Questions tagged [passwords]

Passwords are secret keys which human beings can memorize.

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How to crack my laptop password? [closed]

Suddenly I forget my Laptop password, I tried a lot but my laptop is not accepting. I just go through the internet, so that how can I crack the laptop password. I came to know, maybe "Brute-Force ...
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1answer
110 views

What kind of a strategy can be used to crack this password?

The password is 11 chars. It has 5 letters and 6 numeric characters. There is at least 1 uppercase and 1 lowercase in it at the same time. Can an attacker benefit from these information even though he ...
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How can AES 256 be implemented in C? [closed]

I want to implement AES 256 encryption in a program written in C (using OpenSSL, which I have installed) which would accept a string or a .txt file from the user and encrypt it with a hash of a user ...
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How to calculate the entropy for a fixed length random passwords which has restrictions on the type of characters used

If we have a set amount of usable characters, but no other restrictions on the potential characters in a completely random fixed length password, we can easily calculate the entropy by doing: $\log_2(...
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How should I calculate the entropy of a password?

If part of the password is a whole regular English word, does the entropy of that part depend on the number of English words in existence, the number of English words known by the choosing algorithm, ...
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1answer
124 views

Any ideas on login using Digital Signature PKCS

I am curious to know about possibility to login into web application just by identifying the user based on digital signature in usb token. any reference in this direction?
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1answer
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Is storing salts encrypted a good idea?

I've read that storing password hashes in a database, you can store the salt in plaintext alongside the actual hash with no detriment to security. I was thinking that one could derive a key from the ...
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2answers
137 views

How many passwords are possible in this scenario?

A password string consists of one or more of the 26 characters A..Z and can be of any length from $1$ to $8$ characters. How many password are possible in this scenario? As my calculation, it should ...
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Could someone please explain the implementation of public-private key encryption for storing passwords?

As someone new to cryptography,I have a question about how logins work on websites. I understand mathematically how asymmetric encryption works and how https web requests work to securely send ...
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1answer
64 views

Combining algorithms for password storage?

Is it more secure to combine algorithms for password hashing, for example, Scrypt, Bcrypt, SHA-3, etc.? If an attacker wants to use dedicated hardware, he would need one for each algorithm. However, I ...
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1answer
54 views

How to provide secure password based encryption with password reset option

I am trying to build website that will encrypt some data for the user using his/her the output of scrypt on it, now the idea is that this schema is not flexible because if the user loose their ...
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how many iterations of SHA3 (keccak256) hashing would be required to provide reasonable protection for the following data structure?

((A , B , C) , (D , E , F, G, H)) Where: A is 0x0-0xF, (1 of 16) B is 0x00-0xFF (1 of 256) C is an 8 digit integer D is a one of a list of one hundred words padded to 12 characters E is a one ...
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Secure password reset

In my model I use two different keys, one for authentication and the other for the encryption / decryption of the data that the user saves, each derived from the master password with a KDF function. ...
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1answer
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Can you correct my understanding of Argon2? [closed]

I'm a bit new to the cryptography field (completely new), and could really use your guidance. Please, correct my understanding, as defined by the following statements. The ...
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3answers
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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 ...
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Relation between Zoom id,password and join URL [closed]

We all are using zoom application for joining/hosting meetings in this corona virus period. As we create a meeting, a new id, password and a url is generated. Some real examples follow- Id: ...
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1answer
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Do all PAKE assume that all parties already have a password?

I was looking for a means to perform a key exchange without relying on a PKI. I discovered Password Authenticated Key Exchange (PAKE) and after reading J-PAKE; I have the following questions: Do PAKE ...
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How to validate a PBKDF2 password

I want to encrypt several files correctly with a PBKDF2 generated key (using a password and salt), I am currently doing so but if I enter the wrong password, as expected an exception occurs. Note: ...
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2answers
671 views

Just how insecure are VeraCrypt containers encrypted with short passwords?

When I create a VeraCrypt file container using the GUI, it displays a warning whenever I type in a password under a given number of characters. I was wondering just how insecure, in practical terms, ...
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1answer
184 views

Storing passwords in a publicly available database

I have a public database where users need to store configuration files. The file can contain passwords. Everyone can read config files but only the server can read passwords in them. In the browser, ...
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3answers
204 views

How to securely store and validate a 4-digit PIN used on a mobile device?

I want to be able to securely (1) create and (2) validate a PIN, typed by a user primarily in a mobile app. There is no 'typical' password, although there is another 2nd factor. The starting point ...
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Is the password based key exchange secure even if the public key is known to adversary?

I am assuming the answer for part 1 to be a "NO" as the adversary knows the public key he can get the password by offline attack IN part 2 : the answer is "yes" as the public key is freshly generated ...
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2answers
120 views

How much entropy do I need to add to passwords if they are NOT used in conjunction with logins

I'm building a system to authenticate users to a website via a single use login token. This token can either be included in links OR typed in directly by the user as a code. Because of that second ...
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72 views

For uniterated SHA-256 of salted password, should the password precede the salt?

This is a follow-up to this question (thanks to answers from @fgrieu and @kelalaka ) about the format of a salt when hashing a salted password. I realize this is pretty much academic, as the proposed ...
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2answers
144 views

What format should a salt be when it is concatenated with the password?

Assume that, in the available environment, it is not possible to use modern password hashing functions (bcrypt, scrypt, Argon2, PBKDF2, etc.), so it is necessary to roll my own stand-in, until they ...
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Encryption algorithm used in WPA/WPA2

I want to know how EXACTLY the WPA password gets encrypted I have been searching through and I was able to catch: The actual password is converted to some hash Salting is applied to the hash The ...
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1answer
206 views

Hardware, Handheld Password Manager

I am currently working on a hardware project that will utilize the native USB and keyboard emulation capabilities of the Teensy device. Essentially, the user will store an encrypted password database ...
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1answer
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Does pepper *require* an HMAC?

Assume you are already given a properly-salted, password hash $X$ from some slow PBKDF (e.g., like Argon2id). Now, you want to apply some large (~256-bit) secret "pepper" $S$ to it before storing it ...
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5answers
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Is there a practical way to crack an AES encryption password?

I heard that the fastest method to crack an AES-128 encryption, or and AES-256 encryption is by brute force, which can take billions of years. But I can't help thinking there's got to be a faster way. ...
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Signal Key Stretching Regarding Their Blog Post

I just read this blog post (Signal - Technology Preview for secure value recovery) by Signal and something is not quite clear to me. In section "Stretching beyond a KDF" they generate a ...
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1answer
173 views

Is it safe to reuse the same nonce for decryption an indefinite amount of times in this context?

I'm creating a password management application and I'm considering using the following procedure to keep passwords safe: Asking the user for raw_password, for ...
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5answers
154 views

How passwords are fed to key derivation functions?

Suppose I want to encrypt data, send it over the network, and decrypt it on the receiver side. I know the elegant way to do this is by using a symmetric key to encrypt the data and an asymmetric key ...
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Are longer passwords really safer against brute force attacks?

If we take two password strings of different length and attempt to bruteforce match them, it is obvious that the longer one will take longer to crack on average. However if we assume that when ...
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1answer
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Choosing between hash functions instead of providing a salt for a password hash

I am working on some programs that require the users to store their passwords in my databases. However, due to the fact that I am not sure whether salt should be stored in databases due to my ...
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1answer
75 views

How slow is the hash used for Mac FileVault encryption?

Certain password strength estimators (for instance, zxcvbn) give estimates that vary with the speed of the hash and the assumed resources of the attacker. I am curious what hash is used by the MacOS ...
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1answer
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Two party protocol using only hash function

I have been told by my professor to compare two passwords as we do it in Yao's two-party protocol but without using any crypto functions. We are only allowed to use a hash function. The passwords are ...
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1answer
89 views

PAKE password change

Is there any way to change a password using a PAKE-like algorithm, without the server getting the plaintext of either the old or new password?
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Is it safe to use a deterministic salt as an input to KDF (Argon2)?

I'm prototyping an app that uses client-side password hashing in order to hide the "real" account password from a server (the server hashes any recieved password anyway, so no plaintext records in the ...
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1answer
198 views

What's the algorithm behind MySQL's sha256_password hashing scheme?

MySQL's old mysql_native_password hashing scheme was the equivalent of this in PHP: sha1(sha1('password', true)); That's a ...
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What makes a hash function good for password hashing?

Using a cryptographic hash to store e.g. passwords in a database is considered good practice (as opposed to storing them plaintext), but is subject to attacks on said cryptographic hash, assuming the ...
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BIP32 Extended Key to EC Private and Public Key Pair

We are working on an application in Android using Java. In our project, we used to generate EC key pairs (of size 384 bits) using SpongyCastle - an old Android version of Bouncy Castle. The problem ...
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How hard is it to guess a 8 digit PIN?

Say that there are different live situations where you have to select own PIN numbers. Can someone say if it is possible to guess a 8 digit pin within 3 tries, given any methods or resources? Is ...
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After downloading the Breach Compilation.torrent, how do I properly introduce new breach lists? [closed]

So I downloaded the Breach Compilation (the 1.4 billion usernames w/ respective passwords). When doing so, the friendly dev-like homies they are over @ github where the .torrent file for the latter is ...
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2answers
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Is using 7-8 random words from all words of a language as password a good idea?

The Bitcoin Bip-39 dictionary has 2048 words. And a random 24 of them are pretty secure together. What if the source is bigger (all words in the language) but there are only about 7-8 words? These ...
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1answer
4k views

Decrypting SHA-512

I was recently solving a CTF problem and it involved a shadow and passwd file. I got to know the username easily but I am unable to find the password since it is SHA-512 hashed. My doubt is that when ...
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1answer
1k views

Choice between AES-128 and AES-256 for password protection in MS Office

Why are we still using the default of AES-128 when password protecting a Microsoft Word document. My answer is and always has been - because its good enough and MS don't recommend changing to AES-256. ...
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What is the formula to calculate password entropy? [closed]

I saw in another thread: Is using 7-8 random words from all words of a language as password a good idea? These calculations: If we assume that English has 171,476 words. Then with 8 words the ...
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Advice in password auto-generation

I'm creating a program with key access for a determined term. I've made a code that will generate a key (password) with 16 characters length. The following information is encoded: initial date 6 ...
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3answers
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Is there a ready report about character order frequency in most common passwords?

There are charts about most used letters in English. What about the letter order? For example letter X has a bigger chance to appear than letter Y as the first character and something else for the 2nd ...
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1answer
62 views

Is there a way to generate a password from another but those 2 will have no relation?

For example I have the password X and I want to encrypt 2 different things. Even if one of them was stolen due to a keylogger, other will be completely safe. I wonder how safe something like this ...

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