132 lines
3.7 KiB
Go
132 lines
3.7 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
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import (
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"bytes"
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"crypto/cipher"
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"crypto/des"
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"crypto/x509/pkix"
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"encoding/asn1"
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"errors"
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"golang.org/x/crypto/pkcs12/internal/rc2"
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)
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var (
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oidPBEWithSHAAnd3KeyTripleDESCBC = asn1.ObjectIdentifier([]int{1, 2, 840, 113549, 1, 12, 1, 3})
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oidPBEWithSHAAnd40BitRC2CBC = asn1.ObjectIdentifier([]int{1, 2, 840, 113549, 1, 12, 1, 6})
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)
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// pbeCipher is an abstraction of a PKCS#12 cipher.
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type pbeCipher interface {
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// create returns a cipher.Block given a key.
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create(key []byte) (cipher.Block, error)
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// deriveKey returns a key derived from the given password and salt.
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deriveKey(salt, password []byte, iterations int) []byte
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// deriveKey returns an IV derived from the given password and salt.
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deriveIV(salt, password []byte, iterations int) []byte
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}
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type shaWithTripleDESCBC struct{}
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func (shaWithTripleDESCBC) create(key []byte) (cipher.Block, error) {
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return des.NewTripleDESCipher(key)
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}
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func (shaWithTripleDESCBC) deriveKey(salt, password []byte, iterations int) []byte {
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return pbkdf(sha1Sum, 20, 64, salt, password, iterations, 1, 24)
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}
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func (shaWithTripleDESCBC) deriveIV(salt, password []byte, iterations int) []byte {
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return pbkdf(sha1Sum, 20, 64, salt, password, iterations, 2, 8)
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}
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type shaWith40BitRC2CBC struct{}
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func (shaWith40BitRC2CBC) create(key []byte) (cipher.Block, error) {
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return rc2.New(key, len(key)*8)
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}
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func (shaWith40BitRC2CBC) deriveKey(salt, password []byte, iterations int) []byte {
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return pbkdf(sha1Sum, 20, 64, salt, password, iterations, 1, 5)
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}
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func (shaWith40BitRC2CBC) deriveIV(salt, password []byte, iterations int) []byte {
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return pbkdf(sha1Sum, 20, 64, salt, password, iterations, 2, 8)
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}
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type pbeParams struct {
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Salt []byte
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Iterations int
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}
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func pbDecrypterFor(algorithm pkix.AlgorithmIdentifier, password []byte) (cipher.BlockMode, int, error) {
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var cipherType pbeCipher
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switch {
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case algorithm.Algorithm.Equal(oidPBEWithSHAAnd3KeyTripleDESCBC):
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cipherType = shaWithTripleDESCBC{}
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case algorithm.Algorithm.Equal(oidPBEWithSHAAnd40BitRC2CBC):
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cipherType = shaWith40BitRC2CBC{}
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default:
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return nil, 0, NotImplementedError("algorithm " + algorithm.Algorithm.String() + " is not supported")
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}
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var params pbeParams
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if err := unmarshal(algorithm.Parameters.FullBytes, ¶ms); err != nil {
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return nil, 0, err
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}
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key := cipherType.deriveKey(params.Salt, password, params.Iterations)
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iv := cipherType.deriveIV(params.Salt, password, params.Iterations)
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block, err := cipherType.create(key)
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if err != nil {
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return nil, 0, err
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}
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return cipher.NewCBCDecrypter(block, iv), block.BlockSize(), nil
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}
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func pbDecrypt(info decryptable, password []byte) (decrypted []byte, err error) {
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cbc, blockSize, err := pbDecrypterFor(info.Algorithm(), password)
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if err != nil {
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return nil, err
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}
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encrypted := info.Data()
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if len(encrypted) == 0 {
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return nil, errors.New("pkcs12: empty encrypted data")
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}
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if len(encrypted)%blockSize != 0 {
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return nil, errors.New("pkcs12: input is not a multiple of the block size")
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}
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decrypted = make([]byte, len(encrypted))
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cbc.CryptBlocks(decrypted, encrypted)
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psLen := int(decrypted[len(decrypted)-1])
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if psLen == 0 || psLen > blockSize {
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return nil, ErrDecryption
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}
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if len(decrypted) < psLen {
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return nil, ErrDecryption
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}
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ps := decrypted[len(decrypted)-psLen:]
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decrypted = decrypted[:len(decrypted)-psLen]
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if bytes.Compare(ps, bytes.Repeat([]byte{byte(psLen)}, psLen)) != 0 {
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return nil, ErrDecryption
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}
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return
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}
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// decryptable abstracts an object that contains ciphertext.
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type decryptable interface {
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Algorithm() pkix.AlgorithmIdentifier
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Data() []byte
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}
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