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Questions tagged [aes]

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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Understanding AES Keys and Passphrases

I am trying to get my head around how AES works and in particular I have queries around the key generation and 'passphrases'. My understanding is that AES has a 128 bit block size but the key length ...
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Collision Security

Question concerning collision issue in CBC-mode: If we are using CBC mode with AES for 1 message, the birthday paradox indicates that we risk a collision after 2^(n/2) so 2^64 plaintext of 128 bits of ...
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Why do Browsers in their TLS1.3 Client Hello do not request for CCM ciphers?

As per TLS 1.3 RFC 8846, following 5 ciphers are supported. TLS_AES_128_GCM_SHA256 TLS_AES_256_GCM_SHA384 TLS_CHACHA20_POLY1305_SHA256 TLS_AES_128_CCM_SHA256 TLS_AES_128_CCM_8_SHA256 ...
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Which KEK can wrap AES, RSA and ECDSA keys securely?

If I have AES256, RSA4K and ECDSA-512 keys as CEKs, which I need to securely store, what KEK can I use to securely wrap these without reducing the bit strength? I am aware that an AES256 key can wrap ...
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Is double encrypting with AES safe?

Is it safe to encrypt twice with AES, with any mode? Are any combinations of AES, e.g. AES with XTS and AES with CBC, or twice with AES and XTS, more unsafe than just having it encrypted once? I know ...
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117 views

Is it secure to store a cryptographic key in a class member variable?

Consider an application that runs locally on a Windows PC. The application uses a local folder for reading/storing encrypted data (i.e. images). A user logs in (authenticated from a local encrypted DB)...
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How secure is Microsoft's Office and LibreOffice's password protection?

AFAIK both Microsoft Office and LibreOffice have features to add passwords to protect the content. In general, there are two ways: protect from editing/changing (without a revision at least) protect ...
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138 views

Can we write both encrypted text and plain text to the same file?

We have a requirement from customer to write payment transaction information to a text file. Of many lines of data per transaction, only one line contains cardholder information, which needs ...
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operation mode of an encryption algorithm

The operating mode of an encryption algorithm, especially a block cipher, describes how to use the encryption function for a single block repeatedly to encrypt or decrypt an entire messages with a ...
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Windows BitLocker- Is the drive Password the same as the Key used by AES to encrypt the drive?

I am using BitLocker on my Win10. I encryted my usb drive using my Windows BitLocker with a strong password. I know that Bitlocker uses AES-~256 bit key for encryption. My question what is the key ...
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101 views

how much is AES GCM's security affected when not using unique IV's

I've read some articles and tutorials about AES GCM and was using this cipher for one of my java-projects, so let's say I know some basics. I read that you should use an IV-length of 12 bytes which ...
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Why does OpenSSL fail to decrypt when the key is too large?

I have the following groovy script: cmd1 = "echo ${really_long_key}" ssl_cmd = "openssl aes-256-cbc -md md5 -nosalt -a -pass pass:${encryptPassword} dec" def process = cmd1.execute() | ssl_cmd....
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AES256 with 128 bit key

A popular zero-knowledge file sharing site uses a 128-bit master key for encryption. However, they claim to be using AES256. When questioned, they explained the master key is widened using PBKDF2 ...
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Null IV for AES CBC vs GCM [duplicate]

If we agree that using a null IV for AES in CBC and GCM mode is not a good idea, but for whatever reason one is encouraged to use a null vector for several messages using the same key, is there a "...
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Public key encryption confusion

I'm learning Linux, and currently SSH. But there are details that I don't really understand. I've seen and understood how Diffie-Hellman key exchanges work from a mathematical point of view, but what ...
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Cross platform OpenSSL aes encryption

I encrypted a file by using the following command from a stackoverflow answer: openssl enc -in file_name -aes-256-cbc -pass stdin -out file_name.aes; I can decrypt this file by running: openssl enc ...
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Decrypting AES-128-CBC leads to first block being correct, the rest corrupt

I'm currently investigating a piece of software which encrypts it's files with AES-128-CBC. From disassembly it is truly known that the algorithm used is correct (log messages plus calls to the ...
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Why boxcryptor use hybrid cryptosystem to encrypt files

I do not understand why they need asymmetric key encryption, if the client does not use the public key. As far as I understand it, the user password is used to decrypt the private key and no public ...
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When using openssl to encrypt a file, how would I create a key made up of specific letters? [closed]

I want to create a 128bit AES key made up of specific letters. I think I would need to use something like openssl genrsa -aes128 -out privkey.pem or openssl genrsa -out privkey.pem but I'm not ...
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encrypting TCP and UDP with self signed cert

I don't have much experience in computer security and I am developing a server for a project. I'm using a tcp connection and UDP packets for some real time data transmission. I want both of these ...
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195 views

Safe encryption algorithm that works with files bigger than 68GB

In my Java application, I used AES/GCM/NoPadding algorithm for encryption, however it throws an exception when I try to encrypt files bigger than ~68GB. From what I read, it is limit of data that can ...
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Are there any known examples of companies who were successfully breached using POODLE, BEAST or SWEET32?

When this was first announced back in 2014, Brian Krebs reported on how much of a threat these kinds of birthday attacks were, but I have not been able to find a case study of a successful breach. Is ...
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Length of a stretched gnupg passphrase that is comparable in strength to an unstretched string of 256 random bits

Assume that we want to encrypt a file with gnupg using AES-256 as the encryption algorithm. (Hence, symmetric encryption.) In this mode, gnupg requires a passphrase from the user. I understand that ...
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Decrypting gpg2-symmetrically-encrypted files using non-gpg2 tools

If I encrypt a file using gpg2 and specifying AES256 as my encryption algorithm, can I decrypt it with tools other than gpg2? More generally, does the fact that one tool used AES256 for encrypting a ...
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Is AES-256 not the best decision for mantaining performance in a Datalake?

I'm worried about performance in a Data Lake used for Data Science purposes. I need to encrypt confidential data and, because of definitions I won't dive into here, the algorithm to fulfill this ...
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want to know best way to my case is to encrypt the UART communication channel? [closed]

I have device connected to scooter it’s 4- wire uart communication. My fear is some can read the ascii data and send the at commands and unlock my scooter and steal the scooter. I want to secure the ...
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Is GPG's AES encryption that much stronger than its RSA headers? [duplicate]

Correct me if I'm wrong at any point of this questino. I understand that AES is a lot cheaper to compute than RSA (or any form of asymmetric encryption) and that that is why GPG and similar programs (...
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133 views

AES, RSA, ECC Key size [closed]

It is generally said that 2048-bit RSA keys are roughly equivalent to 112-bit symmetric keys and 2048-bit RSA keys are "sufficient for commercial use until around the year 2030" (https://security....
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98 views

How to combine symmetric and asymmetric encryption to encrypt large files?

I understand that it is possible to combine symmetric and asymmetric encryption in a way that makes use of the performance of symmetric encryption, and also getting the benefits of being able to ...
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66 views

Why is authentication impossible with CBC mode?

Suppose I have a protocol where fixed-length messages (1280 bytes, no padding) are encrypted with AES in CBC mode. I want to put some data in the message body to verify that the message is authentic. ...
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What is the impact of the reported weak IV in 7 Zip?

It has been reported that 7 Zip generates IVs in the weak manner. What is the actual impact of this? I'm asking about historical Zip files that I've sent. I've no plans to use 7 Zip going forward ...
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Can Honey Encryption be used for CAN bus security? [closed]

AES encryption was one of the best encryption techniques used but it had a major disadvantage that it cannot handle brute force attack. Hence honey encryption was introduced which can handle brute ...
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AES Keys Storage for encrypting hashes of SAM file in Windows 10

Hashes of user account passwords in Windows 10 (like in older versions) are stored in SAM file. Using standard utility pwdump 7 for getting these hashes gives following result: ::LM hash : NTLM hash ...
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How long is Key lifetime of AES-GCM key?

As I know the AES-GCM used a nonce and if the two message has the same nonce then the secret key can be retrieved. If two computers use the AES-GCM to encrypt exchange messages, then what is the key's ...
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60 views

How does key exchange work? Using symmetric algorithm such as AES

I was wondering how does the sender give the encrypted file and the key to the receiver securely? Particularly on situations where the sender doesnt meet with the receiver (through email or through ...
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1answer
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How should I share the key of the AES algorithm in each client?

My doubt would be the following: How should each client know the encryption key? Using the AES algorithm. (or the best way): Save it in a file encrypted by password? Save it in a DB? Send it over ...
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1answer
870 views

is AES-128-CBC already broken?

I just want to know if AES-128-CBC is secure enough to use in an OPENVPN,I asked and they told me AES-128-CBC is completely broken and is considered a weak encryption. is it so?
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Can I use RSA to encrypt an AES256 key that I put at the beginning of my AES256 encrypted file?

I have a master server generating large files for other (known) servers to download. Those files: Are quite big. From 20MB to 5GB. Are written once by the server and then it forgets about them. ...
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1answer
165 views

AES/Rijndael Encryption Does block size matter for security?

Would AES with a 256-bit block size be more secure than a 128-bit block size? I'm curious if block size really makes something more secure. I'm dealing with a third party to use their API and they ...
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105 views

AES Encryption is this overcomplicated encryption?

I'm working with a vendor's API and it recommends the following steps for transmitting an encrypted value: 1) Convert the encryption password to a byte array. 2) Convert the value to be ...
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Can I use a user's password hash as the AES key to make a one time token?

I want to make a one time token that users use to reset their password. The token should be invalidated once it is used, is it safe to use their currently hashed password as the aes key to encrypt the ...
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Can I recover a lost AES key?

I had encrypted 2 MySQL databases with AES_ENCRYPT in ECB 128 bit mode. Now I forgot my encryption key, but I have plain text (I have one database without encryption and same with encryption). How to ...
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1answer
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Is there any 'Open Enrypted File Container' Format?

Tools that create 'encrypted file containers' use open encryption standards like AES to encrypt container contents, however the container format is proprietary, I am guessing, so need the same tool to ...
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2answers
159 views

Understand aes cbc IV

When I use AES CBC, the encrypt function needs to get an input-buffer to encrypt + key + IV? Is IV like one more key, or IV is generated by the key (so the encrypt function only needs to get the ...
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1answer
40 views

Potential security issue with md5 filename

I've been storing files using a filename of the md5 hash of the file. This allows me to not store duplicates of the same file and avoids any filename clashes. Each file has uses a different salt/iv. ...
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1answer
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How to use login details to make a key for AES encryption and decryption

I have recently starting looking into AES encryption for a side project. I am researching this till now so if there is something wrong about my concept please correct it. According to me If i want to ...
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333 views

Decrypt AES 128 CTR with the IVs (counter) but not the key

I have the encrypted files, the random IV for each encrypted files and the counter increment function but I miss the key. Is there anyway for me to decrypt the files?
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Help me understand Encryptpad and 7-zip for encryption

I was looking to encrypt some text files (containing sensitive data) so I could safely keep them online (e.g. Google drive). I have found three options: 7-zip, which does AES-256 Encryptpad, which ...
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1answer
846 views

OpenSSL: what's the difference between -kfile and -pass?

It seems both -kfile and -pass can be used to encrypt files with a 2048 bit keyfile? I don't understand the difference between the two methods: $ openssl enc -salt -aes-256-cbc -in inputfile.txt -...
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The way to determine IV for AES encryption, possible security problems with this approach

I am trying to make a folder encryption with maximum automation (except password input). Inside a bash script I do the following: echo $RANDOM | md5sum | cut -d' ' -f1 > iv and then using it: ...