Rating: 4.0
Beginner's Luck
========
> John Hammond | Monday, February 6th, 2017
--------------------------------------------
> Derp just had his first class of cryptography, and he feels really confident about his skills in this field. Can you break his algorithm and get the flag?
The fourth crypto challenge, worth `40` points.
You can download the files and if you check out the [Python] script used to encrypt the file:
``` python
#!/usr/bin/env python
def supa_encryption(s1, s2):
res = [chr(0)]*24
for i in range(len(res)):
q = ord(s1[i])
d = ord(s2[i])
k = q ^ d
res[i] = chr(k)
res = ''.join(res)
return res
def add_pad(msg):
L = 24 - len(msg)%24
msg += chr(L)*L
return msg
with open('fullhd.png','rb') as f:
data = f.read()
data = add_pad(data)
with open('key.txt') as f:
key = f.read()
enc_data = ''
for i in range(0, len(data), 24):
enc = supa_encryption(data[i:i+24], key)
enc_data += enc
with open('BITSCTFfullhd.png', 'wb') as f:
f.write(enc_data)
```
And obviously the [PNG] image was not able to be read since it was encrypted somehow.
The code above tells us that we added some bytes at the end of the image for [padding]. I also see an [XOR] operation, with this original `res` variable just a bunch of zeroes.
Knowing that it was a binary file (a [PNG] image), I figured the most common character might be a `00` byte. Just on a whim I threw that at [`xortool`][xortool] with that as the character.
```
xortool -c 00 BITSCTFfullhd.png
```
Then, it apparently found a good keylength (which agreed with some other recon on [XOR Cracker]) and a feasable key. [`xortool`][xortool] tried to decrypt it for us, so I thought I would check out the files.
```
cd xortool_out
file 0.out
0.out: PNG image data, 1920 x 1080, 8-bit/color RGB, non-interlaced
```
Oh?
Looks like it got it!
__The flag was: `BITSCTF{p_en_gee}`__
[netcat]: https://en.wikipedia.org/wiki/Netcat
[Wikipedia]: https://www.wikipedia.org/
[Linux]: https://www.linux.com/
[man page]: https://en.wikipedia.org/wiki/Man_page
[man pages]: https://en.wikipedia.org/wiki/Man_page
[man]: https://en.wikipedia.org/wiki/Man_page
[PuTTY]: http://www.putty.org/
[ssh]: https://en.wikipedia.org/wiki/Secure_Shell
[Windows]: http://www.microsoft.com/en-us/windows
[virtual machine]: https://en.wikipedia.org/wiki/Virtual_machine
[operating system]:https://en.wikipedia.org/wiki/Operating_system
[OS]: https://en.wikipedia.org/wiki/Operating_system
[VMWare]: http://www.vmware.com/
[VirtualBox]: https://www.virtualbox.org/
[hostname]: https://en.wikipedia.org/wiki/Hostname
[port number]: https://en.wikipedia.org/wiki/Port_%28computer_networking%29
[port]: https://en.wikipedia.org/wiki/Port_%28computer_networking%29
[ports]: https://en.wikipedia.org/wiki/Port_%28computer_networking%29
[distribution]:https://en.wikipedia.org/wiki/Linux_distribution
[Ubuntu]: http://www.ubuntu.com/
[ISO]: https://en.wikipedia.org/wiki/ISO_image
[standard streams]: https://en.wikipedia.org/wiki/Standard_streams
[standard output]: https://en.wikipedia.org/wiki/Standard_streams
[standard input]: https://en.wikipedia.org/wiki/Standard_streams
[read]: http://ss64.com/bash/read.html
[variable]: https://en.wikipedia.org/wiki/Variable_%28computer_science%29
[command substitution]: http://www.tldp.org/LDP/abs/html/commandsub.html
[permissions]: https://en.wikipedia.org/wiki/File_system_permissions
[redirection]: http://www.tldp.org/LDP/abs/html/io-redirection.html
[redirect]: http://www.tldp.org/LDP/abs/html/io-redirection.html
[pipe]: http://www.tldp.org/LDP/abs/html/io-redirection.html
[piped]: http://www.tldp.org/LDP/abs/html/io-redirection.html
[piping]: http://www.tldp.org/LDP/abs/html/io-redirection.html
[tmp]: http://www.tldp.org/LDP/Linux-Filesystem-Hierarchy/html/tmp.html
[curl]: http://curl.haxx.se/
[cl1p.net]: https://cl1p.net/
[request]: http://www.w3.org/Protocols/rfc2616/rfc2616-sec5.html
[POST request]: https://en.wikipedia.org/wiki/POST_%28HTTP%29
[Python]: http://python.org/
[interpreter]: https://en.wikipedia.org/wiki/List_of_command-line_interpreters
[requests]: http://docs.python-requests.org/en/latest/
[urllib]: https://docs.python.org/2/library/urllib.html
[file handling with Python]: https://docs.python.org/2/tutorial/inputoutput.html#reading-and-writing-files
[bash]: https://www.gnu.org/software/bash/
[Assembly]: https://en.wikipedia.org/wiki/Assembly_language
[the stack]: https://en.wikipedia.org/wiki/Stack_%28abstract_data_type%29
[register]: http://www.tutorialspoint.com/assembly_programming/assembly_registers.htm
[hex]: https://en.wikipedia.org/wiki/Hexadecimal
[hexadecimal]: https://en.wikipedia.org/wiki/Hexadecimal
[archive file]: https://en.wikipedia.org/wiki/Archive_file
[zip file]: https://en.wikipedia.org/wiki/Zip_%28file_format%29
[.zip]: https://en.wikipedia.org/wiki/Zip_%28file_format%29
[gigabytes]: https://en.wikipedia.org/wiki/Gigabyte
[GB]: https://en.wikipedia.org/wiki/Gigabyte
[GUI]: https://en.wikipedia.org/wiki/Graphical_user_interface
[Wireshark]: https://www.wireshark.org/
[FTP]: https://en.wikipedia.org/wiki/File_Transfer_Protocol
[client and server]: https://simple.wikipedia.org/wiki/Client-server
[RETR]: http://cr.yp.to/ftp/retr.html
[FTP server]: https://help.ubuntu.com/lts/serverguide/ftp-server.html
[SFTP]: https://en.wikipedia.org/wiki/SSH_File_Transfer_Protocol
[SSL]: https://en.wikipedia.org/wiki/Transport_Layer_Security
[encryption]: https://en.wikipedia.org/wiki/Encryption
[HTML]: https://en.wikipedia.org/wiki/HTML
[Flask]: http://flask.pocoo.org/
[SQL]: https://en.wikipedia.org/wiki/SQL
[and]: https://en.wikipedia.org/wiki/Logical_conjunction
[Cyberstakes]: https://cyberstakesonline.com/
[cat]: https://en.wikipedia.org/wiki/Cat_%28Unix%29
[symbolic link]: https://en.wikipedia.org/wiki/Symbolic_link
[ln]: https://en.wikipedia.org/wiki/Ln_%28Unix%29
[absolute path]: https://en.wikipedia.org/wiki/Path_%28computing%29
[CTF]: https://en.wikipedia.org/wiki/Capture_the_flag#Computer_security
[Cyberstakes]: https://cyberstakesonline.com/
[OverTheWire]: http://overthewire.org/
[Leviathan]: http://overthewire.org/wargames/leviathan/
[ls]: https://en.wikipedia.org/wiki/Ls
[grep]: https://en.wikipedia.org/wiki/Grep
[strings]: http://linux.die.net/man/1/strings
[ltrace]: http://linux.die.net/man/1/ltrace
[C]: https://en.wikipedia.org/wiki/C_%28programming_language%29
[strcmp]: http://linux.die.net/man/3/strcmp
[access]: http://pubs.opengroup.org/onlinepubs/009695399/functions/access.html
[system]: http://linux.die.net/man/3/system
[real user ID]: https://en.wikipedia.org/wiki/User_identifier
[effective user ID]: https://en.wikipedia.org/wiki/User_identifier
[brute force]: https://en.wikipedia.org/wiki/Brute-force_attack
[brute-force]: https://en.wikipedia.org/wiki/Brute-force_attack
[for loop]: https://en.wikipedia.org/wiki/For_loop
[bash programming]: http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO.html
[Behemoth]: http://overthewire.org/wargames/behemoth/
[command line]: https://en.wikipedia.org/wiki/Command-line_interface
[command-line]: https://en.wikipedia.org/wiki/Command-line_interface
[cli]: https://en.wikipedia.org/wiki/Command-line_interface
[PHP]: https://php.net/
[URL]: https://en.wikipedia.org/wiki/Uniform_Resource_Locator
[TamperData]: https://addons.mozilla.org/en-US/firefox/addon/tamper-data/
[Firefox]: https://www.mozilla.org/en-US/firefox/new/?product=firefox-3.6.8&os=osx%E2%8C%A9=en-US
[Caesar Cipher]: https://en.wikipedia.org/wiki/Caesar_cipher
[Google Reverse Image Search]: https://www.google.com/imghp
[PicoCTF]: https://picoctf.com/
[JavaScript]: https://www.javascript.com/
[base64]: https://en.wikipedia.org/wiki/Base64
[client-side]: https://en.wikipedia.org/wiki/Client-side_scripting
[client side]: https://en.wikipedia.org/wiki/Client-side_scripting
[javascript:alert]: http://www.w3schools.com/js/js_popup.asp
[Java]: https://www.java.com/en/
[2147483647]: https://en.wikipedia.org/wiki/2147483647_%28number%29
[XOR]: https://en.wikipedia.org/wiki/Exclusive_or
[XOR cipher]: https://en.wikipedia.org/wiki/XOR_cipher
[quipqiup.com]: http://www.quipqiup.com/
[PDF]: https://en.wikipedia.org/wiki/Portable_Document_Format
[pdfimages]: http://linux.die.net/man/1/pdfimages
[ampersand]: https://en.wikipedia.org/wiki/Ampersand
[URL encoding]: https://en.wikipedia.org/wiki/Percent-encoding
[Percent encoding]: https://en.wikipedia.org/wiki/Percent-encoding
[URL-encoding]: https://en.wikipedia.org/wiki/Percent-encoding
[Percent-encoding]: https://en.wikipedia.org/wiki/Percent-encoding
[endianness]: https://en.wikipedia.org/wiki/Endianness
[ASCII]: https://en.wikipedia.org/wiki/ASCII
[struct]: https://docs.python.org/2/library/struct.html
[pcap]: https://en.wikipedia.org/wiki/Pcap
[packet capture]: https://en.wikipedia.org/wiki/Packet_analyzer
[HTTP]: https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol
[Wireshark filters]: https://wiki.wireshark.org/DisplayFilters
[SSL]: https://en.wikipedia.org/wiki/Transport_Layer_Security
[Assembly]: https://en.wikipedia.org/wiki/Assembly_language
[Assembly Syntax]: https://en.wikipedia.org/wiki/X86_assembly_language#Syntax
[Intel Syntax]: https://en.wikipedia.org/wiki/X86_assembly_language
[Intel or AT&T]: http://www.imada.sdu.dk/Courses/DM18/Litteratur/IntelnATT.htm
[AT&T syntax]: https://en.wikibooks.org/wiki/X86_Assembly/GAS_Syntax
[GET request]: https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Request_methods
[GET requests]: https://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol#Request_methods
[IP Address]: https://en.wikipedia.org/wiki/IP_address
[IP Addresses]: https://en.wikipedia.org/wiki/IP_address
[MAC Address]: https://en.wikipedia.org/wiki/MAC_address
[session]: https://en.wikipedia.org/wiki/Session_%28computer_science%29
[Cookie Manager+]: https://addons.mozilla.org/en-US/firefox/addon/cookies-manager-plus/
[hexedit]: http://linux.die.net/man/1/hexedit
[Google]: http://google.com/
[Scapy]: http://www.secdev.org/projects/scapy/
[ARP]: https://en.wikipedia.org/wiki/Address_Resolution_Protocol
[UDP]: https://en.wikipedia.org/wiki/User_Datagram_Protocol
[SQL injection]: https://en.wikipedia.org/wiki/SQL_injection
[sqlmap]: http://sqlmap.org/
[sqlite]: https://www.sqlite.org/
[MD5]: https://en.wikipedia.org/wiki/MD5
[OpenSSL]: https://www.openssl.org/
[Burpsuite]:https://portswigger.net/burp/
[Burpsuite.jar]:https://portswigger.net/burp/
[Burp]:https://portswigger.net/burp/
[NULL character]: https://en.wikipedia.org/wiki/Null_character
[Format String Vulnerability]: http://www.cis.syr.edu/~wedu/Teaching/cis643/LectureNotes_New/Format_String.pdf
[printf]: http://pubs.opengroup.org/onlinepubs/009695399/functions/fprintf.html
[argument]: https://en.wikipedia.org/wiki/Parameter_%28computer_programming%29
[arguments]: https://en.wikipedia.org/wiki/Parameter_%28computer_programming%29
[parameter]: https://en.wikipedia.org/wiki/Parameter_%28computer_programming%29
[parameters]: https://en.wikipedia.org/wiki/Parameter_%28computer_programming%29
[Vortex]: http://overthewire.org/wargames/vortex/
[socket]: https://docs.python.org/2/library/socket.html
[file descriptor]: https://en.wikipedia.org/wiki/File_descriptor
[file descriptors]: https://en.wikipedia.org/wiki/File_descriptor
[Forth]: https://en.wikipedia.org/wiki/Forth_%28programming_language%29
[github]: https://github.com/
[buffer overflow]: https://en.wikipedia.org/wiki/Buffer_overflow
[try harder]: https://www.offensive-security.com/when-things-get-tough/
[segmentation fault]: https://en.wikipedia.org/wiki/Segmentation_fault
[seg fault]: https://en.wikipedia.org/wiki/Segmentation_fault
[segfault]: https://en.wikipedia.org/wiki/Segmentation_fault
[shellcode]: https://en.wikipedia.org/wiki/Shellcode
[sploit-tools]: https://github.com/SaltwaterC/sploit-tools
[Kali]: https://www.kali.org/
[Kali Linux]: https://www.kali.org/
[gdb]: https://www.gnu.org/software/gdb/
[gdb tutorial]: http://www.unknownroad.com/rtfm/gdbtut/gdbtoc.html
[payload]: https://en.wikipedia.org/wiki/Payload_%28computing%29
[peda]: https://github.com/longld/peda
[git]: https://git-scm.com/
[home directory]: https://en.wikipedia.org/wiki/Home_directory
[NOP slide]:https://en.wikipedia.org/wiki/NOP_slide
[NOP]: https://en.wikipedia.org/wiki/NOP
[examine]: https://sourceware.org/gdb/onlinedocs/gdb/Memory.html
[stack pointer]: http://stackoverflow.com/questions/1395591/what-is-exactly-the-base-pointer-and-stack-pointer-to-what-do-they-point
[little endian]: https://en.wikipedia.org/wiki/Endianness
[big endian]: https://en.wikipedia.org/wiki/Endianness
[endianness]: https://en.wikipedia.org/wiki/Endianness
[pack]: https://docs.python.org/2/library/struct.html#struct.pack
[ash]:https://en.wikipedia.org/wiki/Almquist_shell
[dash]: https://en.wikipedia.org/wiki/Almquist_shell
[shell]: https://en.wikipedia.org/wiki/Shell_%28computing%29
[pwntools]: https://github.com/Gallopsled/pwntools
[colorama]: https://pypi.python.org/pypi/colorama
[objdump]: https://en.wikipedia.org/wiki/Objdump
[UPX]: http://upx.sourceforge.net/
[64-bit]: https://en.wikipedia.org/wiki/64-bit_computing
[breakpoint]: https://en.wikipedia.org/wiki/Breakpoint
[stack frame]: http://www.cs.umd.edu/class/sum2003/cmsc311/Notes/Mips/stack.html
[format string]: http://codearcana.com/posts/2013/05/02/introduction-to-format-string-exploits.html
[format specifiers]: http://web.eecs.umich.edu/~bartlett/printf.html
[format specifier]: http://web.eecs.umich.edu/~bartlett/printf.html
[variable expansion]: https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html
[base pointer]: http://stackoverflow.com/questions/1395591/what-is-exactly-the-base-pointer-and-stack-pointer-to-what-do-they-point
[dmesg]: https://en.wikipedia.org/wiki/Dmesg
[Android]: https://www.android.com/
[.apk]:https://en.wikipedia.org/wiki/Android_application_package
[decompiler]: https://en.wikipedia.org/wiki/Decompiler
[decompile Java code]: http://www.javadecompilers.com/
[jadx]: https://github.com/skylot/jadx
[.img]: https://en.wikipedia.org/wiki/IMG_%28file_format%29
[binwalk]: http://binwalk.org/
[JPEG]: https://en.wikipedia.org/wiki/JPEG
[JPG]: https://en.wikipedia.org/wiki/JPEG
[disk image]: https://en.wikipedia.org/wiki/Disk_image
[foremost]: http://foremost.sourceforge.net/
[eog]: https://wiki.gnome.org/Apps/EyeOfGnome
[function pointer]: https://en.wikipedia.org/wiki/Function_pointer
[machine code]: https://en.wikipedia.org/wiki/Machine_code
[compiled language]: https://en.wikipedia.org/wiki/Compiled_language
[compiler]: https://en.wikipedia.org/wiki/Compiler
[scripting language]: https://en.wikipedia.org/wiki/Scripting_language
[scripts]: https://en.wikipedia.org/wiki/Scripting_language
[script]: https://en.wikipedia.org/wiki/Scripting_language
[shell-storm.org]: http://shell-storm.org/
[shell-storm]:http://shell-storm.org/
[shellcode database]: http://shell-storm.org/shellcode/
[gdb-peda]: https://github.com/longld/peda
[x86]: https://en.wikipedia.org/wiki/X86
[Intel x86]: https://en.wikipedia.org/wiki/X86
[sh]: https://en.wikipedia.org/wiki/Bourne_shell
[/bin/sh]: https://en.wikipedia.org/wiki/Bourne_shell
[SANS]: https://www.sans.org/
[Holiday Hack Challenge]: https://holidayhackchallenge.com/
[USCGA]: http://uscga.edu/
[United States Coast Guard Academy]: http://uscga.edu/
[US Coast Guard Academy]: http://uscga.edu/
[Academy]: http://uscga.edu/
[Coast Guard Academy]: http://uscga.edu/
[Hackfest]: https://www.sans.org/event/pen-test-hackfest-2015
[SSID]: https://en.wikipedia.org/wiki/Service_set_%28802.11_network%29
[DNS]: https://en.wikipedia.org/wiki/Domain_Name_System
[Python:base64]: https://docs.python.org/2/library/base64.html
[OpenWRT]: https://openwrt.org/
[node.js]: https://nodejs.org/en/
[MongoDB]: https://www.mongodb.org/
[Mongo]: https://www.mongodb.org/
[SuperGnome 01]: http://52.2.229.189/
[Shodan]: https://www.shodan.io/
[SuperGnome 02]: http://52.34.3.80/
[SuperGnome 03]: http://52.64.191.71/
[SuperGnome 04]: http://52.192.152.132/
[SuperGnome 05]: http://54.233.105.81/
[Local file inclusion]: http://hakipedia.com/index.php/Local_File_Inclusion
[LFI]: http://hakipedia.com/index.php/Local_File_Inclusion
[PNG]: http://www.libpng.org/pub/png/
[.png]: http://www.libpng.org/pub/png/
[Remote Code Execution]: https://en.wikipedia.org/wiki/Arbitrary_code_execution
[RCE]: https://en.wikipedia.org/wiki/Arbitrary_code_execution
[GNU]: https://www.gnu.org/
[regular expression]: https://en.wikipedia.org/wiki/Regular_expression
[regular expressions]: https://en.wikipedia.org/wiki/Regular_expression
[uniq]: https://en.wikipedia.org/wiki/Uniq
[sort]: https://en.wikipedia.org/wiki/Sort_%28Unix%29
[binary data]: https://en.wikipedia.org/wiki/Binary_data
[binary]: https://en.wikipedia.org/wiki/Binary
[automation is divine]: https://www.youtube.com/watch?v=36AA3JGRP9s
[repos]:https://help.ubuntu.com/community/Repositories/Ubuntu
[repo]:https://help.ubuntu.com/community/Repositories/Ubuntu
[repository]:https://help.ubuntu.com/community/Repositories/Ubuntu
[repositories]: https://help.ubuntu.com/community/Repositories/Ubuntu
[hex dump]: https://en.wikipedia.org/wiki/Hex_dump
[hexdump]: https://en.wikipedia.org/wiki/Hex_dump
[xxd]: http://linuxcommand.org/man_pages/xxd1.html
[mkdir]: https://en.wikipedia.org/wiki/Mkdir
[file]: https://en.wikipedia.org/wiki/File_%28command%29
[gzip]: http://www.gzip.org/
[file extension]: https://en.wikipedia.org/wiki/Filename_extension
[bzip]: http://www.bzip.org/
[bzip2]: http://www.bzip.org/
[tar]: https://en.wikipedia.org/wiki/Tar_%28computing%29
[tar command]: http://linuxcommand.org/man_pages/tar1.html
[private key]: https://help.ubuntu.com/community/SSH/OpenSSH/Keys
[s_client]: https://www.openssl.org/docs/manmaster/apps/s_client.html
[nmap]: https://nmap.org/
[IP address]: https://en.wikipedia.org/wiki/IP_address
[RSA]: https://en.wikipedia.org/wiki/RSA_(cryptosystem)
[ssh private key]: https://help.ubuntu.com/community/SSH/OpenSSH/Keys
[file permissions]: https://www.linux.com/learn/understanding-linux-file-permissions
[octal file permission]: http://www.cyberciti.biz/faq/how-linux-file-permissions-work/
[octal file permissions]: http://www.cyberciti.biz/faq/how-linux-file-permissions-work/
[chmod]: https://en.wikipedia.org/wiki/Chmod
[diff]: http://man7.org/linux/man-pages/man1/diff.1.html
[.bashrc]: http://unix.stackexchange.com/questions/129143/what-is-the-purpose-of-bashrc-and-how-does-it-work
[bashrc]: http://unix.stackexchange.com/questions/129143/what-is-the-purpose-of-bashrc-and-how-does-it-work
[setuid]: https://en.wikipedia.org/wiki/Setuid
[user id]: https://en.wikipedia.org/wiki/User_identifier
[effective user id]: https://en.wikipedia.org/wiki/User_identifier#Effective_user_ID
[cron]: https://en.wikipedia.org/wiki/Cron
[file extension]: https://en.wikipedia.org/wiki/Filename_extension
[file extensions]: https://en.wikipedia.org/wiki/Filename_extension
[bash script]: https://linuxconfig.org/bash-scripting-tutorial
[bash script]: https://linuxconfig.org/bash-scripting-tutorial
[bash scripts]: https://linuxconfig.org/bash-scripting-tutorial
[shebang line]: https://en.wikipedia.org/wiki/Shebang_(Unix)
[she-bang line]: https://en.wikipedia.org/wiki/Shebang_(Unix)
[sha-bang line]: https://en.wikipedia.org/wiki/Shebang_(Unix)
[shabang line]: https://en.wikipedia.org/wiki/Shebang_(Unix)
[sha bang line]: https://en.wikipedia.org/wiki/Shebang_(Unix)
[nano]: https://en.wikipedia.org/wiki/GNU_nano
[text editor]: https://en.wikipedia.org/wiki/Text_editor
[whoami]: https://en.wikipedia.org/wiki/Whoami
[echo]: https://en.wikipedia.org/wiki/Echo_(command)
[md5sum]: http://www.tutorialspoint.com/unix_commands/md5sum.htm
[checksum]: https://en.wikipedia.org/wiki/Checksum
[hash]: https://en.wikipedia.org/wiki/Cryptographic_hash_function
[cut]: https://en.wikipedia.org/wiki/Cut_(Unix)
[daemon]: https://en.wikipedia.org/wiki/Daemon_(computing)
[temporary directory]: https://en.wikipedia.org/wiki/Temporary_folder
[temp directory]: https://en.wikipedia.org/wiki/Temporary_folder
[temp folder]: https://en.wikipedia.org/wiki/Temporary_folder
[temporary folder]: https://en.wikipedia.org/wiki/Temporary_folder
[seq]: http://www.cyberciti.biz/tips/tag/seq-command
[/etc/passwd]: https://en.wikipedia.org/wiki/Passwd#Password_file
[more]: https://en.wikipedia.org/wiki/More_(command)
[vi]: https://en.wikipedia.org/wiki/Vi
[vim]: http://www.vim.org/
[caesar cipher]: https://en.wikipedia.org/wiki/Caesar_cipher
[vignere cipher]: https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher
[substitution cipher]: https://en.wikipedia.org/wiki/Substitution_cipher
[DNA]: https://en.wikipedia.org/wiki/Nucleic_acid_sequence
[Python bytecode]: http://security.coverity.com/blog/2014/Nov/understanding-python-bytecode.html
[uncompyle]: https://github.com/gstarnberger/uncompyle
[Easy Python Decompiler]: https://github.com/aliansi/Easy-Python-Decompiler-v1.3.2
[marshal]: https://docs.python.org/2/library/marshal.html
[IDLE]: https://en.wikipedia.org/wiki/IDLE
[bytecode]: http://whatis.techtarget.com/definition/bytecode
[dis]: https://docs.python.org/2/library/dis.html
[rot13]: https://en.wikipedia.org/wiki/ROT13
[calendar]: https://docs.python.org/2/library/calendar.html
[datetime]: https://docs.python.org/2/library/datetime.html
[primefac]: https://pypi.python.org/pypi/primefac
[re]: https://docs.python.org/2/library/re.html
[IDA pro]: https://www.hex-rays.com/products/ida/
[IDA]: https://www.hex-rays.com/products/ida/
[QR Code]: https://en.wikipedia.org/wiki/QR_code
[RGB]: https://en.wikipedia.org/wiki/RGB_color_model
[RGB color]: https://en.wikipedia.org/wiki/RGB_color_model
[exiftool]: http://www.sno.phy.queensu.ca/~phil/exiftool/
[robots.txt]: http://www.robotstxt.org/
[XSS]: https://en.wikipedia.org/wiki/Cross-site_scripting
[cross-site scripting]: https://en.wikipedia.org/wiki/Cross-site_scripting
[cross site scripting]: https://en.wikipedia.org/wiki/Cross-site_scripting
[cookie catcher]: http://hackwithstyle.blogspot.com/2011/11/what-is-cookie-catcher-and-how-to-get.html
[johnhammond.org]: http://johnhammond.org
[HTTP cookie]: https://en.wikipedia.org/wiki/HTTP_cookie
[HTTP cookies]: https://en.wikipedia.org/wiki/HTTP_cookie
[cookie]: https://en.wikipedia.org/wiki/HTTP_cookie
[cookies]: https://en.wikipedia.org/wiki/HTTP_cookie
[HTTP GET]: http://www.w3schools.com/Tags/ref_httpmethods.asp
[tee]: https://en.wikipedia.org/wiki/Tee_(command)
[reverse engineering]: https://en.wikipedia.org/wiki/Reverse_engineering
[cryptography]: https://en.wikipedia.org/wiki/Cryptography
[crypto]: https://en.wikipedia.org/wiki/Cryptography
[sed]: https://en.wikipedia.org/wiki/Sed
[padding]: https://en.wikipedia.org/wiki/Padding_(cryptography)
[xortool]: https://github.com/hellman/xortool
[XOR Cracker]: https://wiremask.eu/tools/xor-cracker/
