Tagged Questions

The Advanced Encryption Standard (AES) is a symmetric-key encryption standard adopted by the U.S. government. The standard comprises three block ciphers, AES-128, AES-192 and AES-256, adopted from a larger collection originally published as Rijndael.

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2answers
409 views

How to implement shamir's secret sharing algorithm using AES_ENCYRPT

I am using MySQL AES_ENCRYTP() and AES_DECRYPT() to store sensitive details in a database, and currently storing the key in a php file outside of the web root with read access only. The key file looks ...
2
votes
2answers
844 views

Login system using authenticated encryption without storing user password

I'm not a security expert, so I might be asking a silly question, but let me describe what I am thinking about. First, I know that a lot of web sites store hashed/encrypted passwords which could be ...
2
votes
1answer
83 views

Is it safe to derive an IV partially from the secret data if it is hashed before use?

To help ensure uniqueness of IV's used in a CFB AES-256 cipher, software I know of gathers bits from various sources including the plaintext being enciphered, and runs that through an SHA-256 hash. ...
0
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1answer
225 views

Should I run my password through Bcrypt before using it for encrypting a file with AES-256? [duplicate]

I need to encrypt a file with a password that can be memorized. So I was thinking about running the password through some rounds of Bcrypt before using it for AES encryption, so every time I want to ...
2
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2answers
197 views

What's wrong with using AES directly/“raw”?

When developing applications that require crypto routines, I know to use libraries like keyczar and libsodium rather than "raw" crypto routines myself. However, for the specific case of using AES-CBC ...
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1answer
492 views

Is AES more secure than Rijndael? [closed]

Which algorithm is generally considered to be more secure, and is AES-192/AES-256 still considered to be secure? After reading this it's lead me to belive that the Rijndael algorithm would be a more ...
2
votes
1answer
419 views

AES in CTR mode with same random IV to create same ciphertext

I am currently working on a little project. I am trying to generate an AES key with that I would like to encrypt a private RSA key. I have to do it this way. However, I do not want to save the AES ...
-2
votes
1answer
801 views

Cascading Encryption Algorithm using mcrypt or GnuGP

I'm trying to a cascading cipher encryption algorithm to encrypt a textfile via mcrypt. I'm essentially trying to emulate the behavior of TrueCrypt, where it can cascade two or three different cipher ...
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1answer
2k views

Using JTR to crack Skype Passwords

The scenario: coworker's Skype somehow lost his auto-fill password. He doesn't remember it anymore, and the account is hooked up to an email address that no longer exists. He's never purchased any ...
5
votes
2answers
5k views

Encrypting using AES 256, do I need IV? [duplicate]

I'm looking into encrypting with AES using a 256bit key, and I notice that a number of methods in various languages, for instance http://php.net/manual/en/function.openssl-encrypt.php, and I notice ...
12
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1answer
4k views

Different performance of openssl speed on the same hardware with AES 256 (EVP and non EVP API)

If I run openssl 1.0.1e like this : $ ./openssl speed aes-256-cbc (i.e without EVP API) Doing aes-256 cbc for 3s on 16 size blocks: 14388425 aes-256 cbc's in 3.00s Doing aes-256 cbc for 3s on 64 size ...
3
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1answer
229 views

Remote System Administration of an Encryption-Switch-Encrypted Infrastructure

I can't seem to find a decent explanation anywhere of the practicalities of remote system administration (e.g. SSH) of an encryption-switch-encrypted SAN-stored infrastructure. The environment will ...
2
votes
1answer
654 views

Is OpenSSL AES GCM standardized?

I have been reading about the perils of not going the pages of my own encrypt-then-mac implementation, because there so many things can go awry. So decided to use EVP_aes_256_gcm. But some questions ...
7
votes
6answers
622 views

Is leaking the hash of your encryption key a security risk?

I've been trying to design a simple archive format, that allows me to just bundle a bunch of encrypted files together. The idea, I currently have is to embed not the encryption key but a truncated ...
5
votes
5answers
7k views

RSA maximum bytes to encrypt, comparison to AES in terms of security?

What is the maximum number of bytes for encrypting a plaintext message using RSA that is reasonably secure and also efficient and would AES be better for the same size in bytes? The encryption doesn't ...
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2answers
1k views

Questions to hybrid encryption. RSA with AES

I want to use a hybrid encryption in my application, so after reading a lot of lines I ended with this implemantation, please critizie it ;) (I want to stick to .Net) byte[] aesKey = ...
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votes
1answer
164 views

What mode of operation is secure for block ciphers?

as RC4 is not secure and AES-CBC is same thing the only solution is using EAX mode for AES. but why mozilla NSS don't support EAX mod ? is there any secure EAX implementation ? and why wikipedia says ...
2
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2answers
454 views

7zip AES encrypted archive, padding oracle attack

I created an encrypted but forgot the password. When I attempted a pattern based brute force it said it had over a 100 trillion passwords to check. And to my knowledge that could take a few years. ...
4
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2answers
2k views

Where do I securely store application-specific symmetric key?

I am writing an application App1. This application uses SQLite database and I plan to encrypt it using AES256. For symmetric encryption I need a key, which I need to store somewhere. From a similar ...
2
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1answer
1k views

Can active attacks really decrypt a particular AES-256, CBC, PKCS#7 encrypted file?

I recently found out that active attacks are a threat against AES-256, CBC mode, padded with PKCS#7 (the CBC mode in particular. I should supposedly change to EAX to guard against these attacks). ...
6
votes
2answers
429 views

How less secure is an encryption if we know something about the original data?

I have a number of files encrypted with a key derived from a password. In line with standard practice, I use a random salt and password and do many PBKDF2 iterations to obtain an encryption key and ...
0
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1answer
3k views

How does PKCS#7 padding work with AES-256, CBC mode?

I'm a bit confused with AES-256, CBC, and how it works with padding (PKCS#7). Whenever I encrypt data of multiples of 16 bytes (the block size), extra 16 bytes are always padded at the end. For ...
3
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2answers
1k views

LastPass One Time Recovery Passwords--How?

The LastPass password manager stores One Time Recovery Passwords locally in each browser you use the plugin with: http://helpdesk.lastpass.com/account-recovery/ My question is, how can you have more ...
3
votes
1answer
1k views

Key length and hash function in PBKDF2

On this page: http://www.ruby-doc.org/stdlib-2.0/libdoc/openssl/rdoc/OpenSSL/PKCS5.html they make a statement that strikes me as rather weird: Key Length Specifies the length in bytes of ...
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4answers
553 views

Is it safe to have the salt equal to IV?

If I'm using AES-256 CBC to encrypt, getting the 32 byte key using multiple iterations of the PBKDF2 function with a 16 byte salt, is it safe for me to let IV be equal to the salt? (Edit: The salt is ...
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1answer
217 views

Key distribution advice

I have been thinking for days about that problem! The application is based on a student system management. I am implementing database encryption on a column level and The encryption occurs at the ...
3
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2answers
245 views

Confidentiality and integrity for web session

When the client authenticates with our service, he is issued an opaque "token". This token includes the information, that identifies the client and some other information about the client ("payload"). ...
0
votes
1answer
672 views

What AES mode does SQL Server 2012 use?

I looked at this link that shows how to encrypt a SQL column via a certificate (RSA??) and AES256. I created a dummy table (script at GitHub) intentionally using identical plain text (Credit Card = ...
4
votes
2answers
5k views

How X509 Certificates are used for Encryption

I have small doubt regarding the process of X509. I am aware of OpenPGP Encryption/Decryption, where we generate the public key and private key. We can share the public key to vendors and they can ...
1
vote
1answer
296 views

AES encrypt secret key with plaintext

We need to be able to retrieve password. Hashing is one-way, we can't do that. So we ended up using AES. We want to know if the following schema is safe or not. I am only familiar with modulo PK ...
2
votes
2answers
215 views

Slow down symetric encryption

I'm developing a program in Java. In one step data should be encrypted and exported in a file. As of now we are encrypting in AES-256 I want to slow down a possible brute force attack as much as ...
0
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2answers
4k views

Why does OpenSSL not include AES-256-GCM? [closed]

I'm trying to implement AES-256-GCM in Ruby. Ruby's OpenSSL wrapper library and aead library both clearly seem to believe that OpenSSL itself supports this. However, neither 0.9.8r (which I had ...
1
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1answer
2k views

Weakness of AES OFB mode

I found these comments regarding AES OFB Mode "This mode is a slightly less common mode, quite similar to CFB above, but which should not be used as a stream cipher due to inherent weaknesses when the ...
0
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1answer
112 views

Securing the SOAP Messages

One of my clients wants to encrypt few sensitive information which will be transferred through webservices / SOAP. My client has the following suggestions: Encrypt the sensitive data with AES ...
5
votes
2answers
2k 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, ...
3
votes
1answer
2k views

aes cfb 128 decryption /encryption problem between Erlang and PHP

Update 2 - it works Thanks to Tom Leek for his answer. The CFB mode of mycrypt for Rijndael uses a 8-bit feedback loop and not a feedback loop the length of the key/iv. You have to force it to use ...
5
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3answers
9k views

AES CBC padding when the message length is a multiple of the block size

Assuming that a 32-byte plaintext is encrypted by AES 128 CBC - is it mandatory to add 16-byte padding, according to the different padding schemes?
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2answers
625 views

How to correctly implement AES in a backup application

I am writing a back-up application which should have the feature of encrypting the back-up. It must encrypt file data, paths and filenames. The application is being written in C# (.NET). Target is ...
3
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2answers
243 views

Remedy for not having filled the disk with random data?

Filling a large HDD with /dev/urandom prior to encryption can be extremely slow (even with netcat, multiple instances in parallel, etc) and for this reason I'm sure a lot of users skip this advice ...
10
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1answer
5k views

Is AES-GCM recommended for SSL?

I'm looking at turning on site-wide SSL for a website I manage, and I'm wondering what the best practices for SSL configuration. I'm not too worried about compatibility with old browsers and more ...
5
votes
1answer
2k views

Security of bcrypt/sha256 key used with AES to encrypt a file

I'm looking to encrypt files using secure hashing and encryption algorithms in Python. Having used bcrypt in the past, I decided to use it for my passphrase calculator, then pass the output through ...
1
vote
1answer
182 views

Need advice on Cryptography digital files project

I have to choose a topic for my end-of-year school project and I need some advice. I was thinking of implementing an online tutorial materials (digital files) project. I have been researching on ...
6
votes
2answers
388 views

Implications of having a service account in AD use RC4 rather than AES for Kerberos?

Bear with me, I know this is sloppy, but here is the back story: We have a partner that uses Jira and is using spnego with a custom auth back-end that expects certain group membership in the token. ...
1
vote
1answer
207 views

Implementation review - Independent key, admin side and user side

The admin of the website needs to read user data. So, if the key is derived from the user pass, then the admin has to know the user pass, not exactly a good idea. The following encryption scheme was ...
5
votes
2answers
7k views

openssl: recover key and IV by passphrase

A large amount of files were encrypted by openssl enc -aes-256-cbc -pass pass:MYPASSWORD Openssl should derive key+IV from passphrase. I'd like to know key+IV equivalent of that MYPASSWORD. Is ...
5
votes
2answers
4k views

Pitfalls of SSD encryption

Encrypting an SSD is a process that is sometimes warned should be done with caution. E.g. http://en.gentoo-wiki.com/wiki/DM-Crypt_with_LUKS mentions how the SSD may keep hidden space used for wear ...
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2answers
674 views

Filling the disk with random data prior to encryption?

Filling the disk with random data prior to encrypting it will supposedly make it harder for the attacker to perform any cryptanalysis. Most sources seem to state this is because it will be harder for ...
16
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2answers
27k views

Security comparsion of 3DES and AES

Which one is more secure and least possible to be broken through cryptanalysis AES or 3DES (no matter performance)? I need to use encryption for my projects to store and secure sensitive information ...
0
votes
1answer
228 views

Password protection of encryption and signature keys

I would like to store encrypted backup of text files on my computer. I'm developing a python script using Pycrypto to achieve that, based on this code to use the library. (current code) The basic ...
6
votes
2answers
3k views

WPA2 Enterprise AES encryption key size?

I have recently set up a RADIUS server with EAP for my wireless router, however, I have some questions about the key size and how WPA2 enterprise (AES) works in general. I have read that in ...