Cryptography Stack Exchange
Cryptography Stack Exchange

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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Why is writing your own encryption discouraged?

Say I want to write an encryption algorithm to communicate between me and my friend for this private use. How is that bad? E.g. I can take the word Hello and encrypt it with a simple algorithm – for example – take each letter and multiply its value…
Pierte
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If WhatsApp cannot read our message, how can the media forwarding happen in an instant?

WhatsApp says even the photos shared on its platform are end-to-end encrypted. When WhatsApp says encrypted I assume the data is encrypted in my device and then sent across to the recipient. When we are sending a photo for the first time we can see…
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Encryption that purposefully take hours to decrypt

My problem: I want to block sites on my router. I want to generate new password for my router after blocking sites. This new password I want to encrypt. But to decrypt it, I want it to take 2 to 8 hour to decrypt. Is there any solution that could…
Matt Rybin
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Is it possible to derive the encryption method from encrypted text?

Is it possible to identify the encryption method, or at least rule out some of them, by looking at the encrypted text? For example, if you have 3 encrypted strings where the first 10 characters are the same on each of the strings.
Shiraz Bhaiji
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Is there a bulletproof way to know a file has been successfully decrypted?

I am wondering whether there is a bulletproof way to know if one is successful in decrypting a file. As an example, say I encrypt a text file and protect it with a 3 letter password. I use brute force to decrypt it, but two different passwords lead…
untreated_paramediensis_karnik
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What is the theoretical and practical status of mental poker?

I'm able to find a lot of scattered papers on the development of mental poker since RSA proposed the initial solution but no recent report (i.e. after 2005) on what is the status of the problem, eg: What are the remaining open problems/challenges? …
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Can I encrypt user input in a way I can't decrypt it for a certain period of time?

I run a baseball league and would like to do silent auctions for free agents. This would require teams to enter their highest bid and the highest bidder at the end of the auction period would win. Unfortunately, my league, my code, my server, I…
dan
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Why are there limitations on using encryption with keys beyond certain length?

I am writing a java program to encrypt a message using 256-bit AES encryption, but I am getting illegal key size error, I have read that I have to use some JCE Unlimited Strength Jurisdiction Policy Files to encrypt/decrypt message with key of…
Riley Willow
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Spoken encryption

I have long had this idea of a simple encryption that can be used during spoken conversations to communicate with someone without being understood by other people in the room. Is there anything like that? The criteria are as follows: Does not have…
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Is there an encryption algorithm, which is a magnitude faster than AES (with weaker guarantees)?

There are current state-of-the-art encryption algorithms, which considered absolutely safe currently, like AES. Their speed is around the 100MB/sec ballpark on current PCs (note: this is the speed when AES instruction set is not used - I'm…
geza
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Why do key fobs/garage doors openers use rolling codes instead of PGP or SSL encryption?

Wouldn't they be more secure if they used the same encryption technology computers use for remote access?
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Analog encryption algorithms

I have a basic understanding of how strong encryption works on digital data. Bits can be changed so that they appear completely random and map one-to-one back to the original set, given the correct decryption key (and possibly other parameters). But…
Luc
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At what point can you you implement crypto algorithms?

First off, this feels like it should be a common question, so I'm sorry if I've missed an older thread. Note that in my question, I'm talking about "implementing AES" rather than "designing AES2" or something. I am of course familiar with the saying…
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Could celestial objects be used in cryptography?

If it were possible to receive a string of numbers from a celestial object (by anyone on the Earth who knows which object to look at, and what time to look) could this be of any use in cryptography? Or would it be useless, because if a bad-actor…
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How long will my encryption remain private?

This is a basic question in cryptography but I have not found a good, comprehensive answer. It is explained that our keys should expire and we should get new, stronger ones with time, reflecting more powerful decryption computing. Does that mean…
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