ + carry_pass() \ + f[0] += 19 * (f[9] >> 25); f[9] &= reduce_mask_25; + + #define carry_pass_final() \ + carry_pass() \ + f[9] &= reduce_mask_25; + + carry_pass_full() + carry_pass_full() + + /* 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. */ + f[0] += 19; + carry_pass_full() + + /* now between 19 and 2^255-1 in both cases, and offset by 19. */ + f[0] += (1 << 26) - 19; + f[1] += (1 << 25) - 1; + f[2] += (1 << 26) - 1; + f[3] += (1 << 25) - 1; + f[4] += (1 << 26) - 1; + f[5] += (1 << 25) - 1; + f[6] += (1 << 26) - 1; + f[7] += (1 << 25) - 1; + f[8] += (1 << 26) - 1; + f[9] += (1 << 25) - 1; + + /* now between 2^255 and 2^256-20, and offset by 2^255. */ + carry_pass_final() + + #undef carry_pass + #undef carry_full + #undef carry_final + + f[1] <<= 2; + f[2] <<= 3; + f[3] <<= 5; + f[4] <<= 6; + f[6] <<= 1; + f[7] <<= 3; + f[8] <<= 4; + f[9] <<= 6; + + #define F(i, s) \ + out[s+0] |= (unsigned char )(f[i] & 0xff); \ + out[s+1] = (unsigned char )((f[i] >> 8) & 0xff); \ + out[s+2] = (unsigned char )((f[i] >> 16) & 0xff); \ + out[s+3] = (unsigned char )((f[i] >> 24) & 0xff); + + out[0] = 0; + out[16] = 0; + F(0,0); + F(1,3); + F(2,6); + F(3,9); + F(4,12); + F(5,16); + F(6,19); + F(7,22); + F(8,25); + F(9,28); + #undef F +} + +/* + * Swap the contents of [qx] and [qpx] iff @swap is non-zero + */ +DONNA_INLINE static void +curve25519_swap_conditional(bignum25519 x, bignum25519 qpx, uint32_t iswap) { + const uint32_t swap = (uint32_t)(-(int32_t)iswap); + uint32_t x0,x1,x2,x3,x4,x5,x6,x7,x8,x9; + + x0 = swap & (x[0] ^ qpx[0]); x[0] ^= x0; qpx[0] ^= x0; + x1 = swap & (x[1] ^ qpx[1]); x[1] ^= x1; qpx[1] ^= x1; + x2 = swap & (x[2] ^ qpx[2]); x[2] ^= x2; qpx[2] ^= x2; + x3 = swap & (x[3] ^ qpx[3]); x[3] ^= x3; qpx[3] ^= x3; + x4 = swap & (x[4] ^ qpx[4]); x[4] ^= x4; qpx[4] ^= x4; + x5 = swap & (x[5] ^ qpx[5]); x[5] ^= x5; qpx[5] ^= x5; + x6 = swap & (x[6] ^ qpx[6]); x[6] ^= x6; qpx[6] ^= x6; + x7 = swap & (x[7] ^ qpx[7]); x[7] ^= x7; qpx[7] ^= x7; + x8 = swap & (x[8] ^ qpx[8]); x[8] ^= x8; qpx[8] ^= x8; + x9 = swap & (x[9] ^ qpx[9]); x[9] ^= x9; qpx[9] ^= x9; +} + |