go/src/math/big/prime_test.go

// Copyright 2016 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.

package big

import (
	"fmt"
	"testing"
)

var primes = []string{
	"2",
	"3",
	"5",
	"7",
	"11",

	"13756265695458089029",
	"13496181268022124907",
	"10953742525620032441",
	"17908251027575790097",

	// https://golang.org/issue/638
	"18699199384836356663",

	"98920366548084643601728869055592650835572950932266967461790948584315647051443",
	"94560208308847015747498523884063394671606671904944666360068158221458669711639",

	// http://primes.utm.edu/lists/small/small3.html
	"449417999055441493994709297093108513015373787049558499205492347871729927573118262811508386655998299074566974373711472560655026288668094291699357843464363003144674940345912431129144354948751003607115263071543163",
	"230975859993204150666423538988557839555560243929065415434980904258310530753006723857139742334640122533598517597674807096648905501653461687601339782814316124971547968912893214002992086353183070342498989426570593",
	"5521712099665906221540423207019333379125265462121169655563495403888449493493629943498064604536961775110765377745550377067893607246020694972959780839151452457728855382113555867743022746090187341871655890805971735385789993",
	"203956878356401977405765866929034577280193993314348263094772646453283062722701277632936616063144088173312372882677123879538709400158306567338328279154499698366071906766440037074217117805690872792848149112022286332144876183376326512083574821647933992961249917319836219304274280243803104015000563790123",

	// ECC primes: http://tools.ietf.org/html/draft-ladd-safecurves-02
	"3618502788666131106986593281521497120414687020801267626233049500247285301239",                                                                                  // Curve1174: 2^251-9
	"57896044618658097711785492504343953926634992332820282019728792003956564819949",                                                                                 // Curve25519: 2^255-19
	"9850501549098619803069760025035903451269934817616361666987073351061430442874302652853566563721228910201656997576599",                                           // E-382: 2^382-105
	"42307582002575910332922579714097346549017899709713998034217522897561970639123926132812109468141778230245837569601494931472367",                                 // Curve41417: 2^414-17
	"6864797660130609714981900799081393217269435300143305409394463459185543183397656052122559640661454554977296311391480858037121987999716643812574028291115057151", // E-521: 2^521-1
}

var composites = []string{
	"0",
	"1",
	"21284175091214687912771199898307297748211672914763848041968395774954376176754",
	"6084766654921918907427900243509372380954290099172559290432744450051395395951",
	"84594350493221918389213352992032324280367711247940675652888030554255915464401",
	"82793403787388584738507275144194252681",
}

func TestProbablyPrime(t *testing.T) {
	nreps := 20
	if testing.Short() {
		nreps = 1
	}
	for i, s := range primes {
		p, _ := new(Int).SetString(s, 10)
		if !p.ProbablyPrime(nreps) {
			t.Errorf("#%d prime found to be non-prime (%s)", i, s)
		}
	}

	for i, s := range composites {
		c, _ := new(Int).SetString(s, 10)
		if c.ProbablyPrime(nreps) {
			t.Errorf("#%d composite found to be prime (%s)", i, s)
		}
		if testing.Short() {
			break
		}
	}

	// check that ProbablyPrime panics if n <= 0
	c := NewInt(11) // a prime
	for _, n := range []int{-1, 0, 1} {
		func() {
			defer func() {
				if n <= 0 && recover() == nil {
					t.Fatalf("expected panic from ProbablyPrime(%d)", n)
				}
			}()
			if !c.ProbablyPrime(n) {
				t.Fatalf("%v should be a prime", c)
			}
		}()
	}
}

func BenchmarkProbablyPrime(b *testing.B) {
	p, _ := new(Int).SetString("203956878356401977405765866929034577280193993314348263094772646453283062722701277632936616063144088173312372882677123879538709400158306567338328279154499698366071906766440037074217117805690872792848149112022286332144876183376326512083574821647933992961249917319836219304274280243803104015000563790123", 10)
	for _, rep := range []int{1, 5, 10, 20} {
		b.Run(fmt.Sprintf("Rep=%d", rep), func(b *testing.B) {
			for i := 0; i < b.N; i++ {
				p.ProbablyPrime(rep)
			}
		})
	}
}