Linked Questions

7
votes
3answers
8k views

File security when encrypting files directly with the openssl command / and what about SHA1 hashing password first?

I've been using this command to encrypt files for a while now: openssl aes-256-cbc -a -salt -in secrets.txt -out secrets.txt.enc Then I type in a password. Can someone tell me, roughly speaking, ...
7
votes
2answers
6k views

openssl enc uses md5 to hash the password and the salt

Wikipedia states that md5's collision resistance is 2^18 (https://en.wikipedia.org/wiki/MD5). I just found out that openssl enc uses md5 to hash the password and the salt. Let's assume that I want ...
6
votes
2answers
8k views

Basic question regarding OpenSSL and AES-GCM

While researching how to encrypt private keys for SSH connections as securely as possible, I have run into the following very basic understanding problems (Note: I have used the newest stable release ...
4
votes
2answers
10k views

With openssl des3, what are the passphrase parameters?

I'm using OpenSSL's des3 tool to encrypt a file, e.g. openssl des3 -salt -k SUPER_SECURE_PASSPHRASE < inputFile > outputFile Everything's working, but now I have to choose a final, fixed ...
7
votes
1answer
2k views

Why brute-force the password instead of the key directly?

This answer on another question on security stackexchange by a very reputed user explains why he prefers GnuPG over OpenSSL for file encryption. From what I understand, it can be summarized as this: ...
4
votes
1answer
5k views

Which file encryption algorithm is used by Synology's Cloud Sync feature? [closed]

I'm trying to find out which encryption method is used by a piece of software I use, viz. the 'Cloud Sync' feature of Synology's DSM 6.0 running on a Synology NAS. (Background. This Cloud Sync ...
2
votes
1answer
2k views

openssl problem decrypting passhrase-encrypted file using the derived IV, Key and Salt

So I followed openssl: recover key and IV by passphrase and managed to retrieve my salt, key and IV using -P in openssl. openssl enc -aes-256-cbc -in encrypted -pass "pass:password" -out m.jpg this ...
4
votes
1answer
2k views

IV Reverse AES-256-CBC PKCS#7

I'm a freshmen in cryptography and want to know more about IV reversing. There's a lot of posts about finding the passphrase with a new IV. But what about the other situation? This is for educational ...
5
votes
1answer
467 views

Why is the Key Derivation Function important?

Let's consider this openssl command : openssl enc -aes-256-cbc -pass pass:PASSWORD Why is it important to have a good Key Derivation Function? This answer to another question suggest that GnuPG is ...
0
votes
0answers
1k views

Generate symmetric key programmatically using openssl EVP

Am learning OpenSSL EVP API and trying to understand the ways to generate a symmetric key using OpenSSL EVP in C++ program. I have two questions in this regard: 1) To understand what the command ...
0
votes
1answer
646 views

Secure file encryption with OpenSSL and a little trick?

I try to really securely encrypt a file with OpenSSL. I´m new to OpenSSL and just read here, that it´s not very secure due to it´s behavior in generating salt & IV, and storing it within the ...
1
vote
1answer
264 views

openssl - difference between passphrase (-k) and key (-K)?

I'm using openssl for a project and came across two options: -k passphrase and -K raw_key (hex). What's the difference between the two options? I've been attempting to port something from openssl to ...
1
vote
1answer
110 views

Can't recover IV from openssl output

Reading other posts like this one give me the impression that the iv can be retrieved from an openssl enc output, and indeed, I see that under one circumstance, it works: # These two commands print ...
0
votes
0answers
118 views

DigitalOcean Spaces for personal backups

Sorry for the naive question. I wonder how DigitalOcean Spaces (S3 compatible) fits personal backups. I found a lot of information about security of Amazon S3 and its security is undoubted, however, ...