Cryptography Stack Exchange
Cryptography Stack Exchange

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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How are side-channel attacks executed? What does an attacker need to execute a side channel attack?

I've been reading about side-channel attacks on Wikipedia, and it seems that some of these can only be executed on the victim's computer. (I am specifically asking about the side-channel attacks listed on the Wikipedia page and any more that are…
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How long does it take to crack RSA 1024 with a PC?

Using an Intel Core i5 CPU, how long does it take to crack RSA using a key size of 1024 bit (generated using a secure key pair generation function)? Suppose for instance that we have thousands of zombies or a big network of computers. To calculate…
R1w
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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 story: There are two parties involved that are…
Nicola
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Why does the Bombe not consider the Ringstellung when determining stecker pairs?

I am doing research on the Bombe Machine, and I read that when the Bombe tries to find the stecker (plugboard) partners of letters, it only needs to use the rotor types and arrangement and also the "rotor core offset," which is just a combination of…
Queso Pez
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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 very minor role in what I'm writing, there's very…
Nicola
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Would creating a custom human language be stronger protection than encrypting a known human language?

There are some languages that people haven't been able to read (Cretan Hieroglyphics for example). Does that mean that you can better protect data by making your own language than by encrypting an existing one? Or are all human languages really just…
Mike
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Decryption using randomness

There exist public-key encryption (PKE) schemes where any well-formed ciphertext can be decrypted if the random coins used during encryption are known. For instance, in ElGamal encryption, the public key is $pk = (G, q, g, h = g^x)$ and the secret…
Mahesh S R
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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 $P:\mathbb{F}^n\rightarrow \mathbb{F}^m$ has $n\geq m$ whereas for encryption $m\geq…
Shweta Aggrawal
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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 time for the end user. Let's say ~10 minutes. Let me…
user89318
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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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Encryption and decryption with Diffie-Hellman

I don't understand how it works. I only found explanations about the key exchange, but what about the actual encryption and decryption? Do you use the session key $K$ with a symmetric algorithm? Do you use something similar to RSA like $m^d \bmod…
OstrichDog
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Where does signing/decrypting take place on a YubiKey 5 for PGP private key?

I have found similar question for PIV (and not PGP) I assume PIV and OpenPGP would work in similar ways. I also assumes that the GPG private key never leaves the Yubikey. If these assumptions are correct then: at encryption: a symmetric key is…
AlexVal
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Does file size significantly affect brute-force time?

Suppose you have two files encrypted with AES-256. One of the two files is 5MB, the other one is over 1GB. Their passwords are reasonably strong: >12 characters, letters, numbers, upper and lower case characters. If you tried to brute-force them,…
Nicola
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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 "Hello") into an int. I see python codes like this: from Crypto.Util.number import…
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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 $c = Enc(M_1,k_1)$ and later find another key so that a different message of my choice gets…
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