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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Understanding the PRINCE cipher linear layer

I am struggling to understand how to implement the PRINCE cipher linear layer. (https://eprint.iacr.org/2012/529.pdf) From my understanding I need to multiply the state with M, and with M' in between ...
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Is it possible to make an encrypted text look like a sentence consists of random words?

Without having any knowledge of common encryption methods, I wonder if an encrypted text can look like random valid words as if it is a sentence. Is it possible? If so, what methods should I use?
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How to decrypt a PGP message with only the two primes and the public exponent?

I'm trying to decrypt a PGP Message that is encrypted with an RSA key, but I only have this information: Public exponent: 65537 Prime 1: ...
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prepaid meters that rely on a disconnected system

i have some experience with cryptography in the banking sectors, mostly in block ciphers like DES 3DES etc. im interested in prepaid electricity meters as it is a number that is generated from a ...
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22 views

Is sending encrypted message and signed message a secure way of transmitting data? [duplicate]

I know that the industrial standard is normally sending data in the following format: Send Encr(msg, Sign(msg)) Is the following way a secure as well? ...
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56 views

Enigma algorithm Question about the Ringstellung

This might be a stupid question but I need to implement the Enigma algorithm and I don't fully understand how it works. I've googled the subject and I am confused about what the Ringstellung is and ...
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1answer
64 views

If someone had a list of all primes, would it be possible for them to factor any integer in polynomial time? [duplicate]

For example, if they somehow got a function that would churn out any arbitrary amount of primes in a row. Could they break the RSA problem then?
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74 views

Rabin cryptosystem with 1 mod 4

We have p and q which are distinct primes congruent to 1 mod 4. Then we have n = p*q. Do you know any algorith for calculating square roots for the decryption in this case? I'm asking for some ...
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27 views

Does it make sense to have multiple values of authentication and cipher offsets while encrypting a packet?

Consider a packet with N segments. cofsset(cipher offset - from where one must cipher) lies in arbitrary Segment "A". aoffset (authentication offset - from where one must authenticate) lies in ...
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32 views

Would a pictographic, phoneme-based, hand cipher be difficult to crack with computer crypt-analysis?

What I'm talking about is a hand cipher which uses phonemes instead of individual characters and pictograms instead of the usual shuffling/substitution methods (e.g Caesar, Solitare, Vignere). The ...
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49 views

DSA: Authentication and assurance of authorized parties

When dealing with Asymmetric cryptographic algorithms, usually the sender of the critical data asks the listener for a Public Key for encrypting the data and sending them. This is while the private ...
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common ways / methods to try to break a SP network

I have a very little cryptography background (but a relatively solid maths background) so my below question is very general. Basically I have been given a SP network with an output to reverse. I ...
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Composition of non-perfect encryption keys

Definition 1: A key $k$ is called perfect if it is uniformly distributed from the adversary's point of view; a key $k$ is called $ε$-perfect, if its distribution has an $ε$ trace (statistical) ...
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97 views

Why not send the identity in the encrypted message?

I've recently started reading the book "Applied Cryptography" written by Bruce Schneier. Quite a few times I stumbled across protocols who send the identity outside of the encrypted message (see step ...
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49 views

Requested to encrypt data with AES256, digital certification, timestamped

at my job we have been tasked by gov to encrypt some data we send to them. The "law" says we have to do the title above, but they only need us to do the AES256 thing because the data is not really ...
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53 views

Key length requirement in a simple XOR implementation

I don't have much previous experience at all with cryptography, this is pretty much the first time I've tried anything similar. I'm trying to implement an extremely simple XOR encryption system in ...
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33 views

Transport SA bundled inside a tunnel with encryption applied before authentication?

For IPsec I am considering different formats of ESP encryption and authentication. I am not sure what happens with "Transport SA bundled inside a tunnel with encryption applied before ...
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25 views

Looking for an adjustable compute bound decryption function

I'm looking for a way to decrypt data, but make it require varying amounts of CPU power to do so. Maybe this could be illustrated as e(m) = m' and ...
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127 views

Substitution-permutation network

Can anyone in 6th grade English explain the steps in the Substitution-permutation network algorithm or just point a link that does so? (which is included in many of the top modern algorithms) ...
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64 views

How does double-encryption work with a client server model

With mobile applications like Accompli (now the base for the Android Outlook application), credentials are stored. Reading from the Accompli website: Each user’s credentials are double-encrypted ...
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compression with codebook and Cryptography

a question about the difference between code book based compression method and key based cryptography. As I know Crypto != Compression. The Shannon said Crypto is try to reduce the information of ...
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44 views

Is signing a message just encrypting it with private key? [duplicate]

I have a simple question, When I sign a message (in RSA) does the program encrypt the text with my private key? Because I can decrypt it with my public key. Yes or no. Is signing a message just ...
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1answer
34 views

Cipher for human interpretation [duplicate]

Please suggest algorithms to encrypt and decrypt text messages that can be easily performed by human in a considerably short time. It doesn't have to be really secure, but sufficient to fool ...
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Data anonymization and search with wild-cards

Broadcast encryption technique proposed by Water et al. http://www.slideserve.com/nairi/revocation-systems-with-very-small-private-keys takes a leap from earlier schemes as it provides smaller user ...
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84 views

Is ASCON cipher broken?

http://eprint.iacr.org/2015/030 present several attacks of ASCON but does not have a conclusion section. I'm having troubles estimating what are the consequences on the use of ASCON. What's your ...
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How does multi platform encrypted cloud storage work?

I'm really interested in end-to-end encrypted cloud storage and couldn't find out how following scenario could work: A user of a cloud provider which provides zero-knowledge-authentication (like for ...
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250 views

Public key encryption and big files with NaCL

I am trying to encrypt big files using NaCL (actually PyNaCL) - see http://nacl.cr.yp.to/box.html After reading some docs, I came up with this prototype : Bob wants to send a big file to Sarah. They ...
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111 views

Possible to know who is the owner of a message encrypted with RSA public key

Given the scenario in which I want to send 10 messages either to Stalio or Olio. I encrypt these messages with their respective public keys using textbook RSA, before sending the messages to their ...
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Brute force against computational security

One-time pad is secure under brute force with respect to either of the definitions \begin{align} \Pr[M = m] &= \Pr[M = m | C = c]\\ \Pr[C = c | M = m_0] &= \Pr[C = c | M = m_1] \end{align} ...
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67 views

Oblivious transfer variation question

Now I am doing a variation of the oblivious transfer, I have to use 2 people, pebbles, and boxes. I need to find out if who has a larger number between Alice and Bob (variation of Yao's Millionaires' ...
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How to compare security parameters of different schemes (Sign-Encrypt, Encrypt-Sign, etc)? [duplicate]

How can one compare the security parameters (confidentiality, integrity, non repudiation, etc.) for different schemes (Sign-Encrypt, Encrypt-Sign, Sign-Encrypt-Sign, Encrypt-Sign-Encrypt)? Are there ...
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41 views

how can I change representation of point to Jacobian coordinates in Edward's Curve

I want to simulate this algorithm but I want to change it's output to Jacobian coordinates. what should I do ? In the other way how can we change extended homogeneous coordinates to Jacobian ...
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27 views

Encrypt algorithm [duplicate]

Is it possible to encrypt an algorithm? What I mean by this is have a remote/cloud computer execute a program that will process some data... And the remote computer would not be able to know anything ...
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RSA OAEP: prevention of partial decryption of ciphertexts

I'm trying to understand RSA encryption (as a beginner in cryptography). go on this wiki page http://en.wikipedia.org/wiki/Optimal_asymmetric_encryption_padding scroll down to the 2 numbered points: ...
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Mifare Classic and crypto1 algorithm

Mifare's Crypto1 algorithm uses a 48-bit LFSR. What does the 48-bit LFSR do exactly ?
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How can I calculate the size of an encryption key?

I have encryption algorithm that has two variables are used as encryption key. How can I calculate the size of the encryption key. I will show an example of what the variables can be: ...
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28 views

Do OpenPGP SmartCards have the same or better security than an air-gapped machine?

Are OpenPGP SmartCards, such as the OpenPGP SmartCard V2, suitable enough to have secure communications? Meaning, if I connect my smart card to my Mac which is connected to the internet and always ...
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symmetric encryption A5/1 and A5/2 algorithms

where does the key (Kc) used to generate the keystream comes from and also where does the 22bits counter comes from
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75 views

Public key encryption without ciphertext expansion

Say I have a database column that is defined as VARCHAR(255) that stores names. I can assume that names can be up to 255 chars. I need a public key encryption so that I can replace names with their ...
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1answer
96 views

A one way Function provably reversible at N applications with the same seed?

I'm looking for a function that is generally one way from some secret $F(s, A) \rightarrow Y$, where $A$ is known, $Y$ is produced (also known), and $s$ is kept secret. But whose repeated application ...
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Need help solving message encrypted on an Enigma machine?

So basically I'm in a class an one problem we were given a while ago was one involving an enigma machine and a few messages. I do not have any idea of how to approach it, and I really need help. The ...
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Is Attribute based encryption sub-class of Identity based encryption [duplicate]

I have a basic question related to Identity and Attribute based encryption. Construction of IBE scheme was first shown by Boneh et al. in 2001 and I think in 2004 Sahai and Waters introduced ...
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Don't Understand these Parameters

I don't understand section 3 of the paper Fully Homomorphic Encryption over the Integers. How can one calculate these paramters and make these equations in pictures into code?
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183 views

fuzzy commitment implemenation to make secure biometric template

I want implement some ideas from an article that is about making secure biometric templates using fuzzy commitment and fuzzy vault. I need to implement just the fuzzy commitment (fuzzy commitment is a ...
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P = NP security implications [duplicate]

If someone finds an efficient way (ridiculous or not) to turn NP into P (such as creating multiple universes, saving the one with the correct answer), would we have any good algorithms for encryption, ...
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61 views

AES/CBC fixed Initial vector use-case [duplicate]

I am using AES/CBC to encrypt my http cookie. I never encrypt the same cookie value twice so my understanding is I don't need to use a random initial vector - using a fixed initial vector is fine for ...
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245 views

Blum-Blum-Shub Cryptosystem

I am given $N$, which is Bob's encryption key. I was able to successfully factor $N$ into $N=p*q$. Alice encrypts a messages for bob and sends $a = [1,1,1,0,0,0,1,0,1,1,0,...]$ $b = 1545164156...$ ...
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2answers
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Elliptic Curve Cryptography Encryption and text representation implementation

I'm writing a coursework and right now I've implemented the ECDSA algorithm, but I also need to encrypt and decrypt small text files (.txt) using elliptic curve cryptography. The problem is that I do ...
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Which one these alternatives using authentication and encryption will solve this multiple-user database problem?

Which one these alternatives using authentication and encryption will solve this multiple-user database problem ? I'm trying to understand the field of cryptography, so I've started reading a ...
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If the text was compressed before using traditional cryptography, how much difficulty increases for frequency analysis attack?

Traditional encryption is weak and no longer be used. They can be easily broken by using frequency analysis is a well-known fact. But, the frequency analysis often depends on the number of captured ...