pkcs12_pem.go

// Copyright 2015, 2018, 2019 Opsmate, Inc. All rights reserved.
// 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

import (
	"crypto/ecdsa"
	"crypto/rsa"
	"crypto/x509"
	"encoding/hex"
	"encoding/pem"
	"errors"
)

// PEM block types
const (
	certificateType = "CERTIFICATE"
	privateKeyType  = "PRIVATE KEY"
)

// ToPEM converts all "safe bags" contained in pfxData to PEM blocks.
//
// Deprecated: ToPEM creates invalid PEM blocks (private keys
// are encoded as raw RSA or EC private keys rather than PKCS#8 despite being
// labeled "PRIVATE KEY").  To decode a PKCS#12 file, use [DecodeChain] instead,
// and use the [encoding/pem] package to convert to PEM if necessary.
func ToPEM(pfxData []byte, password string) ([]*pem.Block, error) {
	encodedPassword, err := bmpStringZeroTerminated(password)
	if err != nil {
		return nil, ErrIncorrectPassword
	}

	bags, encodedPassword, err := getSafeContents(pfxData, encodedPassword, 2, 2)

	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("pkcs12: found unknown private key type in PKCS#8 wrapping")
		}
	default:
		return nil, errors.New("pkcs12: 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
}