Questions tagged [xor]

Exclusive or (xor) is a logical operation that outputs true only when both inputs differ (one is true, the other is false).

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Decode message in esoteric audio file

I'm having a reverse engineering lab at school and my last project is to beat a 10 level reverse engineering CTF-like challenge. It's got plenty of interesting things. What I need to do is find a ...
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How to guess the key of XOR encryption in java?

I am trying to find the key of XOR encrypted string in java. It is very much probable that the key is eight characters long. I have the encrypted string. I am not able to understand how to go ...
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Tektronix firmware XOR puzzle

As a means of learning about packing firmware and for fun I am trying to unpack the latest firmware for an entry level Tektronix Function generator firmware attached I have read the forum and ...
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File Decryption Problems

over the past year, I provided an English patch to a community of thousands of players of a game I love and which is not available in English (just Chinese and Korean). Sadly, besides me, other ...
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Does someone recognize this “lookup table”? (used for xor encryption)

This table is part of the packet encryption of an old game for which I am developing a server. The crypto algorithm doesn't just xor the password with the message. It uses a multiple of the ascii ...
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935 views

Identify password generation algorithm

I'm a newbie who just started own way through reverse engineering so I apologize if my question is not appropriate. Currently I'm going through different Crackme puzzles and now I'm stuck. I've spend ...
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474 views

Help me understand how to actually break an XOR/Vigenère cipher

My friend's server was recently hacked and I'm trying to decipher the malicious files I found in hopes of understanding the hack better. I can tell that they're using an XOR/Vigenère cipher and I've ...
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349 views

Inverse And operation

I'm trying to write a keygen to a crack me that I'm learning from and I got stuck. What happens there is pretty simple: Let's say that I entered the password: "12121212" XOR DWORD PTR DS:[ECX+EAX],...
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2k views

Simple 8bit checksum

I'm trying to find out, how the checksumming in an RS485 communication works. The data is packetized and seems to be using 8bit checksums. One packet per line, the last byte that isn't 0x00 seems to ...
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1k views

How XOR works in my code?

I have this assembly code: XOR DWORD PTR DS:[ECX+EAX],1234567 And what it does is just xoring the first 4 bytes of EAX with 1234567. So if the first 4 bytes are : 31 32 31 32 After xor they become:...
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2k views

Help me reverse this

It's been 4 nights I'm struggling decompiling this one. It's an Android native library that I ran through IDA to get C code. Java signature : byte[] resultArray = new byte[-2 + dataArray.length]; ...
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1k views

XOR Encryption (XPost from Crypto)

Dear ReverseEngineering@SE, Background information: I have reason to believe that an old game I've played is still using their XOR encryption for nearly all in/out-going packets. I also believe that ...
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How to decrypt data in binary file by XOR operator using a given key at specific offset? [closed]

I've a binary data files which are encrypted by a simple XOR cipher using a given key at offset +0x88 (which is 0x80 long), then the data (+0x108) is compressed by lzo1x. What would be the most ...
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4k views

How does scanf interact with my code in assembly

I have recently started getting into assembly for the purpose of reverse engineering. I started small with understanding basic datatypes, but I want to move on to more complex datatypes and functions. ...
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164 views

How to find out what encryption/encoding has been used

So my uni just had some on break into the email server and send out a load of emails with a suspicious looking executable. I'm on Linux so I downloaded the file and ran the Strings command and saw a ...
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163 views

Getting Encryption Method When I Know Encrypted File Name & Original File Name

I'm busy trying to decrypt some game data. All the encrypted filenames are hexadecimal strings with the same length e.g. 1790C6E445C7E38EFCD5B3042F9B4443. I've figured out that a few of the files ...
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928 views

What kind of compression/obfuscation algorithm is this?

I have a couple of streams that look pretty odd within a DICOM file. In a few words, DICOM is very close to what binary XML would look like. Almost all of the information from those DICOM files are ...
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688 views

How to efficiently debug Loops with OllyDbg/Immunity?

I'm currently reversing a function which looks like the following .text:0040383F 8D 04 BF lea eax, [edi+edi*4] .text:00403842 6A 14 push 20 .text:00403844 C1 E0 03 ...
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450 views

XORing command-line for encryption?

I have the following lines push [ebp+dwBytes] push 8 ; dwFlags call ds:GetProcessHeap push eax ; hHeap call ds:HeapAlloc push [ebp:lpCmdLine] ; char * mov ...