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crypto/x509: add DecryptBlock function for loading password protected keys
Adds a DecryptBlock function which takes a password and a *pem.Block and returns the decrypted DER bytes suitable for passing into other crypto/x509 functions. R=golang-dev, agl, leterip CC=golang-dev https://golang.org/cl/6555052
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133
src/pkg/crypto/x509/pem_decrypt.go
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133
src/pkg/crypto/x509/pem_decrypt.go
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@ -0,0 +1,133 @@
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// Copyright 2012 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 x509
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// RFC 1423 describes the encryption of PEM blocks. The algorithm used to
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// generate a key from the password was derived by looking at the OpenSSL
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// implementation.
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/des"
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"crypto/md5"
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"encoding/hex"
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"encoding/pem"
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"errors"
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"strings"
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)
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// rfc1423Algos represents how to create a block cipher for a decryption mode.
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type rfc1423Algo struct {
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cipherFunc func([]byte) (cipher.Block, error)
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keySize int
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}
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// deriveKey uses a key derivation function to stretch the password into a key
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// with the number of bits our cipher requires. This algorithm was derived from
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// the OpenSSL source.
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func (c rfc1423Algo) deriveKey(password, salt []byte) []byte {
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hash := md5.New()
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out := make([]byte, c.keySize)
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var digest []byte
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for i := 0; i < len(out); i += len(digest) {
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hash.Reset()
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hash.Write(digest)
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hash.Write(password)
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hash.Write(salt)
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digest = hash.Sum(digest[:0])
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copy(out[i:], digest)
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}
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return out
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}
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// rfc1423Algos is a mapping of encryption algorithm to an rfc1423Algo that can
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// create block ciphers for that mode.
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var rfc1423Algos = map[string]rfc1423Algo{
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"DES-CBC": {des.NewCipher, 8},
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"DES-EDE3-CBC": {des.NewTripleDESCipher, 24},
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"AES-128-CBC": {aes.NewCipher, 16},
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"AES-192-CBC": {aes.NewCipher, 24},
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"AES-256-CBC": {aes.NewCipher, 32},
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}
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// IsEncryptedPEMBlock returns if the PEM block is password encrypted.
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func IsEncryptedPEMBlock(b *pem.Block) bool {
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_, ok := b.Headers["DEK-Info"]
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return ok
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}
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// IncorrectPasswordError is returned when an incorrect password is detected.
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var IncorrectPasswordError = errors.New("x509: decryption password incorrect")
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// DecryptPEMBlock takes a password encrypted PEM block and the password used to
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// encrypt it and returns a slice of decrypted DER encoded bytes. It inspects
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// the DEK-Info header to determine the algorithm used for decryption. If no
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// DEK-Info header is present, an error is returned. If an incorrect password
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// is detected an IncorrectPasswordError is returned.
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func DecryptPEMBlock(b *pem.Block, password []byte) ([]byte, error) {
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dek, ok := b.Headers["DEK-Info"]
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if !ok {
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return nil, errors.New("x509: no DEK-Info header in block")
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}
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idx := strings.Index(dek, ",")
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if idx == -1 {
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return nil, errors.New("x509: malformed DEK-Info header")
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}
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mode, hexIV := dek[:idx], dek[idx+1:]
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iv, err := hex.DecodeString(hexIV)
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if err != nil {
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return nil, err
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}
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if len(iv) < 8 {
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return nil, errors.New("x509: not enough bytes in IV")
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}
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ciph, ok := rfc1423Algos[mode]
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if !ok {
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return nil, errors.New("x509: unknown encryption mode")
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}
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// Based on the OpenSSL implementation. The salt is the first 8 bytes
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// of the initialization vector.
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key := ciph.deriveKey(password, iv[:8])
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block, err := ciph.cipherFunc(key)
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if err != nil {
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return nil, err
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}
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data := make([]byte, len(b.Bytes))
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dec := cipher.NewCBCDecrypter(block, iv)
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dec.CryptBlocks(data, b.Bytes)
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// Blocks are padded using a scheme where the last n bytes of padding are all
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// equal to n. It can pad from 1 to 8 bytes inclusive. See RFC 1423.
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// For example:
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// [x y z 2 2]
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// [x y 7 7 7 7 7 7 7]
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// If we detect a bad padding, we assume it is an invalid password.
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dlen := len(data)
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if dlen == 0 {
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return nil, errors.New("x509: invalid padding")
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}
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last := data[dlen-1]
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if dlen < int(last) {
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return nil, IncorrectPasswordError
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}
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if last == 0 || last > 8 {
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return nil, IncorrectPasswordError
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}
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for _, val := range data[dlen-int(last):] {
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if val != last {
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return nil, IncorrectPasswordError
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}
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}
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return data[:dlen-int(last)], nil
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}
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119
src/pkg/crypto/x509/pem_decrypt_test.go
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119
src/pkg/crypto/x509/pem_decrypt_test.go
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@ -0,0 +1,119 @@
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// Copyright 2012 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 x509
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import (
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"encoding/pem"
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"testing"
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)
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func TestDecrypt(t *testing.T) {
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for _, data := range testData {
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block, rest := pem.Decode(data.pemData)
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if len(rest) > 0 {
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t.Error(data.kind, "extra data")
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}
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der, err := DecryptPEMBlock(block, data.password)
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if err != nil {
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t.Error(data.kind, err)
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continue
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}
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if _, err := ParsePKCS1PrivateKey(der); err != nil {
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t.Error(data.kind, "Invalid private key")
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}
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}
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}
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var testData = []struct {
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kind string
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password []byte
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pemData []byte
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}{
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{
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kind: "DES-CBC",
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password: []byte("asdf"),
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pemData: []byte(`
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-----BEGIN RSA PRIVATE KEY-----
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Proc-Type: 4,ENCRYPTED
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DEK-Info: DES-CBC,34F09A4FC8DE22B5
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WXxy8kbZdiZvANtKvhmPBLV7eVFj2A5z6oAxvI9KGyhG0ZK0skfnt00C24vfU7m5
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ICXeoqP67lzJ18xCzQfHjDaBNs53DSDT+Iz4e8QUep1xQ30+8QKX2NA2coee3nwc
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6oM1cuvhNUDemBH2i3dKgMVkfaga0zQiiOq6HJyGSncCMSruQ7F9iWEfRbFcxFCx
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qtHb1kirfGKEtgWTF+ynyco6+2gMXNu70L7nJcnxnV/RLFkHt7AUU1yrclxz7eZz
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XOH9VfTjb52q/I8Suozq9coVQwg4tXfIoYUdT//O+mB7zJb9HI9Ps77b9TxDE6Gm
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4C9brwZ3zg2vqXcwwV6QRZMtyll9rOpxkbw6NPlpfBqkc3xS51bbxivbO/Nve4KD
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r12ymjFNF4stXCfJnNqKoZ50BHmEEUDu5Wb0fpVn82XrGw7CYc4iug==
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-----END RSA PRIVATE KEY-----`),
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},
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{
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kind: "DES-EDE3-CBC",
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password: []byte("asdf"),
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pemData: []byte(`
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-----BEGIN RSA PRIVATE KEY-----
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Proc-Type: 4,ENCRYPTED
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DEK-Info: DES-EDE3-CBC,C1F4A6A03682C2C7
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0JqVdBEH6iqM7drTkj+e2W/bE3LqakaiWhb9WUVonFkhyu8ca/QzebY3b5gCvAZQ
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YwBvDcT/GHospKqPx+cxDHJNsUASDZws6bz8ZXWJGwZGExKzr0+Qx5fgXn44Ms3x
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8g1ENFuTXtxo+KoNK0zuAMAqp66Llcds3Fjl4XR18QaD0CrVNAfOdgATWZm5GJxk
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Fgx5f84nT+/ovvreG+xeOzWgvtKo0UUZVrhGOgfKLpa57adumcJ6SkUuBtEFpZFB
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ldw5w7WC7d13x2LsRkwo8ZrDKgIV+Y9GNvhuCCkTzNP0V3gNeJpd201HZHR+9n3w
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3z0VjR/MGqsfcy1ziEWMNOO53At3zlG6zP05aHMnMcZoVXadEK6L1gz++inSSDCq
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gI0UJP4e3JVB7AkgYymYAwiYALAkoEIuanxoc50njJk=
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-----END RSA PRIVATE KEY-----`),
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},
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{
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kind: "AES-128-CBC",
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password: []byte("asdf"),
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pemData: []byte(`
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-----BEGIN RSA PRIVATE KEY-----
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Proc-Type: 4,ENCRYPTED
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DEK-Info: AES-128-CBC,D4492E793FC835CC038A728ED174F78A
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EyfQSzXSjv6BaNH+NHdXRlkHdimpF9izWlugVJAPApgXrq5YldPe2aGIOFXyJ+QE
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ZIG20DYqaPzJRjTEbPNZ6Es0S2JJ5yCpKxwJuDkgJZKtF39Q2i36JeGbSZQIuWJE
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GZbBpf1jDH/pr0iGonuAdl2PCCZUiy+8eLsD2tyviHUkFLOB+ykYoJ5t8ngZ/B6D
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33U43LLb7+9zD4y3Q9OVHqBFGyHcxCY9+9Qh4ZnFp7DTf6RY5TNEvE3s4g6aDpBs
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3NbvRVvYTgs8K9EPk4K+5R+P2kD8J8KvEIGxVa1vz8QoCJ/jr7Ka2rvNgPCex5/E
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080LzLHPCrXKdlr/f50yhNWq08ZxMWQFkui+FDHPDUaEELKAXV8/5PDxw80Rtybo
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AVYoCVIbZXZCuCO81op8UcOgEpTtyU5Lgh3Mw5scQL0=
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-----END RSA PRIVATE KEY-----`),
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},
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{
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kind: "AES-192-CBC",
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password: []byte("asdf"),
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pemData: []byte(`
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-----BEGIN RSA PRIVATE KEY-----
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Proc-Type: 4,ENCRYPTED
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DEK-Info: AES-192-CBC,E2C9FB02BCA23ADE1829F8D8BC5F5369
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cqVslvHqDDM6qwU6YjezCRifXmKsrgEev7ng6Qs7UmDJOpHDgJQZI9fwMFUhIyn5
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FbCu1SHkLMW52Ld3CuEqMnzWMlhPrW8tFvUOrMWPYSisv7nNq88HobZEJcUNL2MM
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Y15XmHW6IJwPqhKyLHpWXyOCVEh4ODND2nV15PCoi18oTa475baxSk7+1qH7GuIs
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Rb7tshNTMqHbCpyo9Rn3UxeFIf9efdl8YLiMoIqc7J8E5e9VlbeQSdLMQOgDAQJG
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ReUtTw8exmKsY4gsSjhkg5uiw7/ZB1Ihto0qnfQJgjGc680qGkT1d6JfvOfeYAk6
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xn5RqS/h8rYAYm64KnepfC9vIujo4NqpaREDmaLdX5MJPQ+SlytITQvgUsUq3q/t
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Ss85xjQEZH3hzwjQqdJvmA4hYP6SUjxYpBM+02xZ1Xw=
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-----END RSA PRIVATE KEY-----`),
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},
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{
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kind: "AES-256-CBC",
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password: []byte("asdf"),
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pemData: []byte(`
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-----BEGIN RSA PRIVATE KEY-----
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Proc-Type: 4,ENCRYPTED
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DEK-Info: AES-256-CBC,8E7ED5CD731902CE938957A886A5FFBD
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4Mxr+KIzRVwoOP0wwq6caSkvW0iS+GE2h2Ov/u+n9ZTMwL83PRnmjfjzBgfRZLVf
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JFPXxUK26kMNpIdssNnqGOds+DhB+oSrsNKoxgxSl5OBoYv9eJTVYm7qOyAFIsjr
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DRKAcjYCmzfesr7PVTowwy0RtHmYwyXMGDlAzzZrEvaiySFFmMyKKvtoavwaFoc7
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Pz3RZScwIuubzTGJ1x8EzdffYOsdCa9Mtgpp3L136+23dOd6L/qK2EG2fzrJSHs/
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2XugkleBFSMKzEp9mxXKRfa++uidQvMZTFLDK9w5YjrRvMBo/l2BoZIsq0jAIE1N
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sv5Z/KwlX+3MDEpPQpUwGPlGGdLnjI3UZ+cjgqBcoMiNc6HfgbBgYJSU6aDSHuCk
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clCwByxWkBNgJ2GrkwNrF26v+bGJJJNR4SKouY1jQf0=
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-----END RSA PRIVATE KEY-----`),
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},
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}
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@ -300,7 +300,10 @@ var pkgDeps = map[string][]string{
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"L4", "CRYPTO-MATH", "CGO", "OS",
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"crypto/x509", "encoding/pem", "net", "syscall",
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},
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"crypto/x509": {"L4", "CRYPTO-MATH", "OS", "CGO", "crypto/x509/pkix", "encoding/pem", "syscall"},
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"crypto/x509": {
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"L4", "CRYPTO-MATH", "OS", "CGO",
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"crypto/x509/pkix", "encoding/pem", "encoding/hex", "syscall",
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},
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"crypto/x509/pkix": {"L4", "CRYPTO-MATH"},
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// Simple net+crypto-aware packages.
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