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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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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What is the meaning of [(CZI) <subscript 26>]? How do I use this to decode a message? [closed]

"qfmpr qrmpw" is the message. (CZI) 26 {26 in subscript} is written below it. Please help.
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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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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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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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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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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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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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RSA algorithm implementation

$$m^{ed} \equiv m \bmod n$$ $n =pq$, so by Chinese Remainder Theorem it is equivalent to $$m^{ed} \equiv m \bmod 𝑝, m^{ed} \equiv m \bmod q$$ where $n=p\cdot q$ So how did 2 come from 1 by the ...
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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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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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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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Encryption and decryption of Request and response for REST API

I am working on encryption/decryption for the rest of the API. The client here can be mobile, desktop, web browsers, etc and all the requests will be made to an https endpoint. The main goal here is ...
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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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Good layperson analogy for password and encryption keys

NOTE: QUESTION UPDATED. SEE BOTTOM OF THIS POST. I'm writing something where I need to make someone come across as though they know cryptography. I don't know enough, but as cryptography plays only a ...
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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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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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359 views

Can I use ECC for encryption/decryption, just like RSA? [duplicate]

I'm familiar with RSA for asymmetric encryption. I also understand it's only supposed to encrypt small amounts of data (smaller than the key) so for encrypting arbitrary data I would typically ...
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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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Conditional decryption

Is it possible for one party to encrypt some data and have another party (unknown to the first party) view that original data if a certain condition is met? I cannot find any information about this ...
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How is asymmetric cryptography safe if one of the keys is public?

Let's suppose $A$ is sending a message $m$ to $B$ using asymmetric cryptography. To guarantee the authenticity of a message, $A$ encrypts $m$ with $A$'s private key: $E(m, k_A) = m_A$. Then, $A$ ...
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Need help cracking a Vigenère cypher with a period of 2

How do you crack a long Vigenère cypher when the key is unknown? I have tried frequency analysis, but I'm not making any progress.
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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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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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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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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, ...
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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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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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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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Why “encipher” instead of “encrypt” and “decipher” instead of “decrypt”?

According to a book I am reading, Applied Cryptography by Bruce Schneier, the ISO 7498-2 standard uses the terms “encipher” instead of "encrypt" and “decipher” instead of "decrypt" ...
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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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Zodiac unsolved 340 cipher decryption in 2020

This is a rather general question, but I'd really appreciate your (experts, in my view) opinion on this subject. I was wondering if, using current tech like machine learning, quantum computers and ...
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Are there any tools to analyze cryptographic algorithms performance?

How can I analyze a cryptographic algorithm performance to make a table and charts comparing them. I have seen several papers but there's no paper explaining how it is exactly done. As comparing data ...
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How do I invert the final round S Boxes during linear cryptanalysis

I'm using Howard Hey's tutorial on linear cryptanalysis, however I don't understand the final stages. I understand using exhaustive partial subkeys to turn the ciphertext into the final round output, ...
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How to decipher an ADFGVX cipher?

I got introduced to the ADFGVX cipher, and it seems very tedious to decipher such ciphertexts. If I do not have access to the key square and the keyword, and I am just given the ciphertext and a ...