Questions tagged [decryption]

In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Only authorized parties can decipher a ciphertext back to plaintext and access the original information.

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RSA DECRYPTION when N gives only one prime number

I am getting only 1 prime factor to some power if i factorize N for RSA decryption. So, in this case what will be the value of P and Q. P will be that one Prime Factor and then there is nothing left ...
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Decryption of an unknown cipher

How can I identify the cipher that encrypted the data shown below? I'm very new to this field, so I am not sure. For example: How does one know which cipher is used in the following line? How can one ...
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Where to start? decrypting .enc files [closed]

I'm looking for a simple way to brute force a series of .enc files. My particular use case is that I have a CD containing purchased photos from a photographer that is no longer in business, and there ...
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Hidden message in photo [closed]

png with hidden message inside, but i cannot decrypt (understand) the message, do you have any suggestions? The code: h5BA68F35I_%3E%3B%3BG3gdc%3E%3EFF9g5deA82hhh%3F%3Ea%3B22gdh%3Ee%3B%3B%6025%...
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decryption in IDEA if the encryption was made without the output transformation

I'm implementing IDEA encryption and decryption and I'm trying to implement it in different variants(e.g if we didn't do the output transformation or if we don't do full 8-round encryption). I got the ...
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1answer
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What is the correct order of operations for one-time pad cipher when using subtraction and mod 10 arithmetic?

What would be the proper order of operations for OTP encryption/decryption when using subtraction and mod 10? E.g. P - K = C or K - P = C Most of the sources I have seen do not cover this topic or I ...
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Where exactly do you add the zeroes to a URL in a padding oracle attack? Also, how would you decrypt a file this way?

I have been studying various crypto attacks, and one of the attacks that I have recently studied was the padding oracle attack. Now, I mostly understand it, but there is one aspect of the padding ...
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Completing RSA Encryption

Being new to cryptology, I'm trying to understand how I would complete RSA encryption by hand. I can only follow the formula so far before becoming very confused. I want to encrypt the value "123&...
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How can I go about decrypting some files that were most likely encrypted using android's file-based encryption?

I am looking to try and decrypt some files from a phone that I no longer have. I've tried to provide some background information here for context purposes. The files in question were backed up from ...
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Extra bytes when decryping with OpenSSL

The string is encrypted with the following properties (using C#): myAes.Mode = CipherMode.CBC myAes.KeySize = 128 myAes.Padding = PaddingMode.PKCS7 myAes.BlockSize = 128 myAes.FeedbackSize = 128 Key: ...
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Cryptography Challenge [closed]

I have been messing around with cryptography (for recreational use) and I have created my own function that encrypts things for me. Now, with that being said, I freely admit that I am by no means an ...
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Decryption of Kerberos ticket contents using AES256 keys [migrated]

I am using Microsoft CNG functions to decrypt different parts of the Kerberos tickets and encrypted items in Kerberos messages. The decrypted content that I am getting is not the correct one. I was ...
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crypt algorithm by a vectored key and the error is Proportional to the difference between input key and real key

I want to find an crypt algorithm which provides the functionality described below. Given a key (a vector Vkey) and a data (an image), use this key to encry the image; the encrypted image can not be ...
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Am I Doing RSA Correctly?

I am trying to figure out how to complete RSA manually. I am trying to encode a simple block message (Mi). I used CrypTool to determine the encryption. When I "manually" computed the ...
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1answer
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It possible to encrypt .bmp bitmap files using Stream Cipher Chacha20?

Maybe this sounds like a stupid question. I'm sorry for that. I just wanted to know is it possible to encrypt a bitmap image file like *.BMP, and generate the ciphertext which is an obscure bitmap ...
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How can I decrypt AES-256 GCM with key with a IV that is missing?

I want to decrypt a file that has been encrypted using AES-256 in GCM mode in libressl. I have the key but I don't have the IV, is there any way I can still decrypt?
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Decrypt web https-transmitted file manually [closed]

When the communication between server and client starts -after a request, the computers agree on an encryption protocol to protect the data, the TLS handshake. The data may not be encrypted on the ...
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How do I preform the inverse key expansion of aes decryption? [duplicate]

I’m working on an aes encryption and decryption project in 8086 assembly! I managed to code an encryption algorithm and it worked perfectly. No I’m working on the decryption algorithm. I’ve managed to ...
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How to decrypt raw TLS bytes?

Is there any tool / way to decrypt raw bytes of a TLS 1.2 session, when the master key is known, even if forward secrecy is used? The closest I found is this. I know its possible using Wireshark, but ...
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4answers
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Are there any cryptographic algorithms, which lets the user apply some modifications on the encoded data, without decoding it?

I would like to encode some data with a key, and send it to a third party. They don't know the key to decode it, but I would like to make it possible for them to apply some modifications on it. Then ...
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1answer
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Can we sign and encrypt with RSA keys of both sender and receiver?

By using RSA encryption, it is possible to "encrypt" sign with sender's private key and then with receiver's public key, and decrypt with receiver's private key and then with sender's public ...
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Is there a way to find the two generator polynomials of a JPL sequence?

I am decoding a binary sequence that was detected as an unpractically long LFSR by the Berlekamp-Massey algorithm. First of all, the generated sequence is far longer than it needs to be and since it ...
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AES (or otherwise): can you decrypt concatenated encrypted messages as one?

Say I have 20 distinct encrypted messages. Using AES, I am only getting the correct output if I decrypt each of the 20 messages individually. Is it possible using AES or another method to call my ...
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Special characters in AES Encryption Key

We all know that AES uses Key, IV and salt. But what if we add special ASCII characters like Alternate 255 (" ") or Alternatively 163 ("£") or Alternate 224 ("α") in the ...
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Can you obtain private key d and compute plaintext from El-Gamal?

Given an Elgamal encryption scheme with public parameters $k_{pub}=(p,\alpha,\beta)$ and an unknown private key $k_{pr}=d$. Due to an erroneous implementation of the random number generator of the ...
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How to break a vigenere cipher with a period of 2, and knowing a part of the plaintext

the encrypt code is "ARJHNRIUCGQHPFGQFHTXPDEHTLNOC", and the part that i ​know of the plaintext is "DERUNA". The key is period of 2, so the key are 2 letters. Each letter of the ...
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How can I force slow decryption in the browser?

I have a string that I will encrypt on the server. I then want to send the encrypted string along with a decryption method for it to be decrypted in the browser. I want the decryption to take some ...
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Is there a possibility to apply Moni Naor and Adi Shamir's “visual cryptography” on text ( paragraph)?

[Instead of two images I want to consider two paragraphs(text) when combined should give me a secret message] In their algorithm, the image has been split into two component images. Each component ...
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How would I go about breaking Playfair cipher with the alphabet and the encrypted message? [closed]

I was wondering how I could crack a Playfair cipher with only the alphabet and the ciphered message. Ive tried looking for tools online, but still no luck.
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Add setup to GPG symmetric

I use GPG symmetric, to encrypt text file. Is it possible to use GPG symmetric, to encrypt a text file, and at the same time, add additional setting to the encrypted file, to give us 2 conditions: ...
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Using same key pairs in several different encryption tools and version

can we use the same key pairs created by an encryption tool, for encryption decryption, in another encryption tool ? for ex, created by hypercrypt, but being used in cryptermite, or maybe within the ...
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Decrypt the same ciphertext to multiple messages of my choice if I can use any key I want to decrypt

In a modern secure encryption scheme, is it possible(both theoretically and practically) to encrypt a message using a key to get the following ciphertext c = Enc(M1,k1) and later find another key so ...
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1answer
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How to encode and decode message into polynomial form on NTRU

This question is based on a previously asked question. How to make a message into a polynomial on NTRU encryption? I am tasked to implement NTRU with toy parameters such as $N=7$ or $N=11$ and I have ...
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How to solve this decryption algorithm given the encryption algorithm?

Consider the following cryptosystem with plaintexts from the set $M$ and ciphertexts from the set $S$ with $M = S = \{0, 1\}^4$ . A plaintext $P = (P_1, P_2, P_3, P_4)$ is encrypted to a ciphertext $C ...
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Can I map 2 plaintext letters to 1 ciphertext letter?

Plaintext: "abcd" where P1,P2,P3,P4 map to each corresponding letter. And C is the ciphertext where C1,C2,C3,C4 map to each corresponding letter. Keys = (x,y,z) Can I use the following ...
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64 views

Evaluate the time of Paillier decryption

If I have 4 kilobytes of Paillier encrypted data, how can I know the time needed to decrypt it?
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How is the second digram a legal mapping? (Playfair Cipher)

So this is a partly completed key I have: _ R _ _ _ _ T _ _ _ _ _ H _ _ _ _ L _ _ _ P _ _ W And this is my plaintext/ciphertext: ...
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Decryption formula of Plaintext Block Chaining (PBC) mode of a block cipher

Considering that $C_n = E_k(M_n) \oplus M_{n-1}$ formula is used in encryption side of this mode of block cipher, and knowing that instead of M0 a randomly chosen initialization vector (IV) is used in ...
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Verify correct answer transparently

The following problem needs to be solved: Person A will be guessing the number that Person B has in mind. Only Person B can confirm that the answer provided by Person A is correct. Person A can not ...
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1answer
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plaintext decrypted form a cipher text using key = 3 in Caesar Cipher and that plain text with the following ciphertext to get the key [closed]

how to use the plaintext from that was decrypted form a cipher text using key = 3 in Caesar Cipher and using that plain text with the following ciphertext to get the key.
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How to sign messages using the NOISE Protocol Framework?

I wanted to learn more about secure messaging and started a personal project using the libhydrogen library. From my understanding, instead of using public-key ...
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83 views

Encryption algorithms that require more work to decrypt versus encrypt?

Are there any encryption algorithms that require significantly more work to decrypt, versus the amount of work required to encrypt? I'm looking for a method of fast encryption, but which will require ...
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Looking for encryption function given decryption function (2048-bit ciphertext and key, addition and subtraction operations)

I have a decryption algorithm for 256-byte (2048-bit) blocks and want to find the matching encryption algorithm. What I know about the algorithm and have: 256-byte ciphertext (I have multiple ...
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1answer
53 views

Suitable hybrid encryption approach?

I need help for my bachelor thesis. I have a general question regarding hybrid encryption in different ransomware. The hybrid encryption often uses symmetric and asymmetric encryption techniques. ...
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CP-ABE (partially hidden access structure)

Anyone aware of the implementation of paper "Lai, Junzuo, Robert H. Deng, and Yingjiu Li. 'Expressive CP-ABE with partially hidden access structures.' 2012" specially in python or Charm ...
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568 views

Advantages and possible usages of encryption schemes with probabilistic decryption

We can define deterministic and probabilistic encryption; Deterministic $c = E(k,m)$, and Examples are textbook RSA, block ciphers in ECB mode. Deterministic encryption fails to achieve CPA security....
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Black box solver [closed]

I want to know if there is any mathematical or brute force approach to decipher simple black box A: Is only one digit (0...9) B: Is 2 digits (00..99) C: Is a result of a linear function between A &...
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Can I use a Friedman test when decrypting a playfair cipher

I have a playfair cipher I’d like to decrypt however I need to find the key word first. Is it possible to use the Friedman test here to find the length of the key word? My cipher has no J’s in it ...
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Can I alter encrypted data without decrypting it? [duplicate]

I didn't find a direct solution for it. Can I modify encrypted data without accessing it? If there is an example, I would appreciate it.
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How to correctly implement an archetypal encrypt-then-MAC AES-CTR + HMAC mode cipher?

I've created an AES implementation in Python as a learning experience (mainly for encrypting/decrypting files), and wanted to make sure that I haven't made any huge mistakes in my logic (of course, ...