# 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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### identify how to solve this cipher please! its fun and a mystery

I have roughly 25 three digit numbers between 0 and 200, that are a cipher. if i know what some letters are (for instance a=2, c= 9, and f-3) then how can i solve for this?
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### Data corruption to protect the encryption?

On KeePass help center it's stated that: ... if the header of the database (first few bytes) is corrupted, you're out of luck, too: the repair functionality won't be able to restore any entries (...
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### How do you find the cipher formula for a cipher like this?

I'm new to ciphers and cryptology in general, so apologies in advanced. ((When I say I'm new, I mean I only started looking up cryptography in response to being given this cipher this morning, so I ...
2k views

### What's the difference beteween SIDH and SIKE?

I'm a semi newbie in crypto (I've had that uni course of discrete math that includes basic cryptography principles) and wanted to go a bit further in isogeny graphs. I have downloaded the C ...
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1 vote
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### What is Plaintext-awareness?

Could you explain with an example what does it mean to be Plaintext-awareness. I have read the wiki definition. It says that "A cryptosystem is plaintext-aware if it cannot genenerate a valid ...
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### Decryption using multiple keys

0 I have a PHP application which calls third party api with username and password embedded in the XML API call from my side. I would like to encrypt and store the username and password embedded in the ...
57 views

### Vigenere applied to encrypted data

What happens if you encrypt data with a good cypher that produces a cyphertext that looks random (say, AES but avoiding ECB mode), and then apply a Vigenere cypher to the encrypted random-looking data?...
1 vote
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### Security of the encryptions, using a PRG for the keyGen

I recently got doubtful to the usefulness of psuedorandom generators(PRG) in cryptography. Based on Kereckhoff's principle, we always assume that the used algorithms are made public. So, when we use a ...
1 vote
107 views

### How does AES GCM encryption work

Previously, I used AES CBC 256 with 256 bit key and 128 bit IV. However it seems slow so I decide to switch to AES GCM 256 bit key, 96 bit IV which has some parts I don't understand such as: Auth tag:...
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### Is partial digest recognition possible?

TL;DR Does hashing a private key, then XOR[ing] the digest (twice recursively, with offset) on the secret have any glaring issues? Is partial digest recognition possible? Description User provides a ...