Current File : //usr/local/go119/src/crypto/internal/nistec/fiat/p256.go
// Copyright 2021 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.
// Code generated by generate.go. DO NOT EDIT.
package fiat
import (
"crypto/subtle"
"errors"
)
// P256Element is an integer modulo 2^256 - 2^224 + 2^192 + 2^96 - 1.
//
// The zero value is a valid zero element.
type P256Element struct {
// Values are represented internally always in the Montgomery domain, and
// converted in Bytes and SetBytes.
x p256MontgomeryDomainFieldElement
}
const p256ElementLen = 32
type p256UntypedFieldElement = [4]uint64
// One sets e = 1, and returns e.
func (e *P256Element) One() *P256Element {
p256SetOne(&e.x)
return e
}
// Equal returns 1 if e == t, and zero otherwise.
func (e *P256Element) Equal(t *P256Element) int {
eBytes := e.Bytes()
tBytes := t.Bytes()
return subtle.ConstantTimeCompare(eBytes, tBytes)
}
var p256ZeroEncoding = new(P256Element).Bytes()
// IsZero returns 1 if e == 0, and zero otherwise.
func (e *P256Element) IsZero() int {
eBytes := e.Bytes()
return subtle.ConstantTimeCompare(eBytes, p256ZeroEncoding)
}
// Set sets e = t, and returns e.
func (e *P256Element) Set(t *P256Element) *P256Element {
e.x = t.x
return e
}
// Bytes returns the 32-byte big-endian encoding of e.
func (e *P256Element) Bytes() []byte {
// This function is outlined to make the allocations inline in the caller
// rather than happen on the heap.
var out [p256ElementLen]byte
return e.bytes(&out)
}
func (e *P256Element) bytes(out *[p256ElementLen]byte) []byte {
var tmp p256NonMontgomeryDomainFieldElement
p256FromMontgomery(&tmp, &e.x)
p256ToBytes(out, (*p256UntypedFieldElement)(&tmp))
p256InvertEndianness(out[:])
return out[:]
}
// p256MinusOneEncoding is the encoding of -1 mod p, so p - 1, the
// highest canonical encoding. It is used by SetBytes to check for non-canonical
// encodings such as p + k, 2p + k, etc.
var p256MinusOneEncoding = new(P256Element).Sub(
new(P256Element), new(P256Element).One()).Bytes()
// SetBytes sets e = v, where v is a big-endian 32-byte encoding, and returns e.
// If v is not 32 bytes or it encodes a value higher than 2^256 - 2^224 + 2^192 + 2^96 - 1,
// SetBytes returns nil and an error, and e is unchanged.
func (e *P256Element) SetBytes(v []byte) (*P256Element, error) {
if len(v) != p256ElementLen {
return nil, errors.New("invalid P256Element encoding")
}
for i := range v {
if v[i] < p256MinusOneEncoding[i] {
break
}
if v[i] > p256MinusOneEncoding[i] {
return nil, errors.New("invalid P256Element encoding")
}
}
var in [p256ElementLen]byte
copy(in[:], v)
p256InvertEndianness(in[:])
var tmp p256NonMontgomeryDomainFieldElement
p256FromBytes((*p256UntypedFieldElement)(&tmp), &in)
p256ToMontgomery(&e.x, &tmp)
return e, nil
}
// Add sets e = t1 + t2, and returns e.
func (e *P256Element) Add(t1, t2 *P256Element) *P256Element {
p256Add(&e.x, &t1.x, &t2.x)
return e
}
// Sub sets e = t1 - t2, and returns e.
func (e *P256Element) Sub(t1, t2 *P256Element) *P256Element {
p256Sub(&e.x, &t1.x, &t2.x)
return e
}
// Mul sets e = t1 * t2, and returns e.
func (e *P256Element) Mul(t1, t2 *P256Element) *P256Element {
p256Mul(&e.x, &t1.x, &t2.x)
return e
}
// Square sets e = t * t, and returns e.
func (e *P256Element) Square(t *P256Element) *P256Element {
p256Square(&e.x, &t.x)
return e
}
// Select sets v to a if cond == 1, and to b if cond == 0.
func (v *P256Element) Select(a, b *P256Element, cond int) *P256Element {
p256Selectznz((*p256UntypedFieldElement)(&v.x), p256Uint1(cond),
(*p256UntypedFieldElement)(&b.x), (*p256UntypedFieldElement)(&a.x))
return v
}
func p256InvertEndianness(v []byte) {
for i := 0; i < len(v)/2; i++ {
v[i], v[len(v)-1-i] = v[len(v)-1-i], v[i]
}
}
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