Current File : //usr/local/go119/src/crypto/internal/nistec/fiat/p521.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"
)
// P521Element is an integer modulo 2^521 - 1.
//
// The zero value is a valid zero element.
type P521Element struct {
// Values are represented internally always in the Montgomery domain, and
// converted in Bytes and SetBytes.
x p521MontgomeryDomainFieldElement
}
const p521ElementLen = 66
type p521UntypedFieldElement = [9]uint64
// One sets e = 1, and returns e.
func (e *P521Element) One() *P521Element {
p521SetOne(&e.x)
return e
}
// Equal returns 1 if e == t, and zero otherwise.
func (e *P521Element) Equal(t *P521Element) int {
eBytes := e.Bytes()
tBytes := t.Bytes()
return subtle.ConstantTimeCompare(eBytes, tBytes)
}
var p521ZeroEncoding = new(P521Element).Bytes()
// IsZero returns 1 if e == 0, and zero otherwise.
func (e *P521Element) IsZero() int {
eBytes := e.Bytes()
return subtle.ConstantTimeCompare(eBytes, p521ZeroEncoding)
}
// Set sets e = t, and returns e.
func (e *P521Element) Set(t *P521Element) *P521Element {
e.x = t.x
return e
}
// Bytes returns the 66-byte big-endian encoding of e.
func (e *P521Element) Bytes() []byte {
// This function is outlined to make the allocations inline in the caller
// rather than happen on the heap.
var out [p521ElementLen]byte
return e.bytes(&out)
}
func (e *P521Element) bytes(out *[p521ElementLen]byte) []byte {
var tmp p521NonMontgomeryDomainFieldElement
p521FromMontgomery(&tmp, &e.x)
p521ToBytes(out, (*p521UntypedFieldElement)(&tmp))
p521InvertEndianness(out[:])
return out[:]
}
// p521MinusOneEncoding 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 p521MinusOneEncoding = new(P521Element).Sub(
new(P521Element), new(P521Element).One()).Bytes()
// SetBytes sets e = v, where v is a big-endian 66-byte encoding, and returns e.
// If v is not 66 bytes or it encodes a value higher than 2^521 - 1,
// SetBytes returns nil and an error, and e is unchanged.
func (e *P521Element) SetBytes(v []byte) (*P521Element, error) {
if len(v) != p521ElementLen {
return nil, errors.New("invalid P521Element encoding")
}
for i := range v {
if v[i] < p521MinusOneEncoding[i] {
break
}
if v[i] > p521MinusOneEncoding[i] {
return nil, errors.New("invalid P521Element encoding")
}
}
var in [p521ElementLen]byte
copy(in[:], v)
p521InvertEndianness(in[:])
var tmp p521NonMontgomeryDomainFieldElement
p521FromBytes((*p521UntypedFieldElement)(&tmp), &in)
p521ToMontgomery(&e.x, &tmp)
return e, nil
}
// Add sets e = t1 + t2, and returns e.
func (e *P521Element) Add(t1, t2 *P521Element) *P521Element {
p521Add(&e.x, &t1.x, &t2.x)
return e
}
// Sub sets e = t1 - t2, and returns e.
func (e *P521Element) Sub(t1, t2 *P521Element) *P521Element {
p521Sub(&e.x, &t1.x, &t2.x)
return e
}
// Mul sets e = t1 * t2, and returns e.
func (e *P521Element) Mul(t1, t2 *P521Element) *P521Element {
p521Mul(&e.x, &t1.x, &t2.x)
return e
}
// Square sets e = t * t, and returns e.
func (e *P521Element) Square(t *P521Element) *P521Element {
p521Square(&e.x, &t.x)
return e
}
// Select sets v to a if cond == 1, and to b if cond == 0.
func (v *P521Element) Select(a, b *P521Element, cond int) *P521Element {
p521Selectznz((*p521UntypedFieldElement)(&v.x), p521Uint1(cond),
(*p521UntypedFieldElement)(&b.x), (*p521UntypedFieldElement)(&a.x))
return v
}
func p521InvertEndianness(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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