mirror of https://gogs.blitter.com/RLabs/xs
129 lines
3.5 KiB
Go
129 lines
3.5 KiB
Go
package hkexsh
|
|
|
|
// Copyright (c) 2017-2018 Russell Magee
|
|
// Licensed under the terms of the MIT license (see LICENSE.mit in this
|
|
// distribution)
|
|
//
|
|
// golang implementation by Russ Magee (rmagee_at_gmail.com)
|
|
|
|
/* Support functions to set up encryption once an HKEx Conn has been
|
|
established with FA exchange and support channel operations
|
|
(echo, file-copy, remote-cmd, ...) */
|
|
|
|
import (
|
|
"crypto"
|
|
"crypto/aes"
|
|
"crypto/cipher"
|
|
"encoding/hex"
|
|
"fmt"
|
|
"hash"
|
|
"log"
|
|
"math/big"
|
|
"os"
|
|
|
|
"golang.org/x/crypto/blowfish"
|
|
"golang.org/x/crypto/twofish"
|
|
// hash algos must be manually imported thusly:
|
|
// (Would be nice if the golang pkg docs were more clear
|
|
// on this...)
|
|
_ "crypto/sha256"
|
|
)
|
|
|
|
// Available ciphers for hkex.Conn
|
|
const (
|
|
CAlgAES256 = iota
|
|
CAlgTwofish128 // golang.org/x/crypto/twofish
|
|
CAlgBlowfish64 // golang.org/x/crypto/blowfish
|
|
CAlgNoneDisallowed
|
|
)
|
|
|
|
// Available HMACs for hkex.Conn (TODO: not currently used)
|
|
const (
|
|
HmacSHA256 = iota
|
|
HmacNoneDisallowed
|
|
)
|
|
|
|
/* Support functionality to set up encryption after a channel has
|
|
been negotiated via hkexnet.go
|
|
*/
|
|
func (hc Conn) getStream(keymat *big.Int) (rc cipher.Stream, mc hash.Hash) {
|
|
var key []byte
|
|
var block cipher.Block
|
|
var iv []byte
|
|
var ivlen int
|
|
var err error
|
|
|
|
copts := hc.cipheropts & 0xFF
|
|
// TODO: each cipher alg case should ensure len(keymat.Bytes())
|
|
// is >= 2*cipher.BlockSize (enough for both key and iv)
|
|
switch copts {
|
|
case CAlgAES256:
|
|
key = keymat.Bytes()[0:aes.BlockSize]
|
|
block, err = aes.NewCipher(key)
|
|
ivlen = aes.BlockSize
|
|
iv = keymat.Bytes()[aes.BlockSize : aes.BlockSize+ivlen]
|
|
rc = cipher.NewOFB(block, iv)
|
|
log.Printf("[cipher AES_256 (%d)]\n", copts)
|
|
break
|
|
case CAlgTwofish128:
|
|
key = keymat.Bytes()[0:twofish.BlockSize]
|
|
block, err = twofish.NewCipher(key)
|
|
ivlen = twofish.BlockSize
|
|
iv = keymat.Bytes()[twofish.BlockSize : twofish.BlockSize+ivlen]
|
|
rc = cipher.NewOFB(block, iv)
|
|
log.Printf("[cipher TWOFISH_128 (%d)]\n", copts)
|
|
break
|
|
case CAlgBlowfish64:
|
|
key = keymat.Bytes()[0:blowfish.BlockSize]
|
|
block, err = blowfish.NewCipher(key)
|
|
ivlen = blowfish.BlockSize
|
|
// N.b. Bounds enforcement of differing cipher algorithms
|
|
// ------------------------------------------------------
|
|
// cipher/aes and x/cipher/twofish appear to allow one to
|
|
// pass an iv larger than the blockSize harmlessly to
|
|
// cipher.NewOFB(); x/cipher/blowfish implementation will
|
|
// segfault here if len(iv) is not exactly blowfish.BlockSize.
|
|
//
|
|
// I assume the other two check bounds and only
|
|
// copy what's needed whereas blowfish does no such check.
|
|
iv = keymat.Bytes()[blowfish.BlockSize : blowfish.BlockSize+ivlen]
|
|
rc = cipher.NewOFB(block, iv)
|
|
log.Printf("[cipher BLOWFISH_64 (%d)]\n", copts)
|
|
break
|
|
default:
|
|
log.Printf("[invalid cipher (%d)]\n", copts)
|
|
fmt.Printf("DOOFUS SET A VALID CIPHER ALG (%d)\n", copts)
|
|
os.Exit(1)
|
|
}
|
|
|
|
hopts := (hc.cipheropts >> 8) & 0xFF
|
|
switch hopts {
|
|
case HmacSHA256:
|
|
log.Printf("[hash HmacSHA256 (%d)]\n", hopts)
|
|
halg := crypto.SHA256
|
|
mc = halg.New()
|
|
if !halg.Available() {
|
|
log.Fatal("hash not available!")
|
|
}
|
|
break
|
|
default:
|
|
log.Printf("[invalid hmac (%d)]\n", hopts)
|
|
fmt.Printf("DOOFUS SET A VALID HMAC ALG (%d)\n", hopts)
|
|
os.Exit(1)
|
|
}
|
|
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
|
|
// Feed the IV into the hmac: all traffic in the connection must
|
|
// feed its data into the hmac afterwards, so both ends can xor
|
|
// that with the stream to detect corruption.
|
|
_, _ = mc.Write(iv)
|
|
var currentHash []byte
|
|
currentHash = mc.Sum(currentHash)
|
|
log.Printf("Channel init hmac(iv):%s\n", hex.EncodeToString(currentHash))
|
|
|
|
return
|
|
}
|