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pkcs12.go
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pkcs12.go
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// Copyright 2015 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 pkcs12 implements some of PKCS#12.
//
// This implementation is distilled from https://tools.ietf.org/html/rfc7292
// and referenced documents. It is intended for decoding P12/PFX-stored
// certificates and keys for use with the crypto/tls package.
package pkcs12
import (
"crypto/ecdsa"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/asn1"
"encoding/hex"
"encoding/pem"
"errors"
)
var (
oidDataContentType = asn1.ObjectIdentifier([]int{1, 2, 840, 113549, 1, 7, 1})
oidEncryptedDataContentType = asn1.ObjectIdentifier([]int{1, 2, 840, 113549, 1, 7, 6})
oidFriendlyName = asn1.ObjectIdentifier([]int{1, 2, 840, 113549, 1, 9, 20})
oidLocalKeyID = asn1.ObjectIdentifier([]int{1, 2, 840, 113549, 1, 9, 21})
oidMicrosoftCSPName = asn1.ObjectIdentifier([]int{1, 3, 6, 1, 4, 1, 311, 17, 1})
)
type pfxPdu struct {
Version int
AuthSafe contentInfo
MacData macData `asn1:"optional"`
}
type contentInfo struct {
ContentType asn1.ObjectIdentifier
Content asn1.RawValue `asn1:"tag:0,explicit,optional"`
}
type encryptedData struct {
Version int
EncryptedContentInfo encryptedContentInfo
}
type encryptedContentInfo struct {
ContentType asn1.ObjectIdentifier
ContentEncryptionAlgorithm pkix.AlgorithmIdentifier
EncryptedContent []byte `asn1:"tag:0,optional"`
}
func (i encryptedContentInfo) Algorithm() pkix.AlgorithmIdentifier {
return i.ContentEncryptionAlgorithm
}
func (i encryptedContentInfo) Data() []byte { return i.EncryptedContent }
type safeBag struct {
Id asn1.ObjectIdentifier
Value asn1.RawValue `asn1:"tag:0,explicit"`
Attributes []pkcs12Attribute `asn1:"set,optional"`
}
type pkcs12Attribute struct {
Id asn1.ObjectIdentifier
Value asn1.RawValue `asn1:"set"`
}
type encryptedPrivateKeyInfo struct {
AlgorithmIdentifier pkix.AlgorithmIdentifier
EncryptedData []byte
}
func (i encryptedPrivateKeyInfo) Algorithm() pkix.AlgorithmIdentifier {
return i.AlgorithmIdentifier
}
func (i encryptedPrivateKeyInfo) Data() []byte {
return i.EncryptedData
}
// PEM block types
const (
certificateType = "CERTIFICATE"
privateKeyType = "PRIVATE KEY"
)
// unmarshal calls asn1.Unmarshal, but also returns an error if there is any
// trailing data after unmarshaling.
func unmarshal(in []byte, out interface{}) error {
trailing, err := asn1.Unmarshal(in, out)
if err != nil {
return err
}
if len(trailing) != 0 {
return errors.New("pkcs12: trailing data found")
}
return nil
}
// ConvertToPEM converts all "safe bags" contained in pfxData to PEM blocks.
func ToPEM(pfxData []byte, password string) ([]*pem.Block, error) {
encodedPassword, err := bmpString(password)
if err != nil {
return nil, ErrIncorrectPassword
}
bags, encodedPassword, err := getSafeContents(pfxData, encodedPassword)
if err != nil {
return nil, err
}
blocks := make([]*pem.Block, 0, len(bags))
for _, bag := range bags {
block, err := convertBag(&bag, encodedPassword)
if err != nil {
return nil, err
}
blocks = append(blocks, block)
}
return blocks, nil
}
func convertBag(bag *safeBag, password []byte) (*pem.Block, error) {
block := &pem.Block{
Headers: make(map[string]string),
}
for _, attribute := range bag.Attributes {
k, v, err := convertAttribute(&attribute)
if err != nil {
return nil, err
}
block.Headers[k] = v
}
switch {
case bag.Id.Equal(oidCertBag):
block.Type = certificateType
certsData, err := decodeCertBag(bag.Value.Bytes)
if err != nil {
return nil, err
}
block.Bytes = certsData
case bag.Id.Equal(oidPKCS8ShroundedKeyBag):
block.Type = privateKeyType
key, err := decodePkcs8ShroudedKeyBag(bag.Value.Bytes, password)
if err != nil {
return nil, err
}
switch key := key.(type) {
case *rsa.PrivateKey:
block.Bytes = x509.MarshalPKCS1PrivateKey(key)
case *ecdsa.PrivateKey:
block.Bytes, err = x509.MarshalECPrivateKey(key)
if err != nil {
return nil, err
}
default:
return nil, errors.New("found unknown private key type in PKCS#8 wrapping")
}
default:
return nil, errors.New("don't know how to convert a safe bag of type " + bag.Id.String())
}
return block, nil
}
func convertAttribute(attribute *pkcs12Attribute) (key, value string, err error) {
isString := false
switch {
case attribute.Id.Equal(oidFriendlyName):
key = "friendlyName"
isString = true
case attribute.Id.Equal(oidLocalKeyID):
key = "localKeyId"
case attribute.Id.Equal(oidMicrosoftCSPName):
// This key is chosen to match OpenSSL.
key = "Microsoft CSP Name"
isString = true
default:
return "", "", errors.New("pkcs12: unknown attribute with OID " + attribute.Id.String())
}
if isString {
if err := unmarshal(attribute.Value.Bytes, &attribute.Value); err != nil {
return "", "", err
}
if value, err = decodeBMPString(attribute.Value.Bytes); err != nil {
return "", "", err
}
} else {
var id []byte
if err := unmarshal(attribute.Value.Bytes, &id); err != nil {
return "", "", err
}
value = hex.EncodeToString(id)
}
return key, value, nil
}
// Decode extracts a certificate and private key from pfxData. This function
// assumes that there is only one certificate and only one private key in the
// pfxData.
func Decode(pfxData []byte, password string) (privateKey interface{}, certificate *x509.Certificate, err error) {
encodedPassword, err := bmpString(password)
if err != nil {
return nil, nil, err
}
bags, encodedPassword, err := getSafeContents(pfxData, encodedPassword)
if err != nil {
return nil, nil, err
}
if len(bags) != 2 {
err = errors.New("pkcs12: expected exactly two safe bags in the PFX PDU")
return
}
for _, bag := range bags {
switch {
case bag.Id.Equal(oidCertBag):
if certificate != nil {
err = errors.New("pkcs12: expected exactly one certificate bag")
}
certsData, err := decodeCertBag(bag.Value.Bytes)
if err != nil {
return nil, nil, err
}
certs, err := x509.ParseCertificates(certsData)
if err != nil {
return nil, nil, err
}
if len(certs) != 1 {
err = errors.New("pkcs12: expected exactly one certificate in the certBag")
return nil, nil, err
}
certificate = certs[0]
case bag.Id.Equal(oidPKCS8ShroundedKeyBag):
if privateKey != nil {
err = errors.New("pkcs12: expected exactly one key bag")
}
if privateKey, err = decodePkcs8ShroudedKeyBag(bag.Value.Bytes, encodedPassword); err != nil {
return nil, nil, err
}
}
}
if certificate == nil {
return nil, nil, errors.New("pkcs12: certificate missing")
}
if privateKey == nil {
return nil, nil, errors.New("pkcs12: private key missing")
}
return
}
func getSafeContents(p12Data, password []byte) (bags []safeBag, updatedPassword []byte, err error) {
pfx := new(pfxPdu)
if err := unmarshal(p12Data, pfx); err != nil {
return nil, nil, errors.New("pkcs12: error reading P12 data: " + err.Error())
}
if pfx.Version != 3 {
return nil, nil, NotImplementedError("can only decode v3 PFX PDU's")
}
if !pfx.AuthSafe.ContentType.Equal(oidDataContentType) {
return nil, nil, NotImplementedError("only password-protected PFX is implemented")
}
// unmarshal the explicit bytes in the content for type 'data'
if err := unmarshal(pfx.AuthSafe.Content.Bytes, &pfx.AuthSafe.Content); err != nil {
return nil, nil, err
}
if len(pfx.MacData.Mac.Algorithm.Algorithm) == 0 {
return nil, nil, errors.New("pkcs12: no MAC in data")
}
if err := verifyMac(&pfx.MacData, pfx.AuthSafe.Content.Bytes, password); err != nil {
if err == ErrIncorrectPassword && len(password) == 2 && password[0] == 0 && password[1] == 0 {
// some implementations use an empty byte array
// for the empty string password try one more
// time with empty-empty password
password = nil
err = verifyMac(&pfx.MacData, pfx.AuthSafe.Content.Bytes, password)
}
if err != nil {
return nil, nil, err
}
}
var authenticatedSafe []contentInfo
if err := unmarshal(pfx.AuthSafe.Content.Bytes, &authenticatedSafe); err != nil {
return nil, nil, err
}
if len(authenticatedSafe) != 2 {
return nil, nil, NotImplementedError("expected exactly two items in the authenticated safe")
}
for _, ci := range authenticatedSafe {
var data []byte
switch {
case ci.ContentType.Equal(oidDataContentType):
if err := unmarshal(ci.Content.Bytes, &data); err != nil {
return nil, nil, err
}
case ci.ContentType.Equal(oidEncryptedDataContentType):
var encryptedData encryptedData
if err := unmarshal(ci.Content.Bytes, &encryptedData); err != nil {
return nil, nil, err
}
if encryptedData.Version != 0 {
return nil, nil, NotImplementedError("only version 0 of EncryptedData is supported")
}
if data, err = pbDecrypt(encryptedData.EncryptedContentInfo, password); err != nil {
return nil, nil, err
}
default:
return nil, nil, NotImplementedError("only data and encryptedData content types are supported in authenticated safe")
}
var safeContents []safeBag
if err := unmarshal(data, &safeContents); err != nil {
return nil, nil, err
}
bags = append(bags, safeContents...)
}
return bags, password, nil
}