Encryption using a key derived from a password or passphrase entered by the user.

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1answer
23 views

Encrypt a small amount of data with a password derived from PBKDF2

I have a small amount of data (about 128 bits) to secured with a strong password. I plan to run PBKDF2-SHA2-256 on the password and a 128 bit random salt to generate a 256 bit derived key. Then with ...
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1answer
83 views

How can I create pre-determined encrypted results?

I want my encryption results to be the lyrics to Star Spangled Banner. The original text I'm encrypting would be, for instance, the menu to a local pizza place. I know what I want my passphrase to be. ...
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1answer
49 views

Is it safe to use a key as message in keyed hashing (HMAC)?

Scenario: User gives password. A "password key" is derived from the password (e.g. by PBKDF2). A random salt is applied. The password key is hashed with a HMAC algorithm (e.g. HMAC-SHA256), with ...
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5answers
33k views

Can you help me understand what a cryptographic “salt” is?

I'm a beginner to cryptography and looking to understand in very simple terms what a cryptographic "salt" is, when I might need to use it, and why I should or should not use it. Can anyone offer me a ...
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1answer
676 views

Encrypting user data with their password?

I had an idea once that all of the user data (including the username) could be encrypted with the user's password. Obviously, most sites would store different data, so using the same password and ...
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1answer
31 views

How to add passphrase to an RSA key?

If I want to protect a private RSA key, do I just XOR the password into the key, or do I do something else? Is it secure? Edit: I got a good answer from a comment - Hash the password/passphrase with ...
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1answer
75 views

Properly storing an E-mail Password

I'm creating a messaging application that will use an outlook account to send an email. However, I'm unsure about the proper steps to store the e-mail password on the user's computer. Suppose I had ...
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3answers
787 views

How can mega store my login details and still be secure?

I understand how Mega's encryption works. For a quick summary of all those in the future looking for an answer on this... here is how it works: Upon first signing up for an account you make a ...
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2answers
246 views

Length of encryption password aes-256-cbc

I'm encrypting a file with sensitive information with cat secret | openssl aes-256-cbc -a -salt > secret.enc I am choosing a random encryption password with <...
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1answer
72 views

How to use AES-CBC to password-encrypt a small block of stored data

I have a small block of data (16 bytes) that I am required to encrypt, store (in an unsecure, visible location). Later I have to retrieve and decrypt it. I must use AES-CBC and a user-entered ...
4
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1answer
78 views

Password-based encryption with small typos allowed

I'm trying to write some software to encrypt and decrypt some messages with a password. I am trying to implement it using this post: How can I securely convert a "string" password to a key used in ...
7
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1answer
219 views

How to generate a key using any $m$ passwords out of total $n$?

My application requires an AES-256 key K for some secure operation. In order to avoid saving this key in application, I have implemented following scheme: There ...
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3answers
705 views

how much is secure to encrypt a password using itself (as encryption key) for storing it on a unsecure media?

I want to store a password securely on a storage (suppose in a usual unencrypted file). I use this password as AES key to encrypt itself (using AES-ECB) & then store it on the media (the password ...
7
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2answers
422 views

Need for salt with IV

I have mainly referred to this question. Definitely in case of using a salt, IV has a use of adding randomisation to each and every key. But isn't it redundant in case of using an IV to use a salt? (...
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1answer
48 views

Could a key derivation function be used to encrypt data with a weaker key?

To allow the key to be more easily remembered. Example: To encrypt a hard drive without having a remember a key with 128 bits of entropy. From what I find they seem mostly used to hash passwords so ...
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2answers
1k views

How can I make my cipher show the avalanche effect?

I am a beginner in cryptography. I designed an password based encryption-decryption algorithm, which uses a random salt and a password to encrypt a message. I'm using SHA-512 for hashing, matrix ...
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0answers
59 views

Encrypt/Decrypt cloud passwords with master password

I know it's generally bad to store password in the clouds, and that I should be using salted-hashed password only. I'm making an application that will authenticate a user (with salted-hash), and then ...
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1answer
74 views

How to change the master password in a password manager

For a personal project, I'm building a password manager, based off the project in this syllabus from Stanford http://crypto.stanford.edu/~dabo/cs255/hw_and_proj/proj1.pdf Since I don't exactly have ...
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1answer
130 views

Generating a key to use with AES

I'm going paperless, and I want to encrypt the documents that I scan. I'd like to use CommonCrypto to perform AES-XTS encryption on each file. I'm a software engineer, and I like the idea of being ...
0
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1answer
112 views

Making both the IV and salt public for PBE with AES-CFB

Is it okay to make both the IV for AES-CFB and the salt for PBKDF2 public? Does this action of mine compromise security in any way? I have an implementation of this cipher and had previously asked a ...
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1answer
85 views

PBEWithMD5AndDES Cipher does not check for integrity first?

I am running FindBugs with findsecbugs plugin to scan java code for security issues. I am getting "Cipher With No Integrity" error for a Cipher function implemented with "PBEWithMD5AndDES". The legend ...
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1answer
82 views

Username and Password: How does it work?

Suppose a client (Alice) goes to an HTTPS website (Bob) over TLS 1.2. Alice sends Client Hello with some random number $r_a$. Bob sends Server Hello with another random number $r_b$. Suppose they ...
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1answer
136 views

Cryptography of numbers

Is there any algorithm capable of encrypt securely (symmetric) N numeric digits in a numeric message of M digits (N < M)? I am especially interested in a specific case in which N = 10 and M = N + 3....
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2answers
90 views

The benefit of PBKDF2 for big keyfile?

The man page of cryptsetup says: Whenever a passphrase is added to a LUKS header (luksAddKey, luksFormat), the user may specify how much the time the passphrase processing should consume. The ...
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2answers
127 views

Is it worth hiding an AES encrypted text string in a PNG image for better security?

I need advice as to whether it is worth the extra "security" and processing of an AES encrypted text string to be hidden in a PNG image as opposed to an AES encrypted text string to be saved in a read-...
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1answer
673 views

Recommended password complexity for SSH key encryption using AES-256-CBC

When protecting SSH private keys with password-based encryption, what would be a good minimum password complexity+length standard to make cracking the password too difficult to be worthwhile anytime ...
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96 views
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1answer
252 views

Extracting a WinRAR password

If I have an original file and a WinRAR password protected .rar file containing that file, than can I extract the password?
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0answers
91 views

How do I verify a reset token if the token is hashed in DB?

I've been searching around the web for best practice how-to on secure password reset system (email with reset url), and the idea to hash the token in the database, which I did not implement at first, ...
3
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1answer
85 views

Is there a tangible benefit in keeping the number of PBKDF iterations secret and not storing them with the ciphertext?

Suppose I have a local file and it is encrypted with a symmetric key derived from a strong passphrase, unique salt and $x$ number of PBKDF (e.g. Scrypt) iterations. I am interested in keeping this ...
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1answer
250 views

Encrypt file name

I'm looking to encrypt (rename) mutiple files name based on a passphrase. Currently the passphrase would be numeric but I can change that to something else if required. I would like to be able to ...
3
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1answer
150 views

Is it safe to derive two different keys with the same password and key derivation function using two different salts?

I would like to know if the following process would harm the security of a fictional system if the persisted data would be stolen: in this system a user has a single password. The password will be ...
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1answer
134 views

What is the proper way to generate a fixed length key from a variable length password?

The password is entered by the user and the key is processed locally. Neither the password nor the key will be stored, only used and forgotten (but hopefully not by the user). Is SHA256 by itself ...
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1answer
220 views

How does ccrypt work?

On many Linux/GNU distributions CCrypt (ccrypt) by Peter Selinger is available as a command line utility to encrypt files. How does the protocol work and is it ...
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1answer
301 views

Bouncy Castle and Salsa 20 [closed]

I want to use Salsa 20 in Java, so I downloaded Bouncy Castle, and... it makes no sense to me. I've got it working, but most of my choices were essentially random. But I can't see there anything ...
1
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1answer
132 views

Basic question about design of program with data encryption

I need to store encrypted files on a hard disk. The actual code side is not important for me now (I plan to use C# and AES-GCM encryption from Bouncy Castle library, please tell me if you think that's ...
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1answer
157 views

Which algorithm do you recommend for practical use to generate unique passwords for each website?

So, in my imagination there is this simple algorithm with only one master password, let's say a prime number 'p', which I have to remember. Using only the address of the website and p, the algorithm ...
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1answer
148 views

Rate my idea: is that a stronger GPG-like algorithm?

I came up with a simple idea but I don't know if it is really secure or not. I know that you shouldn't create any algorithm on your own. I'm just curious, that's all. Algorithm explanation: First ...
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2answers
240 views

Using PBKDF2 twice with different argument order

I'm pretty sure this is a really bad approach (in theory), but one of my clients is doing this and I was wondering… How bad it is to perform pbkdf-2 in this way (with 2000 iterations)? ...
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3answers
715 views

Can I create a fixed length output from a fixed length input?

I use AES256 for various purposes in my app. However, the purpose I am now trying to achieve is the following: Input is for example AU00000001 and I would like a ...
5
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0answers
321 views

Is there a “brainwallet” for GPG keys? [closed]

“Brainwallet” is a program that takes a passphrase (hopefully a good one) and deterministically creates a Bitcoin wallet. This wallet can be used for transactions, then deleted from the computer. To ...
3
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1answer
520 views

Rfc2898DeriveBytes - password length

Trying to find related answer for a long time, but not convinced yet. What I am trying is to encrypt using RijndaelManaged. To create Key, I am passing password, ...
5
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2answers
809 views

Encryption Key derivation from numeric PIN?

I want to store data encrypted within an Android application. Keeping an encryption key safe outside the app is not an option so I looked into password derived key algorithms. I found a nice example ...
0
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1answer
248 views

How to store keys for a cascading encryption?

What is the best way to implement a cascade encryption? I'm trying to figure out how to cipher a string (or message) using Serpent-Twofish-AES and then store the keys. I'll provide an explanation, ...
3
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1answer
141 views

What security differences are there between E(p',“well-known-plaintext”) vs. hash(p') where p'=KDF(p)

I am using a KDF to derive a key, p' from a password p. I would like to know if the password is correct before using the derived ...
2
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1answer
190 views

How to design a cryptographically secure file hosting service

How one would go about design something like Google Drive/Dropbox providing the following features: files are encrypted and decrypted on the client files can be synced between devices the service ...
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1answer
479 views

Testing if a password for an eCryptfs mount is valid [closed]

I'm using "eCryptfs" on several directories on my dedicated Debian server. I mount them manually via mount -t ecryptfs [dir] [mountpoint] But after some weeks ...
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2answers
518 views

How terribly flawed is this design for key storage?

Dave here, with a plan for storing secrets. Threat model: Database and keyfile may (will?) be stored on un-trusted servers. Database contains many valuable secrets (passwords), encrypted by key ...
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3answers
150 views

Securing content and login with “same” password

I'm writing a client application that wants to store some secret information with a storage service. The client has to authenticate the user with the service and the service should not be able to ...
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2answers
591 views

How to derive two keys from one password

What is the best way to generate two independent symmetric keys from one user-entered password or passphrase? Would using both scrypt and pbkdf2 achieve this?