"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
digest = hash.Sum(digest[:0])
copy(out[i:], digest)
}
-
return out
}
}
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
// [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:] {
}
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
+}
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-----
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-----
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-----
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-----
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-----
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-----
eND9l7C9meCirWovjj9QWVHrXyugFuDIqgdhQ8iHTgCfF3lrmcttVrbIfMDw+smD
hTP8O1mS/MHl92NE0nhv0w==
-----END RSA PRIVATE KEY-----`),
+ plainDER: `
+MGMCAQACEQC6ssxmYuauuHGOCDAI54RdAgMBAAECEQCWIn6Yv2O+kBcDF7STctKB
+AgkA8SEfu/2i3g0CCQDGNlXbBHX7kQIIK3Ww5o0cYbECCQDCimPb0dYGsQIIeQ7A
+jryIst8=`,
},
}