// Copyright 2014 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 x509_test

import (
	"crypto/dsa"
	"crypto/ecdsa"
	"crypto/rsa"
	"crypto/x509"
	"encoding/pem"
	"fmt"
)

func ExampleCertificate_Verify() {
	// Verifying with a custom list of root certificates.

	const rootPEM = `
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`

	const certPEM = `
-----BEGIN CERTIFICATE-----
MIIDujCCAqKgAwIBAgIIE31FZVaPXTUwDQYJKoZIhvcNAQEFBQAwSTELMAkGA1UE
BhMCVVMxEzARBgNVBAoTCkdvb2dsZSBJbmMxJTAjBgNVBAMTHEdvb2dsZSBJbnRl
cm5ldCBBdXRob3JpdHkgRzIwHhcNMTQwMTI5MTMyNzQzWhcNMTQwNTI5MDAwMDAw
WjBpMQswCQYDVQQGEwJVUzETMBEGA1UECAwKQ2FsaWZvcm5pYTEWMBQGA1UEBwwN
TW91bnRhaW4gVmlldzETMBEGA1UECgwKR29vZ2xlIEluYzEYMBYGA1UEAwwPbWFp
bC5nb29nbGUuY29tMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEfRrObuSW5T7q
5CnSEqefEmtH4CCv6+5EckuriNr1CjfVvqzwfAhopXkLrq45EQm8vkmf7W96XJhC
7ZM0dYi1/qOCAU8wggFLMB0GA1UdJQQWMBQGCCsGAQUFBwMBBggrBgEFBQcDAjAa
BgNVHREEEzARgg9tYWlsLmdvb2dsZS5jb20wCwYDVR0PBAQDAgeAMGgGCCsGAQUF
BwEBBFwwWjArBggrBgEFBQcwAoYfaHR0cDovL3BraS5nb29nbGUuY29tL0dJQUcy
LmNydDArBggrBgEFBQcwAYYfaHR0cDovL2NsaWVudHMxLmdvb2dsZS5jb20vb2Nz
cDAdBgNVHQ4EFgQUiJxtimAuTfwb+aUtBn5UYKreKvMwDAYDVR0TAQH/BAIwADAf
BgNVHSMEGDAWgBRK3QYWG7z2aLV29YG2u2IaulqBLzAXBgNVHSAEEDAOMAwGCisG
AQQB1nkCBQEwMAYDVR0fBCkwJzAloCOgIYYfaHR0cDovL3BraS5nb29nbGUuY29t
L0dJQUcyLmNybDANBgkqhkiG9w0BAQUFAAOCAQEAH6RYHxHdcGpMpFE3oxDoFnP+
gtuBCHan2yE2GRbJ2Cw8Lw0MmuKqHlf9RSeYfd3BXeKkj1qO6TVKwCh+0HdZk283
TZZyzmEOyclm3UGFYe82P/iDFt+CeQ3NpmBg+GoaVCuWAARJN/KfglbLyyYygcQq
0SgeDh8dRKUiaW3HQSoYvTvdTuqzwK4CXsr3b5/dAOY8uMuG/IAR3FgwTbZ1dtoW
RvOTa8hYiU6A475WuZKyEHcwnGYe57u2I2KbMgcKjPniocj4QzgYsVAVKW3IwaOh
yE+vPxsiUkvQHdO2fojCkY8jg70jxM+gu59tPDNbw3Uh/2Ij310FgTHsnGQMyA==
-----END CERTIFICATE-----`

	// First, create the set of root certificates. For this example we only
	// have one. It's also possible to omit this in order to use the
	// default root set of the current operating system.
	roots := x509.NewCertPool()
	ok := roots.AppendCertsFromPEM([]byte(rootPEM))
	if !ok {
		panic("failed to parse root certificate")
	}

	block, _ := pem.Decode([]byte(certPEM))
	if block == nil {
		panic("failed to parse certificate PEM")
	}
	cert, err := x509.ParseCertificate(block.Bytes)
	if err != nil {
		panic("failed to parse certificate: " + err.Error())
	}

	opts := x509.VerifyOptions{
		DNSName: "mail.google.com",
		Roots:   roots,
	}

	if _, err := cert.Verify(opts); err != nil {
		panic("failed to verify certificate: " + err.Error())
	}
}

func ExampleParsePKIXPublicKey() {
	const pubPEM = `
-----BEGIN PUBLIC KEY-----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-----END PUBLIC KEY-----`

	block, _ := pem.Decode([]byte(pubPEM))
	if block == nil {
		panic("failed to parse PEM block containing the public key")
	}

	pub, err := x509.ParsePKIXPublicKey(block.Bytes)
	if err != nil {
		panic("failed to parse DER encoded public key: " + err.Error())
	}

	switch pub := pub.(type) {
	case *rsa.PublicKey:
		fmt.Println("pub is of type RSA:", pub)
	case *dsa.PublicKey:
		fmt.Println("pub is of type DSA:", pub)
	case *ecdsa.PublicKey:
		fmt.Println("pub is of type ECDSA:", pub)
	default:
		panic("unknown type of public key")
	}
}