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Source file src/crypto/x509/x509.go

Documentation: crypto/x509

     1  // Copyright 2009 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  // Package x509 parses X.509-encoded keys and certificates.
     6  package x509
     7  
     8  import (
     9  	"bytes"
    10  	"crypto"
    11  	"crypto/ecdsa"
    12  	"crypto/ed25519"
    13  	"crypto/elliptic"
    14  	"crypto/rsa"
    15  	"crypto/sha1"
    16  	"crypto/x509/pkix"
    17  	"encoding/asn1"
    18  	"encoding/pem"
    19  	"errors"
    20  	"fmt"
    21  	"io"
    22  	"math/big"
    23  	"net"
    24  	"net/url"
    25  	"strconv"
    26  	"time"
    27  	"unicode"
    28  
    29  	// Explicitly import these for their crypto.RegisterHash init side-effects.
    30  	// Keep these as blank imports, even if they're imported above.
    31  	_ "crypto/sha1"
    32  	_ "crypto/sha256"
    33  	_ "crypto/sha512"
    34  
    35  	"golang.org/x/crypto/cryptobyte"
    36  	cryptobyte_asn1 "golang.org/x/crypto/cryptobyte/asn1"
    37  )
    38  
    39  // pkixPublicKey reflects a PKIX public key structure. See SubjectPublicKeyInfo
    40  // in RFC 3280.
    41  type pkixPublicKey struct {
    42  	Algo      pkix.AlgorithmIdentifier
    43  	BitString asn1.BitString
    44  }
    45  
    46  // ParsePKIXPublicKey parses a public key in PKIX, ASN.1 DER form.
    47  // The encoded public key is a SubjectPublicKeyInfo structure
    48  // (see RFC 5280, Section 4.1).
    49  //
    50  // It returns a *rsa.PublicKey, *dsa.PublicKey, *ecdsa.PublicKey, or
    51  // ed25519.PublicKey. More types might be supported in the future.
    52  //
    53  // This kind of key is commonly encoded in PEM blocks of type "PUBLIC KEY".
    54  func ParsePKIXPublicKey(derBytes []byte) (pub interface{}, err error) {
    55  	var pki publicKeyInfo
    56  	if rest, err := asn1.Unmarshal(derBytes, &pki); err != nil {
    57  		if _, err := asn1.Unmarshal(derBytes, &pkcs1PublicKey{}); err == nil {
    58  			return nil, errors.New("x509: failed to parse public key (use ParsePKCS1PublicKey instead for this key format)")
    59  		}
    60  		return nil, err
    61  	} else if len(rest) != 0 {
    62  		return nil, errors.New("x509: trailing data after ASN.1 of public-key")
    63  	}
    64  	algo := getPublicKeyAlgorithmFromOID(pki.Algorithm.Algorithm)
    65  	if algo == UnknownPublicKeyAlgorithm {
    66  		return nil, errors.New("x509: unknown public key algorithm")
    67  	}
    68  	return parsePublicKey(algo, &pki)
    69  }
    70  
    71  func marshalPublicKey(pub interface{}) (publicKeyBytes []byte, publicKeyAlgorithm pkix.AlgorithmIdentifier, err error) {
    72  	switch pub := pub.(type) {
    73  	case *rsa.PublicKey:
    74  		publicKeyBytes, err = asn1.Marshal(pkcs1PublicKey{
    75  			N: pub.N,
    76  			E: pub.E,
    77  		})
    78  		if err != nil {
    79  			return nil, pkix.AlgorithmIdentifier{}, err
    80  		}
    81  		publicKeyAlgorithm.Algorithm = oidPublicKeyRSA
    82  		// This is a NULL parameters value which is required by
    83  		// RFC 3279, Section 2.3.1.
    84  		publicKeyAlgorithm.Parameters = asn1.NullRawValue
    85  	case *ecdsa.PublicKey:
    86  		publicKeyBytes = elliptic.Marshal(pub.Curve, pub.X, pub.Y)
    87  		oid, ok := oidFromNamedCurve(pub.Curve)
    88  		if !ok {
    89  			return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: unsupported elliptic curve")
    90  		}
    91  		publicKeyAlgorithm.Algorithm = oidPublicKeyECDSA
    92  		var paramBytes []byte
    93  		paramBytes, err = asn1.Marshal(oid)
    94  		if err != nil {
    95  			return
    96  		}
    97  		publicKeyAlgorithm.Parameters.FullBytes = paramBytes
    98  	case ed25519.PublicKey:
    99  		publicKeyBytes = pub
   100  		publicKeyAlgorithm.Algorithm = oidPublicKeyEd25519
   101  	default:
   102  		return nil, pkix.AlgorithmIdentifier{}, fmt.Errorf("x509: unsupported public key type: %T", pub)
   103  	}
   104  
   105  	return publicKeyBytes, publicKeyAlgorithm, nil
   106  }
   107  
   108  // MarshalPKIXPublicKey converts a public key to PKIX, ASN.1 DER form.
   109  // The encoded public key is a SubjectPublicKeyInfo structure
   110  // (see RFC 5280, Section 4.1).
   111  //
   112  // The following key types are currently supported: *rsa.PublicKey, *ecdsa.PublicKey
   113  // and ed25519.PublicKey. Unsupported key types result in an error.
   114  //
   115  // This kind of key is commonly encoded in PEM blocks of type "PUBLIC KEY".
   116  func MarshalPKIXPublicKey(pub interface{}) ([]byte, error) {
   117  	var publicKeyBytes []byte
   118  	var publicKeyAlgorithm pkix.AlgorithmIdentifier
   119  	var err error
   120  
   121  	if publicKeyBytes, publicKeyAlgorithm, err = marshalPublicKey(pub); err != nil {
   122  		return nil, err
   123  	}
   124  
   125  	pkix := pkixPublicKey{
   126  		Algo: publicKeyAlgorithm,
   127  		BitString: asn1.BitString{
   128  			Bytes:     publicKeyBytes,
   129  			BitLength: 8 * len(publicKeyBytes),
   130  		},
   131  	}
   132  
   133  	ret, _ := asn1.Marshal(pkix)
   134  	return ret, nil
   135  }
   136  
   137  // These structures reflect the ASN.1 structure of X.509 certificates.:
   138  
   139  type certificate struct {
   140  	Raw                asn1.RawContent
   141  	TBSCertificate     tbsCertificate
   142  	SignatureAlgorithm pkix.AlgorithmIdentifier
   143  	SignatureValue     asn1.BitString
   144  }
   145  
   146  type tbsCertificate struct {
   147  	Raw                asn1.RawContent
   148  	Version            int `asn1:"optional,explicit,default:0,tag:0"`