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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17
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1answer
23k 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 ...
4
votes
2answers
2k 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 ...
27
votes
6answers
44k 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 ...
14
votes
6answers
19k 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 ...
12
votes
5answers
7k 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 ...
12
votes
4answers
102k 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! ...
7
votes
10answers
6k 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 ...
11
votes
4answers
9k 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 ...
6
votes
2answers
197 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. ...
3
votes
1answer
19k 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 ...
2
votes
1answer
328 views

How is the FileVault master key protected?

FileVault has the functionality to both allow and disable user accounts from booting up the encrypted drive. Reference: this cnet article. See also the stack exchange question How does FileVault 2 ...
1
vote
2answers
453 views

Seeking lightweight encryption - shareable between Delphi & C

I want to encrypt a text file in Delphi & decrypt it, line by line, in C on an embedded system which does not have much RAM (so, only one line in RAM at a time). FOSS must be available for both ...
91
votes
11answers
13k 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 ...
44
votes
3answers
6k 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 ...
8
votes
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 ...
4
votes
2answers
820 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 ...
11
votes
5answers
758 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 ...
9
votes
2answers
4k 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, ...
7
votes
3answers
500 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
votes
6answers
679 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 ...
7
votes
7answers
2k 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 ...
7
votes
4answers
5k 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 ...
4
votes
4answers
626 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 ...
3
votes
2answers
3k 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.
2
votes
2answers
1k views

What does Gazzang zNcrypt actually protect against?

In an effort to increase security of our website, I'm reading up on Gazzang zNcrypt, which claims to protect data in databases from breaches. Technically, it seems to do filesystem encryption. As far ...
2
votes
1answer
247 views

AES + CBC to encrypt individual local files, fixed IV?

I am using AES and CBC to encrypt a local files separately. I don't plan to transmit them over any network. What are the risks of using a fixed IV for my encrypting application? The only problem I ...
2
votes
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 ...
1
vote
0answers
152 views

Does Sookasa really make Dropbox more secure? [closed]

Sookasa is a service that integrates with Dropbox and claims to make your files more secure by seamlessly encrypting them. In their article Is Dropbox secure? 3 weaknesses you should know about, ...
1
vote
1answer
102 views

Securing data on a mobile device (even from the user/owner)?

I am writing an application to generate OTP codes for two factor authentication where I need to securely store data locally. This data must be secure from both the owner/user as well as intruders. I ...
1
vote
2answers
2k 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 ...