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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106
votes
11answers
19k views

Technology that can survive a "Rubber-Hose attack"

In the documentary film Citizenfour, Edward Snowden says about documents: I'm comfortable in my technical ability to protect [documents]. I mean you could literally shoot me or torture me and I ...
69
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3answers
37k views

What security scheme is used by PDF password encryption, and why is it so weak?

Many PDFs are distributed as encrypted PDFs to lock out some of their functionality (eg printing, writing, copying). However, PDF cracking software is available online, which usually cracks the PDF ...
39
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7answers
72k views

Does password protecting an archived file actually encrypt it?

For example if I use WinRAR to encrypt a file and put a password on the archive how secure is it? I keep a personal journal and am thinking of doing this, or is there a better way? It's just one huge ....
23
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2answers
50k views

Brute Forcing Password to a Truecrypt-encrypted file with Partial Knowledge

A while back, I encrypted a few files with Truecrypt, and stored the password in my head. Now I need to access it again, the password isn't working. I'm sure most of it is right, but I'm off by one or ...
16
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4answers
13k views

What are you doing when you move your mouse randomly during a truecrypt volume creation?

Is that called a 'round' every time you move your mouse when creating a new volume? I'm talking about the screen with the random numbers during the volume creation process. What is the purpose of ...
12
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2answers
8k views

After How Much Data Encryption (AES-256) we should change key?

Considering AES-256 encryption, what is the maximum amount of data should be encrypted with one key? Does Block cipher modes/IV/counters also governs the limit? If say the maximum amount is 50GB, ...
41
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5answers
57k views

How secure is a Windows password protected zip file?

I need to send some sensitive information to a client. I thought I would email a password protected zip file I created using Windows XP and then call them with the password. Presuming I pick a good ...
33
votes
6answers
35k views

How secure is NTFS encryption?

How secure is the data in a encrypted NTFS folder on Windows (XP, 7)? (The encryption option under file|folder -> properties -> advanced -> encrypt.) If the user uses a decent password, can this ...
14
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1answer
88k views

Forgot password to 7-Zip archive

I think I already know the answer to this question, but I thought I'd ask the experts anyway. A few months back, I created a password-protected 7-Zip archive which housed the source code of a simple ...
19
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8answers
11k views

Are there any "real world" implementations of secret-sharing encryption schemes?

Imagine something like TrueCrypt where user A can decrypt his files, or any 3 of the 10 directors in his organization can decrypt user A's files. As I understand it this is similar to the way the ...
27
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3answers
11k views

Is EncFS secure for encrypting Dropbox?

I've encrypted my Dropbox folder with EncFS according to a few tutorials I found on the web, advocating this approach. But I've found the following critical statement concerning EncFS's security in ...
4
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3answers
594 views

Safely remove original file after encryption

My application encrypts a file, and the result is written to a different one. How do I safely remove the original one (C++)? Update. Wow! The problem is more complicated than I thought of it... 1) ...
61
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4answers
112k views

Why would I ever use AES-256-CBC if AES-256-GCM is more secure?

I guess the gist of my question is: Are there cases in which CBC is better than GCM? The reason I'm asking is that from reading this post by Matthew Green, and this question on cryptography stack ...
20
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9answers
17k views

Keep encrypted files in sync on a cloud service, without having to upload an entire encrypted volume each time

Situation: User has several folders worth of GBs which they want to keep in sync on a cloud service (for example Mega or Dropbox) in an encrypted form; User does not want to sync a single encrypted ...
15
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4answers
12k views

What's the standard way to encrypt a file with a public key in Java?

I'm writing a client app in Java that sends encrypted data back to the server. All clients have my RSA public key. Is there a standard way to encrypt a given file with it to send it back to the server?...
13
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5answers
12k views

How can I decrypt data with Java, without hard-coding the key?

I hope this is not a chicken-egg problem or reinventing the wheel but here goes. I have a Java application that needs to access a password protected file (actually during the application startup). The ...
3
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2answers
3k views

How to protect from copying files?

Is possible to protect files from being copied if you are the administrator of a machine? I heard that this behaviour is possible: one software developer sells his software in such a way. He installs ...
13
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2answers
3k views

Is ccrypt 'AES 256' file encryption fundamentally flawed

The unix/linux utility ccrypt claims to be a more secure replacement for the old unix crypt. However it seems to me that it has a fundamental flaw. When you encrypt a file using ccrypt it uses the ...
11
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12answers
14k views

How can I share files with other individuals using the cloud in a secure way?

I would like to use a dropbox because it is easy and convenient. But I want to encrypt the files with the public key of the intended recipient, so he will be the only one who can access the data in ...
10
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2answers
4k views

Microsoft Office 2013 File Encryption

To what extent can the native file encryption provided by Microsoft Office 2013 (Word, Powerpoint, Excel, etc.) be relied upon to maintain the confidentiality of documents, especially within the ...
8
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3answers
661 views

Secure cleaning of deleted files

So I know how to secure delete files. But at our company, we have a laptop which had many important documents, which now have been deleted, but not in a secure way. We can't perform a full format of ...
6
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2answers
897 views

Decrypting arbitrary offset of encrypted file

I want to store encrypted files on some storage backend that allows me to fetch bytes X through Y of the encrypted file. I can obviously decrypt the entire file locally and send it back to the client. ...
4
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1answer
3k views

Encryption Using 7z or Zip File

I'm wondering which encrypted 7-Zip file format has better encryption: 7z with 256 AES or zip file with 256 AES? Assume that a strong password is used, then which encrypted 7zip file format has ...
53
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5answers
383k views

How to recover a lost zip file password?

I have some files I was given by my teacher at University, I could chase him up, but I may as well try getting blood from a stone, his response rate isn't great and I completed my degree a year ago! ...
21
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3answers
4k views

Would it be plausible to write your own anti-crypto-ransomware tool? [closed]

Question After reading about how basic ransomware targets and encrypts your files. I was wondering if it would be plausible to write your own script to try and detect such activities? Initial ...
13
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1answer
1k views

Secure backup encryption with OpenSSL

I know, the general advice is "keep your hands off crypto stuff". And the standard way to encrypt backup data securely would be using GnuPG. However, for a rather academic exercise, I would like to ...
22
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2answers
3k views

Does File-Based Encryption offer comparable security to Full-Disk Encryption on Android?

Between version 4.4 and 9, Android supported Full-Disk Encryption (FDE). On Android 7, a new system called File-Based Encryption (FBE) was introduced, and was subsequently made mandatory on Android 10....
14
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4answers
2k views

Encrypting data by parts vs encrypting the whole data

Suppose I have a file with records, and I have two options to encrypt it: encrypt the file as a whole encrypt each record separately and store them together. Which way is generally preferable and ...
8
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3answers
2k views

time to crack file-encryption password - more than just iteration

I have often seen that takes x amount of time to crack a certain length password. But this just seems to be the amount of time it takes to iterate through all the possibilities. What about the time it ...
11
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3answers
3k views

Linux Plausibly Deniable File System

Is there any way to encrypt a Linux filesystem in such a way to maintain plausible deniability? E.g. "Hidden OS support," the way TrueCrypt and Veracrypt work, they only support Windows OS due to low ...
5
votes
1answer
404 views

Is there readily available encryption algorithms for current computers, that is safe from quantum computers?

Is there readily available encryption algorithms for current computers, that is safe from quantum computers? I know a bunch of currently popular encryption algorithms that are safe from current ...
4
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2answers
1k views

Security review: is this PHP mcrypt wrapper class safe?

> **Update (6 February 2015):** > It seems like the class in question has actually updated as a response to the answers here (through an issue, now closed, raised on github). I was looking for an ...
2
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2answers
964 views

Is it safe to store encrypted volumes on cloud syncing services?

A recent discussion on another website prompted a proclamation that storing (TrueCrypt, LUKS, DMG, etc) on cloud sync services like Dropbox is unsafe, since a version history is kept of each file, and ...
2
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3answers
2k views

Do file-encrypting software give a false sense of security? [closed]

I sometimes use a VeraCrypt volume to store personal data (mostly backups from another computer) on a Windows computer I don't own. But I learned over the years that modern OSes store users' data in ...
1
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2answers
1k views

Various questions about file compression and encryption regarding hacking (zip, rar, 7z) [closed]

So I'm curious about a few aspects of compressed files (Zip, rar, 7z, etc), and how they impact hack-ability. There is enough on this subject that I'm not clear about (since this isn't a career of ...
12
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5answers
1k views

Security of using passwords or even passphrases to encrypt files

Is it ever appropriate to use real-world passwords to encrypt files to be sent via unsecure means. By real world, I mean a password that is memorable and memorisable by a mere person? I am implying ...
11
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4answers
14k views

Are MySQL's database files encrypted?

I'm trying to securely store user credentials in a MySQL database which is hosted on a different server than the application (the communication between the two is secure). I have initially assumed ...
10
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4answers
2k views

How to quickly find out what the threat nature of a password protected archive is without getting infected?

I have recently received an e-mail from an existing support group e-mail box with the following characteristics: written in the language used in company's HQ (different from English which is the ...
9
votes
7answers
5k views

Verify the password of an encrypted file without waiting for complete decryption

I am currently working on an application that encrypts files with AES 256. The problem is that I want the user to see whether the password is wrong before the file is decrypted. For example if you ...
8
votes
1answer
2k views

PDF file encrypted with my password, does that mean my password is stored in plaintext?

Every month, I receive an encrypted Portable Document Format (PDF) file with my payslip. I can open the file for reading with my password. Without providing my password, I cannot open the file at ...
7
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6answers
1k views

Applying file deltas to an encrypted file

I am developing software that will be used for data backup. The server will run on Linux. Security in transportation is not an issue (HTTPS or SSH), but the data must be stored encrypted on the ...
5
votes
3answers
955 views

Is it safe to store my login credentials in a Veracrypt volume?

I have a list of login credentials (usernames and passwords) that I wanna keep safe. I'm planning to keep it in an encrypted Veracrypt virtual drive with AES, SHA-512, and an 8-character password. Is ...
3
votes
1answer
592 views

Is there a ransomware variant that checks for file's magic numbers to encrypt?

Is there a known ransomware-variant (Cryptolocker, Cryptowall etc.) that before encrypting the files checks for their magic numbers? Lets say that there's a Word file, that had its file extension ...
2
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2answers
2k views

How to use 'key material' so that multiple people can access protected files?

I'm not sure if this is the right SE to ask this question, but it seems more I have a database of files that needs to be encrypted such that multiple people with different passwords/logins to this ...
-2
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6answers
10k views

How to prevent illegal file transfer or copying of video files from a PC? [closed]

I have developed a windows desktop application using VB.NET. My applications main purpose is to play videos. I have some videos which has copyrights on them, that are not suppose to be distributed or ...
9
votes
2answers
11k views

can I trust Boxcryptor closed source software? Encryption of files for cloud hoster

Boxcryptor https://www.boxcryptor.com is not Open Source. Can I trust this? Is it secure? No government backdoor? Because there is no alternative for OS X and iOS.
8
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3answers
3k views

Encrypted password inside compressed archive

File compression utilities like Winrar or ZIP or 7zip encrypt the password and store it inside the archive. How safe is that? I mean you are giving away the archive with the password inside,it's not ...
7
votes
4answers
9k views

when people say a file has a checked md5 hash, what exactly does that mean?

ok I was just reading this site: http://www.zdnet.com/blog/bott/stay-safe-online-5-secrets-every-pc-and-mac-owner-should-know/3542?pg=4&tag=mantle_skin;content and thought of something I always ...
5
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2answers
3k views

Single File Encryption in a Windows Environment

Would it be correct to assume that encrypting a single file in a Windows environment, for example a simple text file containing login credentials for a variety of accounts, is inherently insecure? It ...
4
votes
4answers
825 views

How to securely delete a table in MS-Access?

I have a Windows 7 computer which currently has a large working Microsoft Access 2007 database on it containing some tables with confidential data. I would like to securely delete/remove the tables ...