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