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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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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2answers
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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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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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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? (http://www.moonbaseotago.com/onerng/theory.html).
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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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1answer
177 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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1answer
254 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
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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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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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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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1answer
575 views

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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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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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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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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1answer
538 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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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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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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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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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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1answer
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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 ...
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2answers
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What is a good AES mode to use on file encryption?

I'm new to encryption and cryptography, I was wondering if there is a good or best suited AES mode for file encryption (Planning on zipping a folder and encrypt it as a file). If there is, how complex ...
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Verifying valid public key and finding private key? [duplicate]

A naive user of RSA has announced the public key $n = 2903239, e = 5$. Eve has worked out that $n = 1237×2347$. Verify that the public key is valid and explain why the private key is $d = 2319725$. [...
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1answer
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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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How secure is a system that retrieves encrypted private keys from a public database?

The system in question is one with multiple users. Each user has a password associated with their account, and each user owns several public-private keypairs. A user's private keys are encrypted using ...
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1answer
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Which symmetric algorithm should I use for storing files in untrusted servers?

I have gigabites of files, which I have to backup. I have some servers for storing this files. But these servers are untrusted. So I need to encrypt files, then backup files. When my PC breaks down, ...
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3answers
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Reusing IV in AES for encrypting file

Everyone says that you shouldn't use the same IV and Key. Is it safe to use the same IV and Key on only one file. EDIT: I will be using CBC or CFB encryption modes so the IV will be updated based on ...
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Rsa encryption security

What tool is used to measure the security of rsa encryption? If no, is there any tool to measure rsa encryption in terms of security. Or any idea how to measure security of rsa encryption?
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Robust cryptosystem for files/chunks protection?

I'm not a cryptographic expert by far but I do understand that when it comes to cryptography it's best to stick with established standards. I have to ensure confidentiality and integrity of a bunch ...
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1answer
538 views

Why does Apple use One-Pass Diffie-Hellman for file encryption?

I was reading the iOS Security Guide (snapshot) and stumbled upon the following file protection class on page 15: (NSFileProtectionCompleteUnlessOpen): Some files may need to be written while the ...
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1answer
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A file chunk in a group/field

I am reading a paper by Shacham and Waters on Compact Proofs of Retrievability. In this paper on page number 3 under section 1.1 in the very first line the author states that an encoded file is broken ...
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Can a hash of the original plain text file be used to brute force an encrypted copy?

I have encrypted files stored on a public cloud, in the same directory on the cloud I have the sha256 hash of the files before they were encrypted in a text file. The keys used to encrypt the files ...
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Do I need to generate unique IV for CBC encryption of a file if I encrypt multiple blocks of data?

The situation is that I download a mp3 file (song) and I encrypt blocks of data (4096 bites for example). The output of every encryption operation I save it in a new file. When I play the song (...
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1answer
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Simple secret key encryption with PyNaCl [closed]

I am playing around with PyNaCl to get a bit into cryptography atm. Now I wrote two scripts to encrypt a file with a secret key and then decrypt it again using that key. The encryption part works ...
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1answer
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Best complementary algorithm to AES

I'm looking to protect sensitive data from deletion by hosting it on Amazon Glacier. I'd like to secure that data against possible hacks of Amazon by encrypting it, and I'd like for the data to be ...
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1answer
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What is the fuss about 'dot blockchain' and music metadata? [closed]

and how does it work? http://wmot.org/post/music-money-and-metadata-promise-blockchain#stream/0 claims that this is an answer to the metadata woes of the music/recorded media industry. I don't see ...
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Can multi-encrypted file be decrypted with one password only?

Let's say I have a single file I want to encrypt with AES and I encrypt it twice (first encrypt the unencrypted file, then encrypt the encrypted file again). The first time I use password 'ABC', the ...
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Conforming to best practices in password file (keyring) encryption

In order to implement a plaintext password file safe (keyring), while adhering to best Crypto practices today, I came up with this scheme: A user's master password is hashed with Argon2 (\$argon2id\$...
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AES OCB with Argon2 KDF for keyring file encryption

I've just released a python keyring companion package to encrypt the passwords in a file, available here. Description The project is mainly targeted to provide a sufficiently secure storage for ...
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What is a safe maximum message size limit when encrypting files to disk with AES-GCM before the need to re-generate the key or NONCE

The general limits from the NIST recommendation are as follows: Maximum Encrypted Plaintext Size ≤ 239 - 256 bits; Maximum Processed Additional Authenticated Data ≤ 264 - 1 bits; This stack ...
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787 views

Can I use a deterministic NONCE for AES-GCM file encryption if I generate “fresh” keys for each encrypted file

The NIST specification states that the deterministic NONCE(IV) should be 96 bits. It should consist of two fields: fixed field of 32 bits and a 64 bit counter. The use of a random 96 bit NONCE is ...
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567 views

Derivation of many (Key, IV) pairs from random 128 nonces and one secret 512 master key

The ext4 encryption system encrypt files with aes-256-xts. Each file uses two unique keys which are derived from a 512 bit master key and a per-file 128 bit nonce randomly generated when the file is ...
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1answer
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Warding an ECIES setup against MitM: ECDSA?

Is it necessary/appropriate to digitally sign an ETM file in an ECIES context? The encryption mode is CTR(using Inferno). The current output is: [shared public key] [ciphertext] [MAC]. The encrypted ...