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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What's the best way to recover an AES-256 key from partial key, ciphertext, plaintext and IV?

So I'm trying to decrypt AES encryption with a 32-byte key. I know the first 7 bytes, and the final 19. I also have the plain text, as well as the IV and the encrypted text. I'm currently running ...
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How to reverse a CRC-16 from the the entire data? [duplicate]

I am trying to reverse the BLE communications with the Daly BMS (Battery Management System) in order to implement it on my own app. I already reversed almost all reads and therefore started to deal ...
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How can I reverse a so-called CRC16 from the data?

I am trying to understand a request I reverse engineered which is sent to a Daly BMS over BLE. Those requests change the 'sleep after' in seconds of the BMS: For DDDD seconds: ...
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Is there a discrete log challenge?

RSA challenge is well-known and it has a wiki page. Is there a discrete log for $\mathbb F_p$ where $p$ is Sophie-Germain prime?
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Discrete Logarithm Based algorithm

The private (secret) key in DL (discrete logarithm) based algorithms is uniformly selected from the group Zq*. This private key is then used to compute the public key. Could the opposite be done, for ...
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Can I decrypt AES-CBC ciphertext if I have the key without IV? [duplicate]

Can I decrypt ciphertext from AES-CBC encryption, if I have the key and ciphertext only?
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What's the probability of cracking this cipher using partial information about the private key obtained from $k$ public keys?

For the following cipher, what is the probability of someone without the private key generating a valid public key, using only information from a list of $k$ public keys previously generated with the ...
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Would this hash based encryption algorithm work in theory?

I was just thinking about this and couldn't seem to find anything on it online. So the idea I had was this: Generating a random key of some length. Then hashing this key with SHA256 (or something of ...
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RSA / AES issue : Decryption

I perform the following commands because I need to decrypt a file -encryption key file- (which is longer than module): cat key.enc | base64 -d > encryptedrawfile.txt openssl rsautl -decrypt -inkey ...
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Does encryption of many files shorten the list of possible passwords?

Hopefully this question is not duplicative, nor its answer too elementary. Suppose I have a file. I encrypt it, using a password. The password presumably stipulates a pattern or relationship between ...
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How to share decryption ability to others whose public keys are not used during encryption?

as the title says, for example, A uses B's public key to encrypt a message and sent it to B. In later stages, a new member C joins and B would like to let C be able to see this encrypted message (i.e.,...
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Let negl1 and negl2 be negligible functions [closed]

can we still consider the second function negligible ? is there any main differences between them?
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OFB mode discussion

In OFB mode, I understand that a bit flip in $c_i$ for $i > 0$ only causes a bit flip in message block $m_i$. However, how is it possible for a bit flip in $c_0$ (i.e, in IV) will result in all the ...
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limiting number of queries to Enc. or Dec

Why do we limit the number of queries to Encryption or Decryption oracles in the security analysis of various encryption schemes to be polynomial in the security parameter n?
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calculate a tag of CBC-MAC

with a block cipher having a 256-bit key and 128-bit block length to MAC a 1024-bit message. How many evaluations of the block cipher will be performed to calculate the tag? [Assume there is no ...
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Pseudonymization hashing using public key

I have logs containing sensitive data (mail addresses, usernames etc.) that need not only be made GDPR compliant, but in general be secured as best as possible, so anonymization/hashing would be an ...
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RSA: decrypting short message with a different public key

I am having a hard time understanding what I have come across using RSA-textbook. So I have: e = 3 as an exponent a VERY long public key N of 1991 bits (clearly useless trying to factor) a very short ...
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Plaintext message equals the encrypted message

P=11 Q=29 Euler=280 e=3 d=187 When i take a message “88” for example; Encrypt: 88^3(mod 319) = 88 Decrypt: 88^187(mod 319) = 88 Why does the encrypted message equals the decrypted message and why does ...
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Is it possible to calculate the plaintext length of an RC5-32 encrypted ciphertext?

Calculating the RC5 encrypted size of any data is as simple as rounding up the plaintext length to the nearest multiple of 8. What I'm wondering is whether this can be done in the other direction, to ...
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5 votes
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In multivariate public key cryptography, why can not we use the same public key for both signature and encryption?

In multivariate public key cryptography, why can not we use the same public key for both signature and encryption? I read that for signatures the public polynomial $P:\mathbb{F}^n\rightarrow \mathbb{F}...
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How to decode "SELF-SHIFT" cipher?

I try to use the function $$C_i=E(M_{2i}, M_{2i+1}) = (M_{2i} + M_{2i+1})\bmod 26.$$ to encode English text. For example, Plaintext: The quick brown fox jumps over the lazy dog. Regrouped Text: TH EQ ...
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How can I decode a XOR cipher with a string key I know?

I have a text that has been XORed with the key "77U" (I am sure of this as it is a file created by a code I have, so I have seen every entry getting XORed by 77U. However, none of the online ...
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Is multiple encryption using a block cipher mode of operation that use only encryption processes vulnerable to Meet-in-the-middle attacks?

Some block cipher modes of operation use only encryption processes, such as CFB, OFB and CTR. If doing multiple encryptions using them, will these encipherment schemes be vulnerable to Meet-in-the-...
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Is possible to break the encryption on a password by this encryption? [closed]

I wonder if it is possible to break the encryption on a password by such encryption: Where E is the encryption function that uses a known public key of the server.
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Decrypting a polyalphabetic cipher

I'm currently trying to crack a ciphertext with three rotating substitution ciphers. I've tried dividing the cipher up into three parts and do text frequency analysis since I know the language but no ...
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AES Key vs RSA Key

I am compeletely new to cryptography and recently tried to understand it a bit more thoroughly. My question is: How does the Generation of keys differ in the case of AES and RSA. I understood, that ...
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Use of custom DH parameters for TLS decryption

There are several ways to decrypt TLS e.g. in an enterprise environment. I did not see using "backdoored" DH parameters being mentioned somewhere though according to my understanding it ...
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Comparing different cipher text all saying the same thing

How can I compare different cipher text? When deciphered, say the same thing. I would like to find out the ciphering method. Any help would be appreciated. Thanks. The primary code needs to be a 8 ...
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Are there any schemes for support time-limited decryption that are not based on P2P or TTP models?

Time-lock encryption is a method to encrypt a message such that it can only be decrypted after a certain deadline has passed. This sounds like time-lock decryption. I was wondering if the inverse with ...
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RSA: is it possible for the cube root attack to fail even if e=3?

I've came across an example where the e value is three but no matter what tool/script I try, I can't decrypt it. I'm wondering if the ciphertext and n is super super large, is it possible to crack it ...
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3 votes
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RSA: The algorithm aside, how are we turning a string into an int and vice versa?

Let's say that I want to encrypt the file plain.txt. The very first step is actually to turn the contents of that file (lets say it only contains the string "...
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How to Prove Correct Decryption in ElGamal Cryptosystem

I am working on a project that uses ElGamal cryptography using multiplicative notation. The project is an internet voting implementation that uses the cryptosystem to encrypt the received ballots, re-...
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Decrypt AES-128-CBC encypted partial RSA Key

I am given a private RSA key, which header indicates that it is AES-128-CBC encypted. Note that the last ten lines of the key are missing. (This is part of an educational task.) ...
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Is there any fundamental difference between the block cipher operations encryption and decryption?

Is there any fundamental reason to designate one direction of a block cipher as "encryption" and the other "decryption"? Or are these arbitrary choices? Or perhaps practical ...
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Pretty much confused about pretty good privacy-:

Authentication-: I understand that authentication is basically digital signature. But what I don't understand is how it has been explained here specially the RSA key part. It is leading me to huge ...
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Don't know how to approach this problem, or where to start. Finding an adversary to a hiding and binding game

I have this problem: I also have the python version of this problem here: ...
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2 answers
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How to decrypt a file using RSA and just a public.pem file?

I have an encoded file and a public.pem file. Is it possible to decode the file using the public.pem file or do I have to start looking at private keys? I tried https://github.com/Ganapati/RsaCtfTool ...
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Where to store salt for PBKDF2 and initialization vector for AES via WebCrypto

I would like to build secure notes via javascript and webcrypto. I have found the possibilities to generate strong key via PBKDF2 and encrypt data via ...
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Teaching AI a cryptogram and asking it to solve a similar cryptogram on its own

Say that 1 cipher and another are known to hold some form of correlation. Would it be possible to teach an AI one language through the training of a model and allow it to make make predictions on ...
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Example of exchanging information

I am searching for a simle model that can simulate the following procedure. Suppose that $i$ and $j$ are two agents that each one obtains her state dependets signal $s_i(\omega)$ and $s_j(\omega)$. ...
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How does knowing the factors of the key help me decrypt?

I recently started learning about cryptography and its Quantum aspect and I came across Shor's Algorithm (which solves the following problem: "Given an integer N, find its prime factors"). I ...
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Vigenere Decryption with key length

I have a question. If I have 2 ciphertexts given and the same key has been used on both. They key lenght is the same as the plaintext and cipherrtext length. How do I decrypt them and find the key. So ...
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Is it possible to get the SHA256 hash collision with partial known data

I have a text sentence that consists of 448 digits [0-9] [a-f] (in HEX format). This text sentence is partially cut off, but I know the middle, and the beginning ...
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Can you decode aes by hand if you have the key?

I made a javascript aes encryption program and I do have the key to what I encrypted. Is there a way to use that key and figure out what was encrpyted without help of a program? I encrypted "...
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RSA implementation not working with large values for plaintext [duplicate]

While implementing RSA encryption/decryption (using python), the plaintext doesn't match with the decrypted ciphertext for large values of plaintext. Works fine for smaller values for plaintext (...
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What is the best way to save ChaCha20 Nonce in Cipher-Image BMP file?

I have a question about ChaCha20. As far as I know ChaCha20 is a cipher algorithm that uses 4 inputs: Key (secret) Constant (not secret) Block Number/Counter (keystream block number) Nonce (random ...
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Read ECDHE traffic with Wireshark or the like

There is some https traffic from a specific server (which I have the certificate and private key) that I need legitimately be able to read. This traffic doesn’t come via browser so besides the ...
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How do I progress with cracking this monoalphabetic substitution cipher that ignores natural word divisions?

Having some trouble cracking this cipher (this is part of a homework assignment for a cryptology class) I've looked at letter frequencies but I'm not sure what else there is to help me. Given the ...
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Getting the plaintext encrypting the ciphertext

Context: an encryption game from overthewire (the link to it: https://overthewire.org/wargames/krypton/krypton6.html, also good for more info) where given the ciphertext, one must obtain the plaintext....
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Encrypt private key and decrypt with the public key

Is it possible to encrypt with the RSA private key and decrypt with the RSA public key(not for signature) The task is that I have to encrypt the data with a private key. Transfer this data to another ...
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