36 lines
1.0 KiB
Go
36 lines
1.0 KiB
Go
// Copyright 2023 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build purego || (!amd64 && !arm64 && !ppc64le && !s390x)
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package nistec
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import "sources.truenas.cloud/code/nistec/internal/fiat"
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// Negate sets p = -q and returns p.
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func (p *P256Point) Negate(q *P256Point) *P256Point {
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p.x.Set(&q.x)
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p.y.Sub(new(fiat.P256Element), &q.y)
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p.z.Set(&q.z)
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return p
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}
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// IsInfinity returns 1 if p is the point-at-infinity, 0 otherwise.
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func (p *P256Point) IsInfinity() int {
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return p.z.IsZero()
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}
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// Equal returns 1 if p and q represent the same point, 0 otherwise.
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func (p *P256Point) Equal(q *P256Point) int {
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pinf := p.z.IsZero()
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qinf := q.z.IsZero()
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bothinf := pinf & qinf
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noneinf := (1 - pinf) & (1 - qinf)
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px := new(fiat.P256Element).Mul(&p.x, &q.z)
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qx := new(fiat.P256Element).Mul(&q.x, &p.z)
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py := new(fiat.P256Element).Mul(&p.y, &q.z)
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qy := new(fiat.P256Element).Mul(&q.y, &p.z)
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return bothinf | (noneinf & px.Equal(qx) & py.Equal(qy))
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}
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