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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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1 answer
73 views

"Appendable" encryption scheme

Are there any encryption schemes that could be classified as "appendable"? By appendable I mean being able to add new data to the end of already encrypted data, without needing to decrypt ...
9 votes
3 answers
33k views

Best way to generate a IV for AES-CBC when encrypting files?

The situation is that I want to use symmetric encryption to store some info in files. I'm going to use AES-CBC algorithm. The user is going to remember the password (meaning it will not be stored ...
0 votes
0 answers
46 views

ChaCha20 1Gb encryption speed question

I wrote a simple implementation of ChaCha20 encryptor for files in C using MbedTLS implementation. The process of encryption is standard - I set key, then for each block of fixed size I generate new ...
0 votes
1 answer
516 views

Why does symmetric encryption not provide authentication and integrity? Is it only this type of encryption or cryptology in general have this issue?

Studying for Cryptology and came across a presentation regarding on "Integrity vs Authenticity" where the discussion briefly mentions how Encryption "does not provide integrity or ...
3 votes
1 answer
421 views

Is there any way to measure entropy of encryption algorithms in python?

I am new to cryptography and I am trying to find a way to measure ciphertext entropy of encryption algorithms such as AES, Chacha20, etc for a school project. Is there any way to do it on Python? I ...
2 votes
1 answer
102 views

Would encrypting several layers of a filesystem be a waste?

I've been thinking about ways to improve the security of my data stored and backed up using the "3-2-1" method. Moreover by using several layers of encryption to encrypt and decrypt a ...
78 votes
2 answers
180k views

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 ...
10 votes
3 answers
15k views

Encryption of big files in Java with AES/GCM

I have to encrypt big files. Say their size ranges from 500mb to several of gigabytes. I would like to use AES/GCM/NoPadding as provided by Java 1.8 since that gives me automatic authentication and ...
-1 votes
1 answer
333 views

What's the best encryption algorithm for storing files on a server?

I'm making a cloud-based service. So, basically, my users will be able to upload files (any type of files) and they will be uploaded to a server. I am aware that I have two options: Upload the files ...
2 votes
3 answers
179 views

Long Random Key and XOR - How Secure?

I have an application that encrypts files in the following manner (I think I can hear sighs already but bear with me): Start with two byte arrays generated from random strings of lengths l1 and l2 (...
1 vote
1 answer
176 views

Deterministic salt for KDF

What would be recommended way to make deterministic password based file encryption? I can use SIV mode, but KDF (like Argon) takes salt for which I could use SIV tag, but I cannot make it because I ...
7 votes
4 answers
2k views

Is Porticor's "homomorphic" key encryption something that can really be done or is it just marketing hype?

Porticor has an interesting file encryption offering for encrypting and decrypting files in an MySQL database quickly. They are an Amazon AWS (Amazon Web Service) Partner Network technology partner ...
0 votes
2 answers
497 views

File Size Shrinks After Encryption

I am a Bitcoin enthusiast, but I have never been formally trained in the study of computer science and cryptography. Recently, I tried a new way to encrypt my private key: I wrote it down on a paper, ...
3 votes
1 answer
496 views

Encrypt multiple chunks of data with an AEAD

Assuming that I want to encrypt a 1 GB file with e.g. AES in GCM mode or ChaCha20Poly1305. [I'm specifically referring to the cryptography module for Python: https://cryptography.io/en/latest/hazmat/...
-1 votes
2 answers
1k views

Can I 100% trust the PBKDF2(HMAC-SHA256) AES-256 CBC encryption algorithm for file encryption purposes or not, and why? (Winrar) [closed]

I am not an expert in cryptography and therefore I would like to address this problem to people who have been working on this topic for a long time and thus verify the facts from several sources. I ...
0 votes
1 answer
712 views

GnuPG - provide encryption key for AES rather than deriving it from passphrase

I'd like to encrypt a file with AES256 and provide my own 32-bytes for the encryption, rather than having GPG derive it from the passphrase. I could not find such option, but I'm thinking about a ...
1 vote
1 answer
43 views

multi-user deterministic symmetric encryption

I was wondering whether there exists a symmetric encryption scheme such that there is 1 sender and n receivers. Each receiver has 1 random and independent symmetric key. The sender knows the ...
-3 votes
1 answer
3k views

Best complementary algorithm to AES [closed]

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 ...
2 votes
1 answer
110 views

Get Pixel Data from JPG/JPEG but still bring the integrity? [closed]

As far as I know, JPG is a lossy image compression format Meanwhile, BMP is a generally uncompressed image format, whose file structure consists of bitmapFileHeader (14 bytes) and bitmapInfoHeader (40 ...
3 votes
2 answers
2k views

What are best practices for long term storage (~20 years) of encrypted / sensitive files?

I have some very sensitive family files that I want to store in the cloud on multiple providers for maximal reliability and redundancy. It's essentially a large archive of all our family photos, ...
0 votes
2 answers
745 views

Hash Comparison to Detect Ransomware File Encryption

As detailed in a separate question, I thought I had a way to detect the type of ransomware that encrypts files silently, and then decrypts them on the fly, so as to prevent the user from realizing ...
0 votes
1 answer
421 views

Is CBC mode of encryption still safe as long as it's not use to send messages over a network?

I'm still reading about the Padding Oracle attack and Side Channel attack that can be performed to decrypt cipher text encrypted with CBC though it's still not clear to me. But base on my little ...
0 votes
1 answer
166 views

Does using ECB mode of Vigenère cipher on files (no plain text) with a key of 10,000 byte(char) is secure in today's standard?

Hi I'm fairly new to studying cryptography and I'm just curious about the security of Vigenère cipher. Given today's powerful super computers, how secure/unsecure does Vigenère cipher can get? let us ...
0 votes
3 answers
3k views

Encryption using ASCII instead of bits and bytes (clarification in the body)

I am new to cryptography and I am trying to understand something. I searched it on the internet, though the question is probably a simple one, couldn't find an answer. So, please don't judge me by ...
0 votes
0 answers
24 views

How does encryption systems encrypt strings? (More clarification in the explanation) [duplicate]

I am new to cryptography and I am trying to understand something. I searched it on the internet, though the question is a simple one, couldn't find an answer. So, please don't judge me by that. Here ...
1 vote
1 answer
132 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 ...
1 vote
2 answers
571 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 ...
0 votes
0 answers
109 views

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.
2 votes
1 answer
3k views

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? ...
1 vote
0 answers
39 views

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, ...
1 vote
1 answer
292 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 ...
1 vote
1 answer
253 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 ...
2 votes
2 answers
779 views

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 ...
1 vote
1 answer
198 views

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 ...
6 votes
0 answers
570 views

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, ...
4 votes
2 answers
7k views

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 ...
0 votes
1 answer
284 views

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. ...
1 vote
3 answers
3k views

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 ...
7 votes
4 answers
6k views

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'...
2 votes
2 answers
2k 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 ...
0 votes
2 answers
146 views

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 ...
2 votes
1 answer
453 views

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 ...
2 votes
1 answer
72 views

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 ...
6 votes
3 answers
1k views

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’ ...
3 votes
1 answer
523 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 ...
3 votes
1 answer
1k 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 ...
17 votes
2 answers
70k views

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 ...
1 vote
1 answer
559 views

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 ...
2 votes
1 answer
107 views

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 ...
0 votes
0 answers
41 views

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 ...