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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How can I securely convert a “string” password to a key used in AES?

I'm writing some software where I have to encrypt all files that are written to a specific folder using AES. There is one password/key that is configured somewhere, that is always used. I don't want ...
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2answers
84 views

How secure is aes-256-cbc with a 40 char password

I'm using this command from this article to encrypt a file: openssl enc -aes-256-cbc -in /etc/services -out services.dat -k MYPASSWORD If MYPASSWORD is 40 characters in length, roughly how long ...
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0answers
35 views

AES256 key exchange

I'm trying to get a secure way of exchanging keys between my client application and the server. The goal is to encrypt all XML messages with AES256. These XML's will be transferred to the server ...
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4answers
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How long would it take to bruteforce an AES-128 protected pdf knowing the key is 20 letter long and that the charset is A-Z,0-9?

The question says everything, knowing that a pdf is protected using standard Adobe password encryption that comes with Acrobat Pro (which as far as i know is AES 128) how much would it take to ...
3
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1answer
204 views

Strange Finished message in TLS

I've tried to understand the content of the Finished message of TLS. I'm using WireShark to capture the traffic between my browser and the internet. I noticed a "strangeness" when the chosen ...
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2answers
83 views

Is is possible to shuffle an AES ciphertext without owning the key for it?

I would like to know if it is mathematically feasible to change an AES(CBC) ciphertext and IV without owning the key, so that the ciphertext would look totally different while still decrypting to the ...
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1answer
193 views

How to wipe disks before encryption with dm-crypt if CBC or XTS is used internally?

First, please forgive me if I'm posting this question to the wrong community. Feel free to migrate this post to the right community if I was wrong. I'm quite new to whole disk encryption (but not ...
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2answers
95 views

How are the disk encryption keys protected when a laptop is locked?

If you were installing such operating system as Ubuntu, you would have seen an option to encrypt your home directory or the whole hard drive with an AES 256bit cipher. When your laptop is totally ...
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1answer
105 views

OpenSSL key derivation

I'm trying to manually decrypt DTLS packets sent by OpenSSL. The cipher suite used between the server and the client is TLS_RSA_WITH_AES_256_CBC_SHA256 and my understanding is that the IV used by ...
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1answer
91 views

Effect of “decrypting” clear-text then “re-encrypting” it

I have a (unique) situation where I receive data that is a combination of encrypted (with AES-CBC) and clear-text blocks and I cannot tell which blocks are encrypted. I plan to decrypt all of the data,...
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1answer
88 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 ...
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3answers
135 views

Diffence between AES-128 CMAC & AES-128 ECB/CBC?

Automotive standard for encryption use to talk about following algorithm AES-128 CMAC & AES-128 ECB/CBC. AES-128 CMAC use to provide Security service Authenticity AES-128 ECB & CBC used to ...
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0answers
54 views

AES keyfile size

I would like to encrypt files using a key file instead of a password. What I would do is: 1) Generate X random bits using openssl rand X > mykey 2) openssl enc -aes-256-cbc -in secretfile -out ...
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1answer
84 views

How safe is this “Multidimensional-Encryption method” (includes xAES, familiar from Unseen.is)?

I would like to ask about this encryption method that I found: USPTO patent and it is related to this question here: A service that claims beyond army level encryption Didn't see any updates on this ...
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2answers
86 views

Which of AES modes are safer and faster for transferring data over the network?

I have using Crypto++ in Qt and use of AES Algorithm for encrypting files. I know about AES modes and their applications. I have use of StreamTransformation method for encrypting files in CBC and EAX ...
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3answers
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Can someone explain what exactly is accomplished by generation of DH parameters?

I'm setting up a node.js server: https.createServer({ ... ciphers: 'ECDHE-RSA-AES128-SHA256:AES128-GCM-SHA256:RC4:HIGH:!MD5:!aNULL:!EDH', honorCipherOrder: true }, app).listen(443); ...
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1answer
56 views

How authentication tag is calculated in AES-GCM-256

I have a sample code,which encrypt and decrypt a string using AES-GCM-256. I am unable to understand,how authentication tag is being generated on encrypter side and how is that being used on ...
3
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1answer
62 views

Question about AES-CBC IVs

I'm writing a Java program that encrypts strings with AES-CBC encryption. (Eventually I'm going to add steganography functions too). As you are well aware, CBC needs an IV in order to encrypt the ...
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2answers
59 views

Key-exchange over the network with more than two peers

Me and my team is developing a multiplayer videogame with a Client/Server-Topology. This secures the match from clients who have the intention to cheat because of server authority but still allows the ...
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1answer
54 views

How to use a different key and IV for encrypting a file with AES in C++?

I know how AES encryption works, and different modes (for example EAX, CBC, CCM, ...), and also about CipherBlock and StreamTransformationFilter methods and their implementation in C++. I am using ...
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3answers
1k views

Calculate time taken to break AES key

A 256 bit AES key is required to be broken using the brute force method on a 2GHz computer. How long would it take to break the key in the best case and in the worst case situations? Assume that 1000 ...
3
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1answer
147 views

MasterSecret expansion into keys

I'm trying to deeply understand the steps during a TLS handshake. I've read this answer (which is btw pretty complete), but I stil got a question about the utilisation of the MasterSecret, in the ...
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0answers
104 views

Security of an IoT network using AES (LoRaWAN)

I am studying the security of LoRaWAN. Here is a simplified architecture of the network: As you can see, there are two keys: one for the network security (no mitm, no modificatiof the messages). ...
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1answer
72 views

Firmware protection scheme

Edit: I have found a scheme that fits my limits (little memory, only AES is available): AES-CMAC described in RFC 4493 (just remember to use different key for encryption and MAC ;) . I am working ...
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69 views

How could I encrypt an SD card to store data on it?

I have some data I'd like to carry with me in an encrypted form onto an SD card, so I (and only I) can access it easily from any OS (or at least Windows, OSX and Ubuntu). My idea was like: Two ...
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1answer
83 views

Is using trim on a ssd with LVM LUKS safe?

I know that it can allow an attacker to know the filesystem and file size, but can it allow an attacker to decrypt any files?
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49 views

Choosing Key and IV in AES-256

I am working on a real-life project for a firm. I have to encrypt data using AES 256 as per specification. I want to know how are the key and IV are really chosen in real world projects. /dev/urandom ...
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1answer
88 views

How long does it take to brute force a 7 character long password taken from 16 character set

A database file is encrypted with 256bits AES and the key is the first 7 characters (from the character set 0-9, a - f, all small letter) of MD5 hash . This implies 2^28 bits (268,435,456) possible ...
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1answer
52 views

Does use of fixed padding pattern compromise AES-ECB

I'm working on an application where AES-256-ECB has been specified. It has been asked that a fixed pattern is included at the end of the message to allow the decoding end to ensure the decryption has ...
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1answer
29 views

Is it ok to append the nonce/iv to the ciphertext when using AES GCM?

I want to use AES GCM to encrypt data at rest. When retrieving the data, I want to make sure that the key is valid and the data has not been tempered with. Can I store the nonce/iv along with the ...
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3answers
2k views

What is the point of AES key wrap (with JSON Web Encryption)?

I'm looking at JSON Web Encryption (JWE) and am left a bit confused about why you would use AES key wrapping. The document even talks about using matching key algorithm strengths: Algorithms of ...
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0answers
28 views

AES256 nopadding vs PKCS7Padding

I was looking over AES Crypt's Java lib which seems like a secure AES encryption software and I noticed that they are using nopadding. Can somebody explain to me what the benefit of using nopadding as ...
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1answer
69 views

Questions regarding AES 256

i have googled and searched quite alot but most things just state the same things but not answering my questions so hopefully you guys can help me out abit Story: i am looking at creating an ...
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2answers
101 views

Is it secure to use a part of the key as IV in AES?

I seen a lot of AES implementation samples wide spreaded over the Internet in almost every language I can recognize. There is one difference that I reflect to be repeated between all. Some of them ...
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2answers
163 views

store passwords as one-way-hash, or just use it as an AES key?

I want to store some data so the only one who'll be able to access it is the user itself. Here is my idea: when user registers, his password will be hashed in SHA256 (so it'll fit as an AES key), and ...
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1answer
64 views

OpenSSL brute-force attacking and file size

I use OpenSSL with aes-256-cbc to encrypt a 30 GB tar file containing a recent backup of my hard drive. Now suppose somebody wants to run a brute-force attack on this file, trying out all possible ...
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Client-server encryption technique explanation (TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, 128 bit keys)

I opened a web page using https. When I looked at the page info provided by my browser (Firefox) I saw following: Connection encrypted: High-grade Encryption (...
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0answers
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Why would I use at-rest encryption over a DB's key-based encryption?

Goal I want to store encrypted data in a database. Constraints Application-level encryption (encrypting before sending to the DB) is not a reasonable option for my use case. The DB providers I'm ...
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47 views

Create a TLS Application Data Message for AES-GCM

I was wondering if anyone could help me with structuring a TLS Application Data message for AES-GCM. I don't know how the IV, CipherText, Additional Data, and Tag fit together in a message. Thanks.
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Which block cipher should be used in TLS 1.2 (while keeping 1.3 in mind)?

I have been looking a bit at the various block ciphers for TLS. As everyone should (pipe dream) have migrated to TLS 1.2 by now it should be considered how to prepare for TLS 1.3, when it has been ...
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0answers
28 views

Clarification of RSA Key Exchange (TLS 1.2) and AES for On-Going Message Excahnge

I'm trying to understand the full flow of key exchanges for secure communications. As a potentially incorrect premise, I am under the impression that RSA is a good asymmetric technique for ...
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1answer
74 views

Stateless AEAD (AES-GCM) based tokens

I want to generate secure data tokens which can be shared with the client for uses like password reset, etc. which involves low storage overhead at server end. Ideally I am interested only in managing ...
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1answer
54 views

How can AES-CBC be used for LUKS encryption, when the ciphertext is not static?

In CBC mode of operation, ciphertext from previous block is used as IV in next block. How then can AES-CBC be used for disk encryption (LUKS), when the data on the disk (ie the ciphertext) keeps ...
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2answers
9k 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 ...
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5answers
2k views

Why does IV not need to be secret in AES CBC encryption?

According to Wikipedia, the initialization vector (IV) does not have to be secret, when using the CBC mode of operation. Here is the schema of CBC encryption (also from Wikipedia): What if I ...
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2answers
299 views

Why is 128bit AES considered very strong but 160bit SHA depreciated?

Why is 128bit AES considered very strong but 160bit SHA 'insufficiently secure'? Google/chrome/browsers seems to drop support for SHA1 SSL certificates. I assume it's more simple to calculate SHA than ...
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1answer
85 views

Store password ciphers using Powershell ? DPAPI/AES

Hi and sorry if it is in wrong place I am making a script that requires to have a lot of server's IP and their passwords stored into a file. I wanted to use Windows DPAPI, but as we can easily ...
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3k views

Is this RSA/AES combination good?

The team of developers I am part of is trying to develop a safe way to exchange sensitive data between a server and mobile devices. We have come up with the following algorithm: Device generates ...
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1answer
114 views

AES step by step

I can't seem to find an AES tutorial that starts from Unicode to Cipher text. All of the tutorials I found starts with 128 bit block already. Also, where do I start or what topics do I have to start ...
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Designing my own HSM using an Arduino

I am attempting to build from scratch something similar to Apple's Secure Enclave. What I've done is use an AES library for the Arduino to create a security appliance. A random crypto key and the ...