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gitea/vendor/github.com/mholt/acmez/tlsalpn01.go

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// Copyright 2020 Matthew Holt
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package acmez
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/sha256"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/asn1"
"encoding/pem"
"math/big"
"time"
"github.com/mholt/acmez/acme"
)
// TLSALPN01ChallengeCert creates a certificate that can be used for
// handshakes while solving the tls-alpn-01 challenge. See RFC 8737 §3.
func TLSALPN01ChallengeCert(challenge acme.Challenge) (*tls.Certificate, error) {
keyAuthSum := sha256.Sum256([]byte(challenge.KeyAuthorization))
keyAuthSumASN1, err := asn1.Marshal(keyAuthSum[:sha256.Size])
if err != nil {
return nil, err
}
certKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
return nil, err
}
challengeKeyASN1, err := x509.MarshalECPrivateKey(certKey)
if err != nil {
return nil, err
}
serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
if err != nil {
return nil, err
}
template := x509.Certificate{
SerialNumber: serialNumber,
Subject: pkix.Name{CommonName: "ACME challenge"},
NotBefore: time.Now(),
NotAfter: time.Now().Add(24 * time.Hour * 365),
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
BasicConstraintsValid: true,
DNSNames: []string{challenge.Identifier.Value},
// add key authentication digest as the acmeValidation-v1 extension
// (marked as critical such that it won't be used by non-ACME software).
// Reference: https://www.rfc-editor.org/rfc/rfc8737.html#section-3
ExtraExtensions: []pkix.Extension{
{
Id: idPEACMEIdentifierV1,
Critical: true,
Value: keyAuthSumASN1,
},
},
}
challengeCertDER, err := x509.CreateCertificate(rand.Reader, &template, &template, &certKey.PublicKey, certKey)
if err != nil {
return nil, err
}
challengeCertPEM := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: challengeCertDER})
challengeKeyPEM := pem.EncodeToMemory(&pem.Block{Type: "EC PRIVATE KEY", Bytes: challengeKeyASN1})
cert, err := tls.X509KeyPair(challengeCertPEM, challengeKeyPEM)
if err != nil {
return nil, err
}
return &cert, nil
}
// ACMETLS1Protocol is the ALPN value for the TLS-ALPN challenge
// handshake. See RFC 8737 §6.2.
const ACMETLS1Protocol = "acme-tls/1"
// idPEACMEIdentifierV1 is the SMI Security for PKIX Certification Extension OID referencing the ACME extension.
// See RFC 8737 §6.1. https://www.rfc-editor.org/rfc/rfc8737.html#section-6.1
var idPEACMEIdentifierV1 = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 1, 31}