github.com/twelsh-aw/go/src@v0.0.0-20230516233729-a56fe86a7c81/crypto/internal/nistec/p256_asm_table_test.go (about)

     1  // Copyright 2021 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build amd64 || arm64 || ppc64le || s390x
     6  
     7  package nistec
     8  
     9  import (
    10  	"fmt"
    11  	"testing"
    12  )
    13  
    14  func TestP256PrecomputedTable(t *testing.T) {
    15  	base := NewP256Point().SetGenerator()
    16  
    17  	for i := 0; i < 43; i++ {
    18  		t.Run(fmt.Sprintf("table[%d]", i), func(t *testing.T) {
    19  			testP256AffineTable(t, base, &p256Precomputed[i])
    20  		})
    21  
    22  		for k := 0; k < 6; k++ {
    23  			base.Double(base)
    24  		}
    25  	}
    26  }
    27  
    28  func testP256AffineTable(t *testing.T, base *P256Point, table *p256AffineTable) {
    29  	p := NewP256Point()
    30  	zInv := new(p256Element)
    31  	zInvSq := new(p256Element)
    32  
    33  	for j := 0; j < 32; j++ {
    34  		p.Add(p, base)
    35  
    36  		// Convert p to affine coordinates.
    37  		p256Inverse(zInv, &p.z)
    38  		p256Sqr(zInvSq, zInv, 1)
    39  		p256Mul(zInv, zInv, zInvSq)
    40  
    41  		p256Mul(&p.x, &p.x, zInvSq)
    42  		p256Mul(&p.y, &p.y, zInv)
    43  		p.z = p256One
    44  
    45  		if p256Equal(&table[j].x, &p.x) != 1 || p256Equal(&table[j].y, &p.y) != 1 {
    46  			t.Fatalf("incorrect table entry at index %d", j)
    47  		}
    48  	}
    49  }