Tags: hash crypto bruteforce rockyou
Rating:
```
Hmmm.. we found this hash along with a white paper explaining this custom hashing algorithm.
Can you break it for us?
hash : 435818055906
Flag should be submitted as RS{<cracked hash>}
Author: 1nv8rZim
```
[RITSEC_HASH](<https://www.dropbox.com/s/giqh9yhlbfeegse/RITSEC_HASH.pdf?dl=0>)
**Hint:**
```
The red crosses in the hash diagram are addition
```
**Hint:**
```
Goal here is not to test ur hash cracking rigs, please use rockyou.txt
Solution should be first match and hopefully will be pretty recognizable
```
Studying the pdf, we implement the hash function and bruteforce the password with the infamous *rockyou* wordlist.
```nim
import strformat, strutils, sequtils
const
seed = "RITSEC".mapIt(it.byte)
target = "435818055906".parseHexStr.mapIt(it.byte)
wordlist = "rockyou.txt"
proc H(h: seq[byte], x, r: byte): seq[byte] =
var (A, B, C, D, E, F) = (h[0], h[1], h[2], h[3], h[4], h[5])
@[((C xor E) and F) + B + D shl 2 + x + r, A, D shl 2, B shr 5, A + F, D]
proc hash(h: seq[byte], x: byte): seq[byte] =
result = h
for r in 0 .. 12:
result = H(result, x, r.byte)
echo &"[+] Loading wordlist: {wordlist}"
let passwords = readFile(wordlist).splitLines
echo &"[+] Bruteforcing with: {wordlist}"
for i, password in passwords:
var h = seed
for c in password:
h = hash(h, c.byte)
if h == target:
echo &"[+] Cracked password: {password}"
quit(QuitSuccess)
```
**Remark**:
Even without reading the second hint, we know we cannot reverse the function because it uses `and`, and therefore it is impossible to reverse the values `C`, `E`, `F`.
