Questions tagged [passwords]

Passwords are secret keys which human beings can memorize.

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1answer
109 views

New Passwording? [closed]

I just want to note before you continue reading--this does not specifically apply to hashes or the key to encrypted messages. However, I am initially thinking about password/key solving/remembering by ...
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4answers
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Is using a broken SHA-1 for password hashing secure?

Recently the hashing collision issue of SHA-1 was discovered. Identical hash values for 2 separate PDF files were generated. Does that make SHA-1 any unsafe for using it only for password hashing?. ...
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Is there some encryption scheme which is getting increase “noise” and then can't be indecipherable at last?

There's some function f() which has some "error", so "error" grows when decryption is failed every time and then finally it won't be able to decrypt. But, the "error" will be initialized when its ...
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1answer
118 views

Password-Managers: what is the IND-CDBA attack logic?

In the work of Paolo Gasti and Kasper B. Rasmussen On The Security of Password Manager Database Formats, they describe two attack forms: IND-CDBA and MAL-CDBA. While I understand the MAL-CDBA attack ...
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1answer
125 views

Stateless user-generated one-time passwords

I've been working on my course project lately and got stuck with the problem which I reduced to the following abstract protocol: Alice generates an ID key and gives it to Bob. Bob generates some ...
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1answer
292 views

Can the TLS 1.3 PSK-DHE handshake be turned into a PAKE?

Recently, we had the question whether there's a PAKE that uses more standard, higher-level primitives than what SRP offers. Now this made me think and ask myself: TLS does have a PSK mode, can't we ...
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2answers
145 views

Is there a perpetual 2-factor-authentication scheme that allows temporary password generation?

Recall that current forms of two-factor authentication (2FA) rely on: Something you know, i.e. your password Something you have, i.e. your one-time password (OTP) generator on a trusted device The ...
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scientific research about what is more secure: biometric authentication vs regular [closed]

I've already posted this question on Stackoverflow, but got downvoted and told to post here instead. So here we go. I am searching for citeable sources / papers that research about what is more ...
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1answer
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Key management in Java + Remembering passwords

I'm new within the area of crypto so I apologise if I am bad at explaining this, or have misunderstood certain areas. I'm currently developing a Java Fx application which includes the use of a '...
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0answers
398 views

Relationship between “Entropy” and “Security” in crypto functions

There is a lot of confusion between "entropy" and "security" of a cryptographic function. I like to visualize it as the entropy being the water, and the crypto function being a glass. So for ...
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8answers
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Password cracking: What if attacker is lucky? [closed]

We have always measured password or private key strength by the amount of entropy it contains, but what if the attacker who cracks it is lucky. Consider the following simple scenario, we have 1 bit [...
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1answer
194 views

How can you extract individual characters of an encrypted string such as a password?

Many banks and other systems have some sort of a "select the Nth, Nth, and Nth characters of your password" system. I don't believe they are going to be storing in plain text, nor would it make much ...
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2answers
249 views

How to calculate the needed encryptions in salted passwords?

Consider if a 16-bit salt is used, and it is uniformly applied over a very large password file (200,000 entries). An attacker wants to see if one particular password (say, "bubba") is used by any of ...
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2answers
256 views

Generating password from high entropy file

Assuming We want to generate a password of 32 bytes, using a keyfile as source but not using it directly but via an intermediate step; So: We have a file of 100MB file with high entropy We ask the ...
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1answer
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How to configure Argon2d for commodity hardware?

You may already have heard it: KeePass v2.35 has support for a new database format (KDBX4) which allows for the use of Argon2 (more precisely: Argon2d) as the password-based key derivation function (...
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4answers
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How is the quality of a password calculated and what does it mean?

While using Keepass and using it to generate random passwords, I always have noticed the "quality" section but truthfully have never known what it actually means. So my questions are; How much ...
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309 views

How to use private key with Hash algorithims for storing passwords [duplicate]

UPDATE Found an answer here: Recommended way of adding a pepper/secret key to password before hashing? After reading https://security.stackexchange.com/questions/211/how-to-securely-hash-passwords ...
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1answer
215 views

securing the keystore

When generating a public-private key pair you have the option to secure the keystore with a password. where is that password stored, is it a hashed version that is stored and if that is so which ...
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3answers
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Cryptocurrency serving as hash breaking?

There are many people mining for Bitcoin right this second.[Citation needed] Bitcoin's proof-of-work mining system is based on a hash function (SHA-256, I believe), and there are ASICs built ...
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2answers
196 views

What is the probability of the first half of a hash output being identical to the first half of another hash output?

Let's say for example that I encrypt a password with some hash function and receive a 256-bit hash value in return. What are the chances that the first 128-bits (half) of this value are identical to ...
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3answers
148 views

Require x of y possible passwords to decrypt

Is there a way to set up encryption so that a certian number (x) out of a total (y) number of users/passwords are required to do the decryption? Background: This is mostly a thought experiment, and ...
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2answers
148 views

Which password generation method could provide better security?

We want to generate strings that can be used as passwords (storing later will be done with ex.: bcrypt, but these are the literally meant passwords). On a Linux machine, the two generation methods ...
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2answers
304 views

Very simple, very memory-hard (?) password-based key derivation

I know the problem of memory-hard password-based key derivation functions is better left to the likes of scrypt, argon2, etc... But validated implementations of those algorithims are not always ...
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4answers
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Why bcrypt is one-way while Blowfish is reversible?

While bcrypt is often regarded as an irreversible hashing function, it's based on the reversible Blowfish cipher. I'm just curious about how does this work. Here's ...
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1answer
1k views

Storing passphrase and encrypted private key

I have to protect a key pair with a passphrase and to store these information someway in a table. I read that I can protect the key pair (specifically, the private one) using a digest of the ...
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1answer
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Cryptsetup | Given Enough Passphrase Entropy, Is It Necessary To Use a High Iteration Count?

Let's assume that, for creating a LUKS volume, I generate a random, 40 character passphrase that includes numbers, symbols, and upper and lower case letters, using the ...
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1answer
114 views

Having access to multiple servers, would additional usage of “Secret Sharing” for password storage enhance security?

I am currently learning about secret sharing and I’ve started wondering why larger companies that have access to whole server networks (like – for example – Google, Facebook, etc.) don't use “Secret ...
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1answer
175 views

Better than diceware? And sha512 related question [closed]

I am working on a secure password generator based on the following setup: choose a publicly know (text) file make some deliberate memorable changes to it use collected entropy for a secure password ??...
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1answer
547 views

anything obviously wrong with my custom password hash scheme?

i sha2-256 hash the password, then i base64 encode the hash (per RFC 2045) , resulting in a 44 bytes string looking like LPJNul+wow4m6DsqxbninhsWHlwfp0JecwQzYpOLmCQ=...
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0answers
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How is the strength of password evaluated? [duplicate]

Recently I came across howsecureismypassword.net. The site evaluates how many year a computer would take to crack the given password but they don't provide the ...
2
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1answer
7k views

What is the algorithm used to encrypt Linux passwords?

I noticed during an assignment that, if I create an user with a password (azerty for exemple), and then call the command to change the password but give him exactly ...
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1answer
223 views

estimating entropy of password

How do I calculate the entropy of a password selected as described? Choose 4 distinct words randomly from a list of 2000 words. Words can contain special-character substitutions. For example, the ...
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Using multiple iterations of Argon2i

Consider Argon2i used as a key derivation function (implemented by the libsodium crypto library) to derive an encryption key from a password. Additionally, when entering the password a second time, ...
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1answer
798 views

20 bytes random string hashed with unsalted bcrypt or scrypt?

I have users for which I use a SHA-1 hash as an API key. These are urandom feed into SHA-1 so you can assume they're fully random. There is no username sent along with the API key. I don't want to ...
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3answers
5k views

How many KDF rounds for an SSH key?

What is the best practice on choosing how many key derivation function (KDF) rounds/iterations when generating an SSH key pair with ssh-keygen? Am I correct in saying that it is unnecessary if the ...
2
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1answer
741 views

Encryption in popular compression file formats - 7zip, RAR, Zip

When encrypting a file say with Winrar you have to enter a password. I am under the impression that this password is not stored anywhere but instead the password together with some other attributes ...
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3answers
149 views

Function to derive an integer from a given password

I need to get an int, derived by a given password, to feed it to a deterministic PRNG as a seed. The derived int should not give away any clues about the password. How can I achieve this without ...
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2answers
1k views

Multiple passwords per key with any allowing decryption

How to get secret key based on multiple passwords? e.d we have cipher encrypted by combination of passwords "qwe" and "asd", and our purpose to decode the cipher using any of passwords above ...
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0answers
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Factoring a semiprime with part of one of its factors [duplicate]

This is part of a question I asked on information security stack exchange which might be better suited here. I'm looking to implement a script in an ad-hoc scripting language with no crypto libraries,...
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2answers
624 views

Using master password to encrypt and decrypt user credentials

I need a way to store third party credentials, and I want to avoid storing passwords in plain text. I can't use a hash because I will need to be able to get the raw password to log in to the third ...
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1answer
2k views

Generating passwords using Password-Based Key Derivation Function

I was thinking of using different and independent password for different websites, but not storing them in some password manager so I don't need to backup the passwords. I thought I could use some ...
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1answer
519 views

Commutative Hash Function for Password Challenge?

I had an idea. Could anyone tell me if this is a thing, if they see any problems with it, and if they know of a commutative hash function that would make it work? Suppose you had a pair of ...
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0answers
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Password manager that uses a mix of long and short key derivation functions

I was reading "A Convenient Method for Securely Managing Passwords, Halderman et al., 2005". In short, the authors say to do the following: ...
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3answers
8k views

What is the recommended number of iterations for Argon2?

I've recompiled my operating system ("LionBSD" based on FreeBSD) to use Argon2i as the default password hashing algorithm in crypt/libcrypt. I'm wondering what the recommended number of iterations ...
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1answer
104 views

Security when using same salt for different passwords, compared to using different salts?

I have this question I am struggling about: For example, someone suggested improving UNIX authentication by defining 3 different passwords for a user that are stored in the shadow file. All three ...
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1answer
2k 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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3answers
1k views

Password entropy much lower than entropy of encryption keys. Why is this acceptable?

When talking symmetric encryption, a 56 bit key is known to be so weak. If you use it for your encryption, you are considered a goner. When talking passwords however, the standard these days is ...
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1answer
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Do I need to use a CSPRNG when creating salts for user accounts?

I'm not sure about the need of using CSPRNG to create salts for each user account. I found “Cryptographically Secure Pseudo-Random Number Generator in Qt/C++ (Cross platform)” (at StackOverflow) with ...
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1answer
158 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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2answers
59 views

Validating subset of a password

Is anyone aware of an algorithm/method that allows me to validate just a few letters (or other characters) from a password. For example, the application asks for the 2nd, 3rd, 6th and 9th letters from ...