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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Suitable hybrid encryption approach?

I need help for my bachelor thesis. I have a general question regarding hybrid encryption in different ransomware. The hybrid encryption often uses symmetric and asymmetric encryption techniques. ...
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What was the key length of the Enigma? [closed]

When I type in any plaintext to an Enigma machine (Enigma machine emulator) the substitution does not seem to follow any pattern. In other words, there is no cycle in the use of enciphering alphabets (...
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Bitwise operations in FHE

Im reading about FHE and the libraries implementing it (SEAL, HELib). I saw that SEAL doesn't support bitwise operations but I wondered if its theoretically feasible. For example, bitwise-ing XOR an ...
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How to devise cryptographic system with data-sharing ability and password reset

I originally posted this in the security.stackexchange forums but then I was directed to this one which seems more befitting for my question. I am writing a C# .NET application. For my application the ...
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Is it possible to crack AES-256 ECB when provided with the ciphertext and a portion of the corresponding plaintext? [duplicate]

AES-ECB encrypts the message by breaking it into blocks and encrypting them one by one. Provided the knowledge of the ciphertext, a portion of the plaintext that corresponds to a block in the message, ...
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RSA vs diffie-hellman + polyalphabetic cipher

My basic question is: How does RSA compare to using Diffie-Hellman + <some symmetric key crypto, e.g. a polyalphabetic cipher> Let's assume that factoring large numbers and computing discrete ...
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Time taken for a brute force attack on a key size of 64-bits

You can do $2^{30}$ encryptions per second and the key size is 64 bits. $2^{64}/2^{30}$ should give me the time taken for a brute force attack? What if you double the key size? How can I calculate ...
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Does anybody have test vectors for the LBlock block cipher?

LBlock is a lightweight block cipher with 64-80 bits block-key size, designed by a group of Chinese scholars. Does anybody have LBlock test vectors? I am looking for test vectors, which contain the ...
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Why aren't public-private keys sufficient to build a block chain? Why do we need proof of work/stake?

Taking the simple case of Bitcoin here: If all nodes can validate published transactions by checking the signature (created using the private key of the sender) of the transaction against the public ...
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Why Entropy is low for Python Fernet Encryption

I am using Fernet encryption from python cryptography.fernet and generated the key as below ...
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Should we sign-then-encrypt, or encrypt-then-sign?

Frequently, we want to send messages that are (a) encrypted, so passive attackers can't discover the plaintext of the message, and (b) signed with a private-key digital signature, so active attackers ...
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Test vectors for SIT -encryption algorithm?

Test vectors for SIT -encryption algorithm? I'm looking for Tests Vectors to test my implementation of SIT. Thanks a lot.
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Can an encryption key be inferred by knowing the plaintext and the corresponding ciphertext?

Thinking about validation methods for guaranteeing a proper key is used. Will keeping a dummy plaintext value and its corresponding ciphertext in plaintext code expose any risk?
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Are there any cryptographic algorithms, which lets the user apply some modifications on the encoded data, without decoding it?

I would like to encode some data with a key, and send it to a third party. They don't know the key to decode it, but I would like to make it possible for them to apply some modifications on it. Then ...
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How is hybrid (RSA+DH) more secure than RSA quantitatively?

Is there any graph that serves as a comparative analysis for the factorization problem vs discrete logarithn problem? I am implementing an hybrid encryption algorithm (RSA + Diffie-Hellman) and it is ...
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Can I alter encrypted data without decrypting it? [duplicate]

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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What is U2FsdGVkX1?

Using CryptoJS 3.1 I noticed that using 3Des, the encrypted message always start with U2FsdGVkX1 Why is the first part of the encryption always the same? What information does this hold and how ...
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How does a forward search attack work? [duplicate]

I just came across this term “forward search attack” while reading about Interchange key and Session key. The book mentioned that using session key helps to prevent attacks such as forward search ...
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2answers
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7-Zip Encryption: Practical Effect of Lacking Salt

A previous discussion on Cryptography StackExchange leads me to understand that 7-Zip does not use salt to derive an encryption key from password to use its AES-256 encryption; that this is a ...
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Assistance with Permutation Cipher (Columnar Transposition) [closed]

I was wondering if someone could provide some assistance with understanding a permutation cipher. I have both the cipher text as well as the plaintext but am having some difficulties trying to find ...
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2answers
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Does the diffie helman rachet in double ratchet do anything if one side never replies?

I am a little confused on how this functions so apologies in advance if the question is naive. The way i understand it, the function of the standard sending and receiving ratchets in Double Ratchet is ...
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2answers
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ElGamal and Pailler combined

currently I am working on some secure accounting application. I have few requirements: Application should store items which can be searched by name. Every item has price and tax. Every invoice ...
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1answer
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hello i am a junior coder and programmer . what are the first step towards learning the beauty and function's of data science [closed]

"I really enjoy and would like to learn about cryptography. How and where to start? what programs did you first use, and support teams? I am learning lots of things which I should include in my ...
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What is the use of key iterations?

I read about PBKDF2 on Wikipedia and seen few apps. having option to manually enter number of iterations. I am still not clear on this. (1) With what I understood, key iterations can be used only ...
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How to verify most appropriate cleartext?

So basically I was implementing a decryption tool (just for fun) and the first encryption logic I decided to implement was Caesar Cipher. So if I have the input as ...
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How can I enhance the security level of my RSA code?

I am trying to enhance the security level of my RSA code that I implemented in Python. I tried to add blind operation, randomized algorithm to my RSA code (separately, not together), but I am not sure ...
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1answer
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Decrypting the same message with the same IV using aes-256-cbc

Is it safe to use the same IV when decrypting the exact same encrypted message. From my understanding, there is a security flaw when using the same IV for numerous different messages, as attackers can ...
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What is the name of this public key encryption cryptosystem?

I have been trying to find the name of a public key encryption cryptosystem that I learnt as an introduction to cryptography some years ago but the only scheme I could find was something similar but ...
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Is cypher.js secure for sensitive data? [closed]

Is this library secure? Link to github repo Here's his explanation: Cypher does not encrypt through allocation based on mapping patterns. Cypher encryption process is completely mathematical and ...
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1answer
106 views

How should I assign a letter at random to another?

For my first ever project in Python, I wanted to code a cipher to encrypt simple messages ( no spaces or lower case to avoid that extra hassle for now ). My idea was to either: Choose a letter of ...
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9answers
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Should I use ECB or CBC encryption mode for my block cipher?

Can someone tell me which mode out of ECB and CBC is better, and how to decide which mode to use? Are there any other modes which are better?
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1answer
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Is there any dedicated research group which is working in energy efficient cryptographic functions? [closed]

Is there any dedicated research group which is working in energy efficient cryptographic functions for mobile devices. In mobile devices other than tuning a frequency/voltage, network speed any other ...
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1answer
118 views

Is my Enigma inspired cipher any good?

I am working is a project that would implement a cipher that would output ciphertext that would be easy to transmit through morse code, just like they did in the days of Enigma. Use of AES or the ...
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Cryptographic Principles: Bit-Flipping Attack

I'm working and reading about bit-flipping attack and how to set it up. I just got a question, which I am not sure, how I should answer. Question: 'Why is this easy with a stream cipher but not ...
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Using ECB as RSA encryption mode when encrypted messages are unique?

As I understand, ECB should not be used as encryption mode unless you are encrypting single blocks of data which are always unique and only are encrypted once. I have a collection of ids represented ...
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1answer
53 views

AES-128 CBC encryption : ciphertext size seems too large

I am trying to encrypt messages with the AES symmetric algorithm using C language. I am using a key, an Initialization Vector (IV) and a plaintext, all with a length of 16 bytes. I expected as output ...
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1answer
107 views

Are zero knowledge proofs alternative private key encryption? [closed]

Are they the alternative to private keys. If I understand correctly, because of the increasing computational power in today's world, zero knowledge proofs are more safe than private keys ? Are these ...
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2answers
74 views

What does TLS 1.2 mean by SHA functions?

I'm looking at the technical docs for TLS 1.2 and it says it uses SHA (so hashing algorithms): 7.4.1.4.1. Signature Algorithms But hashing just digests an input, to do things like user authentication....
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1answer
16k views

How do I derive the time complexity of encryption and decryption based on modular arithmetic?

I want to calculate the time complexity of two encryption and decryption algorithms. The first one (RSA-like) has the encryption $$ C := M^e \bmod N $$ and decryption $$ M_P := C^d \bmod N. $$ ...
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12answers
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Is it possible to create a "digital seal" to tell if a document has been opened?

So, in real life we have a handful of ways to leave a physical mark on a packet to know if it has been opened without authorization (eg. you can use 'opened' security tapes, or you can put a signature ...
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What is the number of fixed plaintexts of RSA [duplicate]

Considering RSA, $n=p\,q$ with $p,q$ odd primes and the public key $(n,e)$, where $\gcd(e,\phi(n))=1$, I need a hint on how to show that the number of plaintexts with $E_e(x)=x$ equals $\gcd(e-1,p-...
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1answer
98 views

RSA public key identification

Consider a multi party system where public keys of all receivers are known. Server wants to send message to one of them using (textbook?) RSA. Adversary is given ciphertext and even Message to be send,...
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2answers
83 views

Is it cryptographically insecure to use fixed-length AES-GCM messages?

Is there any weaknesses to encrypting fixed-length messages? Should a random amount of padding be added to the message to decrease the odds of some sort of attack?
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Does watching Youtube generate entrophy

Does watching videos (either online videos such as off youtube or saved locally) generate enough (if any) entropy to create secure encryption keys? I understand that some activities such as memory ...
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58 views

Do I understand $P = NP$ correctly in relation to one-way functions?

If I understand this relation correctly is, that any function whose inverse can be found in polynomial time is not a one way function. The $P = NP$ proved would cause that any candidate for a one-way ...
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AES CBC Encryption Key & Special ASCII characters [duplicate]

Can we add characters like α π Σ µ ...
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1answer
150 views

Which test suit is better to say if PRNG is CSPRNG:TestU01 or NIST?

Actually my concern is that I am planning to apply xoshiro256+ for implementation of stream cipher https://prng.di.unimi.it/ for my cryptographic application. It passes the BigCrush tests. Will it ...
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1answer
86 views

Writing an original encryption algorithm [closed]

Firstly, I'd just like to clarify, I am less than a beginner when it comes to cryptography. Please bear with me. I'm sure its flawed I just don't know how. I was bored one day, and decided to come up ...
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Is it possible to alter the plaintext message without altering the ciphertext?

Is it possible to alter the contents of a plaintext message without altering the ciphertext? Altering the private key is allowed to accomplish this. If the answer is yes, how would I go about in doing ...

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