mirror of https://github.com/cheat/cheat.git
318 lines
8.7 KiB
Go
318 lines
8.7 KiB
Go
package fp25519
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import (
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"encoding/binary"
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"math/bits"
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)
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func cmovGeneric(x, y *Elt, n uint) {
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m := -uint64(n & 0x1)
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x0 := binary.LittleEndian.Uint64(x[0*8 : 1*8])
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x1 := binary.LittleEndian.Uint64(x[1*8 : 2*8])
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x2 := binary.LittleEndian.Uint64(x[2*8 : 3*8])
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x3 := binary.LittleEndian.Uint64(x[3*8 : 4*8])
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y0 := binary.LittleEndian.Uint64(y[0*8 : 1*8])
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y1 := binary.LittleEndian.Uint64(y[1*8 : 2*8])
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y2 := binary.LittleEndian.Uint64(y[2*8 : 3*8])
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y3 := binary.LittleEndian.Uint64(y[3*8 : 4*8])
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x0 = (x0 &^ m) | (y0 & m)
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x1 = (x1 &^ m) | (y1 & m)
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x2 = (x2 &^ m) | (y2 & m)
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x3 = (x3 &^ m) | (y3 & m)
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binary.LittleEndian.PutUint64(x[0*8:1*8], x0)
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binary.LittleEndian.PutUint64(x[1*8:2*8], x1)
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binary.LittleEndian.PutUint64(x[2*8:3*8], x2)
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binary.LittleEndian.PutUint64(x[3*8:4*8], x3)
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}
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func cswapGeneric(x, y *Elt, n uint) {
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m := -uint64(n & 0x1)
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x0 := binary.LittleEndian.Uint64(x[0*8 : 1*8])
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x1 := binary.LittleEndian.Uint64(x[1*8 : 2*8])
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x2 := binary.LittleEndian.Uint64(x[2*8 : 3*8])
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x3 := binary.LittleEndian.Uint64(x[3*8 : 4*8])
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y0 := binary.LittleEndian.Uint64(y[0*8 : 1*8])
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y1 := binary.LittleEndian.Uint64(y[1*8 : 2*8])
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y2 := binary.LittleEndian.Uint64(y[2*8 : 3*8])
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y3 := binary.LittleEndian.Uint64(y[3*8 : 4*8])
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t0 := m & (x0 ^ y0)
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t1 := m & (x1 ^ y1)
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t2 := m & (x2 ^ y2)
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t3 := m & (x3 ^ y3)
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x0 ^= t0
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x1 ^= t1
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x2 ^= t2
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x3 ^= t3
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y0 ^= t0
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y1 ^= t1
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y2 ^= t2
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y3 ^= t3
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binary.LittleEndian.PutUint64(x[0*8:1*8], x0)
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binary.LittleEndian.PutUint64(x[1*8:2*8], x1)
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binary.LittleEndian.PutUint64(x[2*8:3*8], x2)
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binary.LittleEndian.PutUint64(x[3*8:4*8], x3)
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binary.LittleEndian.PutUint64(y[0*8:1*8], y0)
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binary.LittleEndian.PutUint64(y[1*8:2*8], y1)
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binary.LittleEndian.PutUint64(y[2*8:3*8], y2)
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binary.LittleEndian.PutUint64(y[3*8:4*8], y3)
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}
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func addGeneric(z, x, y *Elt) {
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x0 := binary.LittleEndian.Uint64(x[0*8 : 1*8])
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x1 := binary.LittleEndian.Uint64(x[1*8 : 2*8])
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x2 := binary.LittleEndian.Uint64(x[2*8 : 3*8])
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x3 := binary.LittleEndian.Uint64(x[3*8 : 4*8])
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y0 := binary.LittleEndian.Uint64(y[0*8 : 1*8])
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y1 := binary.LittleEndian.Uint64(y[1*8 : 2*8])
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y2 := binary.LittleEndian.Uint64(y[2*8 : 3*8])
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y3 := binary.LittleEndian.Uint64(y[3*8 : 4*8])
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z0, c0 := bits.Add64(x0, y0, 0)
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z1, c1 := bits.Add64(x1, y1, c0)
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z2, c2 := bits.Add64(x2, y2, c1)
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z3, c3 := bits.Add64(x3, y3, c2)
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z0, c0 = bits.Add64(z0, (-c3)&38, 0)
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z1, c1 = bits.Add64(z1, 0, c0)
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z2, c2 = bits.Add64(z2, 0, c1)
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z3, c3 = bits.Add64(z3, 0, c2)
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z0, _ = bits.Add64(z0, (-c3)&38, 0)
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binary.LittleEndian.PutUint64(z[0*8:1*8], z0)
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binary.LittleEndian.PutUint64(z[1*8:2*8], z1)
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binary.LittleEndian.PutUint64(z[2*8:3*8], z2)
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binary.LittleEndian.PutUint64(z[3*8:4*8], z3)
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}
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func subGeneric(z, x, y *Elt) {
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x0 := binary.LittleEndian.Uint64(x[0*8 : 1*8])
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x1 := binary.LittleEndian.Uint64(x[1*8 : 2*8])
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x2 := binary.LittleEndian.Uint64(x[2*8 : 3*8])
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x3 := binary.LittleEndian.Uint64(x[3*8 : 4*8])
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y0 := binary.LittleEndian.Uint64(y[0*8 : 1*8])
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y1 := binary.LittleEndian.Uint64(y[1*8 : 2*8])
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y2 := binary.LittleEndian.Uint64(y[2*8 : 3*8])
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y3 := binary.LittleEndian.Uint64(y[3*8 : 4*8])
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z0, c0 := bits.Sub64(x0, y0, 0)
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z1, c1 := bits.Sub64(x1, y1, c0)
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z2, c2 := bits.Sub64(x2, y2, c1)
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z3, c3 := bits.Sub64(x3, y3, c2)
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z0, c0 = bits.Sub64(z0, (-c3)&38, 0)
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z1, c1 = bits.Sub64(z1, 0, c0)
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z2, c2 = bits.Sub64(z2, 0, c1)
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z3, c3 = bits.Sub64(z3, 0, c2)
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z0, _ = bits.Sub64(z0, (-c3)&38, 0)
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binary.LittleEndian.PutUint64(z[0*8:1*8], z0)
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binary.LittleEndian.PutUint64(z[1*8:2*8], z1)
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binary.LittleEndian.PutUint64(z[2*8:3*8], z2)
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binary.LittleEndian.PutUint64(z[3*8:4*8], z3)
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}
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func addsubGeneric(x, y *Elt) {
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z := &Elt{}
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addGeneric(z, x, y)
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subGeneric(y, x, y)
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*x = *z
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}
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func mulGeneric(z, x, y *Elt) {
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x0 := binary.LittleEndian.Uint64(x[0*8 : 1*8])
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x1 := binary.LittleEndian.Uint64(x[1*8 : 2*8])
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x2 := binary.LittleEndian.Uint64(x[2*8 : 3*8])
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x3 := binary.LittleEndian.Uint64(x[3*8 : 4*8])
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y0 := binary.LittleEndian.Uint64(y[0*8 : 1*8])
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y1 := binary.LittleEndian.Uint64(y[1*8 : 2*8])
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y2 := binary.LittleEndian.Uint64(y[2*8 : 3*8])
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y3 := binary.LittleEndian.Uint64(y[3*8 : 4*8])
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yi := y0
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h0, l0 := bits.Mul64(x0, yi)
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h1, l1 := bits.Mul64(x1, yi)
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h2, l2 := bits.Mul64(x2, yi)
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h3, l3 := bits.Mul64(x3, yi)
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z0 := l0
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a0, c0 := bits.Add64(h0, l1, 0)
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a1, c1 := bits.Add64(h1, l2, c0)
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a2, c2 := bits.Add64(h2, l3, c1)
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a3, _ := bits.Add64(h3, 0, c2)
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yi = y1
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h0, l0 = bits.Mul64(x0, yi)
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h1, l1 = bits.Mul64(x1, yi)
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h2, l2 = bits.Mul64(x2, yi)
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h3, l3 = bits.Mul64(x3, yi)
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z1, c0 := bits.Add64(a0, l0, 0)
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h0, c1 = bits.Add64(h0, l1, c0)
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h1, c2 = bits.Add64(h1, l2, c1)
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h2, c3 := bits.Add64(h2, l3, c2)
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h3, _ = bits.Add64(h3, 0, c3)
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a0, c0 = bits.Add64(a1, h0, 0)
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a1, c1 = bits.Add64(a2, h1, c0)
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a2, c2 = bits.Add64(a3, h2, c1)
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a3, _ = bits.Add64(0, h3, c2)
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yi = y2
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h0, l0 = bits.Mul64(x0, yi)
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h1, l1 = bits.Mul64(x1, yi)
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h2, l2 = bits.Mul64(x2, yi)
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h3, l3 = bits.Mul64(x3, yi)
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z2, c0 := bits.Add64(a0, l0, 0)
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h0, c1 = bits.Add64(h0, l1, c0)
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h1, c2 = bits.Add64(h1, l2, c1)
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h2, c3 = bits.Add64(h2, l3, c2)
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h3, _ = bits.Add64(h3, 0, c3)
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a0, c0 = bits.Add64(a1, h0, 0)
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a1, c1 = bits.Add64(a2, h1, c0)
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a2, c2 = bits.Add64(a3, h2, c1)
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a3, _ = bits.Add64(0, h3, c2)
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yi = y3
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h0, l0 = bits.Mul64(x0, yi)
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h1, l1 = bits.Mul64(x1, yi)
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h2, l2 = bits.Mul64(x2, yi)
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h3, l3 = bits.Mul64(x3, yi)
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z3, c0 := bits.Add64(a0, l0, 0)
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h0, c1 = bits.Add64(h0, l1, c0)
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h1, c2 = bits.Add64(h1, l2, c1)
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h2, c3 = bits.Add64(h2, l3, c2)
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h3, _ = bits.Add64(h3, 0, c3)
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z4, c0 := bits.Add64(a1, h0, 0)
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z5, c1 := bits.Add64(a2, h1, c0)
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z6, c2 := bits.Add64(a3, h2, c1)
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z7, _ := bits.Add64(0, h3, c2)
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red64(z, z0, z1, z2, z3, z4, z5, z6, z7)
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}
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func sqrGeneric(z, x *Elt) {
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x0 := binary.LittleEndian.Uint64(x[0*8 : 1*8])
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x1 := binary.LittleEndian.Uint64(x[1*8 : 2*8])
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x2 := binary.LittleEndian.Uint64(x[2*8 : 3*8])
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x3 := binary.LittleEndian.Uint64(x[3*8 : 4*8])
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h0, a0 := bits.Mul64(x0, x1)
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h1, l1 := bits.Mul64(x0, x2)
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h2, l2 := bits.Mul64(x0, x3)
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h3, l3 := bits.Mul64(x3, x1)
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h4, l4 := bits.Mul64(x3, x2)
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h, l := bits.Mul64(x1, x2)
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a1, c0 := bits.Add64(l1, h0, 0)
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a2, c1 := bits.Add64(l2, h1, c0)
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a3, c2 := bits.Add64(l3, h2, c1)
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a4, c3 := bits.Add64(l4, h3, c2)
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a5, _ := bits.Add64(h4, 0, c3)
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a2, c0 = bits.Add64(a2, l, 0)
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a3, c1 = bits.Add64(a3, h, c0)
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a4, c2 = bits.Add64(a4, 0, c1)
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a5, c3 = bits.Add64(a5, 0, c2)
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a6, _ := bits.Add64(0, 0, c3)
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a0, c0 = bits.Add64(a0, a0, 0)
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a1, c1 = bits.Add64(a1, a1, c0)
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a2, c2 = bits.Add64(a2, a2, c1)
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a3, c3 = bits.Add64(a3, a3, c2)
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a4, c4 := bits.Add64(a4, a4, c3)
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a5, c5 := bits.Add64(a5, a5, c4)
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a6, _ = bits.Add64(a6, a6, c5)
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b1, b0 := bits.Mul64(x0, x0)
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b3, b2 := bits.Mul64(x1, x1)
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b5, b4 := bits.Mul64(x2, x2)
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b7, b6 := bits.Mul64(x3, x3)
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b1, c0 = bits.Add64(b1, a0, 0)
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b2, c1 = bits.Add64(b2, a1, c0)
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b3, c2 = bits.Add64(b3, a2, c1)
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b4, c3 = bits.Add64(b4, a3, c2)
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b5, c4 = bits.Add64(b5, a4, c3)
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b6, c5 = bits.Add64(b6, a5, c4)
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b7, _ = bits.Add64(b7, a6, c5)
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red64(z, b0, b1, b2, b3, b4, b5, b6, b7)
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}
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func modpGeneric(x *Elt) {
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x0 := binary.LittleEndian.Uint64(x[0*8 : 1*8])
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x1 := binary.LittleEndian.Uint64(x[1*8 : 2*8])
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x2 := binary.LittleEndian.Uint64(x[2*8 : 3*8])
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x3 := binary.LittleEndian.Uint64(x[3*8 : 4*8])
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// CX = C[255] ? 38 : 19
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cx := uint64(19) << (x3 >> 63)
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// PUT BIT 255 IN CARRY FLAG AND CLEAR
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x3 &^= 1 << 63
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x0, c0 := bits.Add64(x0, cx, 0)
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x1, c1 := bits.Add64(x1, 0, c0)
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x2, c2 := bits.Add64(x2, 0, c1)
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x3, _ = bits.Add64(x3, 0, c2)
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// TEST FOR BIT 255 AGAIN; ONLY TRIGGERED ON OVERFLOW MODULO 2^255-19
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// cx = C[255] ? 0 : 19
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cx = uint64(19) &^ (-(x3 >> 63))
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// CLEAR BIT 255
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x3 &^= 1 << 63
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x0, c0 = bits.Sub64(x0, cx, 0)
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x1, c1 = bits.Sub64(x1, 0, c0)
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x2, c2 = bits.Sub64(x2, 0, c1)
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x3, _ = bits.Sub64(x3, 0, c2)
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binary.LittleEndian.PutUint64(x[0*8:1*8], x0)
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binary.LittleEndian.PutUint64(x[1*8:2*8], x1)
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binary.LittleEndian.PutUint64(x[2*8:3*8], x2)
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binary.LittleEndian.PutUint64(x[3*8:4*8], x3)
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}
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func red64(z *Elt, x0, x1, x2, x3, x4, x5, x6, x7 uint64) {
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h0, l0 := bits.Mul64(x4, 38)
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h1, l1 := bits.Mul64(x5, 38)
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h2, l2 := bits.Mul64(x6, 38)
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h3, l3 := bits.Mul64(x7, 38)
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l1, c0 := bits.Add64(h0, l1, 0)
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l2, c1 := bits.Add64(h1, l2, c0)
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l3, c2 := bits.Add64(h2, l3, c1)
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l4, _ := bits.Add64(h3, 0, c2)
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l0, c0 = bits.Add64(l0, x0, 0)
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l1, c1 = bits.Add64(l1, x1, c0)
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l2, c2 = bits.Add64(l2, x2, c1)
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l3, c3 := bits.Add64(l3, x3, c2)
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l4, _ = bits.Add64(l4, 0, c3)
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_, l4 = bits.Mul64(l4, 38)
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l0, c0 = bits.Add64(l0, l4, 0)
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z1, c1 := bits.Add64(l1, 0, c0)
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z2, c2 := bits.Add64(l2, 0, c1)
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z3, c3 := bits.Add64(l3, 0, c2)
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z0, _ := bits.Add64(l0, (-c3)&38, 0)
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binary.LittleEndian.PutUint64(z[0*8:1*8], z0)
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binary.LittleEndian.PutUint64(z[1*8:2*8], z1)
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binary.LittleEndian.PutUint64(z[2*8:3*8], z2)
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binary.LittleEndian.PutUint64(z[3*8:4*8], z3)
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}
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