Questions tagged [file-encryption]

The process of encrypting individual files on a storage medium and permitting access to the encrypted data only after proper authentication is provided.

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117 views

Encrypt a file for random access but only after an initial read of the whole file

I'm symmetrically encrypting a file (using a random salt and a user supplied password with PKCS5S2, i.e., nothing special) and I need to be able to access it randomly. Therefore I'm using a stream ...
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241 views

How can we encrypt a file to be just readable (and not writable) after decryption?

Is it possible to encrypt a file (e.g., a text document) such that when a user decrypts it, he/she be able to just read the file and not be able to change the content of the file? I mean, the result ...
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How secure is the encryption with OTP and an OneRNG?

I bought an HWRND last week. What do you think, how secure is the encryption with that and the OTP? See the OneRNG theory of operation here.
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Why use ASCII armor for file encryption?

GPG and age both offer a --armor option but what is the use case when it comes to file encryption? Surely most channels allow for transmitting binary data nowadays? ...
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How does encrypting a file with AES affect file size? [duplicate]

I am wondering if encrypting a file with AES will reduce or increase its file size and generally by how much. Thanks for any tips or advice.
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Does my asymmetric/symmetric mixed file encryption pseudo code pass sanity check?

I realize this depends on my implementation and the implementation of the libraries I use. I am asking about my process assuming that the encryption libraries and my code are not flawed/compromised, ...
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1answer
99 views

Faster alternatives to RSA trapdoor permutation

We're working on web3.0 decentralized internet, a big part of which is a decentralized file storage system where clients upload files to storage providers and pay them for the services. Storage ...
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83 views

How to hide multiple types of information in the same file?

I have a vague memory of watching a video of a guy "unraveling the secret story / lore" from the game Doki Doki Literature Club. And I remember that he took a file, converted it to .txt and ...
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2answers
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How much data can we encrypt using AES 256 before changing the key?

Although this question has been answered in this link (After How Much Data Encryption (AES-256) we should change key?), I am not satisfied with the answers because the Recommendation for Block Cipher ...
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Low Encrypted Entropy on PDF File

Thank you for the answers, I have edited my questions. It is a known fact that encrypting the files increases the file entropy. You can see the average entropy values of encrypted and non-encrypted ...
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File Encryption (EFS method)

I'm implementing (for learning purposes) a file encryptor, which uses the following method (from http://en.wikipedia.org/wiki/Encrypting_File_System). I have 3 kinds of keys: RSA public/private, AES, ...
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How to perform file encryption using 128-bit AES

I am confused. How can I encrypt a file using 128-bit Advanced Encryption Standard? Do I need only to encrypt the file name and it's content or is there something that I need to do to encrypt it? Is ...
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Making a secure file sharing scheme usable

I am trying to realize a secure file sharing scheme based on asymmetric crypto. Users will access this via browser. In short, it works like this: Users register and set their username and password. ...
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What's the preferable encryption for large data and files in terms of speed and security other than AES?

First of all, I'm relatively new to encryption so please bear with me. I'm looking for a way to encrypt large amounts of data only on my device, no need to transfer my encrypted files/data (10-20GB or ...
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Can elliptic curve (25519) be used to encrypt file?

This is probably a simple question, but I haven't been able to see it stated anywhere. Is it possible to directly encrypt a file (of any length) with some form of EC using the 25519 curve. I know it'...
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349 views

Encrypt a big file in blocks with AES-GCM: how many nonce do we need?

I need to encrypt big files using AES-GCM, potentially 10 GB or more. For memory (RAM) reasons, I need to processs them by blocks (let's say 16 MB), rather than doing ...
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How to be able to change the password to access data encrypted with AES-GCM, without reencrypting?

Let's say you need to encrypt plaintext which is 1 TB big. You have a password pwd. This very classical AES-GCM process is ...
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1answer
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How to encrypt many files with AES-GCM, without running the key derivation function each time?

Linked question: AES encrypting multiple files With a password, I have 100k files to encrypt. (Maybe 100k files today; or maybe 50k today, 10k tomorrow, and 40k ...
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1answer
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End-to-end photo storage

I've been tasked with developing an app that will need to store photos a user takes securely, and I've been struggling to think up a method to do this. What I was thinking so far is as follows: When ...
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3answers
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Reusing AES-CTR Keys and IVs for File Encryption

I’m implementing some file encryption module with random-access capability and AES-CTR seems the right way to go. I understand that reusing Keys and IVs can expose the file to ‘Stream Cipher Attacks’ ...
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1answer
322 views

AES-CTR security if S-boxes substituion is omitted?

I understand why s-boxes are needed in general especially when ECB mode is used(because of using the same key for encryption of other blocks)but I wonder if it's ...
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1answer
248 views

Is it dangerous to encrypt lots of small files with the same key?

I want to encrypt 1000s of old files on old hard drives before uploading them to the cloud. I'm planning to use AES-GCM with only one or a few keys. (I'm using Apple's CryptoKit library which provides ...
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Twofish vs. Serpent vs. AES (or a combo)

I've seen some posts and info online, but they are from 2009, 2010, 2011 or 2012, which is 3-6 years ago, which is a very long time. So I'm looking for an up-to-date answer about which of these is the ...
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How do I safely encrypt a file for transport and storage?

So I need to encrypt a file server-side for transport from server to client and storage on client-side. I'm quite confused as to what I have to watch out for, as it seems like it's insanely easy to ...
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1answer
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Can I use my own implementation of a widely used, supposedly secure cryptographic algorithm for securing data at rest?

I know you shouldn't roll your own crypto and generally its not a good idea to implement (and then deploy) any extensively tested and recommended algorithms by yourself either. I have already seen ...
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How Should Form Input be Encrypted for sending to a Server?

I apologise if this question is a duplicate. I couldn't find any similar questions. I am writing a web app that consists of a series of drop-down style question menus. These generate more drop-downs ...
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1answer
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Proper way of encrypting large files with AES-256-GCM

I would like to encrypt and decrypt files with AES-256-GCM. I need a solution that works with Java, PHP and JavaScript. In practice, users can upload, download files via web browser and/or desktop app ...
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1answer
106 views

Reducing a 64 digit integer to 10 digit

Situation:- I am using Python. I am using RSA and I am using two 64 bit keys. I am not an cryptographer . I can provide you the RSA code if needed but i am not posting it as it doesn't have to do ...
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Does encrypting different versions of the same file or folder with the same key make it easier for hackers to attempt the decoding?

Assuming the hacker has access to the ciphers of each of the versions, will it help him/her to decipher the original file(s) by doing some sort of comparison of the ciphers?
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Is it safe to use file's hash as IV?

I'm encrypting some files using AES in CBC mode. I'm also using file's digest (SHA-1) to check that data is decrypted correctly (so I need to store it with file). Is it safe to use this digest as ...
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1answer
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Does Encryption add difficulties to File Recovery?

Seems Yes. People always tell us, it is very hard (or almost impossible) to recover an encrypted hard disk. But after a second thought. I think this is not true. Given that we know the KEY, and the ...
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How to crack rar file with protected pass with only the AES-256 key [closed]

I have rar with protected pass.But I have the AES-256 key can I crack it and if I can. how?
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2answers
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Is this correct/incorrect password for file encryption scheme secure?

I'm writing an AES file encryption program, and I'd like to put in a way to tell whether or not the user has entered the correct password without decrypting the entire file and GCM telling me the tag ...
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How to recover deleted-recovered windows efs-encrypted files?

I'd some EFS-encrypted files on a HDD which were deleted unintentionally. I used a data recovery software to restore them, but afterward, windows does not recognize those recovered files as encrypted ...
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What are the general rules to follow if I want to design a block cipher suitable for file encryption? [duplicate]

Can you please tell me what should be the quality of an encryption function using a key size of 256 bits... I realized from my previous question that a simple XOR of plaintext (256 bits) with a ...
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Isn't the use of public key encryption a redundant step in Encrypting File System, which doesn't improve the security of the File Encryption Key?

With EFS, we know that a symmetric key, File Encryption Key (FEK), is used for encrypting files. The FEK is then protected by encrypting it with the public key of the user that can be recovered by ...
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Safest method for encrypting a file on a local machine

I am looking for a safe method to encrypt a local file on my machine. Let's say I have a file containing my logins and passwords -- how can I make sure that the encryption is reasonably sufficient in ...
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A specific way for deniable encryption

I read the summary of deniable encryption on wikipedia: https://en.wikipedia.org/wiki/Deniable_encryption Then I read a question, by doom123 on security.SE: https:/...
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Learning to encrypt/encryption algorithms [closed]

I am a beginning programmer interested in coding an application of my own to encrypt sensitive files of mine. For example: lists of passwords, bank accounts, Credit Card numbers etc. I was wondering ...
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Is the decompression of compressed and encrypted data without decryption also theoretically impossible?

We have two communication points in an information system, call them A(lice) and B(ackup). B has to store encrypted data received from A. The storage of B is encrypted, but not compressed1. B should ...
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Is EFS vulnerable to chosen plaintext attack?

I have some backup files encrypted with EFS, but I lost the EFS certificate--thus I am unable to decrypt the files. I understand that EFS uses the user certificate public key to encrypt the symmetric ...
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1answer
949 views

How does gpg know what cipher algorithm is needed for decryption?

I am using gpg to make encrypt a tar.gz. My first try uses --verbose --symmetric and then the decryption is done with ...
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1answer
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In GnuPG, what's the difference between --s2k-cipher-algo and --cipher-algo? [duplicate]

I want to change some encryption options while using GnuPG to encrypt a file symmetrically. 1) However, for choosing the cipher algorithm, GnuPG has two commands and I don't know which one to use. ...
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AES encryption with 2048-bit RSA key

I have the following draft to keep my data secure in transit. Generate 2048 bit RSA key sha256sum that private key and use that sum as aad, key and iv parameters in the following aes encryption ...
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How to check a file was encrypted (really & correctly)

I would like to audit how an implementation of an encryption algorithm is really performed with the following given data of the problem: the encryption mechanism is reversible (this isn’t a signature)...
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1answer
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Encrypting (CBC) identical files with same key and different IV, is it less secure?

I would like to learn more about cryptography. Let's say you encrypt multiple files with CBC encryption using the same key, but each file has a unique (and pseudorandom) IV. Does this weaken the ...
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What is safer: ZipCrypto or AES-256?

Like in title: which one of these encryption methods (ZipCrypto, AES-256) is more secure and why? I am asking about it because I'd like to know which should be preferred when compressing files with ...
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1answer
253 views

Best practices when encrypting a file with three different ciphers [closed]

I have some files that contain important information, so I want to encrypt them by the most secure encryption method possible. I've read countless StackExchange answers on similar questions and some ...
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1answer
86 views

How to encrypt sensitive files in a business application? Is it needed? [closed]

I'm currently working on a business Java application, and we store sensitive files related to our users. What is the appropriate approach to store them securely? Is it viable to encrypt/decrypt all ...
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1answer
115 views

Authenticated encryption and file data integrity

I've got a task to provide the integrity and an authenticated encryption for files in our application. I need an assurance if my way of thinking is correct. I can't use AES GCM, I have to stay with ...