Questions tagged [passwords]

Passwords are secret keys which human beings can memorize.

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1answer
30 views

How long would it take all of the supercomputers or cloud computing on Earth to bruteforce a significantly long password?

I was having an argument with a colleague, who thinks that SHA256(password + 64 character long static salt) is "insecure". My argument is that nothing in cryptography is "secure", ...
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How to prove that a rainbow table is complete?

Passwords that are hashed but not salted can be cracked using the rainbow table. I went through this and this which explains the logic behind rainbow table very well. But I am missing something about ...
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Is this method of salting effective?

So this is my first post on this forum, so bear with me if I sound stupid. I am creating my own web application with JavaScript and MongoDB. I am storing all user information in a Mongo table, and ...
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1answer
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Can ECDSA signature signing and verification process replaces password hashed based login system?

ECDSA or DSA in general was to sign a message or data using private key and verify it using public key, if the attacker/imposter doesn't have the private key then they couldn't sign the message ...
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1answer
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Where to obtain a common/weak password list (black list)?

The NIST 800-63B publication specifies recommendations regarding memorized secrets (passwords) https://pages.nist.gov/800-63-3/sp800-63b.html#memsecretver specifically section "5.1.1 Memorized ...
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Number of combinations with a max. of successively repeated characters

I would like to calculate the possible password combinations for a password that is 60 characters long, has the letters a-f and numbers 0-9. Also no character should repeat successively more than 7 ...
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1answer
3k views

Difference between SSHA512 and SHA512

I am using SSHA512 to encrypt email user's passwords. Manually doing this works using doveadm from dovecot. But I can't seem to implement this in my mail client. I can, however, use SHA512. Is SHA512 ...
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What is the purpose of hashing the identifier in the secure remote password (SRP) protocol?

In the secure remote password protocol version 6a, the identifier for the user, I, is hashed along with the salt and the password on the client. While I understand ...
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1answer
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Is this mentally computable password system, cryptographically secure? And anything like this out there I can find?

Please bear with me on this, I'm not learnt in this field, just trying to ask questions about the security of my encryption method. I'm trying to create a mentally computable human password manager ...
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1answer
225 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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What grade of protection does a private key's passphrase provide at best?

Does a passphrase with high entropy provide the same level of security as the private key itself? General scenario: An attacker has access to a private key file that is protected with a passphrase ...
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Can pbkdf2 be used with a fixed salt to give a deterministic slow hash?

I need a password hashing function that is deterministic. Correlation attacks are not a concern. The same password must produce the same hash. I just want to protect the password against dictionary ...
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1answer
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Salt for non-stored passwords

I have read a lot about the concept of adding a salt to a password and understand that it protects against various attacks, especially the use of rainbow tables. But this kind of attack is based on ...
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Can a salt for a password hash be public?

From my understanding, salts in password hashes are used to prevent the precomputation of plaintext→hash values (rainbow tables). I know from different threads that it is unnecessary to keep the salt ...
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How to be able to change the password to access data encrypted with AES-GCM, without reencrypting?

Let's say you need to encrypt plaintext which is 1 TB big. You have a password pwd. This very classical AES-GCM process is ...
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Why is SHA256/SHA512 not broken for shortish passwords

I don't get why SHA-256/SHA-512 hasn't been broken, at least for shortish (10-12 character) passwords It is perfectly plausible to pre-compute a password/hash-pair table using numerous very fast ...
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Is my password database encryption flow secure?

I'm not an expert and I would be very glad if someone could take a look at it and tell if there are any problems with it Things I know/think are problematic using base64 digest + getting the first 32 ...
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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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Are there any methods for constructing a password that can be reconstructed if forgotten and is as secure as randomly generated ones?

Is there a formal name for such a thing, so I know what to google? Is it possible to make them as secure as randomly generated passwords? An illustrative example would be something like picking a ...
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Should I use 2x the number of CPU / core for Argon2id parallelism?

I've read that I should use 2x the number of CPU available from some documentation while others suggest using between 1 and the number of CPU. I realize there is no hard answer here but I'm curious ...
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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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Generating traceable passwords

I'm new to cryptography, so please bear with me as I try to explain what's going in my head. I have an idea to write a program to generate one-time passwords for online conferences that are although ...
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Why should I export my private key instead of well known asymmetric crypto mechanism on openkeychain?

I'm trying to use password-store as password manager under linux. I created a private github repo with my gpg files in order to use it with other devices. I installed android-password-store app for ...
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Is this password-cracking challenge possible?

Taking a graduate computer security class, part of our current assignment is to crack 50 Unix md5crypt password hashes, due on Thursday, October 8th (in eight days.) I've managed to crack 49 out of ...
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What can be deduced/extracted from this local hash extracted from Windows Machine?

I'm new to cryptography. I've been experimenting with getting Windows hashes to see whether it's possible to reverse engineer. The following hash is what I got from my test laptop. What can you ...
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1answer
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How to choose parameters for Argon2 for password vault

I'm creating a password vault and I'm planning on using Argon2id to derive the master key from the master password. For encryption I'm planning on using XChaCha20 with Poly1305. To be clear: a set of ...
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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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1answer
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Is this cumbersome strategy to produce a ridiculously strong password valid?

I'm writing something where somebody wants to have a ridiculously strong password for a file and yet be sure that he will always be able to reconstruct it. The way I have thought of this might be a ...
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Cryptography elements needed for a story

Note: following Maarten Bodewes's answer, I edited this post to make it clearer. I'm writing something partly driven by the need to crack a few encrypted files. This is what needs to happen in the ...
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3answers
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Good layperson analogy for password and encryption keys

NOTE: QUESTION UPDATED. SEE BOTTOM OF THIS POST. I'm writing something where I need to make someone come across as though they know cryptography. I don't know enough, but as cryptography plays only a ...
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1answer
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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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2answers
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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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4answers
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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
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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
158 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
68 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
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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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1answer
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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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0answers
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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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2answers
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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
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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
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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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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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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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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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