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Questions tagged [encryption]

Encryption is the process of transforming plaintext using a cipher into ciphertext to make it unreadable to anyone except those possessing the key. Decryption is the process of transforming that ciphertext back into plaintext, using the key.

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14 views

RSA given p,q,n,c1,c2,e1,e2

I am given the p,q,n,c1,c2,e1,e2 values for an RSA key, along with an encrypted message. Here are those values: ...
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AES-MixColumn layer in the last round

In the "Introduction to Cryptography: With Coding Theory" by Trappe and Washington, in the chapter about AES algorithm the authors say that in the last round of the encryption algorithm the MixColumn ...
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Encryption data [migrated]

I have encrypted data. the MBR partition shows but I can't decrypt the data. What's the likelihood that the USB NAND flash experienced bit rot in the sector that stores the hash but still kept the MBR ...
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For CBC, if the initialization vector is corrupted, can we still decrypt the message?

Actually, I think IV (initialization vector) is random number which is same size as the other block of plaintext. But if the IV is corrupted, message cannot be decrypted because original IV used to ...
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Is 2FA secure, and can it ever be broken? [migrated]

Having weak passwords are so easily cracked by hackers and quantum computers that people introduced an extra layer of security, called Two Factor Authentication. How it works is it sends a message to ...
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49 views

Would adding more rounds to AES increase security?

As the title states, would increasing the rounds by doubling them to Bruce Schneiers recommendation of 16, 20, and 28 increase security? And how much? As a bit more, would increasing rounds, keys, ...
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29 views

Performance of Counter mode (CTR) with Ciphertext Errors

In the "Introduction to Cryptography: With Coding Theory" by Trappe and Washington, in the chapter about Counter mode (CTR) the authors say that: "As a result, its performance is identical to OFB's ...
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OFB mode vs LFSR

In the "Introduction to Cryptography: With Coding Theory" by Trappe and Washington, in the chapter about OFB (Output Feedback) mode the authors say that: The OFB mode produces a bit stream and it ...
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1answer
24 views

XORing a nonce with a ciphertext vs XORing a nonce with plain text and then encrypt

Consider a situation where a symmetric key encryption (such as AES) is used to encrypt the plain text. Moreover, a nonce is used to ensure that old communication cannot be used to perform a replay ...
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51 views

Do these crypto approaches have the same disadvantages of one time pads? [on hold]

Newhope: Specifically, the message from Bob to Alice (the ciphertext) in NewHope-Simple requires only 2176 bytes (compared to 2048 bytes in NewHope); the message from Alice to Bob (the public key) ...
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31 views

Are the quantum resistant Bitcoin solutions just one time pads? [on hold]

I am talking about integer lattices etc. They all seem otp or some batch of otps. Eventually, you would exhaust the encryption (after very long messages) and it would require a new key. Does this ...
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37 views

How can AES-CCM behave as an AEAD stream cipher?

AESCCM- Couter with Cipher Block Chaining Message. As it uses cmac for generation for tag , which is internally aes-cbc (block cipher, need block size, may require padding) And Encryption is done ...
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Meaning of direction in EPS

In EEA and EIA, what exactly does the direction (uplink/downlink) indicate? It's confusing because for both encryption and direction, the direction has to be same.
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35 views

What if the hash code of the genesis block (first block in the block chain) is changed?

If so, what would happen? And if not, what are some limitations to it? The reason I am asking is because I just started getting into the cryptocurrency and am very interested in the cybersecurity ...
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How to generate V3 Onion domains using web javascript? [migrated]

I am trying to create a web based vanity .onion domain generator. I already have the V2 onion working, but this V3 onion is causing me some real trouble. In my HTML I have... ...
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1answer
33 views

Using same key and nonce for different field of the same document

I have some fields, similar to NAME, SURNAME, EMAIL, ADDRESS... I'm using NaCl for symmetric encryption. Is bad If I Encrypt every field with the same key and nonce? They are encrypted and stored ...
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3answers
145 views

How much would this AES modification improve security?

How much would using AES-CTR like 3DES improve security? Like so (Using a 512-bit key split into two; $K_1$ & $K_2$, and seperate nonces for all stages): ...
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27 views

Combine signature with encryption

I have some embedded device for which I want to sign and encrypt firmware files. Firmware updates are generated by me and may be installed by the customer. The encryption is supposed to protect the ...
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1answer
56 views

Which AES modes can decrypt from anywhere in the ciphertext

CTR is amenable to parallelization because you can split the message into chunks, each chunk having a range of counter values associated with it, and encrypt (or ...
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30 views

Initialization Vector in CBC/DES encryption [closed]

How can i prove that the Initialization Vector is always set to zero in the Cryptool when using CBC or ECB/DES mode?
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1answer
48 views

Encypt a file with AES using a secret key derived with Argon2

I would like to encrypt some sensitive files on my computer and smartphone so that they remain unreadable even if the computer is stolen. So far as I'm concerned, AES is the best encryption algorithm,...
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1answer
41 views

What value for a Rfc2898 (PKBDF2) is overkill?

I am working on a project which needs to share messages, and part of that project is deriving a password, I am currently using a value of 65537, totally arbitrary (...
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21 views

AES Encryption Mixcolumn code Verilog [closed]

I am working on implementing AES encryption on Verilog. I have forked a repo for the project but can't understand a piece of the code. Would love if someone can explain a is the data input to ...
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can someone help to modify/extend AES or Blowfish algorithm for me? [closed]

I want to carry out a modification or extension on AES or Blowfish to reduce the memory use and encryption/decryption time but I don't know how to go about it at all. please help
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Why use complex encryption algorithms? [duplicate]

I have recently gotten interested in cryptography, so I looked some things up. I thought, why even use AES or DES or any other complex way for encrypting data when there are far simpler ways, like ...
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Are the type of integer lattices and other approaches intended to make Bitcoin quantum resistant just one time pads? [closed]

https://en.m.wikipedia.org/wiki/Post-quantum_cryptography They are just proposing using a lattice to scramble a message and then the recipient using a public version of the lattice to unscramble. Isn'...
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70 views

Block cipher mode of operator with counter as part of its key or message [closed]

Consider a block cipher (such as AES256) as $E$, a randomly selected key $k$, a counter $i$, and an array of n-bits $M$ as the message. Also consider the following block cipher modes of operations: $...
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63 views

Is there a cryptosystem which allows slicing and concatenating strings without decryption?

I want a cryptosystem with the following four functions: ...
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54 views

Observing cipher suites and certificate algorithms without man-in-the-middle

I manage a proxy server. Is it technically possible to observe and determine which cipher suite is selected between end points (client and server) without changing their SSL certificate, without ...
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52 views

What are the actual merits of Galois/Counter Mode?

GCM (Galois/Counter Mode), in particular in combination with AES, has been a de-facto gold standard for years. Encrypt and authenticate in one step, that's just too awesome, and terms like AEAD work ...
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Can reducing NP problems to subset NP Problems leed to faster calculation of NP problems [migrated]

Integers can be represented with a pair of smaller numbers. To achieve this I use 2 integer sequences. Integer Sequence 1 1,1,2,1,2,3,1,2,3,4... And Integer Sequence 2 1,2,1,3,2,1,4,3,2,1... This ...
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How to use SHA-512 in terminal? [migrated]

I do not understand this problem. I tried my code down below. It says,"can only sign or verify one file." Instructions: Using the hash function SHA‐512 and the key ...
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49 views

Algorithm/encryption technique which outputs a set number of numerical digits e.g. 20 digits from a given input

What the name of the algorithm/encryption technique which outputs a set number of numerical digits e.g. 20 digits based on some input. You can input some data e.g. text or numbers but the output is ...
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45 views

Password to password mapping

DISCLAIMER: I understand the question might be a bit amateurish due to my limited knowledge of cryptography but, please, bear with me for a minute. QUESTION: Suppose a user Alice generates a pass ...
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33 views

Perfect secrecy for a subset of a message space [closed]

I am a beginner in Cryptography and I am studying on Katz's textbook. I still cannot prove most of the questions that is why I need some help. For example this question; Prove that if an ...
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168 views

How can frequency analysis be applied to modern ciphers?

I am building a computer program that deciphers Caesar, Vigenere and monoalphabetic substitution ciphers. All of those are susceptible to frequency analysis. However, it does not seem to be real-world ...
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What if an AES Whitebox 1024-bit (or larger key) is created? Does it increase complexity consistently?

Following the Chow et al paper and Muir's tutorial, I was able to implement the AES algorithm using tables embedding keys of 128, 192 and 256-bit sizes, later extended to 1024, 2048 and 4096-bit sizes....
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61 views

What is the most secure encryption algorithm that keeps the entropy the same or even lowers it?

On top of my mind comes caesar cipher, but that is not really secure so what is the most secure encryption algorithm that doesn't affect entropy or even lowers it? I know this might not be as ...
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91 views

How to prove one hash function can produce a length-fixed output? Is it related to modulus(n)? [closed]

Consider the following hash function based on RSA. The key < n, e > is known to the public. A message M is represented by blocks of predefined fixed size $M_1, M_2, M_3, ..., M_m$ such that $M_i &...
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31 views

S-DES Binary converted to ASCII?

I have been working with the following SDES Encryption templates and got the following as my ciphertext. I believe the ciphertext is correct because when I decrypted it I got my original plaintext. ...
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8 views

Openssl DSA Signature Verification Failure Error not understood [migrated]

I am given a public key in PEM format: ...
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49 views

What is the strength of this machine? [closed]

This machine has the stator, with one half of the alphabet, and three rotors with replications of the other half in different order and repeated twice. There can have two rotors in use or the full ...
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1answer
79 views

OpenSSL: How to maintain padding from encryption after decryption?

One of my professors mentioned in class that there is a way of using PKCS#7 padding to have the padding persistent after decryption. For example, if I encrypt a 20-byte file using ...
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Generating a list of all self-signed certs? [migrated]

I am trying to generate a list of all self-signed certificates in an environment using Powershell. I need this section of my script to be directed toward multiple machines(IP addresses), but am ...
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5 views

Get X.509 Certificate ECDH private and public key on Android (Java/Kotlin) [migrated]

I'm currently trying to implement a ECDH algorithm in my android app. But I'm facing an issue, I would like to store the private and public key in Android KeyStore. However in order to achieve this I ...
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1answer
90 views

“hex” vs. “base64” encoding when enciphering

Examining different implementations of encryption / decryption with cipher on Node.js, I paid attention that some implementations use hex encoding: ...
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Does adding more letters provide added security compared to a standard substitution cipher?

Let's say that a substitution cipher had 52 symbols instead of 26. For this, we would include all lower case and upper case letters. This creates a key space of 52! wehere the cipher text can contain ...
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39 views

Original Byte Recovery from Padding-Oracle Attack [closed]

The last two bytes of a seven-byte message were changed to 05 and 02. I'm thinking this signifies the padding bytes, which in this case are "02 02". Where I'm struggling to get an answer is that I ...
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671 views

Does AES-ECB with random padding added to each block satisfy IND-CPA?

I present a modified version of AES-ECB. Suppose I want to encrypt the string hello, world. this is a test. For each block, I use the first eight bytes as my actual ...
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1answer
58 views

Understanding Encryption length calculation and rounds

I am trying to learn about password encryption by creating a simple password hashing algorithm, although many online articles did warn "Do not create your own algorithm". I discovered that most of ...