Questions tagged [decryption]

Process of decoding an encrypted message with an authorized access (knowledge of the protocol, the encryption algorithm and the key).

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14
votes
5answers
2k views

Decryping TLS packets between Windows 8 apps and Azure

In Windows Store application development for Windows 8, there is a class called remoteSettings that lets a developer store batches of data so that the user will have access to it across several ...
11
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3answers
5k views

Totally unknown file analysis approaches

I guess this is the worst case. I have a file which was initially base64 encoded. This step was easy. But now all I can see is a bunch of rubbish. No structure, nearlly a maximum of entropy, no ...
10
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2answers
12k views

Decrypting IPA Binary on OS X

I've been reading this PDF on reverse-engineering iOS applications and have reached slide 39, decrypting the binary. However, I've been attempting to disassemble and explore the binary in OS X 10.9.5 ...
10
votes
4answers
14k views

AirPlay Mirroring decryption (FairPlay)

I've been spending a good chunk of time looking at some 3rd party applications that were successful in "reproducing" (although I believe not necessarily by understanding the algorithm completely but ...
9
votes
1answer
4k views

How are Apple App Store Apps encrypted?

I know how to decrypt an iOS app use tools. How is this encryption performed? Why can iOS apps only be decrypted on a device? Is there a device-specific key used for encryption?
8
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3answers
9k views

Guessing CRC checksum algorithm

I am trying to reverse engineer a 16 bit checksum algorithm of one relatively old (10 years) LAN game that is no longer supported nor has source code available. As it seems, data packets don't have ...
8
votes
2answers
5k views

Is it possible to decrypt an SSL connection (short of bruteforcing)?

I'm trying to reverse-engineer a protocol (it's for a game whose server's are closing soon). I have two things: 1) the binary for the program 2) a packet dump from Wireshark (I am still able to get ...
7
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2answers
1k views

Reverse Engineering Quebec Canada PDF417 restaurant bills

Let me explain what I'm trying to do, and then where I am at... As you can see on this image : There is a PDF417 at the end containing a string that at my best guess is some base64 string. Here it ...
7
votes
2answers
2k views

Virus uses a custom XOR encryption and need help possibly cracking it / Reversing EXE

As stated in my previous question i was infected by a encrypting virus that encrypts two 1024 byte blocks of any given file (First 1024, and last 1024) in some type of custom CFB XOR encryption. I ...
6
votes
2answers
4k views

How to find file compression or obfuscation type

The program I'm trying to decompile uses several supporting files: somesound.mp3 someimage.jpg etc.. The files are all located in the file system, not embedded into the exe. The files are used at ...
6
votes
1answer
395 views

What is the integrity check used?

I have the following numbers. It is a 14 digit identification number. The first 13 digits (counting from left) are the number itself, the 14th (the least digit) digit is an integrity check code. I ...
5
votes
1answer
1k views

How can I decode this php code?

I found this backdoor on a client's website. http://pastebin.com/wVs8w44v (original format) http://pastebin.com/acfx49QJ (semi - readable) I have gotten rid of it and realise it's an obfuscated ...
5
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1answer
2k views

Question about Keeloq - A car remote control standard

I have a question about Keeloq security. I have an original car remote controller (BFT Mitto 2) and I know this chip uses HCS301 with Keeloq implementation. I would like to clone this remote for my ...
5
votes
1answer
6k views

Decrypting firmware: Is there a true “format” to it, and how does it differ from decryping other files?

I have firmware for a system and I'm trying to decrypt some of it just for the sake of seeing what it all does; nothing illegal or anything like that, such as reproducing copies of it decrypted and ...
5
votes
1answer
1k views

Turning Technologies RF receiver

At my university we're required to purchase these RF clickers with an lcd screen so professors who choose to take attendance can do so in an automated fashion, and occasionally administer simple ...
5
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2answers
2k views

Retrieving encryption/encoding logic from dll

I am trying to retrieve a decrypting/deconing logic from a program. Unfortunately I have virtually no experiencing in reverse engineering. I am building an alternative controller application for a ...
4
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1answer
1k views

Finding out checksum algorithm

I have old serial communication protocol and having some trouble finding out about checksum algorithm that has been used. I've tried several CRC16 algorithms and none of them seem to work. Tx message ...
4
votes
1answer
1k views

Reverse engineer 4-bit CRC in LG IR packet

I am reverse engineering IR protocol of LG air conditioner. AC generally send the whole current state of remote on each key press. Data sent is 28 bits long, last 4 bits seem to be the checksum. I ...
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 ...
4
votes
1answer
287 views

What does this Generate_Key_IV assembler routine?

I want to decompress some files, and found some information on how. Apparently they are encrypted with AES 128 in CFB mode, and sometimes compressed using ZLIB. Each file's key and IV is supposedly ...
4
votes
2answers
936 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 ...
4
votes
1answer
1k views

Decrypting assets (json/png/lua)

Context I am trying to decrypt a game for its assets for learning purposes. I have extracted out said assets from the game package, they are in formats of .json, .png and .lua. However, they are ...
4
votes
2answers
934 views

Reverse engineer 4-bit checksum (?) in Sanyo air conditioning IR packet

I am reverse engineering IR protocol of Sanyo air conditioner. AC sends the whole current state of remote on each key press. Data sent is 67 bits long, last 4 bits seem to be the some kind of error ...
4
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0answers
658 views

Reverse engineer TPMS sensor data

I'm trying to reverse engineer data received from TPMS (car tire pressure) sensors. I was able to receive and demodulate the data (433 MHz, FSK, Manchester encoding). Probable packet fields: ...
3
votes
1answer
405 views

How can I determine if a piece of code is an encryption algorithm?

I am trying to reverse engineer a malware, and came across a piece of code that I suspect is an encryption/decryption procedure, however I do not know for sure. I can recognize that it extracts its ...
3
votes
2answers
364 views

how to find the encryption algorithm?

I have an arm complied so file and find the decrypt function which pseudocode generated by IDA Pro is like this: char __cdecl EncodeUtil::getDecryptStr() { int *v0; // r0 int *v1; // r7 ...
3
votes
1answer
446 views

Animal Crossing: Pocket Camp .zdat File

Hello I am trying to obtain the music from the new game Animal Crossing: Pocket Camp. The music is contained in files like these: https://download-cdn-ac-pocketcamp.akamaized.net/assets/...
3
votes
1answer
143 views

Help reverse decrypt function (decode -> encode)

I have this java function that decode 8bytes text string(encoded as int[]): public static int[] decode(int[] text, int[] key) { int j = 0x3c; //value 60 in decimal int i = 0x33; //value 51 in ...
3
votes
1answer
532 views

Trouble deparsing Perl encrypted with Filter::Crypto::Encrypt

I am trying to use perl -MO=Deparse to get readable source code from encrypted Perl files. The Perl script I'm trying to deparse starts with use Filter::Crypto::Decrypt;. The error I'm getting is: ...
3
votes
1answer
659 views

End of central directory signature not found after extracting an embedded zip file

I'm learning about stenography and found this example. I've followed the instructions but when I write out a new zip file after changing the filename inside the file I get this: unzip nospaces.zip ...
3
votes
1answer
217 views

Reverse engineering file format - ImageLink

I have some technical documentation which is supplied in the form of a generic Windows viewer and a database. The database contains different "books", which are represented by a bunch files: book.bbi ...
3
votes
1answer
741 views

Case study: Extracting a database from a Delphi software

This is my first post here (&hopefully not the last one!) First of all, I gotta say I am no RE expert so I might sound a little confused. So I have got a Delphi program consisting of two files (...
3
votes
0answers
207 views

EEPROM data bytes verification

I'm investigating a tool. I have an section of an eeprom memory dump that this tool uses, shown in the figure below. By my inquiries, the two bytes highlighted in red are based on the bytes ...
3
votes
0answers
139 views

Guessing checksum 8 bit ASCII algorithm

I am trying to reverse engineer an 8-bit checksum algorithm of a Chinese machine with RS485 communication and ASCII encoding. I tried with all the algorithm I could find, but it seems that data ...
3
votes
0answers
568 views

Obtaining the decryption keys for Super Mario Run (Android/iOS Game)

Super Mario Run is a il2cpp Unity game. Most of its assets are downloaded in-game through http requests. I particularly want the OGG files of the music. I can see the list of their names comes from ...
2
votes
2answers
6k views

Reverse Engineering a Firmware. Someone can help me?

I am currently trying to reverse-engineer a firmware file to learn the topic but I am a little bit stuck. I tried to use binwalk to get more information about the file but this did not produce ...
2
votes
2answers
1k views

Put encrypted code blocks back as unencrypted in IDA

So I have some encrypted data in this executable. IDA couldn't do much with it, so it defined it as arrays. Now I know how to decrypt this data, and it has some encrypted code. I could of course, put ...
2
votes
1answer
3k views

How to decrypt encrypted script files for a game?

I want to mod Tony hawks underground 2. I noticed that the files in a folder scripts (down the game's directory tree), are all encrypted. Where do I start if I want to decrypt them?
2
votes
1answer
15k views

Extract text data from a compressed/encrypted .DAT file

Hello, I'm from Uruguay so I'll make my best effort to explain my "problem" in english. I want to read some text that is inside a .DAT file, but is "encrypted" or "compressed" (I don't know which is ...
2
votes
1answer
967 views

Identify decompiled decryption algorithm

I'm trying to analyze a decryption algorithm I'm reverse engineering and am wondering if anyone would from looking at the logic be able to identify one of the standard/common ciphers people use. The ...
2
votes
2answers
437 views

IDA: call a function with different arguments

I'm reversing some software and found the function which decrypts some stuff: As you can see it has the password parameter for it which gets decrypted in this function. Function disassembly: ...
2
votes
1answer
689 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 ...
2
votes
1answer
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]; ...
2
votes
1answer
785 views

How would I go about finding an encryption key or cipher by decompiling a program?

I became curious about how Trend Micro communicated with its servers so I gleaned some of the unique and standard HTTP headers that were being sent back and forth using Fiddler2. I created a winsock ...
2
votes
1answer
184 views

How to locate the code used for encryption

I've been playing around with recording packets being sent to and from applications on my pc. Logically any program that sends or receives packets must have the encryption scheme used. So I'd like to ...
2
votes
1answer
403 views

Lossless Rice Compression

I am trying to figure out how the Lossless Rice compression algorithm works on the following file. Here is a DICOM file. Looking at the information I can see: $ gdcmdump I160 | grep "Tamar ...
2
votes
1answer
564 views

How are the iOS kernel cache and root filesystem decrypted?

On the iPhone Wiki there are decryption keys for several, but not all, of the iPhone firmwares (root filesystems and kernelcache files). How were these keys found?
2
votes
1answer
720 views

is it possible to decrypt Enigma and RC4 encryptions?

i have been working on a bug for almost a year trying to figure out how i can fix it. the app is suppose to show some message like ("Processing")to notify a user that the main function is executed, so ...
2
votes
1answer
293 views

How to retrieve stored information, NAND filesystem with VB.Net

I have been reading and reading about NAND and NOR flash.I am wantina (Usualy 512 bytes) to access some stored information in a nand.bin file but cannot for the life of me figure out what I need to do ...
2
votes
1answer
82 views

How does IPA decryption works?

All IPAs being downloaded from AppStore gets encrypted on servers as part of FairPlay DRM. But decryption is accomplished on local device. As far as I know there is some hardware module which contains ...