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

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1answer
141 views

AES-256 Shift-Rows Offsets

I am currently trying to implement a AES-256 cipher according to this sepcificaciton: http://techheap.packetizer.com/cryptography/encryption/spec.v36.pdf As well as on Wikipedia and in the document ...
5
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1answer
254 views

Secure AES Key Generation via Salsa20?

I am not creating my own cryptography or anything, but to learn about the Dos and Donts of cryptography, I am looking into AES encryption and ways to generate keys for that. As far as I've ...
2
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0answers
42 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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1answer
63 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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1answer
402 views

Decrypt AES-128 with key file but missing IV? [duplicate]

I want to decrypt a file that has been encrypted using AES-128 in CBC mode using OpenSSL. I got the “.key” file – which is 32 digits – but when I try to decrypt with OpenSSL, the program asks me for ...
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1answer
59 views

What is the Geometric Generalised T' Method?

This page by Nicolas T. Courtois mentions Geometric Generalised T' Method. It is described as an advanced geometric algorithm, never published, for finding extra linearly independent equations at ...
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1answer
128 views

AES CBC MAC splicing attack

I'm trying to implement AES CBC MAC splicing attack in Python, the idea is: given a message M, its tag Tm (MAC(M) = T), a new message N and its tag Tn we build a message such as: M||N = (M1, ..., Mn, ...
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2answers
541 views

How secure is the AES master key if Round Keys are found

If an attacker finds some round key of AES256, is it possible to find the master key? How safe is the master key if an attackers finds multiple round keys?
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1answer
506 views

CryptoJS.AES result always has same first few bytes?

When using this very minimal CryptoJS AES example: ...
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2answers
224 views

Should an AES byte key generated with OpenSSL be converted to hex?

I am generating a key & iv with Ruby's OpenSSL wrapper for an AES CBC 256 setup: ...
3
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1answer
864 views

Why is Serpent faster than AES in this benchmark?

I have a laptop without the AES-NI CPU instructions but with SSE4.1. I'm using Linux and tried the (in-memory) cryptsetup benchmark to get the rough tendency which returned: ...
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0answers
128 views

Is this a secure (and correct) sign-then-encrypt technique for transferring messages?

After reading some information on the way iMessage works I have been working on writing some code to try my hand at securely transferring messages in a similar manner and I wanted to confirm that the ...
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1answer
132 views

Hash Based Encryption (fast & simple), how well would this compare to AES? [duplicate]

First of all, I know it's a very bad idea to invent your own encryption algorithm. It's better to use existing known, trusted, extensively tested and studied algorithms with a proven track record. The ...
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1answer
144 views

Hash Based Encryption (fast & simple), how well would this compare to AES? [duplicate]

First of all, I know it's a very bad idea to invent your own encryption algorithm. It's better to use existing known, trusted, extensively tested and studied algorithms with a proven track record. The ...
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0answers
137 views

AES encryption takes more time to decrypt than encrypt

Please let me know if this is not the right place to ask this question. I will remove it. I am trying to find how much time an AES encryption and decryption takes for a given amount of data and key. ...
2
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0answers
60 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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0answers
26 views

Is there a flaw in whole disk encryption vs volume or folder encryption? [duplicate]

My company just implemented whole disk encryption on all laptops (Symantec) and the concept seems flawed. Please correct me if I'm wrong, but if I have known file in plain text and that same file in ...
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1answer
165 views

Understanding multiplication in the AES specification

I am reading through the AES specification and am not able to wrap my head around the multiplication definition (section 4.2). Sorry to refer to a spec but AES is the holy grail in crypto so I hope ...
3
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1answer
191 views

Entropy test for AES Key Schedule

According to the article "Lest We Remember: Cold Boot Attacks on Encryption Keys" there is a quick and dirty entropy test that can help to find possible AES Key Schedules in memory dumps. Although ...
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3answers
193 views

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

I'm generating a key & iv with OpenSSL via: ...
3
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1answer
276 views

Any use for now-defunct Mt Gox Yubikey?

As everyone is now aware, Mt Gox has declared bankruptcy. As what appears to be the very last thing they did, Mt Gox accepted my $35 and fulfilled my special Mt Gox Yubikey. Having just arrived in the ...
2
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0answers
118 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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1answer
105 views

Attacking both authenticity and secrecy in authenticated encryption modes

looks like NIST only approved GCM mode for authenticated encryption and other modes don't have any approval or a good implementation available. Is that possible a weakness in $GHASH$ compromise ...
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0answers
98 views

What is the forward cipher function of AES-XTS?

We're using OpenSSLs EVP_aes_265_xts encryption on data (with unique, random, IVs for every new message encrypted) - which is working well. But, I've been asked; what is the forward cipher function ...
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1answer
404 views

AES CBC Security

I am building an Apache webserver with TLS 1.2 and OpenSSL 1.0.1. So far, I have enabled 2 encryption algorithms - ECDHE AES256 GCM and ECHDE AES128 GCM. Firefox and Chrome(ium) use NSS which ...
2
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1answer
151 views

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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1answer
98 views

How unsafe is to share parts of a password

The best way to ask this question and have a concrete answer is to set a very specific example. This is the example I would be interested in reading an answer to: Consider that my friend Alice has ...
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1answer
225 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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1answer
150 views

crypto design with AES256 MODE OFB

I have the following APP Design key store (contains 1:n user payload as 1:n key store entries) key store salt (is used to extend to key store password to 256 bits, stored in clear text) key store ...
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1answer
111 views

simple multiplication in GF(8)

I am trying to do multiplication in the GF($2^3$) defined by the irreducible minimum binary polynomial $X^3+X^2+1$. I want to multiply $A(x) * B(x)$ where $A(x) = x$ and $B(x) = x^2$. The ...
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1answer
251 views

Is the random data at the end of my decrypted message supposed to be there?

This is my PKCS#5 & AES/ECB Python 3.3 code: ...
0
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1answer
83 views

AES CBC encoding of decomposable OAuth2 tokens

We're building a stateless RESTful API that relies on the content of OAuth2 tokens to identify users and what they have access to. Users authenticate with other means and are given a token, which they ...
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1answer
293 views

Encrypting a payload for transmission over HTTP. AES256 with PBKDF2

I've done some reading about implementing AES256 and deriving a key from a password. If I understand correctly: I want to generate a new salt (for the key) and a new IV (for the encrypted message) ...
2
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1answer
103 views

Why is CBC based on AES malleable in blocks other than the first block?

Perhaps I don't understand the answers to Malleability attacks against encryption without authentication, so trying to be more concrete... please be patient. If I want to change the first block and I ...
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1answer
65 views

Using cryptographic hash to match AES key size

I am making a tool for myself where I intend to store cipher text. I wish to use AES together with arbitrary sized keys to create these cipher text strings. The idea is to use a cryptographic hash ...
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1answer
159 views

Derive both MAC and AES keys from same PBKDF2?

When doing password-based encryption, is it OK to create one instance of PBKDF2 from the password, and then use it to create both the AES key and the MAC key? (Or should a new instance of PBKDF2 be ...
3
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1answer
104 views

Does re-iterate AES128 with different keys gives any benefict?

I'm not cryptography expert (well, I'm here after all!) but I have this doubt… Suppose I have 2 different keys: secretkey1 secretkey2 And a plain text: myReallySecretPlainText If I use AES128 ...
3
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1answer
166 views

TLS: Is Integrity assured when using NULL cipher

In specific implementation we're using TLS 1.0, open ssl 0.9.8 but i'm referring to RFC 5246. For performance reasons, I'm being asked if we can use TLS without encryption. The hope is that the ...
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1answer
266 views

AES mode for file encryption

I'm working on software that should eventually result in a crypto file system similar to encfs. So far, i have a user password that goes through PBKDF2 using ...
3
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1answer
132 views

AES: Is it safe to encrypt same cleartext with same key but with million diferent IV?

The encryption mode that I am using is CBC. Algorithm is AES and the key size is 128bit. I will be encrypting a 36 byte string over 1.3 million times with the same key but with a random IV. My ...
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2answers
199 views

AES-CBC and IV — Encrypting multiple blocks of a file with the same IV?

I have large files which are broken into blocks of 512 KB and uploaded to a server. In my DB I store the IV, and the user knows the security key themselves. When downloading, I use the same IV and ...
2
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2answers
419 views

Json AES128: Security against known plaintext attack

I have a system where I am transmitting json messages securely (using for example AES-128), where each message has the same format. For example ...
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2answers
933 views

Multiplicative inverse in $GF(2^8)$?

I know how to do multiplication over $GF(2^8)$. Logic is... ...
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1answer
2k views

AES Algorithm processing time in Arduino vs Raspberry Pi

The Arduino employs an 8-bit ATmega series microcontroller whereas the Raspberry Pi is based around a 32-bit ARM processor, and the Arduino is typically clocked at between 8-16MHz and with 2-8kB of ...
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1answer
83 views

Is OCB with short MAC malleable?

At the beginning of OCB's white paper [pdf], OCB is compared to other modes, and non-malleability is one of the properties advertised. At the end of the paper, it is mentioned the MAC length can be ...
4
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1answer
646 views

AES mixcolumn stage

I'm studying AES, and am having problems with the "mixcolumn" stage. I read about finite fields, but I still don't know. How do I construct $GF(2^8)$? ...
3
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2answers
257 views

How is the AEScrypt password related to the underlying AES key

AES uses a key that is at most 256 bit. I assume AESCrypt uses AES. When a file is encrypted with AEScrypt, there is no limit to the length of the password. What is the relation between the ...
2
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2answers
371 views

At what stage is DHE and RSA used during the SSL/TLS handshake?

At what stage of the SSL/TLS handshake is the DHE and RSA used and what is the purpose of using a pre-master secret when you could just use RSA to exchange the symmetric key (i.e. AES) for further ...
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2answers
235 views

Should I bother implementing DH + AES, or leave it to a library like Crypto++

I'm making a C++ back end for an application that'll heavily rely on AES-256 and DH. Should I trust third party libraries, or spend (lots of) time to learn about cryptographic implementation and write ...
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1answer
78 views

Hypothetical question about AES output

Consider that you stumble upon 5 different AES output strings. One of these strings can be decrypted with a secret phrase, the other four strings are based on the real string but have had random parts ...