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crypto/x509: implement EncryptPEMBlock

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Arbitrary decisions: order of the arguments and the
fact it takes a block-type argument (rather than
leaving to user to fill it in later); I'm happy whatever
colour we want to paint it.

We also change DecryptPEMBlock so that it won't
panic when the IV has the wrong size.

R=agl, agl
CC=golang-dev
https://golang.org/cl/6820114
This commit is contained in:
Roger Peppe 2012-11-12 15:31:23 +00:00
parent 1e1733a9ac
commit 791fb978dd
2 changed files with 219 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

137
src/pkg/crypto/x509/pem_decrypt.go
View File

@ -16,23 +16,64 @@ import (
"encoding/hex"
"encoding/pem"
"errors"
"io"
"strings"
)
// rfc1423Algos represents how to create a block cipher for a decryption mode.
type PEMCipher int
// Possible values for the EncryptPEMBlock encryption algorithm.
const (
_ PEMCipher = iota
PEMCipherDES
PEMCipher3DES
PEMCipherAES128
PEMCipherAES192
PEMCipherAES256
)
// rfc1423Algo holds a method for enciphering a PEM block.
type rfc1423Algo struct {
cipherFunc func([]byte) (cipher.Block, error)
cipher PEMCipher
name string
cipherFunc func(key []byte) (cipher.Block, error)
keySize int
blockSize int
}
// rfc1423Algos is a mapping of encryption algorithm to an rfc1423Algo that can
// create block ciphers for that mode.
var rfc1423Algos = map[string]rfc1423Algo{
"DES-CBC": {des.NewCipher, 8},
"DES-EDE3-CBC": {des.NewTripleDESCipher, 24},
"AES-128-CBC": {aes.NewCipher, 16},
"AES-192-CBC": {aes.NewCipher, 24},
"AES-256-CBC": {aes.NewCipher, 32},
// rfc1423Algos holds a slice of the possible ways to encrypt a PEM
// block. The ivSize numbers were taken from the OpenSSL source.
var rfc1423Algos = []rfc1423Algo{{
cipher: PEMCipherDES,
name: "DES-CBC",
cipherFunc: des.NewCipher,
keySize: 8,
blockSize: des.BlockSize,
}, {
cipher: PEMCipher3DES,
name: "DES-EDE3-CBC",
cipherFunc: des.NewTripleDESCipher,
keySize: 24,
blockSize: des.BlockSize,
}, {
cipher: PEMCipherAES128,
name: "AES-128-CBC",
cipherFunc: aes.NewCipher,
keySize: 16,
blockSize: aes.BlockSize,
}, {
cipher: PEMCipherAES192,
name: "AES-192-CBC",
cipherFunc: aes.NewCipher,
keySize: 24,
blockSize: aes.BlockSize,
}, {
cipher: PEMCipherAES256,
name: "AES-256-CBC",
cipherFunc: aes.NewCipher,
keySize: 32,
blockSize: aes.BlockSize,
},
}
// deriveKey uses a key derivation function to stretch the password into a key
@ -51,7 +92,6 @@ func (c rfc1423Algo) deriveKey(password, salt []byte) []byte {
digest = hash.Sum(digest[:0])
copy(out[i:], digest)
}
return out
}
@ -81,16 +121,16 @@ func DecryptPEMBlock(b *pem.Block, password []byte) ([]byte, error) {
}
mode, hexIV := dek[:idx], dek[idx+1:]
ciph, ok := rfc1423Algos[mode]
if !ok {
ciph := cipherByName(mode)
if ciph == nil {
return nil, errors.New("x509: unknown encryption mode")
}
iv, err := hex.DecodeString(hexIV)
if err != nil {
return nil, err
}
if len(iv) < 8 {
return nil, errors.New("x509: not enough bytes in IV")
if len(iv) != ciph.blockSize {
return nil, errors.New("x509: incorrect IV size")
}
// Based on the OpenSSL implementation. The salt is the first 8 bytes
@ -112,15 +152,14 @@ func DecryptPEMBlock(b *pem.Block, password []byte) ([]byte, error) {
// [x y 7 7 7 7 7 7 7]
// If we detect a bad padding, we assume it is an invalid password.
dlen := len(data)
blockSize := block.BlockSize()
if dlen == 0 || dlen%blockSize != 0 {
if dlen == 0 || dlen%ciph.blockSize != 0 {
return nil, errors.New("x509: invalid padding")
}
last := int(data[dlen-1])
if dlen < last {
return nil, IncorrectPasswordError
}
if last == 0 || last > blockSize {
if last == 0 || last > ciph.blockSize {
return nil, IncorrectPasswordError
}
for _, val := range data[dlen-last:] {
@ -130,3 +169,65 @@ func DecryptPEMBlock(b *pem.Block, password []byte) ([]byte, error) {
}
return data[:dlen-last], nil
}
// EncryptPEMBlock returns a PEM block of the specified type holding the
// given DER-encoded data encrypted with the specified algorithm and
// password.
func EncryptPEMBlock(rand io.Reader, blockType string, data, password []byte, alg PEMCipher) (*pem.Block, error) {
ciph := cipherByKey(alg)
if ciph == nil {
return nil, errors.New("x509: unknown encryption mode")
}
iv := make([]byte, ciph.blockSize)
if _, err := io.ReadFull(rand, iv); err != nil {
return nil, errors.New("x509: cannot generate IV: " + err.Error())
}
// The salt is the first 8 bytes of the initialization vector,
// matching the key derivation in DecryptPEMBlock.
key := ciph.deriveKey(password, iv[:8])
block, err := ciph.cipherFunc(key)
if err != nil {
return nil, err
}
enc := cipher.NewCBCEncrypter(block, iv)
pad := ciph.blockSize - len(data)%ciph.blockSize
encrypted := make([]byte, len(data), len(data)+pad)
// We could save this copy by encrypting all the whole blocks in
// the data separately, but it doesn't seem worth the additional
// code.
copy(encrypted, data)
// See RFC 1423, section 1.1
for i := 0; i < pad; i++ {
encrypted = append(encrypted, byte(pad))
}
enc.CryptBlocks(encrypted, encrypted)
return &pem.Block{
Type: blockType,
Headers: map[string]string{
"Proc-Type": "4,ENCRYPTED",
"DEK-Info": ciph.name + "," + hex.EncodeToString(iv),
},
Bytes: encrypted,
}, nil
}
func cipherByName(name string) *rfc1423Algo {
for i := range rfc1423Algos {
alg := &rfc1423Algos[i]
if alg.name == name {
return alg
}
}
return nil
}
func cipherByKey(key PEMCipher) *rfc1423Algo {
for i := range rfc1423Algos {
alg := &rfc1423Algos[i]
if alg.cipher == key {
return alg
}
}
return nil
}

111
src/pkg/crypto/x509/pem_decrypt_test.go
View File

@ -5,34 +5,79 @@
package x509
import (
"bytes"
"crypto/rand"
"encoding/base64"
"encoding/pem"
"testing"
)
func TestDecrypt(t *testing.T) {
for _, data := range testData {
for i, data := range testData {
t.Logf("test %d. %s", i, data.kind)
block, rest := pem.Decode(data.pemData)
if len(rest) > 0 {
t.Error(data.kind, "extra data")
t.Error("extra data")
}
der, err := DecryptPEMBlock(block, data.password)
if err != nil {
t.Error(data.kind, err)
t.Error("decrypt failed: ", err)
continue
}
if _, err := ParsePKCS1PrivateKey(der); err != nil {
t.Error(data.kind, "Invalid private key")
t.Error("invalid private key: ", err)
}
plainDER, err := base64.StdEncoding.DecodeString(data.plainDER)
if err != nil {
t.Fatal("cannot decode test DER data: ", err)
}
if !bytes.Equal(der, plainDER) {
t.Error("data mismatch")
}
}
}
func TestEncrypt(t *testing.T) {
for i, data := range testData {
t.Logf("test %d. %s", i, data.kind)
plainDER, err := base64.StdEncoding.DecodeString(data.plainDER)
if err != nil {
t.Fatal("cannot decode test DER data: ", err)
}
password := []byte("kremvax1")
block, err := EncryptPEMBlock(rand.Reader, "RSA PRIVATE KEY", plainDER, password, data.kind)
if err != nil {
t.Error("encrypt: ", err)
continue
}
if !IsEncryptedPEMBlock(block) {
t.Error("PEM block does not appear to be encrypted")
}
if block.Type != "RSA PRIVATE KEY" {
t.Errorf("unexpected block type; got %q want %q", block.Type, "RSA PRIVATE KEY")
}
if block.Headers["Proc-Type"] != "4,ENCRYPTED" {
t.Errorf("block does not have correct Proc-Type header")
}
der, err := DecryptPEMBlock(block, password)
if err != nil {
t.Error("decrypt: ", err)
continue
}
if !bytes.Equal(der, plainDER) {
t.Errorf("data mismatch")
}
}
}
var testData = []struct {
kind string
kind PEMCipher
password []byte
pemData []byte
plainDER string
}{
{
kind: "DES-CBC",
kind: PEMCipherDES,
password: []byte("asdf"),
pemData: []byte(`
-----BEGIN RSA PRIVATE KEY-----
@ -47,9 +92,17 @@ XOH9VfTjb52q/I8Suozq9coVQwg4tXfIoYUdT//O+mB7zJb9HI9Ps77b9TxDE6Gm
4C9brwZ3zg2vqXcwwV6QRZMtyll9rOpxkbw6NPlpfBqkc3xS51bbxivbO/Nve4KD
r12ymjFNF4stXCfJnNqKoZ50BHmEEUDu5Wb0fpVn82XrGw7CYc4iug==
-----END RSA PRIVATE KEY-----`),
plainDER: `
MIIBPAIBAAJBAPASZe+tCPU6p80AjHhDkVsLYa51D35e/YGa8QcZyooeZM8EHozo
KD0fNiKI+53bHdy07N+81VQ8/ejPcRoXPlsCAwEAAQJBAMTxIuSq27VpR+zZ7WJf
c6fvv1OBvpMZ0/d1pxL/KnOAgq2rD5hDtk9b0LGhTPgQAmrrMTKuSeGoIuYE+gKQ
QvkCIQD+GC1m+/do+QRurr0uo46Kx1LzLeSCrjBk34wiOp2+dwIhAPHfTLRXS2fv
7rljm0bYa4+eDZpz+E8RcXEgzhhvcQQ9AiAI5eHZJGOyml3MXnQjiPi55WcDOw0w
glcRgT6QCEtz2wIhANSyqaFtosIkHKqrDUGfz/bb5tqMYTAnBruVPaf/WEOBAiEA
9xORWeRG1tRpso4+dYy4KdDkuLPIO01KY6neYGm3BCM=`,
},
{
kind: "DES-EDE3-CBC",
kind: PEMCipher3DES,
password: []byte("asdf"),
pemData: []byte(`
-----BEGIN RSA PRIVATE KEY-----
@ -64,9 +117,17 @@ ldw5w7WC7d13x2LsRkwo8ZrDKgIV+Y9GNvhuCCkTzNP0V3gNeJpd201HZHR+9n3w
3z0VjR/MGqsfcy1ziEWMNOO53At3zlG6zP05aHMnMcZoVXadEK6L1gz++inSSDCq
gI0UJP4e3JVB7AkgYymYAwiYALAkoEIuanxoc50njJk=
-----END RSA PRIVATE KEY-----`),
plainDER: `
MIIBOwIBAAJBANOCXKdoNS/iP/MAbl9cf1/SF3P+Ns7ZeNL27CfmDh0O6Zduaax5
NBiumd2PmjkaCu7lQ5JOibHfWn+xJsc3kw0CAwEAAQJANX/W8d1Q/sCqzkuAn4xl
B5a7qfJWaLHndu1QRLNTRJPn0Ee7OKJ4H0QKOhQM6vpjRrz+P2u9thn6wUxoPsef
QQIhAP/jCkfejFcy4v15beqKzwz08/tslVjF+Yq41eJGejmxAiEA05pMoqfkyjcx
fyvGhpoOyoCp71vSGUfR2I9CR65oKh0CIC1Msjs66LlfJtQctRq6bCEtFCxEcsP+
eEjYo/Sk6WphAiEAxpgWPMJeU/shFT28gS+tmhjPZLpEoT1qkVlC14u0b3ECIQDX
tZZZxCtPAm7shftEib0VU77Lk8MsXJcx2C4voRsjEw==`,
},
{
kind: "AES-128-CBC",
kind: PEMCipherAES128,
password: []byte("asdf"),
pemData: []byte(`
-----BEGIN RSA PRIVATE KEY-----
@ -81,9 +142,17 @@ GZbBpf1jDH/pr0iGonuAdl2PCCZUiy+8eLsD2tyviHUkFLOB+ykYoJ5t8ngZ/B6D
080LzLHPCrXKdlr/f50yhNWq08ZxMWQFkui+FDHPDUaEELKAXV8/5PDxw80Rtybo
AVYoCVIbZXZCuCO81op8UcOgEpTtyU5Lgh3Mw5scQL0=
-----END RSA PRIVATE KEY-----`),
plainDER: `
MIIBOgIBAAJBAMBlj5FxYtqbcy8wY89d/S7n0+r5MzD9F63BA/Lpl78vQKtdJ5dT
cDGh/rBt1ufRrNp0WihcmZi7Mpl/3jHjiWECAwEAAQJABNOHYnKhtDIqFYj1OAJ3
k3GlU0OlERmIOoeY/cL2V4lgwllPBEs7r134AY4wMmZSBUj8UR/O4SNO668ElKPE
cQIhAOuqY7/115x5KCdGDMWi+jNaMxIvI4ETGwV40ykGzqlzAiEA0P9oEC3m9tHB
kbpjSTxaNkrXxDgdEOZz8X0uOUUwHNsCIAwzcSCiGLyYJTULUmP1ESERfW1mlV78
XzzESaJpIM/zAiBQkSTcl9VhcJreQqvjn5BnPZLP4ZHS4gPwJAGdsj5J4QIhAOVR
B3WlRNTXR2WsJ5JdByezg9xzdXzULqmga0OE339a`,
},
{
kind: "AES-192-CBC",
kind: PEMCipherAES192,
password: []byte("asdf"),
pemData: []byte(`
-----BEGIN RSA PRIVATE KEY-----
@ -98,9 +167,17 @@ ReUtTw8exmKsY4gsSjhkg5uiw7/ZB1Ihto0qnfQJgjGc680qGkT1d6JfvOfeYAk6
xn5RqS/h8rYAYm64KnepfC9vIujo4NqpaREDmaLdX5MJPQ+SlytITQvgUsUq3q/t
Ss85xjQEZH3hzwjQqdJvmA4hYP6SUjxYpBM+02xZ1Xw=
-----END RSA PRIVATE KEY-----`),
plainDER: `
MIIBOwIBAAJBAMGcRrZiNNmtF20zyS6MQ7pdGx17aFDl+lTl+qnLuJRUCMUG05xs
OmxmL/O1Qlf+bnqR8Bgg65SfKg21SYuLhiMCAwEAAQJBAL94uuHyO4wux2VC+qpj
IzPykjdU7XRcDHbbvksf4xokSeUFjjD3PB0Qa83M94y89ZfdILIqS9x5EgSB4/lX
qNkCIQD6cCIqLfzq/lYbZbQgAAjpBXeQVYsbvVtJrPrXJAlVVQIhAMXpDKMeFPMn
J0g2rbx1gngx0qOa5r5iMU5w/noN4W2XAiBjf+WzCG5yFvazD+dOx3TC0A8+4x3P
uZ3pWbaXf5PNuQIgAcdXarvhelH2w2piY1g3BPeFqhzBSCK/yLGxR82KIh8CIQDD
+qGKsd09NhQ/G27y/DARzOYtml1NvdmCQAgsDIIOLA==`,
},
{
kind: "AES-256-CBC",
kind: PEMCipherAES256,
password: []byte("asdf"),
pemData: []byte(`
-----BEGIN RSA PRIVATE KEY-----
@ -115,11 +192,19 @@ Pz3RZScwIuubzTGJ1x8EzdffYOsdCa9Mtgpp3L136+23dOd6L/qK2EG2fzrJSHs/
sv5Z/KwlX+3MDEpPQpUwGPlGGdLnjI3UZ+cjgqBcoMiNc6HfgbBgYJSU6aDSHuCk
clCwByxWkBNgJ2GrkwNrF26v+bGJJJNR4SKouY1jQf0=
-----END RSA PRIVATE KEY-----`),
plainDER: `
MIIBOgIBAAJBAKy3GFkstoCHIEeUU/qO8207m8WSrjksR+p9B4tf1w5k+2O1V/GY
AQ5WFCApItcOkQe/I0yZZJk/PmCqMzSxrc8CAwEAAQJAOCAz0F7AW9oNelVQSP8F
Sfzx7O1yom+qWyAQQJF/gFR11gpf9xpVnnyu1WxIRnDUh1LZwUsjwlDYb7MB74id
oQIhANPcOiLwOPT4sIUpRM5HG6BF1BI7L77VpyGVk8xNP7X/AiEA0LMHZtk4I+lJ
nClgYp4Yh2JZ1Znbu7IoQMCEJCjwKDECIGd8Dzm5tViTkUW6Hs3Tlf73nNs65duF
aRnSglss8I3pAiEAonEnKruawgD8RavDFR+fUgmQiPz4FnGGeVgfwpGG1JECIBYq
PXHYtPqxQIbD2pScR5qum7iGUh11lEUPkmt+2uqS`,
},
{
// generated with:
// openssl genrsa -aes128 -passout pass:asdf -out server.orig.key 128
kind: "AES-128-CBC",
kind: PEMCipherAES128,
password: []byte("asdf"),
pemData: []byte(`
-----BEGIN RSA PRIVATE KEY-----
@ -130,5 +215,9 @@ DEK-Info: AES-128-CBC,74611ABC2571AF11B1BF9B69E62C89E7
eND9l7C9meCirWovjj9QWVHrXyugFuDIqgdhQ8iHTgCfF3lrmcttVrbIfMDw+smD
hTP8O1mS/MHl92NE0nhv0w==
-----END RSA PRIVATE KEY-----`),
plainDER: `
MGMCAQACEQC6ssxmYuauuHGOCDAI54RdAgMBAAECEQCWIn6Yv2O+kBcDF7STctKB
AgkA8SEfu/2i3g0CCQDGNlXbBHX7kQIIK3Ww5o0cYbECCQDCimPb0dYGsQIIeQ7A
jryIst8=`,
},
}