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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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Binary Cryptography Problem [on hold]

i have some problem about a binary crypthography. i have the code and the solution but i can't found the key to understand the meaning. our value is ...
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21 views

How to securely store encryption keys in android? [migrated]

I want to know how to securely store encryption key in Android(API Level < 23)? What is the best scenario to protect encryption and secrete keys?
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How to encrypt data when send over https

I know its not practical to encrypt data when you send over https for widespread consumer use. But if i had to, how would i do that?. One way is for the server and client to agree upon an additional ...
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1answer
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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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1answer
41 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
61 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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1answer
38 views

Can the encrypt-and-authenticate method result in secure authenticated encryption if the MAC scheme has unique tags(non-deterministic)?

If we use non-deterministic MACs in encrypt-and-authenticate approach, is it secure?
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1answer
48 views

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 ...
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556 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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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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2answers
172 views

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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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
56 views

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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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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23 views

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 ...
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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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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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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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36 views

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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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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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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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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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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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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2answers
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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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How to find multiplicative inverse of a hexadecimal number in the finite field GF(2^8)? [duplicate]

I am new to cryptography. As I was reading a note regarding S-box construction, I found a step mentioning multiplicative inverse of a number in the finite field GF(2^8). I couldn't understand it!! Can ...
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Can a Jefferson Wheel Cypher be strengthened by arranging the message along the wheels in a railfence pattern?

Instead of aligning the message in a straight line, could one strengthen the Jefferson Cypher by arranging them like in a rail fence cipher on the device?
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164 views

What type of encryption is this homebrew “encyption algorithm”? ${}$

Background: Quite a long time ago (somewhere 1998) I thought I was really clever and invented my own encryption/decryption code. Looking through old code I rediscovered my old algorithm. (No, it was ...
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1answer
61 views

Can ECB be turned into a secure algorithm by adding obfuscation of the plaintext patterns?

Just to preface this I'm very new to cryptography. However, I've been reading that ECB should not be used under most circumstances due to its symmetry which allows attackers to gain information about ...
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42 views

Filling an encrypted disk

For a full-disk encryption setup, with a physical disk X and the induced logical volume X_crypt, there are several ways to initially fill the disk: (A): Fill X with zeros; (B): Fill X with random ...
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1answer
51 views

silly possibly original AE construction

This idea is inspired by a recent question about sending 32 byte messages, encrypted, without a MAC but still achieving the equivalent protection of a MAC just by using a block cipher, extra ...
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1answer
33 views

IVs in WEP encryption

I'll start of by saying I am pretty new to the world of encryption,from my understanding the plain text along with a crc is exclusively or'd with the IV and the key( or more accurately the key/stream ...
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Importance of the order of public/private key application to a signed encrypted message [duplicate]

Let's say two users (U1, U2) each have a private key they keep to themselves, and each broadcast a corresponding public key to the world. Let's then say that U1 wants to send a signed encrypted ...
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41 views

Problem with e-cash system with multiple banks

Say that many banks issue electronic cash of a particular type. If there is a malicious bank and user collusion, the malicious bank signs electronic cash for a particular user. This user then takes ...
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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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1answer
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How can I get select messages ciphers for salsa20poly1305 for unit tests?

In order to avoid memory errors, I always write safe C++ wrappers with strong type-safety for any C encryption library I use. To test my wrapper of ...
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2answers
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How can I follow the validation and verification recommendations of the NaCl (sodium) secretbox library?

I was advised to use crypto_secretbox_xsalsa20poly1305 due to its simplicity and because it's safe against timing attacks. I'm reading the secretbox tutorial, and ...
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1answer
867 views

Difference between decryption and deciphering?

Is there a technical difference between decryption and deciphering?
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1answer
51 views

How to generate a unique numerical value for an alpha-numeric string?

I need to create a unique numerical value for every alpha-numeric string input. Size of output numerical value can be of any size like 32, 64 128 bits. The input string will always be a mongoID type ...
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68 views

Is it possible to recover the key to a decrypted file? [duplicate]

Is it possible to recover the key to a decrypted file if you have the initialization vector and it uses RijndaelManaged in CBC mode? If so how? The file I want to recover the key from is a xml that ...
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1answer
178 views

How will be cipher selected when client is running on version TLS 1.3 and server is running on TLS 1.2?

How will be cipher selected when a client is running on version TLS 1.3 and server is running on TLS 1.2? The cipher list provided by TLS 1.3 client will be different than the version supported on ...
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0answers
22 views

Recovering password from zip file [migrated]

I have a few zip files from a long time ago but they are encrypted and I don't know the passwords. I have the unencrypted, uncompressed file that is in one of them. With this pair, I am trying to ...
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1answer
71 views

Euler's totient function and Carmichael's totient function in RSA [duplicate]

I'm a high school student taking IB and I'm doing my EE on Maths, more specifically on the effectiveness of Euler's totient function and Carmichael's totient function in RSA. Am I right in thinking ...
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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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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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1answer
59 views

Can you derive ed25519 keys from secp256k1?

Alice has a secp256k1 key pair that she used some time ago when she communicated with Bob. Bob can no longer user secp256k1 but he only uses ed25519 instead. Is there a secure algorithm that Bob can ...
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1answer
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How can I derive an ed25519 key pair from a secp256k1 key pair? [duplicate]

Alice has a secp256k1 key pair that she used some time ago when she communicated with Bob. Bob can no longer user secp256k1 but he only uses ed25519 instead. Alice and Bob cannot exchange any messages....
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How to change the known ciphertext so the known plaintext is changed in AES CBC mode?

I already read a blog about the padding oracle and also some posts about how to change the plaintext but it didn't work out. So I have the encrypted cookie (AES_CBC): ...