From 649bf79117e30895108b7782d62daafd07bc5e6e Mon Sep 17 00:00:00 2001 From: Niall Sheridan Date: Sun, 22 May 2016 01:23:33 +0100 Subject: Use govendor --- .../ed25519/internal/edwards25519/edwards25519.go | 1771 ++++++++++++++++++++ 1 file changed, 1771 insertions(+) create mode 100644 vendor/golang.org/x/crypto/ed25519/internal/edwards25519/edwards25519.go (limited to 'vendor/golang.org/x/crypto/ed25519/internal/edwards25519/edwards25519.go') diff --git a/vendor/golang.org/x/crypto/ed25519/internal/edwards25519/edwards25519.go b/vendor/golang.org/x/crypto/ed25519/internal/edwards25519/edwards25519.go new file mode 100644 index 0000000..5f8b994 --- /dev/null +++ b/vendor/golang.org/x/crypto/ed25519/internal/edwards25519/edwards25519.go @@ -0,0 +1,1771 @@ +// Copyright 2016 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package edwards25519 + +// This code is a port of the public domain, “ref10” implementation of ed25519 +// from SUPERCOP. + +// FieldElement represents an element of the field GF(2^255 - 19). An element +// t, entries t[0]...t[9], represents the integer t[0]+2^26 t[1]+2^51 t[2]+2^77 +// t[3]+2^102 t[4]+...+2^230 t[9]. Bounds on each t[i] vary depending on +// context. +type FieldElement [10]int32 + +var zero FieldElement + +func FeZero(fe *FieldElement) { + copy(fe[:], zero[:]) +} + +func FeOne(fe *FieldElement) { + FeZero(fe) + fe[0] = 1 +} + +func FeAdd(dst, a, b *FieldElement) { + dst[0] = a[0] + b[0] + dst[1] = a[1] + b[1] + dst[2] = a[2] + b[2] + dst[3] = a[3] + b[3] + dst[4] = a[4] + b[4] + dst[5] = a[5] + b[5] + dst[6] = a[6] + b[6] + dst[7] = a[7] + b[7] + dst[8] = a[8] + b[8] + dst[9] = a[9] + b[9] +} + +func FeSub(dst, a, b *FieldElement) { + dst[0] = a[0] - b[0] + dst[1] = a[1] - b[1] + dst[2] = a[2] - b[2] + dst[3] = a[3] - b[3] + dst[4] = a[4] - b[4] + dst[5] = a[5] - b[5] + dst[6] = a[6] - b[6] + dst[7] = a[7] - b[7] + dst[8] = a[8] - b[8] + dst[9] = a[9] - b[9] +} + +func FeCopy(dst, src *FieldElement) { + copy(dst[:], src[:]) +} + +// Replace (f,g) with (g,g) if b == 1; +// replace (f,g) with (f,g) if b == 0. +// +// Preconditions: b in {0,1}. +func FeCMove(f, g *FieldElement, b int32) { + b = -b + f[0] ^= b & (f[0] ^ g[0]) + f[1] ^= b & (f[1] ^ g[1]) + f[2] ^= b & (f[2] ^ g[2]) + f[3] ^= b & (f[3] ^ g[3]) + f[4] ^= b & (f[4] ^ g[4]) + f[5] ^= b & (f[5] ^ g[5]) + f[6] ^= b & (f[6] ^ g[6]) + f[7] ^= b & (f[7] ^ g[7]) + f[8] ^= b & (f[8] ^ g[8]) + f[9] ^= b & (f[9] ^ g[9]) +} + +func load3(in []byte) int64 { + var r int64 + r = int64(in[0]) + r |= int64(in[1]) << 8 + r |= int64(in[2]) << 16 + return r +} + +func load4(in []byte) int64 { + var r int64 + r = int64(in[0]) + r |= int64(in[1]) << 8 + r |= int64(in[2]) << 16 + r |= int64(in[3]) << 24 + return r +} + +func FeFromBytes(dst *FieldElement, src *[32]byte) { + h0 := load4(src[:]) + h1 := load3(src[4:]) << 6 + h2 := load3(src[7:]) << 5 + h3 := load3(src[10:]) << 3 + h4 := load3(src[13:]) << 2 + h5 := load4(src[16:]) + h6 := load3(src[20:]) << 7 + h7 := load3(src[23:]) << 5 + h8 := load3(src[26:]) << 4 + h9 := (load3(src[29:]) & 8388607) << 2 + + FeCombine(dst, h0, h1, h2, h3, h4, h5, h6, h7, h8, h9) +} + +// FeToBytes marshals h to s. +// Preconditions: +// |h| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc. +// +// Write p=2^255-19; q=floor(h/p). +// Basic claim: q = floor(2^(-255)(h + 19 2^(-25)h9 + 2^(-1))). +// +// Proof: +// Have |h|<=p so |q|<=1 so |19^2 2^(-255) q|<1/4. +// Also have |h-2^230 h9|<2^230 so |19 2^(-255)(h-2^230 h9)|<1/4. +// +// Write y=2^(-1)-19^2 2^(-255)q-19 2^(-255)(h-2^230 h9). +// Then 0> 25 + q = (h[0] + q) >> 26 + q = (h[1] + q) >> 25 + q = (h[2] + q) >> 26 + q = (h[3] + q) >> 25 + q = (h[4] + q) >> 26 + q = (h[5] + q) >> 25 + q = (h[6] + q) >> 26 + q = (h[7] + q) >> 25 + q = (h[8] + q) >> 26 + q = (h[9] + q) >> 25 + + // Goal: Output h-(2^255-19)q, which is between 0 and 2^255-20. + h[0] += 19 * q + // Goal: Output h-2^255 q, which is between 0 and 2^255-20. + + carry[0] = h[0] >> 26 + h[1] += carry[0] + h[0] -= carry[0] << 26 + carry[1] = h[1] >> 25 + h[2] += carry[1] + h[1] -= carry[1] << 25 + carry[2] = h[2] >> 26 + h[3] += carry[2] + h[2] -= carry[2] << 26 + carry[3] = h[3] >> 25 + h[4] += carry[3] + h[3] -= carry[3] << 25 + carry[4] = h[4] >> 26 + h[5] += carry[4] + h[4] -= carry[4] << 26 + carry[5] = h[5] >> 25 + h[6] += carry[5] + h[5] -= carry[5] << 25 + carry[6] = h[6] >> 26 + h[7] += carry[6] + h[6] -= carry[6] << 26 + carry[7] = h[7] >> 25 + h[8] += carry[7] + h[7] -= carry[7] << 25 + carry[8] = h[8] >> 26 + h[9] += carry[8] + h[8] -= carry[8] << 26 + carry[9] = h[9] >> 25 + h[9] -= carry[9] << 25 + // h10 = carry9 + + // Goal: Output h[0]+...+2^255 h10-2^255 q, which is between 0 and 2^255-20. + // Have h[0]+...+2^230 h[9] between 0 and 2^255-1; + // evidently 2^255 h10-2^255 q = 0. + // Goal: Output h[0]+...+2^230 h[9]. + + s[0] = byte(h[0] >> 0) + s[1] = byte(h[0] >> 8) + s[2] = byte(h[0] >> 16) + s[3] = byte((h[0] >> 24) | (h[1] << 2)) + s[4] = byte(h[1] >> 6) + s[5] = byte(h[1] >> 14) + s[6] = byte((h[1] >> 22) | (h[2] << 3)) + s[7] = byte(h[2] >> 5) + s[8] = byte(h[2] >> 13) + s[9] = byte((h[2] >> 21) | (h[3] << 5)) + s[10] = byte(h[3] >> 3) + s[11] = byte(h[3] >> 11) + s[12] = byte((h[3] >> 19) | (h[4] << 6)) + s[13] = byte(h[4] >> 2) + s[14] = byte(h[4] >> 10) + s[15] = byte(h[4] >> 18) + s[16] = byte(h[5] >> 0) + s[17] = byte(h[5] >> 8) + s[18] = byte(h[5] >> 16) + s[19] = byte((h[5] >> 24) | (h[6] << 1)) + s[20] = byte(h[6] >> 7) + s[21] = byte(h[6] >> 15) + s[22] = byte((h[6] >> 23) | (h[7] << 3)) + s[23] = byte(h[7] >> 5) + s[24] = byte(h[7] >> 13) + s[25] = byte((h[7] >> 21) | (h[8] << 4)) + s[26] = byte(h[8] >> 4) + s[27] = byte(h[8] >> 12) + s[28] = byte((h[8] >> 20) | (h[9] << 6)) + s[29] = byte(h[9] >> 2) + s[30] = byte(h[9] >> 10) + s[31] = byte(h[9] >> 18) +} + +func FeIsNegative(f *FieldElement) byte { + var s [32]byte + FeToBytes(&s, f) + return s[0] & 1 +} + +func FeIsNonZero(f *FieldElement) int32 { + var s [32]byte + FeToBytes(&s, f) + var x uint8 + for _, b := range s { + x |= b + } + x |= x >> 4 + x |= x >> 2 + x |= x >> 1 + return int32(x & 1) +} + +// FeNeg sets h = -f +// +// Preconditions: +// |f| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc. +// +// Postconditions: +// |h| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc. +func FeNeg(h, f *FieldElement) { + h[0] = -f[0] + h[1] = -f[1] + h[2] = -f[2] + h[3] = -f[3] + h[4] = -f[4] + h[5] = -f[5] + h[6] = -f[6] + h[7] = -f[7] + h[8] = -f[8] + h[9] = -f[9] +} + +func FeCombine(h *FieldElement, h0, h1, h2, h3, h4, h5, h6, h7, h8, h9 int64) { + var c0, c1, c2, c3, c4, c5, c6, c7, c8, c9 int64 + + /* + |h0| <= (1.1*1.1*2^52*(1+19+19+19+19)+1.1*1.1*2^50*(38+38+38+38+38)) + i.e. |h0| <= 1.2*2^59; narrower ranges for h2, h4, h6, h8 + |h1| <= (1.1*1.1*2^51*(1+1+19+19+19+19+19+19+19+19)) + i.e. |h1| <= 1.5*2^58; narrower ranges for h3, h5, h7, h9 + */ + + c0 = (h0 + (1 << 25)) >> 26 + h1 += c0 + h0 -= c0 << 26 + c4 = (h4 + (1 << 25)) >> 26 + h5 += c4 + h4 -= c4 << 26 + /* |h0| <= 2^25 */ + /* |h4| <= 2^25 */ + /* |h1| <= 1.51*2^58 */ + /* |h5| <= 1.51*2^58 */ + + c1 = (h1 + (1 << 24)) >> 25 + h2 += c1 + h1 -= c1 << 25 + c5 = (h5 + (1 << 24)) >> 25 + h6 += c5 + h5 -= c5 << 25 + /* |h1| <= 2^24; from now on fits into int32 */ + /* |h5| <= 2^24; from now on fits into int32 */ + /* |h2| <= 1.21*2^59 */ + /* |h6| <= 1.21*2^59 */ + + c2 = (h2 + (1 << 25)) >> 26 + h3 += c2 + h2 -= c2 << 26 + c6 = (h6 + (1 << 25)) >> 26 + h7 += c6 + h6 -= c6 << 26 + /* |h2| <= 2^25; from now on fits into int32 unchanged */ + /* |h6| <= 2^25; from now on fits into int32 unchanged */ + /* |h3| <= 1.51*2^58 */ + /* |h7| <= 1.51*2^58 */ + + c3 = (h3 + (1 << 24)) >> 25 + h4 += c3 + h3 -= c3 << 25 + c7 = (h7 + (1 << 24)) >> 25 + h8 += c7 + h7 -= c7 << 25 + /* |h3| <= 2^24; from now on fits into int32 unchanged */ + /* |h7| <= 2^24; from now on fits into int32 unchanged */ + /* |h4| <= 1.52*2^33 */ + /* |h8| <= 1.52*2^33 */ + + c4 = (h4 + (1 << 25)) >> 26 + h5 += c4 + h4 -= c4 << 26 + c8 = (h8 + (1 << 25)) >> 26 + h9 += c8 + h8 -= c8 << 26 + /* |h4| <= 2^25; from now on fits into int32 unchanged */ + /* |h8| <= 2^25; from now on fits into int32 unchanged */ + /* |h5| <= 1.01*2^24 */ + /* |h9| <= 1.51*2^58 */ + + c9 = (h9 + (1 << 24)) >> 25 + h0 += c9 * 19 + h9 -= c9 << 25 + /* |h9| <= 2^24; from now on fits into int32 unchanged */ + /* |h0| <= 1.8*2^37 */ + + c0 = (h0 + (1 << 25)) >> 26 + h1 += c0 + h0 -= c0 << 26 + /* |h0| <= 2^25; from now on fits into int32 unchanged */ + /* |h1| <= 1.01*2^24 */ + + h[0] = int32(h0) + h[1] = int32(h1) + h[2] = int32(h2) + h[3] = int32(h3) + h[4] = int32(h4) + h[5] = int32(h5) + h[6] = int32(h6) + h[7] = int32(h7) + h[8] = int32(h8) + h[9] = int32(h9) +} + +// FeMul calculates h = f * g +// Can overlap h with f or g. +// +// Preconditions: +// |f| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc. +// |g| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc. +// +// Postconditions: +// |h| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc. +// +// Notes on implementation strategy: +// +// Using schoolbook multiplication. +// Karatsuba would save a little in some cost models. +// +// Most multiplications by 2 and 19 are 32-bit precomputations; +// cheaper than 64-bit postcomputations. +// +// There is one remaining multiplication by 19 in the carry chain; +// one *19 precomputation can be merged into this, +// but the resulting data flow is considerably less clean. +// +// There are 12 carries below. +// 10 of them are 2-way parallelizable and vectorizable. +// Can get away with 11 carries, but then data flow is much deeper. +// +// With tighter constraints on inputs, can squeeze carries into int32. +func FeMul(h, f, g *FieldElement) { + f0 := int64(f[0]) + f1 := int64(f[1]) + f2 := int64(f[2]) + f3 := int64(f[3]) + f4 := int64(f[4]) + f5 := int64(f[5]) + f6 := int64(f[6]) + f7 := int64(f[7]) + f8 := int64(f[8]) + f9 := int64(f[9]) + + f1_2 := int64(2 * f[1]) + f3_2 := int64(2 * f[3]) + f5_2 := int64(2 * f[5]) + f7_2 := int64(2 * f[7]) + f9_2 := int64(2 * f[9]) + + g0 := int64(g[0]) + g1 := int64(g[1]) + g2 := int64(g[2]) + g3 := int64(g[3]) + g4 := int64(g[4]) + g5 := int64(g[5]) + g6 := int64(g[6]) + g7 := int64(g[7]) + g8 := int64(g[8]) + g9 := int64(g[9]) + + g1_19 := int64(19 * g[1]) /* 1.4*2^29 */ + g2_19 := int64(19 * g[2]) /* 1.4*2^30; still ok */ + g3_19 := int64(19 * g[3]) + g4_19 := int64(19 * g[4]) + g5_19 := int64(19 * g[5]) + g6_19 := int64(19 * g[6]) + g7_19 := int64(19 * g[7]) + g8_19 := int64(19 * g[8]) + g9_19 := int64(19 * g[9]) + + h0 := f0*g0 + f1_2*g9_19 + f2*g8_19 + f3_2*g7_19 + f4*g6_19 + f5_2*g5_19 + f6*g4_19 + f7_2*g3_19 + f8*g2_19 + f9_2*g1_19 + h1 := f0*g1 + f1*g0 + f2*g9_19 + f3*g8_19 + f4*g7_19 + f5*g6_19 + f6*g5_19 + f7*g4_19 + f8*g3_19 + f9*g2_19 + h2 := f0*g2 + f1_2*g1 + f2*g0 + f3_2*g9_19 + f4*g8_19 + f5_2*g7_19 + f6*g6_19 + f7_2*g5_19 + f8*g4_19 + f9_2*g3_19 + h3 := f0*g3 + f1*g2 + f2*g1 + f3*g0 + f4*g9_19 + f5*g8_19 + f6*g7_19 + f7*g6_19 + f8*g5_19 + f9*g4_19 + h4 := f0*g4 + f1_2*g3 + f2*g2 + f3_2*g1 + f4*g0 + f5_2*g9_19 + f6*g8_19 + f7_2*g7_19 + f8*g6_19 + f9_2*g5_19 + h5 := f0*g5 + f1*g4 + f2*g3 + f3*g2 + f4*g1 + f5*g0 + f6*g9_19 + f7*g8_19 + f8*g7_19 + f9*g6_19 + h6 := f0*g6 + f1_2*g5 + f2*g4 + f3_2*g3 + f4*g2 + f5_2*g1 + f6*g0 + f7_2*g9_19 + f8*g8_19 + f9_2*g7_19 + h7 := f0*g7 + f1*g6 + f2*g5 + f3*g4 + f4*g3 + f5*g2 + f6*g1 + f7*g0 + f8*g9_19 + f9*g8_19 + h8 := f0*g8 + f1_2*g7 + f2*g6 + f3_2*g5 + f4*g4 + f5_2*g3 + f6*g2 + f7_2*g1 + f8*g0 + f9_2*g9_19 + h9 := f0*g9 + f1*g8 + f2*g7 + f3*g6 + f4*g5 + f5*g4 + f6*g3 + f7*g2 + f8*g1 + f9*g0 + + FeCombine(h, h0, h1, h2, h3, h4, h5, h6, h7, h8, h9) +} + +func feSquare(f *FieldElement) (h0, h1, h2, h3, h4, h5, h6, h7, h8, h9 int64) { + f0 := int64(f[0]) + f1 := int64(f[1]) + f2 := int64(f[2]) + f3 := int64(f[3]) + f4 := int64(f[4]) + f5 := int64(f[5]) + f6 := int64(f[6]) + f7 := int64(f[7]) + f8 := int64(f[8]) + f9 := int64(f[9]) + f0_2 := int64(2 * f[0]) + f1_2 := int64(2 * f[1]) + f2_2 := int64(2 * f[2]) + f3_2 := int64(2 * f[3]) + f4_2 := int64(2 * f[4]) + f5_2 := int64(2 * f[5]) + f6_2 := int64(2 * f[6]) + f7_2 := int64(2 * f[7]) + f5_38 := 38 * f5 // 1.31*2^30 + f6_19 := 19 * f6 // 1.31*2^30 + f7_38 := 38 * f7 // 1.31*2^30 + f8_19 := 19 * f8 // 1.31*2^30 + f9_38 := 38 * f9 // 1.31*2^30 + + h0 = f0*f0 + f1_2*f9_38 + f2_2*f8_19 + f3_2*f7_38 + f4_2*f6_19 + f5*f5_38 + h1 = f0_2*f1 + f2*f9_38 + f3_2*f8_19 + f4*f7_38 + f5_2*f6_19 + h2 = f0_2*f2 + f1_2*f1 + f3_2*f9_38 + f4_2*f8_19 + f5_2*f7_38 + f6*f6_19 + h3 = f0_2*f3 + f1_2*f2 + f4*f9_38 + f5_2*f8_19 + f6*f7_38 + h4 = f0_2*f4 + f1_2*f3_2 + f2*f2 + f5_2*f9_38 + f6_2*f8_19 + f7*f7_38 + h5 = f0_2*f5 + f1_2*f4 + f2_2*f3 + f6*f9_38 + f7_2*f8_19 + h6 = f0_2*f6 + f1_2*f5_2 + f2_2*f4 + f3_2*f3 + f7_2*f9_38 + f8*f8_19 + h7 = f0_2*f7 + f1_2*f6 + f2_2*f5 + f3_2*f4 + f8*f9_38 + h8 = f0_2*f8 + f1_2*f7_2 + f2_2*f6 + f3_2*f5_2 + f4*f4 + f9*f9_38 + h9 = f0_2*f9 + f1_2*f8 + f2_2*f7 + f3_2*f6 + f4_2*f5 + + return +} + +// FeSquare calculates h = f*f. Can overlap h with f. +// +// Preconditions: +// |f| bounded by 1.1*2^26,1.1*2^25,1.1*2^26,1.1*2^25,etc. +// +// Postconditions: +// |h| bounded by 1.1*2^25,1.1*2^24,1.1*2^25,1.1*2^24,etc. +func FeSquare(h, f *FieldElement) { + h0, h1, h2, h3, h4, h5, h6, h7, h8, h9 := feSquare(f) + FeCombine(h, h0, h1, h2, h3, h4, h5, h6, h7, h8, h9) +} + +// FeSquare2 sets h = 2 * f * f +// +// Can overlap h with f. +// +// Preconditions: +// |f| bounded by 1.65*2^26,1.65*2^25,1.65*2^26,1.65*2^25,etc. +// +// Postconditions: +// |h| bounded by 1.01*2^25,1.01*2^24,1.01*2^25,1.01*2^24,etc. +// See fe_mul.c for discussion of implementation strategy. +func FeSquare2(h, f *FieldElement) { + h0, h1, h2, h3, h4, h5, h6, h7, h8, h9 := feSquare(f) + + h0 += h0 + h1 += h1 + h2 += h2 + h3 += h3 + h4 += h4 + h5 += h5 + h6 += h6 + h7 += h7 + h8 += h8 + h9 += h9 + + FeCombine(h, h0, h1, h2, h3, h4, h5, h6, h7, h8, h9) +} + +func FeInvert(out, z *FieldElement) { + var t0, t1, t2, t3 FieldElement + var i int + + FeSquare(&t0, z) // 2^1 + FeSquare(&t1, &t0) // 2^2 + for i = 1; i < 2; i++ { // 2^3 + FeSquare(&t1, &t1) + } + FeMul(&t1, z, &t1) // 2^3 + 2^0 + FeMul(&t0, &t0, &t1) // 2^3 + 2^1 + 2^0 + FeSquare(&t2, &t0) // 2^4 + 2^2 + 2^1 + FeMul(&t1, &t1, &t2) // 2^4 + 2^3 + 2^2 + 2^1 + 2^0 + FeSquare(&t2, &t1) // 5,4,3,2,1 + for i = 1; i < 5; i++ { // 9,8,7,6,5 + FeSquare(&t2, &t2) + } + FeMul(&t1, &t2, &t1) // 9,8,7,6,5,4,3,2,1,0 + FeSquare(&t2, &t1) // 10..1 + for i = 1; i < 10; i++ { // 19..10 + FeSquare(&t2, &t2) + } + FeMul(&t2, &t2, &t1) // 19..0 + FeSquare(&t3, &t2) // 20..1 + for i = 1; i < 20; i++ { // 39..20 + FeSquare(&t3, &t3) + } + FeMul(&t2, &t3, &t2) // 39..0 + FeSquare(&t2, &t2) // 40..1 + for i = 1; i < 10; i++ { // 49..10 + FeSquare(&t2, &t2) + } + FeMul(&t1, &t2, &t1) // 49..0 + FeSquare(&t2, &t1) // 50..1 + for i = 1; i < 50; i++ { // 99..50 + FeSquare(&t2, &t2) + } + FeMul(&t2, &t2, &t1) // 99..0 + FeSquare(&t3, &t2) // 100..1 + for i = 1; i < 100; i++ { // 199..100 + FeSquare(&t3, &t3) + } + FeMul(&t2, &t3, &t2) // 199..0 + FeSquare(&t2, &t2) // 200..1 + for i = 1; i < 50; i++ { // 249..50 + FeSquare(&t2, &t2) + } + FeMul(&t1, &t2, &t1) // 249..0 + FeSquare(&t1, &t1) // 250..1 + for i = 1; i < 5; i++ { // 254..5 + FeSquare(&t1, &t1) + } + FeMul(out, &t1, &t0) // 254..5,3,1,0 +} + +func fePow22523(out, z *FieldElement) { + var t0, t1, t2 FieldElement + var i int + + FeSquare(&t0, z) + for i = 1; i < 1; i++ { + FeSquare(&t0, &t0) + } + FeSquare(&t1, &t0) + for i = 1; i < 2; i++ { + FeSquare(&t1, &t1) + } + FeMul(&t1, z, &t1) + FeMul(&t0, &t0, &t1) + FeSquare(&t0, &t0) + for i = 1; i < 1; i++ { + FeSquare(&t0, &t0) + } + FeMul(&t0, &t1, &t0) + FeSquare(&t1, &t0) + for i = 1; i < 5; i++ { + FeSquare(&t1, &t1) + } + FeMul(&t0, &t1, &t0) + FeSquare(&t1, &t0) + for i = 1; i < 10; i++ { + FeSquare(&t1, &t1) + } + FeMul(&t1, &t1, &t0) + FeSquare(&t2, &t1) + for i = 1; i < 20; i++ { + FeSquare(&t2, &t2) + } + FeMul(&t1, &t2, &t1) + FeSquare(&t1, &t1) + for i = 1; i < 10; i++ { + FeSquare(&t1, &t1) + } + FeMul(&t0, &t1, &t0) + FeSquare(&t1, &t0) + for i = 1; i < 50; i++ { + FeSquare(&t1, &t1) + } + FeMul(&t1, &t1, &t0) + FeSquare(&t2, &t1) + for i = 1; i < 100; i++ { + FeSquare(&t2, &t2) + } + FeMul(&t1, &t2, &t1) + FeSquare(&t1, &t1) + for i = 1; i < 50; i++ { + FeSquare(&t1, &t1) + } + FeMul(&t0, &t1, &t0) + FeSquare(&t0, &t0) + for i = 1; i < 2; i++ { + FeSquare(&t0, &t0) + } + FeMul(out, &t0, z) +} + +// Group elements are members of the elliptic curve -x^2 + y^2 = 1 + d * x^2 * +// y^2 where d = -121665/121666. +// +// Several representations are used: +// ProjectiveGroupElement: (X:Y:Z) satisfying x=X/Z, y=Y/Z +// ExtendedGroupElement: (X:Y:Z:T) satisfying x=X/Z, y=Y/Z, XY=ZT +// CompletedGroupElement: ((X:Z),(Y:T)) satisfying x=X/Z, y=Y/T +// PreComputedGroupElement: (y+x,y-x,2dxy) + +type ProjectiveGroupElement struct { + X, Y, Z FieldElement +} + +type ExtendedGroupElement struct { + X, Y, Z, T FieldElement +} + +type CompletedGroupElement struct { + X, Y, Z, T FieldElement +} + +type PreComputedGroupElement struct { + yPlusX, yMinusX, xy2d FieldElement +} + +type CachedGroupElement struct { + yPlusX, yMinusX, Z, T2d FieldElement +} + +func (p *ProjectiveGroupElement) Zero() { + FeZero(&p.X) + FeOne(&p.Y) + FeOne(&p.Z) +} + +func (p *ProjectiveGroupElement) Double(r *CompletedGroupElement) { + var t0 FieldElement + + FeSquare(&r.X, &p.X) + FeSquare(&r.Z, &p.Y) + FeSquare2(&r.T, &p.Z) + FeAdd(&r.Y, &p.X, &p.Y) + FeSquare(&t0, &r.Y) + FeAdd(&r.Y, &r.Z, &r.X) + FeSub(&r.Z, &r.Z, &r.X) + FeSub(&r.X, &t0, &r.Y) + FeSub(&r.T, &r.T, &r.Z) +} + +func (p *ProjectiveGroupElement) ToBytes(s *[32]byte) { + var recip, x, y FieldElement + + FeInvert(&recip, &p.Z) + FeMul(&x, &p.X, &recip) + FeMul(&y, &p.Y, &recip) + FeToBytes(s, &y) + s[31] ^= FeIsNegative(&x) << 7 +} + +func (p *ExtendedGroupElement) Zero() { + FeZero(&p.X) + FeOne(&p.Y) + FeOne(&p.Z) + FeZero(&p.T) +} + +func (p *ExtendedGroupElement) Double(r *CompletedGroupElement) { + var q ProjectiveGroupElement + p.ToProjective(&q) + q.Double(r) +} + +func (p *ExtendedGroupElement) ToCached(r *CachedGroupElement) { + FeAdd(&r.yPlusX, &p.Y, &p.X) + FeSub(&r.yMinusX, &p.Y, &p.X) + FeCopy(&r.Z, &p.Z) + FeMul(&r.T2d, &p.T, &d2) +} + +func (p *ExtendedGroupElement) ToProjective(r *ProjectiveGroupElement) { + FeCopy(&r.X, &p.X) + FeCopy(&r.Y, &p.Y) + FeCopy(&r.Z, &p.Z) +} + +func (p *ExtendedGroupElement) ToBytes(s *[32]byte) { + var recip, x, y FieldElement + + FeInvert(&recip, &p.Z) + FeMul(&x, &p.X, &recip) + FeMul(&y, &p.Y, &recip) + FeToBytes(s, &y) + s[31] ^= FeIsNegative(&x) << 7 +} + +func (p *ExtendedGroupElement) FromBytes(s *[32]byte) bool { + var u, v, v3, vxx, check FieldElement + + FeFromBytes(&p.Y, s) + FeOne(&p.Z) + FeSquare(&u, &p.Y) + FeMul(&v, &u, &d) + FeSub(&u, &u, &p.Z) // y = y^2-1 + FeAdd(&v, &v, &p.Z) // v = dy^2+1 + + FeSquare(&v3, &v) + FeMul(&v3, &v3, &v) // v3 = v^3 + FeSquare(&p.X, &v3) + FeMul(&p.X, &p.X, &v) + FeMul(&p.X, &p.X, &u) // x = uv^7 + + fePow22523(&p.X, &p.X) // x = (uv^7)^((q-5)/8) + FeMul(&p.X, &p.X, &v3) + FeMul(&p.X, &p.X, &u) // x = uv^3(uv^7)^((q-5)/8) + + var tmpX, tmp2 [32]byte + + FeSquare(&vxx, &p.X) + FeMul(&vxx, &vxx, &v) + FeSub(&check, &vxx, &u) // vx^2-u + if FeIsNonZero(&check) == 1 { + FeAdd(&check, &vxx, &u) // vx^2+u + if FeIsNonZero(&check) == 1 { + return false + } + FeMul(&p.X, &p.X, &SqrtM1) + + FeToBytes(&tmpX, &p.X) + for i, v := range tmpX { + tmp2[31-i] = v + } + } + + if FeIsNegative(&p.X) != (s[31] >> 7) { + FeNeg(&p.X, &p.X) + } + + FeMul(&p.T, &p.X, &p.Y) + return true +} + +func (p *CompletedGroupElement) ToProjective(r *ProjectiveGroupElement) { + FeMul(&r.X, &p.X, &p.T) + FeMul(&r.Y, &p.Y, &p.Z) + FeMul(&r.Z, &p.Z, &p.T) +} + +func (p *CompletedGroupElement) ToExtended(r *ExtendedGroupElement) { + FeMul(&r.X, &p.X, &p.T) + FeMul(&r.Y, &p.Y, &p.Z) + FeMul(&r.Z, &p.Z, &p.T) + FeMul(&r.T, &p.X, &p.Y) +} + +func (p *PreComputedGroupElement) Zero() { + FeOne(&p.yPlusX) + FeOne(&p.yMinusX) + FeZero(&p.xy2d) +} + +func geAdd(r *CompletedGroupElement, p *ExtendedGroupElement, q *CachedGroupElement) { + var t0 FieldElement + + FeAdd(&r.X, &p.Y, &p.X) + FeSub(&r.Y, &p.Y, &p.X) + FeMul(&r.Z, &r.X, &q.yPlusX) + FeMul(&r.Y, &r.Y, &q.yMinusX) + FeMul(&r.T, &q.T2d, &p.T) + FeMul(&r.X, &p.Z, &q.Z) + FeAdd(&t0, &r.X, &r.X) + FeSub(&r.X, &r.Z, &r.Y) + FeAdd(&r.Y, &r.Z, &r.Y) + FeAdd(&r.Z, &t0, &r.T) + FeSub(&r.T, &t0, &r.T) +} + +func geSub(r *CompletedGroupElement, p *ExtendedGroupElement, q *CachedGroupElement) { + var t0 FieldElement + + FeAdd(&r.X, &p.Y, &p.X) + FeSub(&r.Y, &p.Y, &p.X) + FeMul(&r.Z, &r.X, &q.yMinusX) + FeMul(&r.Y, &r.Y, &q.yPlusX) + FeMul(&r.T, &q.T2d, &p.T) + FeMul(&r.X, &p.Z, &q.Z) + FeAdd(&t0, &r.X, &r.X) + FeSub(&r.X, &r.Z, &r.Y) + FeAdd(&r.Y, &r.Z, &r.Y) + FeSub(&r.Z, &t0, &r.T) + FeAdd(&r.T, &t0, &r.T) +} + +func geMixedAdd(r *CompletedGroupElement, p *ExtendedGroupElement, q *PreComputedGroupElement) { + var t0 FieldElement + + FeAdd(&r.X, &p.Y, &p.X) + FeSub(&r.Y, &p.Y, &p.X) + FeMul(&r.Z, &r.X, &q.yPlusX) + FeMul(&r.Y, &r.Y, &q.yMinusX) + FeMul(&r.T, &q.xy2d, &p.T) + FeAdd(&t0, &p.Z, &p.Z) + FeSub(&r.X, &r.Z, &r.Y) + FeAdd(&r.Y, &r.Z, &r.Y) + FeAdd(&r.Z, &t0, &r.T) + FeSub(&r.T, &t0, &r.T) +} + +func geMixedSub(r *CompletedGroupElement, p *ExtendedGroupElement, q *PreComputedGroupElement) { + var t0 FieldElement + + FeAdd(&r.X, &p.Y, &p.X) + FeSub(&r.Y, &p.Y, &p.X) + FeMul(&r.Z, &r.X, &q.yMinusX) + FeMul(&r.Y, &r.Y, &q.yPlusX) + FeMul(&r.T, &q.xy2d, &p.T) + FeAdd(&t0, &p.Z, &p.Z) + FeSub(&r.X, &r.Z, &r.Y) + FeAdd(&r.Y, &r.Z, &r.Y) + FeSub(&r.Z, &t0, &r.T) + FeAdd(&r.T, &t0, &r.T) +} + +func slide(r *[256]int8, a *[32]byte) { + for i := range r { + r[i] = int8(1 & (a[i>>3] >> uint(i&7))) + } + + for i := range r { + if r[i] != 0 { + for b := 1; b <= 6 && i+b < 256; b++ { + if r[i+b] != 0 { + if r[i]+(r[i+b]<= -15 { + r[i] -= r[i+b] << uint(b) + for k := i + b; k < 256; k++ { + if r[k] == 0 { + r[k] = 1 + break + } + r[k] = 0 + } + } else { + break + } + } + } + } + } +} + +// GeDoubleScalarMultVartime sets r = a*A + b*B +// where a = a[0]+256*a[1]+...+256^31 a[31]. +// and b = b[0]+256*b[1]+...+256^31 b[31]. +// B is the Ed25519 base point (x,4/5) with x positive. +func GeDoubleScalarMultVartime(r *ProjectiveGroupElement, a *[32]byte, A *ExtendedGroupElement, b *[32]byte) { + var aSlide, bSlide [256]int8 + var Ai [8]CachedGroupElement // A,3A,5A,7A,9A,11A,13A,15A + var t CompletedGroupElement + var u, A2 ExtendedGroupElement + var i int + + slide(&aSlide, a) + slide(&bSlide, b) + + A.ToCached(&Ai[0]) + A.Double(&t) + t.ToExtended(&A2) + + for i := 0; i < 7; i++ { + geAdd(&t, &A2, &Ai[i]) + t.ToExtended(&u) + u.ToCached(&Ai[i+1]) + } + + r.Zero() + + for i = 255; i >= 0; i-- { + if aSlide[i] != 0 || bSlide[i] != 0 { + break + } + } + + for ; i >= 0; i-- { + r.Double(&t) + + if aSlide[i] > 0 { + t.ToExtended(&u) + geAdd(&t, &u, &Ai[aSlide[i]/2]) + } else if aSlide[i] < 0 { + t.ToExtended(&u) + geSub(&t, &u, &Ai[(-aSlide[i])/2]) + } + + if bSlide[i] > 0 { + t.ToExtended(&u) + geMixedAdd(&t, &u, &bi[bSlide[i]/2]) + } else if bSlide[i] < 0 { + t.ToExtended(&u) + geMixedSub(&t, &u, &bi[(-bSlide[i])/2]) + } + + t.ToProjective(r) + } +} + +// equal returns 1 if b == c and 0 otherwise, assuming that b and c are +// non-negative. +func equal(b, c int32) int32 { + x := uint32(b ^ c) + x-- + return int32(x >> 31) +} + +// negative returns 1 if b < 0 and 0 otherwise. +func negative(b int32) int32 { + return (b >> 31) & 1 +} + +func PreComputedGroupElementCMove(t, u *PreComputedGroupElement, b int32) { + FeCMove(&t.yPlusX, &u.yPlusX, b) + FeCMove(&t.yMinusX, &u.yMinusX, b) + FeCMove(&t.xy2d, &u.xy2d, b) +} + +func selectPoint(t *PreComputedGroupElement, pos int32, b int32) { + var minusT PreComputedGroupElement + bNegative := negative(b) + bAbs := b - (((-bNegative) & b) << 1) + + t.Zero() + for i := int32(0); i < 8; i++ { + PreComputedGroupElementCMove(t, &base[pos][i], equal(bAbs, i+1)) + } + FeCopy(&minusT.yPlusX, &t.yMinusX) + FeCopy(&minusT.yMinusX, &t.yPlusX) + FeNeg(&minusT.xy2d, &t.xy2d) + PreComputedGroupElementCMove(t, &minusT, bNegative) +} + +// GeScalarMultBase computes h = a*B, where +// a = a[0]+256*a[1]+...+256^31 a[31] +// B is the Ed25519 base point (x,4/5) with x positive. +// +// Preconditions: +// a[31] <= 127 +func GeScalarMultBase(h *ExtendedGroupElement, a *[32]byte) { + var e [64]int8 + + for i, v := range a { + e[2*i] = int8(v & 15) + e[2*i+1] = int8((v >> 4) & 15) + } + + // each e[i] is between 0 and 15 and e[63] is between 0 and 7. + + carry := int8(0) + for i := 0; i < 63; i++ { + e[i] += carry + carry = (e[i] + 8) >> 4 + e[i] -= carry << 4 + } + e[63] += carry + // each e[i] is between -8 and 8. + + h.Zero() + var t PreComputedGroupElement + var r CompletedGroupElement + for i := int32(1); i < 64; i += 2 { + selectPoint(&t, i/2, int32(e[i])) + geMixedAdd(&r, h, &t) + r.ToExtended(h) + } + + var s ProjectiveGroupElement + + h.Double(&r) + r.ToProjective(&s) + s.Double(&r) + r.ToProjective(&s) + s.Double(&r) + r.ToProjective(&s) + s.Double(&r) + r.ToExtended(h) + + for i := int32(0); i < 64; i += 2 { + selectPoint(&t, i/2, int32(e[i])) + geMixedAdd(&r, h, &t) + r.ToExtended(h) + } +} + +// The scalars are GF(2^252 + 27742317777372353535851937790883648493). + +// Input: +// a[0]+256*a[1]+...+256^31*a[31] = a +// b[0]+256*b[1]+...+256^31*b[31] = b +// c[0]+256*c[1]+...+256^31*c[31] = c +// +// Output: +// s[0]+256*s[1]+...+256^31*s[31] = (ab+c) mod l +// where l = 2^252 + 27742317777372353535851937790883648493. +func ScMulAdd(s, a, b, c *[32]byte) { + a0 := 2097151 & load3(a[:]) + a1 := 2097151 & (load4(a[2:]) >> 5) + a2 := 2097151 & (load3(a[5:]) >> 2) + a3 := 2097151 & (load4(a[7:]) >> 7) + a4 := 2097151 & (load4(a[10:]) >> 4) + a5 := 2097151 & (load3(a[13:]) >> 1) + a6 := 2097151 & (load4(a[15:]) >> 6) + a7 := 2097151 & (load3(a[18:]) >> 3) + a8 := 2097151 & load3(a[21:]) + a9 := 2097151 & (load4(a[23:]) >> 5) + a10 := 2097151 & (load3(a[26:]) >> 2) + a11 := (load4(a[28:]) >> 7) + b0 := 2097151 & load3(b[:]) + b1 := 2097151 & (load4(b[2:]) >> 5) + b2 := 2097151 & (load3(b[5:]) >> 2) + b3 := 2097151 & (load4(b[7:]) >> 7) + b4 := 2097151 & (load4(b[10:]) >> 4) + b5 := 2097151 & (load3(b[13:]) >> 1) + b6 := 2097151 & (load4(b[15:]) >> 6) + b7 := 2097151 & (load3(b[18:]) >> 3) + b8 := 2097151 & load3(b[21:]) + b9 := 2097151 & (load4(b[23:]) >> 5) + b10 := 2097151 & (load3(b[26:]) >> 2) + b11 := (load4(b[28:]) >> 7) + c0 := 2097151 & load3(c[:]) + c1 := 2097151 & (load4(c[2:]) >> 5) + c2 := 2097151 & (load3(c[5:]) >> 2) + c3 := 2097151 & (load4(c[7:]) >> 7) + c4 := 2097151 & (load4(c[10:]) >> 4) + c5 := 2097151 & (load3(c[13:]) >> 1) + c6 := 2097151 & (load4(c[15:]) >> 6) + c7 := 2097151 & (load3(c[18:]) >> 3) + c8 := 2097151 & load3(c[21:]) + c9 := 2097151 & (load4(c[23:]) >> 5) + c10 := 2097151 & (load3(c[26:]) >> 2) + c11 := (load4(c[28:]) >> 7) + var carry [23]int64 + + s0 := c0 + a0*b0 + s1 := c1 + a0*b1 + a1*b0 + s2 := c2 + a0*b2 + a1*b1 + a2*b0 + s3 := c3 + a0*b3 + a1*b2 + a2*b1 + a3*b0 + s4 := c4 + a0*b4 + a1*b3 + a2*b2 + a3*b1 + a4*b0 + s5 := c5 + a0*b5 + a1*b4 + a2*b3 + a3*b2 + a4*b1 + a5*b0 + s6 := c6 + a0*b6 + a1*b5 + a2*b4 + a3*b3 + a4*b2 + a5*b1 + a6*b0 + s7 := c7 + a0*b7 + a1*b6 + a2*b5 + a3*b4 + a4*b3 + a5*b2 + a6*b1 + a7*b0 + s8 := c8 + a0*b8 + a1*b7 + a2*b6 + a3*b5 + a4*b4 + a5*b3 + a6*b2 + a7*b1 + a8*b0 + s9 := c9 + a0*b9 + a1*b8 + a2*b7 + a3*b6 + a4*b5 + a5*b4 + a6*b3 + a7*b2 + a8*b1 + a9*b0 + s10 := c10 + a0*b10 + a1*b9 + a2*b8 + a3*b7 + a4*b6 + a5*b5 + a6*b4 + a7*b3 + a8*b2 + a9*b1 + a10*b0 + s11 := c11 + a0*b11 + a1*b10 + a2*b9 + a3*b8 + a4*b7 + a5*b6 + a6*b5 + a7*b4 + a8*b3 + a9*b2 + a10*b1 + a11*b0 + s12 := a1*b11 + a2*b10 + a3*b9 + a4*b8 + a5*b7 + a6*b6 + a7*b5 + a8*b4 + a9*b3 + a10*b2 + a11*b1 + s13 := a2*b11 + a3*b10 + a4*b9 + a5*b8 + a6*b7 + a7*b6 + a8*b5 + a9*b4 + a10*b3 + a11*b2 + s14 := a3*b11 + a4*b10 + a5*b9 + a6*b8 + a7*b7 + a8*b6 + a9*b5 + a10*b4 + a11*b3 + s15 := a4*b11 + a5*b10 + a6*b9 + a7*b8 + a8*b7 + a9*b6 + a10*b5 + a11*b4 + s16 := a5*b11 + a6*b10 + a7*b9 + a8*b8 + a9*b7 + a10*b6 + a11*b5 + s17 := a6*b11 + a7*b10 + a8*b9 + a9*b8 + a10*b7 + a11*b6 + s18 := a7*b11 + a8*b10 + a9*b9 + a10*b8 + a11*b7 + s19 := a8*b11 + a9*b10 + a10*b9 + a11*b8 + s20 := a9*b11 + a10*b10 + a11*b9 + s21 := a10*b11 + a11*b10 + s22 := a11 * b11 + s23 := int64(0) + + carry[0] = (s0 + (1 << 20)) >> 21 + s1 += carry[0] + s0 -= carry[0] << 21 + carry[2] = (s2 + (1 << 20)) >> 21 + s3 += carry[2] + s2 -= carry[2] << 21 + carry[4] = (s4 + (1 << 20)) >> 21 + s5 += carry[4] + s4 -= carry[4] << 21 + carry[6] = (s6 + (1 << 20)) >> 21 + s7 += carry[6] + s6 -= carry[6] << 21 + carry[8] = (s8 + (1 << 20)) >> 21 + s9 += carry[8] + s8 -= carry[8] << 21 + carry[10] = (s10 + (1 << 20)) >> 21 + s11 += carry[10] + s10 -= carry[10] << 21 + carry[12] = (s12 + (1 << 20)) >> 21 + s13 += carry[12] + s12 -= carry[12] << 21 + carry[14] = (s14 + (1 << 20)) >> 21 + s15 += carry[14] + s14 -= carry[14] << 21 + carry[16] = (s16 + (1 << 20)) >> 21 + s17 += carry[16] + s16 -= carry[16] << 21 + carry[18] = (s18 + (1 << 20)) >> 21 + s19 += carry[18] + s18 -= carry[18] << 21 + carry[20] = (s20 + (1 << 20)) >> 21 + s21 += carry[20] + s20 -= carry[20] << 21 + carry[22] = (s22 + (1 << 20)) >> 21 + s23 += carry[22] + s22 -= carry[22] << 21 + + carry[1] = (s1 + (1 << 20)) >> 21 + s2 += carry[1] + s1 -= carry[1] << 21 + carry[3] = (s3 + (1 << 20)) >> 21 + s4 += carry[3] + s3 -= carry[3] << 21 + carry[5] = (s5 + (1 << 20)) >> 21 + s6 += carry[5] + s5 -= carry[5] << 21 + carry[7] = (s7 + (1 << 20)) >> 21 + s8 += carry[7] + s7 -= carry[7] << 21 + carry[9] = (s9 + (1 << 20)) >> 21 + s10 += carry[9] + s9 -= carry[9] << 21 + carry[11] = (s11 + (1 << 20)) >> 21 + s12 += carry[11] + s11 -= carry[11] << 21 + carry[13] = (s13 + (1 << 20)) >> 21 + s14 += carry[13] + s13 -= carry[13] << 21 + carry[15] = (s15 + (1 << 20)) >> 21 + s16 += carry[15] + s15 -= carry[15] << 21 + carry[17] = (s17 + (1 << 20)) >> 21 + s18 += carry[17] + s17 -= carry[17] << 21 + carry[19] = (s19 + (1 << 20)) >> 21 + s20 += carry[19] + s19 -= carry[19] << 21 + carry[21] = (s21 + (1 << 20)) >> 21 + s22 += carry[21] + s21 -= carry[21] << 21 + + s11 += s23 * 666643 + s12 += s23 * 470296 + s13 += s23 * 654183 + s14 -= s23 * 997805 + s15 += s23 * 136657 + s16 -= s23 * 683901 + s23 = 0 + + s10 += s22 * 666643 + s11 += s22 * 470296 + s12 += s22 * 654183 + s13 -= s22 * 997805 + s14 += s22 * 136657 + s15 -= s22 * 683901 + s22 = 0 + + s9 += s21 * 666643 + s10 += s21 * 470296 + s11 += s21 * 654183 + s12 -= s21 * 997805 + s13 += s21 * 136657 + s14 -= s21 * 683901 + s21 = 0 + + s8 += s20 * 666643 + s9 += s20 * 470296 + s10 += s20 * 654183 + s11 -= s20 * 997805 + s12 += s20 * 136657 + s13 -= s20 * 683901 + s20 = 0 + + s7 += s19 * 666643 + s8 += s19 * 470296 + s9 += s19 * 654183 + s10 -= s19 * 997805 + s11 += s19 * 136657 + s12 -= s19 * 683901 + s19 = 0 + + s6 += s18 * 666643 + s7 += s18 * 470296 + s8 += s18 * 654183 + s9 -= s18 * 997805 + s10 += s18 * 136657 + s11 -= s18 * 683901 + s18 = 0 + + carry[6] = (s6 + (1 << 20)) >> 21 + s7 += carry[6] + s6 -= carry[6] << 21 + carry[8] = (s8 + (1 << 20)) >> 21 + s9 += carry[8] + s8 -= carry[8] << 21 + carry[10] = (s10 + (1 << 20)) >> 21 + s11 += carry[10] + s10 -= carry[10] << 21 + carry[12] = (s12 + (1 << 20)) >> 21 + s13 += carry[12] + s12 -= carry[12] << 21 + carry[14] = (s14 + (1 << 20)) >> 21 + s15 += carry[14] + s14 -= carry[14] << 21 + carry[16] = (s16 + (1 << 20)) >> 21 + s17 += carry[16] + s16 -= carry[16] << 21 + + carry[7] = (s7 + (1 << 20)) >> 21 + s8 += carry[7] + s7 -= carry[7] << 21 + carry[9] = (s9 + (1 << 20)) >> 21 + s10 += carry[9] + s9 -= carry[9] << 21 + carry[11] = (s11 + (1 << 20)) >> 21 + s12 += carry[11] + s11 -= carry[11] << 21 + carry[13] = (s13 + (1 << 20)) >> 21 + s14 += carry[13] + s13 -= carry[13] << 21 + carry[15] = (s15 + (1 << 20)) >> 21 + s16 += carry[15] + s15 -= carry[15] << 21 + + s5 += s17 * 666643 + s6 += s17 * 470296 + s7 += s17 * 654183 + s8 -= s17 * 997805 + s9 += s17 * 136657 + s10 -= s17 * 683901 + s17 = 0 + + s4 += s16 * 666643 + s5 += s16 * 470296 + s6 += s16 * 654183 + s7 -= s16 * 997805 + s8 += s16 * 136657 + s9 -= s16 * 683901 + s16 = 0 + + s3 += s15 * 666643 + s4 += s15 * 470296 + s5 += s15 * 654183 + s6 -= s15 * 997805 + s7 += s15 * 136657 + s8 -= s15 * 683901 + s15 = 0 + + s2 += s14 * 666643 + s3 += s14 * 470296 + s4 += s14 * 654183 + s5 -= s14 * 997805 + s6 += s14 * 136657 + s7 -= s14 * 683901 + s14 = 0 + + s1 += s13 * 666643 + s2 += s13 * 470296 + s3 += s13 * 654183 + s4 -= s13 * 997805 + s5 += s13 * 136657 + s6 -= s13 * 683901 + s13 = 0 + + s0 += s12 * 666643 + s1 += s12 * 470296 + s2 += s12 * 654183 + s3 -= s12 * 997805 + s4 += s12 * 136657 + s5 -= s12 * 683901 + s12 = 0 + + carry[0] = (s0 + (1 << 20)) >> 21 + s1 += carry[0] + s0 -= carry[0] << 21 + carry[2] = (s2 + (1 << 20)) >> 21 + s3 += carry[2] + s2 -= carry[2] << 21 + carry[4] = (s4 + (1 << 20)) >> 21 + s5 += carry[4] + s4 -= carry[4] << 21 + carry[6] = (s6 + (1 << 20)) >> 21 + s7 += carry[6] + s6 -= carry[6] << 21 + carry[8] = (s8 + (1 << 20)) >> 21 + s9 += carry[8] + s8 -= carry[8] << 21 + carry[10] = (s10 + (1 << 20)) >> 21 + s11 += carry[10] + s10 -= carry[10] << 21 + + carry[1] = (s1 + (1 << 20)) >> 21 + s2 += carry[1] + s1 -= carry[1] << 21 + carry[3] = (s3 + (1 << 20)) >> 21 + s4 += carry[3] + s3 -= carry[3] << 21 + carry[5] = (s5 + (1 << 20)) >> 21 + s6 += carry[5] + s5 -= carry[5] << 21 + carry[7] = (s7 + (1 << 20)) >> 21 + s8 += carry[7] + s7 -= carry[7] << 21 + carry[9] = (s9 + (1 << 20)) >> 21 + s10 += carry[9] + s9 -= carry[9] << 21 + carry[11] = (s11 + (1 << 20)) >> 21 + s12 += carry[11] + s11 -= carry[11] << 21 + + s0 += s12 * 666643 + s1 += s12 * 470296 + s2 += s12 * 654183 + s3 -= s12 * 997805 + s4 += s12 * 136657 + s5 -= s12 * 683901 + s12 = 0 + + carry[0] = s0 >> 21 + s1 += carry[0] + s0 -= carry[0] << 21 + carry[1] = s1 >> 21 + s2 += carry[1] + s1 -= carry[1] << 21 + carry[2] = s2 >> 21 + s3 += carry[2] + s2 -= carry[2] << 21 + carry[3] = s3 >> 21 + s4 += carry[3] + s3 -= carry[3] << 21 + carry[4] = s4 >> 21 + s5 += carry[4] + s4 -= carry[4] << 21 + carry[5] = s5 >> 21 + s6 += carry[5] + s5 -= carry[5] << 21 + carry[6] = s6 >> 21 + s7 += carry[6] + s6 -= carry[6] << 21 + carry[7] = s7 >> 21 + s8 += carry[7] + s7 -= carry[7] << 21 + carry[8] = s8 >> 21 + s9 += carry[8] + s8 -= carry[8] << 21 + carry[9] = s9 >> 21 + s10 += carry[9] + s9 -= carry[9] << 21 + carry[10] = s10 >> 21 + s11 += carry[10] + s10 -= carry[10] << 21 + carry[11] = s11 >> 21 + s12 += carry[11] + s11 -= carry[11] << 21 + + s0 += s12 * 666643 + s1 += s12 * 470296 + s2 += s12 * 654183 + s3 -= s12 * 997805 + s4 += s12 * 136657 + s5 -= s12 * 683901 + s12 = 0 + + carry[0] = s0 >> 21 + s1 += carry[0] + s0 -= carry[0] << 21 + carry[1] = s1 >> 21 + s2 += carry[1] + s1 -= carry[1] << 21 + carry[2] = s2 >> 21 + s3 += carry[2] + s2 -= carry[2] << 21 + carry[3] = s3 >> 21 + s4 += carry[3] + s3 -= carry[3] << 21 + carry[4] = s4 >> 21 + s5 += carry[4] + s4 -= carry[4] << 21 + carry[5] = s5 >> 21 + s6 += carry[5] + s5 -= carry[5] << 21 + carry[6] = s6 >> 21 + s7 += carry[6] + s6 -= carry[6] << 21 + carry[7] = s7 >> 21 + s8 += carry[7] + s7 -= carry[7] << 21 + carry[8] = s8 >> 21 + s9 += carry[8] + s8 -= carry[8] << 21 + carry[9] = s9 >> 21 + s10 += carry[9] + s9 -= carry[9] << 21 + carry[10] = s10 >> 21 + s11 += carry[10] + s10 -= carry[10] << 21 + + s[0] = byte(s0 >> 0) + s[1] = byte(s0 >> 8) + s[2] = byte((s0 >> 16) | (s1 << 5)) + s[3] = byte(s1 >> 3) + s[4] = byte(s1 >> 11) + s[5] = byte((s1 >> 19) | (s2 << 2)) + s[6] = byte(s2 >> 6) + s[7] = byte((s2 >> 14) | (s3 << 7)) + s[8] = byte(s3 >> 1) + s[9] = byte(s3 >> 9) + s[10] = byte((s3 >> 17) | (s4 << 4)) + s[11] = byte(s4 >> 4) + s[12] = byte(s4 >> 12) + s[13] = byte((s4 >> 20) | (s5 << 1)) + s[14] = byte(s5 >> 7) + s[15] = byte((s5 >> 15) | (s6 << 6)) + s[16] = byte(s6 >> 2) + s[17] = byte(s6 >> 10) + s[18] = byte((s6 >> 18) | (s7 << 3)) + s[19] = byte(s7 >> 5) + s[20] = byte(s7 >> 13) + s[21] = byte(s8 >> 0) + s[22] = byte(s8 >> 8) + s[23] = byte((s8 >> 16) | (s9 << 5)) + s[24] = byte(s9 >> 3) + s[25] = byte(s9 >> 11) + s[26] = byte((s9 >> 19) | (s10 << 2)) + s[27] = byte(s10 >> 6) + s[28] = byte((s10 >> 14) | (s11 << 7)) + s[29] = byte(s11 >> 1) + s[30] = byte(s11 >> 9) + s[31] = byte(s11 >> 17) +} + +// Input: +// s[0]+256*s[1]+...+256^63*s[63] = s +// +// Output: +// s[0]+256*s[1]+...+256^31*s[31] = s mod l +// where l = 2^252 + 27742317777372353535851937790883648493. +func ScReduce(out *[32]byte, s *[64]byte) { + s0 := 2097151 & load3(s[:]) + s1 := 2097151 & (load4(s[2:]) >> 5) + s2 := 2097151 & (load3(s[5:]) >> 2) + s3 := 2097151 & (load4(s[7:]) >> 7) + s4 := 2097151 & (load4(s[10:]) >> 4) + s5 := 2097151 & (load3(s[13:]) >> 1) + s6 := 2097151 & (load4(s[15:]) >> 6) + s7 := 2097151 & (load3(s[18:]) >> 3) + s8 := 2097151 & load3(s[21:]) + s9 := 2097151 & (load4(s[23:]) >> 5) + s10 := 2097151 & (load3(s[26:]) >> 2) + s11 := 2097151 & (load4(s[28:]) >> 7) + s12 := 2097151 & (load4(s[31:]) >> 4) + s13 := 2097151 & (load3(s[34:]) >> 1) + s14 := 2097151 & (load4(s[36:]) >> 6) + s15 := 2097151 & (load3(s[39:]) >> 3) + s16 := 2097151 & load3(s[42:]) + s17 := 2097151 & (load4(s[44:]) >> 5) + s18 := 2097151 & (load3(s[47:]) >> 2) + s19 := 2097151 & (load4(s[49:]) >> 7) + s20 := 2097151 & (load4(s[52:]) >> 4) + s21 := 2097151 & (load3(s[55:]) >> 1) + s22 := 2097151 & (load4(s[57:]) >> 6) + s23 := (load4(s[60:]) >> 3) + + s11 += s23 * 666643 + s12 += s23 * 470296 + s13 += s23 * 654183 + s14 -= s23 * 997805 + s15 += s23 * 136657 + s16 -= s23 * 683901 + s23 = 0 + + s10 += s22 * 666643 + s11 += s22 * 470296 + s12 += s22 * 654183 + s13 -= s22 * 997805 + s14 += s22 * 136657 + s15 -= s22 * 683901 + s22 = 0 + + s9 += s21 * 666643 + s10 += s21 * 470296 + s11 += s21 * 654183 + s12 -= s21 * 997805 + s13 += s21 * 136657 + s14 -= s21 * 683901 + s21 = 0 + + s8 += s20 * 666643 + s9 += s20 * 470296 + s10 += s20 * 654183 + s11 -= s20 * 997805 + s12 += s20 * 136657 + s13 -= s20 * 683901 + s20 = 0 + + s7 += s19 * 666643 + s8 += s19 * 470296 + s9 += s19 * 654183 + s10 -= s19 * 997805 + s11 += s19 * 136657 + s12 -= s19 * 683901 + s19 = 0 + + s6 += s18 * 666643 + s7 += s18 * 470296 + s8 += s18 * 654183 + s9 -= s18 * 997805 + s10 += s18 * 136657 + s11 -= s18 * 683901 + s18 = 0 + + var carry [17]int64 + + carry[6] = (s6 + (1 << 20)) >> 21 + s7 += carry[6] + s6 -= carry[6] << 21 + carry[8] = (s8 + (1 << 20)) >> 21 + s9 += carry[8] + s8 -= carry[8] << 21 + carry[10] = (s10 + (1 << 20)) >> 21 + s11 += carry[10] + s10 -= carry[10] << 21 + carry[12] = (s12 + (1 << 20)) >> 21 + s13 += carry[12] + s12 -= carry[12] << 21 + carry[14] = (s14 + (1 << 20)) >> 21 + s15 += carry[14] + s14 -= carry[14] << 21 + carry[16] = (s16 + (1 << 20)) >> 21 + s17 += carry[16] + s16 -= carry[16] << 21 + + carry[7] = (s7 + (1 << 20)) >> 21 + s8 += carry[7] + s7 -= carry[7] << 21 + carry[9] = (s9 + (1 << 20)) >> 21 + s10 += carry[9] + s9 -= carry[9] << 21 + carry[11] = (s11 + (1 << 20)) >> 21 + s12 += carry[11] + s11 -= carry[11] << 21 + carry[13] = (s13 + (1 << 20)) >> 21 + s14 += carry[13] + s13 -= carry[13] << 21 + carry[15] = (s15 + (1 << 20)) >> 21 + s16 += carry[15] + s15 -= carry[15] << 21 + + s5 += s17 * 666643 + s6 += s17 * 470296 + s7 += s17 * 654183 + s8 -= s17 * 997805 + s9 += s17 * 136657 + s10 -= s17 * 683901 + s17 = 0 + + s4 += s16 * 666643 + s5 += s16 * 470296 + s6 += s16 * 654183 + s7 -= s16 * 997805 + s8 += s16 * 136657 + s9 -= s16 * 683901 + s16 = 0 + + s3 += s15 * 666643 + s4 += s15 * 470296 + s5 += s15 * 654183 + s6 -= s15 * 997805 + s7 += s15 * 136657 + s8 -= s15 * 683901 + s15 = 0 + + s2 += s14 * 666643 + s3 += s14 * 470296 + s4 += s14 * 654183 + s5 -= s14 * 997805 + s6 += s14 * 136657 + s7 -= s14 * 683901 + s14 = 0 + + s1 += s13 * 666643 + s2 += s13 * 470296 + s3 += s13 * 654183 + s4 -= s13 * 997805 + s5 += s13 * 136657 + s6 -= s13 * 683901 + s13 = 0 + + s0 += s12 * 666643 + s1 += s12 * 470296 + s2 += s12 * 654183 + s3 -= s12 * 997805 + s4 += s12 * 136657 + s5 -= s12 * 683901 + s12 = 0 + + carry[0] = (s0 + (1 << 20)) >> 21 + s1 += carry[0] + s0 -= carry[0] << 21 + carry[2] = (s2 + (1 << 20)) >> 21 + s3 += carry[2] + s2 -= carry[2] << 21 + carry[4] = (s4 + (1 << 20)) >> 21 + s5 += carry[4] + s4 -= carry[4] << 21 + carry[6] = (s6 + (1 << 20)) >> 21 + s7 += carry[6] + s6 -= carry[6] << 21 + carry[8] = (s8 + (1 << 20)) >> 21 + s9 += carry[8] + s8 -= carry[8] << 21 + carry[10] = (s10 + (1 << 20)) >> 21 + s11 += carry[10] + s10 -= carry[10] << 21 + + carry[1] = (s1 + (1 << 20)) >> 21 + s2 += carry[1] + s1 -= carry[1] << 21 + carry[3] = (s3 + (1 << 20)) >> 21 + s4 += carry[3] + s3 -= carry[3] << 21 + carry[5] = (s5 + (1 << 20)) >> 21 + s6 += carry[5] + s5 -= carry[5] << 21 + carry[7] = (s7 + (1 << 20)) >> 21 + s8 += carry[7] + s7 -= carry[7] << 21 + carry[9] = (s9 + (1 << 20)) >> 21 + s10 += carry[9] + s9 -= carry[9] << 21 + carry[11] = (s11 + (1 << 20)) >> 21 + s12 += carry[11] + s11 -= carry[11] << 21 + + s0 += s12 * 666643 + s1 += s12 * 470296 + s2 += s12 * 654183 + s3 -= s12 * 997805 + s4 += s12 * 136657 + s5 -= s12 * 683901 + s12 = 0 + + carry[0] = s0 >> 21 + s1 += carry[0] + s0 -= carry[0] << 21 + carry[1] = s1 >> 21 + s2 += carry[1] + s1 -= carry[1] << 21 + carry[2] = s2 >> 21 + s3 += carry[2] + s2 -= carry[2] << 21 + carry[3] = s3 >> 21 + s4 += carry[3] + s3 -= carry[3] << 21 + carry[4] = s4 >> 21 + s5 += carry[4] + s4 -= carry[4] << 21 + carry[5] = s5 >> 21 + s6 += carry[5] + s5 -= carry[5] << 21 + carry[6] = s6 >> 21 + s7 += carry[6] + s6 -= carry[6] << 21 + carry[7] = s7 >> 21 + s8 += carry[7] + s7 -= carry[7] << 21 + carry[8] = s8 >> 21 + s9 += carry[8] + s8 -= carry[8] << 21 + carry[9] = s9 >> 21 + s10 += carry[9] + s9 -= carry[9] << 21 + carry[10] = s10 >> 21 + s11 += carry[10] + s10 -= carry[10] << 21 + carry[11] = s11 >> 21 + s12 += carry[11] + s11 -= carry[11] << 21 + + s0 += s12 * 666643 + s1 += s12 * 470296 + s2 += s12 * 654183 + s3 -= s12 * 997805 + s4 += s12 * 136657 + s5 -= s12 * 683901 + s12 = 0 + + carry[0] = s0 >> 21 + s1 += carry[0] + s0 -= carry[0] << 21 + carry[1] = s1 >> 21 + s2 += carry[1] + s1 -= carry[1] << 21 + carry[2] = s2 >> 21 + s3 += carry[2] + s2 -= carry[2] << 21 + carry[3] = s3 >> 21 + s4 += carry[3] + s3 -= carry[3] << 21 + carry[4] = s4 >> 21 + s5 += carry[4] + s4 -= carry[4] << 21 + carry[5] = s5 >> 21 + s6 += carry[5] + s5 -= carry[5] << 21 + carry[6] = s6 >> 21 + s7 += carry[6] + s6 -= carry[6] << 21 + carry[7] = s7 >> 21 + s8 += carry[7] + s7 -= carry[7] << 21 + carry[8] = s8 >> 21 + s9 += carry[8] + s8 -= carry[8] << 21 + carry[9] = s9 >> 21 + s10 += carry[9] + s9 -= carry[9] << 21 + carry[10] = s10 >> 21 + s11 += carry[10] + s10 -= carry[10] << 21 + + out[0] = byte(s0 >> 0) + out[1] = byte(s0 >> 8) + out[2] = byte((s0 >> 16) | (s1 << 5)) + out[3] = byte(s1 >> 3) + out[4] = byte(s1 >> 11) + out[5] = byte((s1 >> 19) | (s2 << 2)) + out[6] = byte(s2 >> 6) + out[7] = byte((s2 >> 14) | (s3 << 7)) + out[8] = byte(s3 >> 1) + out[9] = byte(s3 >> 9) + out[10] = byte((s3 >> 17) | (s4 << 4)) + out[11] = byte(s4 >> 4) + out[12] = byte(s4 >> 12) + out[13] = byte((s4 >> 20) | (s5 << 1)) + out[14] = byte(s5 >> 7) + out[15] = byte((s5 >> 15) | (s6 << 6)) + out[16] = byte(s6 >> 2) + out[17] = byte(s6 >> 10) + out[18] = byte((s6 >> 18) | (s7 << 3)) + out[19] = byte(s7 >> 5) + out[20] = byte(s7 >> 13) + out[21] = byte(s8 >> 0) + out[22] = byte(s8 >> 8) + out[23] = byte((s8 >> 16) | (s9 << 5)) + out[24] = byte(s9 >> 3) + out[25] = byte(s9 >> 11) + out[26] = byte((s9 >> 19) | (s10 << 2)) + out[27] = byte(s10 >> 6) + out[28] = byte((s10 >> 14) | (s11 << 7)) + out[29] = byte(s11 >> 1) + out[30] = byte(s11 >> 9) + out[31] = byte(s11 >> 17) +} -- cgit v1.2.3