Source File
p256_invert.go
Belonging Package
crypto/internal/fips140/nistec/fiat
// 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 addchain. DO NOT EDIT.
package fiat
// Invert sets e = 1/x, and returns e.
//
// If x == 0, Invert returns e = 0.
func ( *P256Element) ( *P256Element) *P256Element {
// Inversion is implemented as exponentiation with exponent p − 2.
// The sequence of 12 multiplications and 255 squarings is derived from the
// following addition chain generated with github.com/mmcloughlin/addchain v0.4.0.
//
// _10 = 2*1
// _11 = 1 + _10
// _110 = 2*_11
// _111 = 1 + _110
// _111000 = _111 << 3
// _111111 = _111 + _111000
// x12 = _111111 << 6 + _111111
// x15 = x12 << 3 + _111
// x16 = 2*x15 + 1
// x32 = x16 << 16 + x16
// i53 = x32 << 15
// x47 = x15 + i53
// i263 = ((i53 << 17 + 1) << 143 + x47) << 47
// return (x47 + i263) << 2 + 1
//
var = new(P256Element).Set()
var = new(P256Element)
var = new(P256Element)
.Square()
.Mul(, )
.Square()
.Mul(, )
.Square()
for := 1; < 3; ++ {
.Square()
}
.Mul(, )
.Square()
for := 1; < 6; ++ {
.Square()
}
.Mul(, )
for := 0; < 3; ++ {
.Square()
}
.Mul(, )
.Square()
.Mul(, )
.Square()
for := 1; < 16; ++ {
.Square()
}
.Mul(, )
for := 0; < 15; ++ {
.Square()
}
.Mul(, )
for := 0; < 17; ++ {
.Square()
}
.Mul(, )
for := 0; < 143; ++ {
.Square()
}
.Mul(, )
for := 0; < 47; ++ {
.Square()
}
.Mul(, )
for := 0; < 2; ++ {
.Square()
}
.Mul(, )
return .Set()
}
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