Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [cryptography]

the practice and study of techniques for secure communication and sending of data, and the construction and analysis of protocols that accomplish this.

0
votes
1answer
97 views

Is it possible to recover the key to a decrypted file?

Is it possible to recover the key to a decrypted file if you have the initialization vector and it uses RijndaelManaged? If so how? The file I want to recover the key from is a xml that looks like ...
0
votes
0answers
54 views

Does anyone recognise following (USB,HID?) encoding method?

Im reverse engineering a Keyborard RGB LED Control Software and there is a Library called "HidServ.dll" that seems to be the interface between the Keyboard and the Software. Every Function of that ...
0
votes
2answers
144 views

RSA Decryption? [closed]

I am playing a game in my university where you have different puzzles based on cryptography and now in a puzzle named 'rsa', we have 2 files: 'key', 'secret'. The task for this is to decrypt the ...
1
vote
0answers
185 views

Reverse crypto algorythm, based on AES

Hello! I'm working on reversing one library (shared object) written for ARM architecture. It's obfuscated or packed with something pretty strong what makes debugging much harder and almost impossible ...
0
votes
1answer
130 views

Is this firmware using a substitution cipher?

I'm trying to extract data from a firmware file. I used binwalk on the firmware, which found a single chunk of Zlib compressed data. I uncompressed this data, and used strings on the result, which ...
-3
votes
1answer
372 views

Identification of AES portion code in binary

I want to locate AES code portion in binary after reverse engineering. I have tried to locate manually and using plugin findcrypt2 but I was not successful. Kindly show me a direction so that I can ...
2
votes
1answer
443 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 ...
2
votes
2answers
302 views

Running machine code that I need to execute with arguments. How?

There is a program which I expect to run to generate a seed, but I don't know how to proceed and I am new to reversing. I have the machine code of a program which is built for x86 architecture. I ...
1
vote
1answer
195 views

How can I debug this binary (which I suspect does encryption)?

I have a snippet of binary code which performs some encryption algorithm (most likely modified RC4). I have four variables associated with the encryption (seed_key_arg [1-3] and a seed_key) and ...
2
votes
1answer
631 views

Unknown CRC calculation

I am seeking for a CRC calculation on EEPROM content. I try to add options to my car with BOSCH ECU. MCU in this ECU is Tricore TC1793 and EEPROM content seems to be divided into blocks of 128 bytes ...
4
votes
2answers
237 views

Generating a key for a simple algorithm

I have this pseudo code: v5 = serial[6] + serial[0] - serial[7] - serial[2]; LOBYTE(v5) = serial[1]; v8 = serial[3] + v5 - serial[4]; if ( v8 != serial[5] ) goto FAIL; The variable serial[] is ...
7
votes
1answer
230 views

Is there a way to find out which hash standard by studying the source code?

We have an embedded product, which we are carrying for several hardware iterations since more than 5 years ago. We have all the source code, most of it nicely documented. As the product is actively ...
1
vote
0answers
144 views

Decrypting/Decoding encrypted/encoded data

I'm trying to increase the interoperability of some database software. The database can write and read "stored SQL queries". I wanted to figure out the format of these SQL queries so I can build them ...
4
votes
1answer
1k views

Having keys and binary, how do I reverse/decrypt a stream encryption?

I would like to ask if you have any idea or approach to reverse engineer a decryption algorithm to find the opposite encryption function. I do have all required keys and fields and of course the ...
1
vote
0answers
183 views

Overwatch Sombra ARG community asking for Cryto/Steg help [closed]

We are looking for some crypto / security expertise in solving some difficult puzzles in a ARG campaign for a Blizzard game called Overwatch. The challenges introduced and solved by the community ...
1
vote
1answer
554 views

Reverse Engineering Crypto Methods

Since few days, Ive started to Reverse Engineer a little game. That game includes some data files, where the 3d files are stored. I want to write a little Software, where I can add own 3d models, to ...
0
votes
1answer
213 views

How would you protect this Crypter?

Imagine you are working in a kind of crypter that only works with the current function deciphered, rest of the code is ciphered by symmetric encryption. When a new function is about to be called, the ...
1
vote
1answer
600 views

Debug an application for analyzing file decryption

I have an encrypted raw data file generated by an application. This file is used in a second application to generate a readable text file based on the raw data. I need to change a few values in the ...
3
votes
2answers
3k views

Which plugin for identifying crypto algorithms in IDA Pro 6.9?

I stumbled upon findcrypt2 but it seems not to work anymore. Is there a new version of findcryp2 anywhere or are there similar plugins which are able to identify different crypto algorithms by ...
1
vote
1answer
166 views

How the signature level set to the process in Windows 8?

From this blog article: Windows PKI Internals (Signing Levels, Scenarios, Root Keys, EKUs & Runtime Signers). Windows 8 instituted the Signing Level, also sometimes referred to as the ...
1
vote
1answer
123 views

Malware checks for hwid

Recently, I received malware executable to analyse - it's written in C#, and it's packed/obfuscated with unknown tool, so I started analysis from analysing it's traffic - what it's sending and ...
1
vote
0answers
42 views

How to store a string securely inside your app? [duplicate]

Let's say you have an Android or iOS app, how can you store a web API key (a string) in your app securely, making it impossible or harder to reverse engineer. Some solutions I have thought about : ...
3
votes
1answer
514 views

Reverse decryption algorithm

I've been working to disassemble a decryption algorithm for a particular software. The way it works is that the serial key contains all the appropriate information, gets crunched in the algorithm ...
4
votes
1answer
804 views

Protect a key from being recovered by decompilation

I work in a game editor that develop an online game. In our endless struggle against bots (that have negative impacts on server performances, game economy, game experience, ...), one of ours weapons ...
0
votes
0answers
826 views

How does iOS hash and salt passwords on its secondary-storage?

I bought a used iPhone from someone, but I accidentally got a lock screen on the phone and can't figure out what the passcode is. Long story short, how does iOS hash the passcodes for entry, what kind ...
1
vote
1answer
903 views

Firmware encrypted with Openssl [closed]

I managed to copy the Firmware out of a device and tried to extract to content with binwalk but the Signature tells it's encoded with OpenSSL Which are the possible ways to find out which type of ...
6
votes
1answer
2k views

Reverse-engineering a tough-to-crack video game save-file checksum

Been trying to figure this one out for a while now, and would be eternally grateful for anyone with more experience in checksum algorithms lending a hand. I've been trying to alter save files for an ...
1
vote
2answers
503 views

Identifying cryptography algorithm

I have a decryption algorithm that has been pulled from an x86 binary and converted into C# code. The C# works perfectly to decrypt data, but I'd like to identify the algorithm in use, so I could (...
2
votes
2answers
235 views

Understanding a messengers protocol encryption

For my own personal curiosity and development (building a bit of code mimicking the protocol), I am trying to figure out what the communication protocol encryption is made out of in a particular chat ...
2
votes
0answers
202 views

IDA Signatures for OpenSSL [duplicate]

This may be an old topic, but I still haven't find a solution. Sometimes happens to reverse Windows executables that contain strings clearly related to encryption algorithms implemented through ...
4
votes
1answer
1k views

Modifying a binary save-data file for a video game with a CRC/Checksum check

I recently overwrote the save game file of a video game that my girlfriend and I had been playing through. After trying to recover the file a few different ways (game didn't erase but overwrote the ...
1
vote
1answer
676 views

Can Trusted computing/TPM defeat crack attempts?

I read some things about trusted computing platforms (TPM) and its applications in the past. AFAIK, its applications include such things as countering software reverse engineering/crack and cheating ...
3
votes
1answer
430 views

How the author found the initialization vector for the AES CBC whatsapp CRYPT5 db uses?

I was going through DECIPHERING MSGSTORE.DB.CRYPT5, THE NEW DATABASE WHATSAPP & Steal WhatsApp update. The author of the first link published a decryptor which sets the iv for the aes_192_cbc to ...
7
votes
2answers
2k views

How much Cryptography knowledge is important for reverse engineering? [closed]

Is understanding of Cryptography really important for a reverse engineer? Thanks.
5
votes
1answer
595 views

Understanding hardware extracted keys

I'm a crypto newbie, but have been working on card-access systems that encrypt the card data with 128-bit RSA. I have an example (from a card) of 1024 bits of encrypted data. I also have the public ...
2
votes
2answers
7k views

Steps for determining the hash algorithm used

I have 5 test users and they have the same password. I am testing an application which stores the password in the database in an encrypted format. I want learn which hash algorithm has been used on ...
8
votes
2answers
2k views

What is this 'mathematical jigsaw puzzles' obfuscation?

You must have heard about it, it all over the on-line newspapers. Some researchers from UCLA claims to have achieved a breakthrough in software obfuscation through 'mathematical jigsaw puzzles'. ...
20
votes
3answers
36k views

What is the most efficient way to detect and to break xor encryption?

I know that modern cryptographic algorithms are as close as they can to fully random data (ciphertext indistinguishability) and that trying to detect it is quite useless. But, what can we do on weak-...
-3
votes
1answer
204 views

Is it possible to get the encryption key when you have the plain text [closed]

i have a question about SHA256 I know that this algorytm was used to encrypt a text, wich i have, also i have the encrypted version of this text. My question is can i somehow get to the encryption key ...
19
votes
4answers
19k views

Determine Encryption Algorithm

I'm analyzing some software that appears to encrypt its communications over the network, but it does not appear to be SSL. How can I easily determine what encryption algorithm its using, and maybe ...
57
votes
6answers
23k views

Where to find (free) training in reverse engineering? [closed]

Can someone give a list of websites with good (and free) reverse engineering training exercises ?
9
votes
3answers
349 views

Usage of FHE in obfuscation?

FHE (Fully Homomorphic Encryption) is a cryptographic encryption schema in which it is possible to perform arithmetic operations on the ciphered text without deciphering it. Though there is no really ...