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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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Group Encryption or Multi-Party Encryption

I came accross a privacy and cofidentiality problem in medical field where patients medical record is available to certain doctors in full, but researchers/pharmacutical companies can only view the ...
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Affine cipher text [on hold]

I just wanna know the methods that I can force cipher text without knowing the key and the length for this cipher text is random, any ideas?
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3answers
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In public key cryptography, how many keys are required for secure communication between n parties?

In public key cryptography, how many keys are required for secure communication between n parties? In my view the answer should be $n^2$. Reason: There are ‘$n$’ Parties. Every Party has One (1) ...
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Differences between industrial and military cryptography

Industrial and military cryptography should follow the same basic rules, but what does make them different is: Higher key length, protocols unknown to the civilian world, and perhaps unique methods ...
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Prime Generation density and Miller Rabin Testing

I am working on an Cryptographic exercise but I'm not quite sure where to start. We suppose a prime generation consisting over a loop to take a random integer $n$ and pass its number to a 5 round ...
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1answer
40 views

ECIES/ ECDHE/ EC-ElGamal encryption comparison

I need to choose an encryption system, so I am trying to understand the differences between the existing options. I always find that people compare ECIES (Elliptic Curve Integrated Encryption Scheme) ...
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1answer
60 views

Will publishing two or more public keys of the same RSA private key cause a security risk?

I want to make an end-to-end messaging platform where everyone is identified with a unique random private key. Everyone uses other peers' public keys to identify and send encrypted messages and verify ...
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5answers
11k views

Is it better to encrypt before compression or vice versa?

Is it better to encrypt a plain text file before compression, or vice versa?
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Does encrypting with MGF1/SHA-512/1024-bit seed equal to a 1024-bit key block cipher?

Suppose: Alice uses SHA-512 with MGF1(as in PKCS#1 V2) and a 1024-bit random seed to generate a mask, XORs the mask with a message(M), gets a cipher text (CT), and sends the CT to her old friend Bob....
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2answers
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What are the implications of XORing ciphertext with plaintext?

I was intrigued by this question: Does adding complexity mean a more secure cipher? And it led me to wonder: What are the implications (if any) of XORing a ciphertext with the original plaintext ...
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2answers
11k views

Using the same RSA keypair to sign and encrypt

The RSA signature operation is basically the same as encrypting with the private key. In particular, both operations use the same kind of keys. Is it safe to use the same RSA keypair both for ...
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0answers
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What are the practical impacts of Wassenaar Arrangement to crypto development?

Wassenaar Arrangement limits transport of high-grade crypto hardware/software since decades, if I don't err. What are its practical impacts in that direction? In particular, does it hinder in any ...
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1answer
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Can you help me understand Bernstein’s Notes on Diagonal constant of Salsa20?

Explaining the choice of the Salsa20 constant Bernstein explains: [...] shifting the entire Salsa20 hash-function input array along the diagonal has exactly the same effect on the output. The ...
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Encrypt multiple RSA keys with same passphrase

I have to create and store a bunch of RSA key pairs with openssl. The private keys will be encrypted with the aes256 option and a very long, random password. Would it be safe to use the same password ...
5
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2answers
551 views

SHAKE-128/256 or SHA3-256/512

Would it be better to use SHAKE-128/256 or SHA3-256/512? In what situation should I chose one over the other?
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0answers
9 views

Can modular operation used along with bit shif for cryptography? [closed]

Let a be input value, k1 and k2 be two keys. Then X=(a+k1) mod m; X=(x<<4); Y=x^k2; Can i decrypt back? Because i am not getting exact answer while ...
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4answers
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Can a book cipher be cracked without key?

Book cipher works this way : Choose a reference book. For each word find its position in the book. replace each word by its coordinates (ie: 2,3,4 = page 2, 3rd line, 4th word). How would somebody ...
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1answer
115 views

Using a non-secure random generator for IV or salt generation

I was just looking at a post on Code Review when I noticed the other answer to the post. While I would agree mostly with the answer, I do however doubt if having a Cryptographically Secure PRNG is ...
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3answers
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Can data over a very low bandwidth channel still be encrypted?

If you have a very low bandwidth channel, can encryption still be used? Another way of putting this might be, does encrypting well increase the size of the data significantly? Are there good ...
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1answer
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What is the most secure way to check that a given masterkey is valid?

For the purposes of learning, I'm writing a small utility that allows encrypting a list of passwords using a single master key (using AES-256 and PBKDF2) Before encrypting or decrypting any password ...
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3answers
2k views

Does adding complexity mean a more secure cipher?

I have a cryptography workshop question I'm having trouble with as follows; Person A creates a cipher $E_k(m)$ which produces a ciphertext from message $m$ using key $k$. The function inside $E$ is ...
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0answers
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stream cypher Cryptography (ecg signal) [closed]

please how do I perform a XOR operation with a bit stream and an ECG signal? I am trying to encrypt it with bit wise encryption. thanks in advance
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Which algorithm is safest if we exclude AES, Twofish, Serpent and Whirpool? [closed]

TLDR: Which algorithm is safest if we exclude AES, Twofish, Serpent and Whirpool? Full version: Hello, my threat model is archiving and backing up important and private files. Files will be stored ...
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2answers
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How can a hash have a fixed length?

I am very new to cryptography, I apologize if my question is so basic. I do not understand how a hash can have a fixed length, because you can have infinite inputs to a hash function. With a fixed ...
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1answer
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Help with encryption question [duplicate]

I came across the following question and it is confusing me. I'm completely new to cryptography, so please excuse the beginners question. "Having just completed a course in Cryptography, Tom and ...
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0answers
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AES reverse Rijndael key schedule with decryption round keys

I want to get the original encryption key (32 byte) of AES 256 (CBC) implementation. The implementation has the values of the inversed round keys values hard coded into the decryption function. I ...
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1answer
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What is the difference between PKCS#5 padding and PKCS#7 padding

One runtime platform provides an API that supplies PKCS#5 padding for block cipher modes such as ECB and CBC. These modes have been defined for the triple DES, AES and Blowfish block ciphers. The ...
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20answers
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Time Capsule cryptography?

Does there exist any cryptographic algorithm which encrypts data in such a way that it can only be decrypted after a certain period of time? The only idea that I can think of, is something like this: ...
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0answers
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Slow decryption [duplicate]

I would like to encrypt a short string (~30 characters) in such a way it would take about a second (ideally tunable) to decrypt in a web browser. The encryption process should be faster. It should not ...
3
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1answer
229 views

Is order of Correlation Immunity of AES S_box Zero?

I am working on AES S_box and trying to find out its properties like Correlation Immunity, Balancedness, Algebraic Degree, ANF form etc. These Papers 1, 2 give a nice definitions to above said terms. ...
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0answers
32 views

What’s the actual public key and private key in Block chain based time lock encryption?

I just read the paper How to build time lock encryption and understand the author’s scheme construction in concept. The scheme use witness encryption and bitcoin system to make the message can be ...
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0answers
37 views

Is there a protocol for granting access rights to publicly stored encrypted data?

Alice is a data provider and Bob and Charlie are consumers. Alice has a set of data assets $A_*$. Alice wants to share some of her assets with Bob, some with Charlie (they are not necessarily mutually ...
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2answers
131 views

Where should i start? [closed]

I am very interested in cryptography and would like to learn more about it and how to code. However, I dont know how to start. I would love to know some more mathematical background and how to apply ...
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1answer
56 views

The goal, the method, and the interface of the signcrypt primitive.

Some time ago, I proposed making the site more educational by teaching correct cryptographic programming. The proposal had had somewhat good reception, but was met with cold ice as there had been ...
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Acceptable points of failure when applying encryption in an application

I am working an a Windows application that will encrypt and decrypt files using AES Encryption. The 32 byte key which is diversified and derived using a ATSHA204 unique serial number and some addition ...
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0answers
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What choices of $a$ and $b$ of the affine cipher lead to proper encryption functions [duplicate]

Suppose I consider the affine cipher defined by $E(x) = ax + b \bmod n$ on the standard alphabet of 26 letters. Which choices of $a$ and $b$ lead to proper encryption functions? Using the ...
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2answers
39 views

Characteristic of Public Key?

Is Public key used directly to encrypt a message or it is used to derive other keys ? Can we decrypt a message with same public key using which it was encrypted ? So far I understand, as PKI is based ...
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0answers
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Web Crypto: What is the differance between wrapKey and normal encryption? [duplicate]

I can wrap a key with wrapKey but i also can encrypt the key again with the normal encrypt method. So what is the differance and the benefit of wrapKey?
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2answers
73 views

Does an encryption algorithm exist where encrypted data can be decrypted by multiple private keys?

Suppose I have Company1 with their own Public/Private Key Pairs and another Company2 with their public/private key pairs and yet ...
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1answer
113 views

Rapid partial block decryption of compute intensive full encryption

Given a block of data D: Is there a encryption/decryption scheme that would allow me to perform a resource-intensive (compute/time/memory) encryption of the full data set with a key k, but allow for a ...
2
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2answers
73 views

Aggregated encryption

I have one problem about cryptography which I don't if someone already solved it. I want one device (master) to receive one encrypted package from each one of the other $n$ devices (normal) and I want ...
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1answer
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I have created values for rsa encryption but it dosent always work [duplicate]

i am suing the values as follows: (p, q, n, phi(n), e, d) = (1033, 5039, 5205287, 5199216, 65537, 3784241) yes i have made sure e and phi(n) are coprime for example if i were to encrypt the value ...
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1answer
68 views

Is there any identification for common encoding/encryption?

I come across lots of tokens which might be simply encoded and not random, but I don't know any way to identity if they are encoded or random, how to find is there any cheatsheet for the same. For ...
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2answers
94 views

How do I calculate e, d and N based on raw and encrypted message in RSA?

I've got raw and encrypted message, which contains only numbers. For example: Message: 32016550980634121428089400169, encrypted: 35682226122303060179704449482 I'...
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0answers
32 views

End-To-End Encryption w/o User Key Management

I'm trying to build an end-to-end encrypted cloud note-taking system but don't want my users to have to deal with any form of key management. Is there any way to achieve this? One idea is to have ...
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1answer
157 views

Why isn't ElGamal a symmetric-key scheme?

I was asked about this question by a friend. He considers that Alice and Bob share a secret key s=g^(xy). So why isn't it considered a symmentric-key scheme? ...
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1answer
74 views

Which type of non-basic cipher works better with microcontroller which has no interface and keyboard connected to it? [closed]

Did a C++ code on Caesar Cipher to do encryption and decryption with my XMC4500 microcontroller but my lecturer said that Caesar Cipher is too simple. He wants me to use a non basic type of cipher and ...
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2answers
242 views

How to calculate the average key search time for the double des?

How to calculate the average key search time for the double des ?Uses standard DES with 56 key bits, and we can test 10^6 keys per second. Many thanks!
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1answer
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Comparing Ciphertext when there is a change in source plaintext p1

So, i know that if there is a change in source plaintext p1, c1 and rest of cipher blocks will be affected as c is required for the calculation in cfb. What i need to know is that how can i show how ...