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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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RSA encryption/decryption process is not working correctly

I'm trying to apply the RSA cryptosystem to encrypt a byte M=72, using predefined modulus n, public key exponent ...
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How does end to end encrypted emails work? [migrated]

I was thinking about this concept and realized that when a user is decrypting an email on the frontend of the email service, won't the server theoretically be able to "see" the private key and the ...
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2answers
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What is the name of an attack where the compromise of one key compromises the whole system?

Consider the following: A whole system depends on the security of one private key and if this key is, for any reason, compromised, the whole system will be compromised. What's a suitable name for ...
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Is it possible to encrypt a process?

Imagine a hypothetical system as follows: A distributed algorithm running on a Local Area Network (LAN) that allows real-time addition and removal of processors. The addition of a processor is ...
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1answer
35 views

identifying Negligible functions

I am having a hard time understanding and applying the formulas that are used to identify a function is negligible or not? One text defines it as; a function $f$ from the natural numbers to the non-...
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32 views

How crack XOR cipher without key [duplicate]

I must crack XOR cipher, I don't have key, but I know is key is smaller than 70. This is ecrypt text: ...
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1answer
45 views

Encrypting a 64-bit binary number to a text containing upper- and lowercase, and digits

I am making a tool that generates 16 character long password out of a 64-bit binary number. But I dont know how to make an encryption key for that, or where I can find one. To show what i mean, here ...
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37 views

How to break Content Scramble System at complexity of 2^16?

It’s about Content Scramble System (CSS). The key size is 240 but it is possible to break CSS at complexity of 216. So how does it work?
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4answers
69 views

JWT Login Security

I am new to security and I am wondering if JWT is secure enough. From what I have read online the flow goes like this: Clients log in by sending their credentials to the identity provider. The ...
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1answer
45 views

Does hashing an encrypted message suffer from any drawbacks?

I am working on this problem where the set up is like this: There are three hosts: A, B and C. A wants to send a message to C which passes through B. At A the message is hashed, the hash is padded to ...
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0answers
41 views

How to proof that this cipher is perfectly secure?

I am new to Computer Security and I am trying to solve the following exercise: Consider the following encryption function which transmits one letter. Let n be a fixed positive integer. The ...
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28 views

the password is incorrect while its correct [on hold]

i want to test my login page but i used password encryption before password was saved in the database. if i try to enter from login page will display error message "Incorrect password or email". and ...
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1answer
68 views

Newbie question: one-way functions in cryptography

I'm reading this article on the basics of cryptography and it says that the main principle is about taking such an algorithm that knowing the end result and the algorithm, an eavesdropper wouldn't be ...
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DOS 6..2/Windows 98 encryption software [migrated]

Is there any encryption software (full disc encryption or container mode) available for Windows 98? Same question for plain DOS 6.22. Maybe it's strange, but for some reasons I need software like that....
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Patent Status & Usability of AE Modes [on hold]

Post Structure: Sources Cited Question & Details Before You Answer Useful Info From Comments Sources Cited: https://blog.cryptographyengineering.com/2012/05/19/how-to-choose-authenticated-...
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0answers
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Encrypted output from an embedded device? [on hold]

Does this look like encrypted output, please? { 811 #2D #CC29 #C102 #E9 #B5 #C62 E01 #C8 #2139 #68F1 #08 #A6 #672 241 #8C #0E29 #8642 #86 #C6 #262 E61 #4B #0E29 #A942 #...
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0answers
29 views

breaking aes, time taken using quantum computer? [duplicate]

Let say we want to break aes-256 using a quantum computer, that would take 2^128 operations using groove algorithm. Now let say we have a 128 qubit quantum computer, can this be broken instantly ? If ...
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52 views

Double encryption : what method is the best?

Given the block-ciphers defined as follows : $1.$ $C=$ $E_{k1}($$E_{k2}$$(M))$ $2.$ $C=$ $E_{k1{\oplus}k2}$$(M)$ $3.$ $C=$ $(E_{k1}(r),E_{k2}(r$ ${\oplus}$ $M))$ where $C$ is the cipher ...
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32 views

Leveraging patterns in ciphertext

I've got a cipher I believe to be polyalphabetic, which may or may not have a key in which I've discovered some patterns, and I'd like to know how I can use these patterns to try to understand how the ...
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5answers
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Is a PRG more costly than AES or any other encryption standard?

I know that there are many encryption standards that take a key and sometimes an IV, and produces a cipher-text (the most prominent one is AES). These standards usually involve many rounds of addition ...
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0answers
50 views

Is it necessary to encrypt messages client side if using HTTPS? [migrated]

I am creating a messaging service for an app I'm developing and right now the data flow is as follows: Send: message sent to server => message encrypted based on user's public key and signed using ...
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1answer
75 views

Find $F(2x)$ from $F(x) = a^x \bmod p$

Given $F(x) = a^x \bmod p$, where $a$ is a primitive root of $p$, Is it possible to work out what $F(2x)$ or $F(3x)$, etc if you know what $F(x)$ is but not $x$. If you use $F(x)$ then $F(2x)$, etc ...
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1answer
113 views

What role does Representation Theory play in Cryptography?

Shannon said that every cryptosystem can be expressed as a system of linear equations with a large number of unknowns of complex type. In cryptography groups are used since they are a natural ...
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1answer
42 views

Ethereum RLPx protocol for inter-node communication - flaws in the encryption

Ethereum uses RLPx/devp2p for inter-node communication. The protocol is encrypted using Elliptic Curve Integrated Encryption Scheme (see ref) Under Known-Issues I found this paragraph: The RLPx ...
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32 views

ROVER encrypted communication [closed]

I'm making a ROVER where it goes places like pipelines etc., and send me the data through video. how can the ROVER send data in encrypted format? how can I contact that rover in encrypted format?
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Private Key Sharding - How is it Secure in a Distributed Network?

In a Distributed Network in order for a private key not to be compromised sharding will have to take place off the network, correct? If so: Why is it when a Distributed Network shards private keys ...
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RSA questions need help encrypt message ASAAP [duplicate]

My questions is this It is given that : plaintext=...
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0answers
43 views

I invented 5 encryption codes, how can I sell these? [closed]

I don't know how I could sell it, please can someone help me? it's must be Unbreakable Encryption Code.
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2answers
97 views

What is the shortest type of text encryption?

I have the following text that I want to encrypt with a password: "This is my secret password: 1234567890" encrypted with AES: SgAHzFc3vluxLqZuzZKg8dzhy918N41SUU1BfBXN8CoEDfVJ0R9hox8PT2jKYA== pass:...
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0answers
45 views

construct a perfectly secure encryption

How can I construct a perfectly secure encryption scheme with M={000,111} and K={0,1} (M is the message space and K is the key space)?
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1answer
63 views

Is there any way to track if a ciphertext has been decypted?

Just like the case of a box that has been sealed. We can detect if the box has been opened or not by looking at the seal. Is there any way in cryptography or any encryption scheme that allows this to ...
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1answer
70 views

What is the meaning of probabilistic polynomial time adversary?

I learned about probabilistic polynomial time adversary, but I have some doubt. Is probabilistic polynomial time adversary referred to those who attack in polynomial time with the form of ...
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1answer
63 views

How many rounds of encryption is ideal?

I am a newbie to the cryptography world. I am working on a custom algorithm that encrypts the data multiple times and results in a cipher text. It uses a different key in each round to encrypt it. I ...
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1answer
81 views

How can we compare an encrypted number with a normal number?

I am currently doing a project on privacy preserving encryption using a k-means system and the Paillier encryption algorithm (homomorphic algorithm). I have to send an image of a skin disease to the ...
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40 views

Can one design an asymmetric encryption scheme based on any secret sharing scheme? Are they that closely related?

I've seen both asymmetric encryption and secret sharing schemes based on graph 3-coloring, and I'm curious if this is a coincidence due to some peculiar property of graph 3-coloring alone.
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2answers
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How to encrypt the truth table in garbled circuits?

I'm learning about garbled circuits, and I'm using the following tutorial: Yao's Protocol. I have a questions regarding to construction (encryption) of truth table in garbled circuits. Slide 14 says:...
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3answers
338 views

What is different below two Ciphersuites?

I have two questions; I need an explanation for the differences of below two cipher suites. How do they work with SSL/TLS protocol? (my main concern first one doesn't have '...
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1answer
51 views

Multiple encryption using the same key

I am a newbie to this area. I have a program that uses a custom algorithm to encrypt a message. I can encrypt it as many times as I want, but using the same key. I have couple of questions so that I ...
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5answers
69 views

Encrypt a file in a way that decryption requires every recipient's cooperation

The best related concept I can think of is the two-man rule. https://en.wikipedia.org/wiki/Two-man_rule. To put it simply, n people are required to give their authorization before a system / secret ...
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Trying to understand how openssl calculates IV and key from passphrase

Once I generate the encrypted private key, public key and ca certifcates from openssl for radius server. With sha256-pkdf2 and 3des I put these files in ubuntu system for eapol communication. I am ...
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0answers
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TOR Node Settings to make default data routing on iPhone [migrated]

I am trying to setup my iPhone to route data to a tor network by default before it is sent to some other app databases or internet. Any help how can I configure this( if I could know the settings to ...
3
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1answer
75 views

Can modular multiplicative inverse be used to create a secure cipher?

Let $N$ be a large number; and $(e, d, N)$ be a secret-key; where $e$ is a one-time random factor, and large enough (say the more or less the same number of bits as $N$), where $e < N$ and $e * d \...
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Key-space analysis of an algorithm

I have an algorithm that requires a set of keys to encrypt a text (image of size N x N). It is an image encryption algorithm for a project. The key can be thought of as a tuple $x_0, \lambda, d, i, ...
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Signal Protocol: How does it achieve identity hiding in practice?

Assuming that Alice and Bob are ordinary users of a messenger that implements Signal protocol, they have to rely on the server for key exchanges (even the ephemeral ones) and also for forwarding the ...
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0answers
50 views

Pi and One Time Pad [duplicate]

I was reading your questions about complete randomness and I thought, couldn't they use numbers like Pi or Euler's number for One Time Pad. Is this a correct thought?
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4answers
67 views

feistel cipher and number of rounds

In feistel cipher , does it matter that number of rounds be 16 ? is using 16 rounds will give the best result ? Or using any number of rounds is the same? in cryptography and network security by ...
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Question on nCPA Security and Uniform Permutations

I feel I am misunderstanding the idea of nCPA security and its relation to uniform permutations. In particular I've been reading the paper "Hoang, Morris Rogaway; An Enciphering Scheme Based on a Card ...
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29 views

Affine Cipher plus

How to attack this affine cipher; $m+n (a_0,a_1,a_2,a_3,\ldots, a_4,\ldots,k_0,k_1,k_2, k_3, k_4,\ldots)$,with $\gcd(a_i,26)=1,i = 0,1,\ldots,m − 1.$ here are the keyspace $(a_0,a_1,a_2,a_3, a_4,\...
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4answers
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How safe is a book cipher? How would you break it?

This might not be a very specific question, but I was wondering this morning. If one were to encode a message by making a string out of an entire book and writing the message by searching for a random ...
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1answer
48 views

Are the following asymmetric encryption schemes equivalent?

Consider the scenario where you want a machine to be able to send daily encrypted backups to a storage server. You'd prefer to not use simply a symmetric key for encryption, because if the machine ...