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xs
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Initial experiments: HMAC on stream

This commit is contained in:
Russ Magee 2018-02-16 18:46:29 -08:00
parent 6ea206fbc2
commit d465c1ee5b
5 changed files with 41 additions and 32 deletions
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22
demo/server/server.go
View File

@ -75,7 +75,7 @@ func runShellAs(who string, cmd string, interactive bool, conn hkex.Conn) (err e
var uid, gid uint32
fmt.Sscanf(u.Uid, "%d", &uid)
fmt.Sscanf(u.Gid, "%d", &gid)
fmt.Println("uid:", uid, "gid:", gid)
log.Println("uid:", uid, "gid:", gid)
// Need to clear server's env and set key vars of the
// target user. This isn't perfect (TERM doesn't seem to
@ -155,14 +155,14 @@ func main() {
}
defer l.Close()
fmt.Println("Serving on", laddr)
log.Println("Serving on", laddr)
for {
// Wait for a connection.
conn, err := l.Accept()
if err != nil {
log.Fatal(err)
}
fmt.Println("Accepted client")
log.Println("Accepted client")
// Handle the connection in a new goroutine.
// The loop then returns to accepting, so that
@ -179,7 +179,7 @@ func main() {
n, err := fmt.Fscanf(c, "%d %d %d %d\n", &len1, &len2, &len3, &len4)
if err != nil || n < 4 {
fmt.Println("[Bad cmdSpec fmt]")
log.Println("[Bad cmdSpec fmt]")
return err
}
//fmt.Printf(" lens:%d %d %d %d\n", len1, len2, len3, len4)
@ -187,27 +187,27 @@ func main() {
rec.op = make([]byte, len1, len1)
_, err = io.ReadFull(c, rec.op)
if err != nil {
fmt.Println("[Bad cmdSpec.op]")
log.Println("[Bad cmdSpec.op]")
return err
}
rec.who = make([]byte, len2, len2)
_, err = io.ReadFull(c, rec.who)
if err != nil {
fmt.Println("[Bad cmdSpec.who]")
log.Println("[Bad cmdSpec.who]")
return err
}
rec.cmd = make([]byte, len3, len3)
_, err = io.ReadFull(c, rec.cmd)
if err != nil {
fmt.Println("[Bad cmdSpec.cmd]")
log.Println("[Bad cmdSpec.cmd]")
return err
}
rec.authCookie = make([]byte, len4, len4)
_, err = io.ReadFull(c, rec.authCookie)
if err != nil {
fmt.Println("[Bad cmdSpec.authCookie]")
log.Println("[Bad cmdSpec.authCookie]")
return err
}
@ -229,19 +229,19 @@ func main() {
// Returned hopefully via an EOF or exit/logout;
// Clear current op so user can enter next, or EOF
rec.op[0] = 0
fmt.Println("[Command complete]")
log.Println("[Command complete]")
} else if rec.op[0] == 's' {
log.Println("[Running shell]")
runShellAs(string(rec.who), string(rec.cmd), true, conn)
// Returned hopefully via an EOF or exit/logout;
// Clear current op so user can enter next, or EOF
rec.op[0] = 0
fmt.Println("[Exiting shell]")
log.Println("[Exiting shell]")
} else {
log.Println("[Bad cmdSpec]")
}
return
}(conn)
} //endfor
fmt.Println("[Exiting]")
log.Println("[Exiting]")
}

2
herradurakex.go
View File

@ -25,7 +25,6 @@ package herradurakex
golang implementation by Russ Magee (rmagee_at_gmail.com) */
/* This is the core KEx algorithm. For client/server net support code,
See hkexnet.go for a golang/pkg/net for the compatible Conn interface
using this to transparently negotiate keys and secure a network channel. */
@ -148,6 +147,7 @@ func (h *HerraduraKEx) FA() {
h.fa = h.fscxRevolve(h.PeerD, h.b, h.intSz-h.pubSz)
h.fa.Xor(h.fa, h.a)
}
// Output HerraduraKEx type value as a string. Implements Stringer interface.
func (h *HerraduraKEx) String() string {
return fmt.Sprintf("s:%d p:%d\na:%s\nb:%s\nd:->%s\n<-PeerD:%s\nfa:%s",

5
hkexauth.go
View File

@ -5,7 +5,6 @@ package herradurakex
import (
"bytes"
"encoding/csv"
"fmt"
"io"
"io/ioutil"
"log"
@ -19,7 +18,7 @@ func AuthUser(username string, auth string, fname string) (valid bool, allowedCm
b, e := ioutil.ReadFile(fname)
if e != nil {
valid = false
fmt.Println("ERROR: Cannot read hkexsh.passwd file!")
log.Println("ERROR: Cannot read hkexsh.passwd file!")
log.Fatal(e)
}
r := csv.NewReader(bytes.NewReader(b))
@ -46,8 +45,6 @@ func AuthUser(username string, auth string, fname string) (valid bool, allowedCm
}
break
}
//fmt.Println(record)
}
return
}

16
hkexchan.go
View File

@ -8,6 +8,7 @@ import (
"crypto"
"crypto/aes"
"crypto/cipher"
"encoding/hex"
"fmt"
"hash"
"log"
@ -43,6 +44,7 @@ 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
@ -54,7 +56,7 @@ func (hc Conn) getStream(keymat *big.Int) (rc cipher.Stream, mc hash.Hash) {
key = keymat.Bytes()[0:aes.BlockSize]
block, err = aes.NewCipher(key)
ivlen = aes.BlockSize
iv := keymat.Bytes()[aes.BlockSize : aes.BlockSize+ivlen]
iv = keymat.Bytes()[aes.BlockSize : aes.BlockSize+ivlen]
rc = cipher.NewOFB(block, iv)
log.Printf("[cipher AES_256 (%d)]\n", copts)
break
@ -62,7 +64,7 @@ func (hc Conn) getStream(keymat *big.Int) (rc cipher.Stream, mc hash.Hash) {
key = keymat.Bytes()[0:twofish.BlockSize]
block, err = twofish.NewCipher(key)
ivlen = twofish.BlockSize
iv := keymat.Bytes()[twofish.BlockSize : twofish.BlockSize+ivlen]
iv = keymat.Bytes()[twofish.BlockSize : twofish.BlockSize+ivlen]
rc = cipher.NewOFB(block, iv)
log.Printf("[cipher TWOFISH_128 (%d)]\n", copts)
break
@ -79,7 +81,7 @@ func (hc Conn) getStream(keymat *big.Int) (rc cipher.Stream, mc hash.Hash) {
//
// 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]
iv = keymat.Bytes()[blowfish.BlockSize : blowfish.BlockSize+ivlen]
rc = cipher.NewOFB(block, iv)
log.Printf("[cipher BLOWFISH_64 (%d)]\n", copts)
break
@ -109,5 +111,13 @@ func (hc Conn) getStream(keymat *big.Int) (rc cipher.Stream, mc hash.Hash) {
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
}

28
hkexnet.go
View File

@ -27,10 +27,10 @@ import (
"encoding/hex"
"fmt"
"hash"
"io"
"log"
"math/big"
"net"
"strings"
"time"
)
@ -289,25 +289,27 @@ func (hl HKExListener) Accept() (hc Conn, err error) {
//
// See go doc io.Reader
func (c Conn) Read(b []byte) (n int, err error) {
log.Printf("[Decrypting...]\n")
//log.Printf("[Decrypting...]\r\n")
//c.c.SetReadDeadline(time.Now().Add(1 * time.Second))
n, err = c.c.Read(b)
// Normal client 'exit' from interactive session will cause
// (on server side) err.Error() == "<iface/addr info ...>: use of closed network connection"
if err != nil && err.Error() != "EOF" {
//if neterr, ok := err.(net.Error); ok {
// fmt.Printf("[Read() timeout - %s]\n", neterr)
//} else {
// panic(err)
//}
if !strings.HasSuffix(err.Error(), "use of closed network connection") {
log.Println("unexpected Read() err:", err)
} else {
log.Println("[Client hung up]")
}
}
log.Printf(" ctext:%+v\n", b[:n]) // print only used portion
log.Printf(" <:ctext:\r\n%s\r\n", hex.Dump(b[:n])) //EncodeToString(b[:n])) // print only used portion
db := bytes.NewBuffer(b[:n])
// The StreamReader acts like a pipe, decrypting
// whatever is available and forwarding the result
// to the parameter of Read() as a normal io.Reader
rs := &cipher.StreamReader{S: c.r, R: db}
n, err = rs.Read(b)
log.Printf(" ptext:%+v\n", b[:n])
log.Printf(" <-ptext:\r\n%s\r\n", hex.Dump(b[:n])) //EncodeToString(b[:n]))
return
}
@ -315,8 +317,8 @@ func (c Conn) Read(b []byte) (n int, err error) {
//
// See go doc io.Writer
func (c Conn) Write(b []byte) (n int, err error) {
log.Printf("[Encrypting...]\n")
log.Printf(" ptext:%+v\n", b)
//log.Printf("[Encrypting...]\r\n")
log.Printf(" :>ptext:\r\n%s\r\n", hex.Dump(b)) //EncodeToString(b))
var wb bytes.Buffer
// The StreamWriter acts like a pipe, forwarding whatever is
// written to it through the cipher, encrypting as it goes
@ -325,7 +327,7 @@ func (c Conn) Write(b []byte) (n int, err error) {
if err != nil {
panic(err)
}
log.Printf(" ctext:%+v\n", wb.Bytes())
log.Printf(" ->ctext:\r\n%s\r\n", hex.Dump(wb.Bytes())) //EncodeToString(b)) // print only used portion
n, err = c.c.Write(wb.Bytes())
return
}