84 votes

Technology that can survive a "Rubber-Hose attack"

Shamir's Secret Sharing is a method for this. It allows one to encrypt a file with a public / private keypair, and then effectively split up the parts of the private key to be distributed to several ...
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  • 38.1k
81 votes
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Why would an encrypted file be ~35% larger than an unencrypted one?

Most likely, the encrypted file is base64 encoded which would account for 33.3% file increase (you encode three bytes of data in four bytes of base64 data). Inserting a new line every 64 characters ...
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  • 38.7k
81 votes
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What is the attack scenario against which encrypted files provide protection?

File-level encryption can be useful in several cases, here's a few examples: Sending data over insecure channels. You mentioned TLS, and that's enough when you have it. But what if you aren't sure ...
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  • 15.3k
64 votes

Do Veracrypt encrypted volumes have any kind of brute force protection?

Any encryption is vulnerable to brute force attack, for example AES-256 has 2^256 keys, and given enough hardware we can “easily” brute force it. The problem is that there’s not enough silicon on ...
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61 votes

Technology that can survive a "Rubber-Hose attack"

All of our answers are speculation, of course, but I suspect that the most likely way that the documents are protected are by following Bruce Schneier's advice regarding laptop security through ...
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  • 1,124
55 votes
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Why would I ever use AES-256-CBC if AES-256-GCM is more secure?

CBC and GCM are quite different. Both are secure when used correctly, but CBC isn't as parallelizable and lacks built-in authentication. Due to this, CBC is only really practical for encrypting local ...
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  • 2,410
53 votes
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What security scheme is used by PDF password encryption, and why is it so weak?

There are two types of PDF protection: Password-based encryption and User-Interface restrictions. You are describing the second type of protection, namely the missing permission to copy-and-paste, to ...
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52 votes

Strongest file encryption available

The strongest possible way to encrypt data is to start with a threat model. What sort of adversary are you trying to protect your data from? What are they willing to do to get it? All reasonable ...
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  • 9,206
47 votes
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Not understanding why I should use public/private key encryption over password?

The two options are intended for different use cases. Option 1 is intended for your use case. It encrypts the file with a key derived from a password, so that only the person who knows the password (i....
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  • 10.8k
45 votes
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Is Changing a File Type and Name an Effective Security Solution?

What you are doing is no kind of encryption, it is just obfuscation. It relies on security by obscurity. It may be enough to hide your files from an amateur/casual observer, but anyone analyzing the ...
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39 votes
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VeraCrypt/TruCrypt - I can't understand why you'd want to create a "hidden" volume...?

Your first question is really a legal one, and you seem to be assuming two things: The attacker is a government of some sort. That government actually respects citizen privacy and requires some sort ...
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  • 10.2k
38 votes

Technology that can survive a "Rubber-Hose attack"

Here is an original technique I have come up with that can survive a rubber-hose attack: Get a stack of cash, about 50 one-dollar bills. Maybe mix some fives and tens in with them. Shuffle them into ...
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37 votes
Accepted

Is there any reason I shouldn't make a GPG-encrypted file publicly-accessible?

There is always a risk that any given cipher will be broken at some point and data like this will become truly public. So yes there are some risks but it doesn't mean you aren't making a reasonable ...
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  • 14.1k
32 votes

Strongest file encryption available

If you want the strongest, I’d suggest a one-time pad to encrypt the file. If you want realistic, I suggest you rather expand on what your threat model is and take advice as to the actual level of ...
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30 votes
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Why is GPG file encryption so much slower than other AES implementations?

Let's try... First, I create a 500 MBytes file full of random bytes: dd if=/dev/urandom of=/tmp/foo bs=1000000 count=500 then I encrypt it using GnuPG, measuring the time taken by that process ("...
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29 votes
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Downloading a file from a server with a secret: in text or binary?

There isn't really a difference. If you use proper TLS encryption, neither can be read by a man in the middle, and if the server properly authenticates requests, nobody who is not allowed to will be ...
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  • 29k
27 votes

Technology that can survive a "Rubber-Hose attack"

He might be referring to neuroscientific methods of cryptographic primitives such as those outlined in the following paper: https://www.usenix.org/system/files/conference/usenixsecurity12/sec12-...
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  • 2,658
24 votes
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Is it possible to read a text file inside a password-protected zip file without the password?

No. There are two ways of zip encryption, a classic one, which is weaker, and a newer one based on AES. In both cases the password is needed in order to decrypt the contents (i.e. it's not just UI, ...
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  • 17.3k
22 votes

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

Big nitpick: GCM = CBC + Authentication. Nope, GCM = CTR + Authentication. But in general you are right; CBC is an older mode that was invented back in the dark ages cryptographically speaking (...
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22 votes

Do Veracrypt encrypted volumes have any kind of brute force protection?

Didn't veracrypt creators know about this issue? (Not having brute-force protection) As Andrew Morozko notes in his answer, they have addressed this – as far as it is possible – by using a ...
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  • 1,151
22 votes

Not understanding why I should use public/private key encryption over password?

There's one advantage of using public key cryptography over private key cryptography when you're encrypting file for yourself. When you use symmetric cryptography, you need to expose the password ...
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  • 31k
21 votes

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

Why there are not already more anti-crypto-ransomware tools? Because there are. They are called virus scanners and they should have heuristic algorithms to detect this behavior. Unfortunately the ...
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  • 48.8k
20 votes

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

The main problem with password-protecting a PDF file with a password is that you are basing the security on a password, which is some piece of data that a human user, somewhere, came up with in his ...
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19 votes

VeraCrypt/TruCrypt - I can't understand why you'd want to create a "hidden" volume...?

You're wrong in your assumptions. There are many legal jurisdictions where you can be required to produce passwords for encrypted data on suspicion, rather than proof, that the data may be relevant to ...
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  • 10.1k
19 votes
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Is EncFS secure for encrypting Dropbox?

This is basically a full re-write of the answer as of Feb 2020, with significantly more detail. EncFS is reliably safe under the kinds of circumstances and threat models that most casual users would ...
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  • 82k
18 votes

How to recover a lost zip file password?

You can also use this shell script. Source: http://synacl.wordpress.com/2012/08/18/decrypting-a-zip-using-john-the-ripper/ #!/bin/bash echo "ZIP-JTR Decrypt Script"; if [ $# -ne 2 ] then echo "Usage ...
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  • 511
18 votes

Is ccrypt 'AES 256' file encryption fundamentally flawed

Password-based encryption is inherently vulnerable to dictionary attacks. Indeed, when you have the encrypted file, you can always try to decrypt it (or parts of it) with a given password and see if ...
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16 votes

Strongest file encryption available

I know nothing about cryptography. How do we encrypt a file in strongest (emphasis added) possible way such that we can access them some years later. I prefer that it should be fairly resistant from ...
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  • 4,860
15 votes
Accepted

Is it possible to use SSH agent for generic data encryption?

No, it is not at least with OpenSSH -- there are no options to operate in this mode. It is for authenticating with remote servers (validating identity) and then encrypting the network traffic between ...
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  • 38.7k

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