/
session_encrypt.go
71 lines (57 loc) · 1.46 KB
/
session_encrypt.go
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package noscryptoclt
import (
"bytes"
"strings"
)
// EncryptSessionPacket encrypts and returns the packet passed as argument
// using the client's session encryption algorithm.
func EncryptSessionPacket(packet string) (encryptedPacket string) {
var firstbyte byte
var secondbyte byte
var result strings.Builder
evalByte := func(b byte) byte {
switch b {
case 0x00: // NULL
case 0x20: //" "
b = 0x01
break
case 0x2D: //"-"
b = 0x02
break
case 0x2E: //"."
b = 0x03
break
default:
b -= 0x2C
break
}
return b
}
var buf bytes.Buffer
// The first two characters are ignored by the server; will
// result in 0x9A after encryption (0x99 if odd)
buf.WriteByte(0x34) // 4
buf.WriteByte(0x37) // 7
// The format of the packet must be '<packetNumber> <sessionNumber>'
// in order to be accepted by the server
buf.Write([]byte(packet))
// Since we're encrypting two bytes at a time, make it even
if len(packet)%2 != 0 {
buf.WriteByte(0x00) //NULL
}
// Termination characters for the decryption algorithm; will
// result in 0x0E after encryption
buf.WriteByte(0x3B) // ;
buf.WriteByte(0x3B) // ;
packetBytes := buf.Bytes()
for i := 0; i < len(packetBytes); i += 2 {
firstbyte = evalByte(packetBytes[i+1])
secondbyte = evalByte(packetBytes[i])
secondbyte <<= 0x4
firstbyte = firstbyte + secondbyte
secondbyte = firstbyte
result.WriteByte(firstbyte + 0xF)
}
encryptedPacket = result.String()
return encryptedPacket
}