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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plaintext decrypted form a cipher text using key = 3 in Caesar Cipher and that plain text with the following ciphertext to get the key

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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MD5 hash is crashing my computer [migrated]

Hi I have an assignment to get this hash value 2d3114bcc2e5c58bbac77f04237723d9. the hash value is 4 digits. and I am using this code over here for 5-6 minutes of ...
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How to bruteforce 4 digit pin with openssl and open file in plaintext [closed]

I'm trying to decrypt a file with a 4 digit password (numbers 0000->9999) I want to keep looping until the terminal does not return "bad decrypt". My current code is giving my multiple &...
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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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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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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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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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How to decrypt a file to memory and run it from memory using c, c++, or python? [migrated]

I have experience with the basics of encryption and decryption and handling files stored on the filesystem using c, c++, and python. But one curiosity I've recently encountered is how someone might ...
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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?

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, ...
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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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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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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 can we decrypt all RSA messages given a function that can efficiently decrypt a small percentage of all possible ciphertexts? [duplicate]

I saw this question in a paper and was not able to solve it. Assume that we are given an efficient algorithm called RSA_break() that can decrypt, without the ...
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Decrypting iPhone Backup

Are key bag keys rotated between backups? Or if I have keys from an old backup, am I able to use then with a later backup? Short of it, have a friend w/ an incomplete backup and attempting to leverage ...
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Does decryption with a wrong key creates a new encryption?

I'm wondering if decrypting with a wrong key is the same a encrypting in a different way. For example if I encrypt the message "hello" with Caesar cipher with key = 3 it will give the ...
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1answer
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Need to identify cryptographic algorithm [closed]

I have a binary code which decrypts some 64-byte data chunks. There is a decryption key which is always static, and there is a code which does actual decryption. What I need is to find out which ...
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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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What cipher requires the full message to solve

I am working on a scavenger hunt and wanted to encode a clue in a cipher that requires the full message to decipher. My goal in this is to prevent players from predicting the result before obtaining ...
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Decrypting LFSR, knowing the beginning of the cyphertext, and nothing else

I have a cipher-text in binary, I know the beginning of the plain-text. I know that it is encrypted using LFSR, and I know nothing else. How can I attack, and decrypt it? What I have tried; I ...
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How can RSA be used to compactly sign and encrypt?

How can RSA be used for digital signature with message recovery and encryption, providing transmission of a small message with confidentiality and authentication simultaneously, small cryptogram size, ...
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Many-time pad decryption [duplicate]

I have given seven cipher text encryted by the many-time pad. All are encrypted uwith the same random chosen secret key but I have no idea how to decrypt them. There are 7 ciphertexts: ...
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Tonelli-Shank vales are incorrect when trying to get back to c value for Rabin [duplicate]

I'm working (banging head against wall) on a Rabin encryption as part of a challenge. I thought I was making progress as several algorithms had given em the same values for the mod sqrt but it seems ...
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How to decrypt Rabin message when p=q and you have the roots from Tonelli-Shanks

I've been trying to decrypt a message encrypted with Rabin as a challenge. I'm very new to cryptography and these challenges so much of this is new. I've factorised n and determined that p=q which I ...
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ElGamal Decryption variant

I am trying to do some ElGamal encryption but having a different encryption formula. For that I doing the following steps: The key generator: Choosing value $p = 107$ and $a = 2$ Random number $d = ...
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How to alter text that was encrypted with AES CBC using PKCSPadding7

Assuming, I had a ciphertext along with its decrypted plain text result but not the IV or the Secret Key. (keep in mind that the text was encrypted with AES/CBC/PKCSPadding7). How would I go about ...
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Cracking Viginere Ciphers using same-length key used twice

Assuming I had two ciphertexts which were encrypted using the same key that has the same length with the ciphertexts. (However the keys didn't have any repetitions or features that would assist in ...
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How Do I Decipher This Ciphertext? [closed]

Ciphertext:1rUHjDnJs09VNvxLiWZzL7PXeKUHvxFVG5GT59WdS6nvOZ1UypVbKlQTcl4orHFShQMBCFGH8+4+SlFDDv4+dUIcmd3zyaBnsXKCb9lMuGmMJkslgPFvgPKNWGsSVu4BhI6/42dGG3q0Lca465xeDaEKTj3Yan/59/+...
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Can I derive IV, if I know Encrypted Txt, Key and Encryption Method?

I want to know is there any way to derive the initialization vector, if I know all the other details. AES SHA 256bits CBC pkcs5padding Input: Hello Key: 123 Output: xORGCDL88sa8cUrK8JNSCQ== Now, how ...
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Advice on software to be used

I have the following problem: I have a series of numbers (6, 9, 6, 2, 6, 3, 4, 7, 3, 5, 4, 3, 2, 5, 8, 6, 2, 6, 3, 4, 5, 8, 7, 8, 2, 7, 7, 4, 8, 3, 3, 2, 8, 8, 4, 3, 2, 4, 7, 7, 6, etc.), each number ...
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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 to perform a known plaintext attack?

I have got the following documents: (1) The plaintext (2) The ciphertext (3) The python program used to encrypt/decrypt the text My goal is to find the key that was used to encrypt the plaintext into ...
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Decryption : How to secure the Key in offline mode [closed]

I am new to cryptography. I have a package to be shared with Bob which is something like below: Package contains: data.zip and Application where, data.zip is ...
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Can I use ECC for encryption/decryption, just like RSA?

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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Can I and How Decrypt this Online

Although I had a security course in school a long time ago, I am effectively new to cryptography. I have an encrypted text, the encryption key of 44 characters, the encryption method, (Fernet, which ...
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regarding usage of hashing

I have a question regarding pitfalls of using only encryption. Suppose Bob and Alice want to flip a coin over a network. Alice proposes the following protocol. Alice randomly selects a value X ∈ {0,1}...
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Matrix cipher - symmetric or asymmetric cryptosystem?

Matrix cipher is defined by: a) Encryption: $C = K \times Z$, where $C$ is a cryptogram vector, $Z$ is a message vector and $K$ is encryption matrix (encryption key) b) Decryption: $Z = K^{-1} \times ...
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How to calculate time needed for decryption of 64-bit key

I am having trouble figuring out how long it takes to decrypt a 64-bit key, given that a computer can do 1 billion trials per second. I know that there are $2^{64} = 1.844 \times 10^{19}$ possible ...
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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 to encrypt a string and decrypt a string but public can never figure out how to encrypt/decrypt a string

On my website I display an image. To generate this image, it require a string parameters. For example the string 1234,2423,1231 as the parameter. Anyone can use my ...
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Identify the value of the plaintext from a noised expression

Having the following instructions: Using Paillier encryption to encrypt $m$. So, we get $Enc(m)$ Multiply $Enc(m)$ and $A$ to Get $C$. So, $C = Enc(m).A $ Decrypt $C$ using Paillier Decryption ...
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Forgery attack on Poly1305 when the key and nonce reused

Introduction: I've tried to find how reusing one-time key compromises itself but only found information that it breaks the encryption entirely, it is written everywhere. But since no methods to reuse ...
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Will Fernet’s key function at any timeframe?

I’m very new to cryptography and I need to use a symmetric cryptography approach. My simple question is, will the key always at any time be able to decrypt the encrypted text? The encrypted text may ...
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Cryptography elements needed for a story

Note: following Maarten Bodewes's answer, I edited this post to make it clearer. I'm writing something partly driven by the need to crack a few encrypted files. This is what needs to happen in 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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How the message is decrypted in an RSA chosen ciphertext attack when it's a modulo?

During the last stage of decryption of a chosen ciphertext attack we are left off with this equation $$c = m \cdot t \pmod n$$ Removing all exponents like $d$ and $e$ where $c$ is the decrypted ...