AES (Advanced Encryption Standard) is a symmetrical block-cipher algorithm with a 128-bit block size, and key sizes of 128, 192 or 256 bits.

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Is it overkill to run a key generated by OpenSSL through pbkdf2?

I'm generating a key & iv with OpenSSL via: ...
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Is it possible to tweak AES-GCM so that it is satisfactory for whole-disk encryption (like XTS mode)?

Is it possible to leverage a preexisting implementation of AES-GCM to provide the key security benefits essential for full-disk encryption (similar to AES-XTS)? GCM is a popular encryption mode ...
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How to obtain KCV from the key

Simple question: we have AES 128 encryption and a key. How can we calculate the key check value (KCV)? One example: key is 48C3B4286FF421A4A328E68AD9E542A4 and KCV should be 77DC84. I am trying it ...
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720 views

Achieving 256-bit encryption strength with PBKDF2 - HMAC-SHA1

I am interested in the theoretical consideration of the bit strength of an encryption key and its precursor. Assume a given environment as follows: a. My encryption algorithm is AES-256 b. My key ...
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490 views

Review of AES encryption concept for an open source project

i'm working on an opensource project, A generator for static (html/js), password protected photo galleries. The generator AES 256 encrypts many images with the same key in PyCrypto, and decrypt them ...
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686 views

How to break AES CBC with PKCS#5 padding?

If I have a string encoded with AES CBC with PKCS#5 padding, how can one possibly decrypt/crack it? What are the approaches that one can take to break its security?
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Shortcuts / practicality of brute forcing block cipher (AES) + ECB with known plaintext

I know the plaintext (26 bytes long) and cryptotext of block cipher (suspected to be AES) in ECB mode. I can generate hundreds or thousands of such samples, but the samples are not arbitrary. What are ...
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119 views

AES as Integer Program

I read that AES can be broken by solving a Linear Integer Program (IP). From a given encrypted text, how can one construct this IP? How big is the system?
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Consequences of AES without any one of its operations

Suppose AES-$128$. There are $4$ operations in AES's encryption, they are SubByte, Shift Row, MixColumns and AddRoundKey. Question: If I remove one of the following opearations, what will happen to ...
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AES Affine Transformation in $GF(2^4)$

in $GF(2^8)$ the AES affine transformation is defined as \begin{equation*} b( x ) = ( x^7 + x^6 + x^2 + x ) + a ( x )( x^7 + x^6 + x^5 + x^4 + 1) mod (x^8 + 1) \end{equation*} where the polynom $( x^7 ...
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Cracking an appliance's network protocol

I'm trying to crack my thermostat's network protocol. I've captured several rounds of network traffic and here is what I've got to work with. Communicating via HTTP POST The POST data is JSON ...
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57 views

Where is the OID and ASN.1 specified for AES_CMAC?

I have a requirement to implement AES_CMAC as the authentication algorithm in a CMS library. I just can't seem to find the OID and the ASN.1 definition for it. I expected to see the OID under ...
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51 views

AES multiple devices to server communication

I have multiple devices connecting to a server, whose communication needs to be encrypted. At the moment I have an AES library doing the job (possibly inadequately): I am using a database of keys on ...
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51 views

Separate TLS Client Write and Server Write Keys in AES-CCM Mode

I am designing a system that uses TLS-like handshaking on a resource-constrained embedded system. I have settled on AES-CCM mode for symmetric session encryption and authentication, allowing ...
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72 views

Timing attacks against RSA, DH and AES

I have been reading about “Timing Attacks on RSA: Revealing Your Secrets through the Fourth Dimension” by Wing H. Wong. I was wondering if this attack is feasible while signing with RSA and, if yes, ...
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132 views

File Encryption (EFS method)

I'm implementing (for learning purposes) a file encryptor, which uses the following method (from http://en.wikipedia.org/wiki/Encrypting_File_System). I have 3 kind of keys: RSA public/private, AES ...
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555 views

How do I enable AES-NI (hardware acceleration) for Node.js crypto on Linux? [closed]

I wrote a basic function to test the speed of the AES-256-CBC mode of the Node.js built-in crypto functions. These functions use OpenSSL, so they should support AES-NI, but when I correctly enable ...
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How to use HMAC-SHA1, HMAC-SHA2 in conjunction with AES

I understand how to compute HMAC-SHA1, HMAC-SHA2 etcetera. Please explain why/how is the resulting HMAC value is used in conjunction with AES for encryption/decryption and signing/verifying. In ...
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How to solve MixColumns

I can't really understand MixColumns in Advanced Encryption Standard, can anyone help me how to do this? I found some topic in the internet about MixColumns, but I still have a lot of question to ...
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666 views

AES key padding

Is the initial AES key (expanded to the key schedule) byte padded if less than e.g. 16 bytes? Is there a safe way of determining if decryption was successful (i.e. used the correct key)?
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280 views

Secure Hash Function based on AES

How secure would a hash function be which appends an extra block of 16 zeroed out bytes to the end of the message and then AES-encrypts it with a well-known password (say the first 128 bits of pi) ...
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360 views

How to encrypt a file for random access

I am a programmer familiar with C/C++ and Python. Lately, we got an assignment from a team asking us to work on one of their projects: we need to make a small program to encrypt a large file using ...
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184 views

Decryption issue with self-coded AES-128

I have written my own AES-128bit implementation in Java, till yesterday I thought it would be alright. (I was working on the encryption) Now I’m trying to decrypt my encrypted cleartext, but this ...
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216 views

How resilient to attackers with extreme resources available is this encryption method?

How could the following scheme be made more resilient to attacks capable of utilizing massive amounts of resources? Assume all random values are cryptographically secure. Key derivation: scrypt ...
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1answer
164 views

What parts of AES encryption result are safe to pass on the network

I'm using AES to encrypt the message. both sender and receiver know the passphrase, but only sender knows IV and salt I assume that receiver also needs to know IV and salt to decypher text; is it ...
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297 views

What's the difference between AES and earlier block ciphers?

Is there any difference except speed and key and block size from user's point of view? Or does AES have something that ideal block cipher doesn't have?
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605 views

Is storing original file size in an encrypted file header a bad idea?

I'm encrypting a file using AES-256 in CBC mode. I'm padding to the 16-byte input multiple by using the PKCS#7 limit. The problem I'm currently having is that if I'm transferring or reading the ...
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Double Encrypting with two different keys

In terms of security, would it be MORE or LESS secure to take, say, an RC4 output (or Serpent) or other, that is encrypted with one key, and to encrypt that output with AES (using a different key)? ...
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937 views

decrypt AES without whole key

Is there a way to decrypt a AES cipher Text which was encrypted twice with some key, when having a part of this key? (the last 3 bytes of the key are missing)
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324 views

Is splitting AES ecrypted data safe?

Say I have a key, an iv and an AES/GCM/NoPadding encoded string and I want to split this information between three people such that only jointly can they reveal the ...
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AES256-CBC vs AES256-CTR in SSH [duplicate]

I used AES256-CBC to SSH to a remote server. Recently, it stopped working with the following message: ...
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591 views

Combining multiple symmetric encryption algorithms - implications?

I was just wondering if I add more security by combining two or more symmetric encryptions on a plain text. For example: Plaintext → AES → Twofish → Serpent Of ...
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808 views

Generate fixed length cipher text from arbitrary length plaintext

Using an encryption algorithm like AES, is it possible to generate a fixed length cipher text no matter how long the plain text becomes?
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AES Message Authentication Vulnerability

My securities instructor recently posed this question to the class and I am bending my brain in half trying to figure it out. Suppose $y_1 = AES(K, x_1)$ and $y_2 = AES(K,x_2)$, and suppose you ...
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What is the probability of breaking the AES algorithm?

I am doing a project which requires the encryption to be done using AES. Is it really possible (technically) to crack AES? If yes, please tell me: What is the probability of breaking AES? How ...
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AES GCM symmetric encryption of data at rest in c#, ciphertext much longer than plaintext

I've written encryption/decryption routines using AES GCM. Code can be found here. I recently realized that the cipher text is longer than I believe it should be. It should add the tag and IV onto ...
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358 views

How exactly does AES-NI work?

I am looking in to AES-NI which is now supported by many new CPU's and I have read a few papers which states that AES-CBC works faster with AES-NI, but I am unable to understand how exactly AES-NI ...
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334 views

Encrypting firmware with AES and no IV [closed]

I have an embedded device with a AES CBC engine on it that is used to ensure the integrity of the firmware. I know that CBC mode requires unique IVs to be any good, but I'm unsure if it makes a large ...
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197 views

What is the intuition behind AES or SPN?

I'm new to cryptography and have just encountered AES and SPN. I would like to know how the S-box, permutation step and the MixColumn step help improve security. It seems to me (perhaps mistakenly) ...
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907 views

AES-CMAC passes every test except two

i wrote this code: ...
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Counter Mode in Advanced Encryption Standard(AES) Algorithm

In Advanced Encryption Standard, if I used "Counter Mode", how should I handle the nonce? Should I divide the nonce value into two? For example: I have 128-bit of nonce, should I divide it so I get ...
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Initialization vector length insufficient in AES

I use AES with AES/CBC/PKCS5Padding with the following encryption and decryption code sections in Java: ...
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96 views

Is the output of AES-CBC + MAC the same size as the input?

I use AES-CBC and HMAC-SHA256 to encrypt a text file. Will the output be larger in size than the input or will it be the same size? Is it more secure secure if the size of the output is larger?
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98 views

Adding an IV to an AES implementation

I have an embedded project that requires AES, I seem to have found an AES implementation that fits the bill here: http://www.literatecode.com/aes256, but it does not include an IV. Are there any ...
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Key cracking: Prefer many small texts over one large text?

If an attackers sets out to crack the symmetric key of e.g. AES-CTR, would they prefer to have access to many small cryptotexts or one large cryptotext? I.e. is it more interesting for the attacker to ...
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Is CTS necessary on a AES-CBC DRBG?

As I understand it, CTS pads the last block and swaps it with the second last to compensate for a partial block of data. I have written a DRBG (Deterministic Random Bit Generator) using AES-CBC that ...
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72 views

Prefixing data before encryption for passphrase confirmation?

I'm encrypting data with AES, using CryptoJS. CryptoJS returns an empty string in case the data couldn't be encrypted with the given passphrase. I'm not sure if this is intended, or happens in all ...
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How does GCM (Galois/Counter Mode) work? [closed]

Can somebody explain how this mode works? What view has cipher text and how does it help to authenticate input’s data?
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Using IV buffer after altered inside a Rijndael CBC Encryption/Decryption process as IV for next message?

When sending a block to be decrypted or encrypted, with RijndaelCBC, we input the data to decrypt/encrypt and an IV for syncing and to prevent identical outputs for identical inputs. This question is ...