Passwords are secret keys which human beings can memorize.

learn more… | top users | synonyms (1)

0
votes
0answers
37 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 ...
3
votes
1answer
68 views

What is wrong with simple concatenation in salted password hashes?

I once heard that if implementing a password hashing scheme, simply concatenating the password and salt together before hashing could lead to some subtle vulnerabilities, and I'm trying to figure out ...
1
vote
1answer
162 views

Attacking hashed password by timing attack and other means

This question is inspired by this recent one, which raises a point that need to be made quantitative to be meaningfully discussed. I chose an unusual approach: a new question worded as homework that ...
4
votes
1answer
178 views

Is it safe to derive a password from a signature provided by ssh-agent?

I'd like to use a password-based system on a remote host (accessed via SSH) without having to copy-and-paste the password and without storing it on disk. Using the system with some other form of ...
3
votes
2answers
74 views

Long passwords and Bcrypt

I need to store passwords for a web application, and was looking at Bcrypt for a possible solution. After some research, it appears only the first 72 bytes influence the final hash output. While it is ...
3
votes
1answer
32 views

Generating passwords from a master password using rules

I realize it's generally considered bad idea to use the same password everywhere. I can use icloud / lastpass to generate my passwords for me, but that leaves me clueless when I don't have access to ...
1
vote
1answer
87 views

Encrypting passwords

I am using Android's keystore to generate a key which is protected by fingerprint authentication. This key can be used to encrypt any secrets. In my case, I want to encrypt a user password (which is ...
8
votes
4answers
536 views

Hashing a password before using for online accounts

I don't actually know what I'm talking about, so apologies if I get anything wrong. At the moment I have a password naming system for most of my online accounts that looks something like this: ...
4
votes
1answer
59 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 ...
1
vote
1answer
84 views

Cycling hashing in PBKDF's and their limitations in strength?

I hope this question isn't too similar to one that's already been asked. I also want to point out I know part the answer already, AFAIK: I just want some expert input on this. Let's model a hash that ...
0
votes
2answers
95 views

Password in first line of file for AES-256 encryption

I'm using openssl with aes-256-cbc encryption to encrypt a file. The password is on the first line of the file and the ...
1
vote
1answer
56 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 ...
4
votes
1answer
64 views

Is my pin algorithm secure?

I'm a hobby programmer and very new to this field. I opened a bank account recently and got two pins. One for the girocard and the other for a creditcard. And I needed two more pins for the online ...
2
votes
1answer
75 views

How secure is Shamir's Secret Sharing for password sharing when attacker has t-1 shares?

I am designing protocol to share a random generated n long password between k parties using Shamir's Secret Sharing. I know that share alone does not reveal much information about the original ...
0
votes
1answer
164 views

Backdoorable hash function in password database

I want to use a (preferably established) hash function that is backdoorable in a password database. I want to do so because I need password escrow (being able to get the cleartext back. I want to ...
4
votes
2answers
131 views

Public key crypto instead of hashing passwords in a database

Suppose I want to keep a client's password database secure (not in plaintext), while still having access to the plaintext password. Now I generates a public/private keypair. Then I send the public ...
2
votes
1answer
128 views

Is it true that 7zip doesn't use any salt with its KDF?

This issue claims that 7zip does not use any salt with its key derivation function: https://github.com/magnumripper/JohnTheRipper/issues/1679 If that's true, wouldn't that mean you can crack multiple ...
7
votes
3answers
877 views

Can I use a key-derivation-function as the hash function H in SRP?

In the Secure Remote Password Protocol, the verifier must be stored on the server. In the case of a server compromise, an attacker could obtain these verifiers. If nobody reused passwords, this ...
1
vote
1answer
128 views

Cracking passwords with more than 10 characters in a few hours?

I came across this article from 2 years ago: http://www.dailymail.co.uk/sciencetech/article-2331984/Think-strong-password-Hackers-crack-16-character-passwords-hour.html They're describing how a team ...
3
votes
1answer
52 views

gpg --gen-random quality level: is higher “better”?

The GNU Privacy Guard manual pages have this to say about using the gpg --gen-random 0|1|2 count command: Emit count random bytes of the given quality level 0, ...
2
votes
1answer
201 views

Hashing passwords

The common way to store passwords in web applications is this form: $$hash(password||salt)$$ Does it make sense to store them in the following form instead:? ...
1
vote
1answer
58 views

Is it safe to generate ECDSA keys from the hash of the previous, over and over again?

I have memorized a very long and secure passphrase, that when hashed with sha256, I can use the result as an ECDSA private key, and use it as a brain-address for Bitcoin. Now I need more bitcoin ...
2
votes
1answer
60 views

Can the salting function complexity improve the hash robustness?

I'm quite novice in security, and all examples I saw seem to salt the password by concatenating it, or by applying a simple binary OR or XOR. So the hash is based on "salt + password", "salt | ...
2
votes
1answer
96 views

Memory hard password based key derivation functions?

How are memory hard functions designed for the purpose of password based key derivation? To protect against a brute force attack from a parallel machine. What design could work well with Skein? The ...
1
vote
0answers
51 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 ...
1
vote
2answers
594 views

Which is more secure, using just bcrypt or SRP?

OK, here's the two different ways I was thinking about making the authentication for the login thing to store the passwords securely. The first is the following. Client hashes password ...
9
votes
2answers
313 views

How secure is a pronounceable password in terms of entropy?

There are some strong studies which support the use of pronounceable passwords and multiple tools which provide generation of such passwords. According to this question the entropy of a password ...
1
vote
3answers
97 views

Is this client-side password hash scheme secure?

I want to build an app that uses client-side encryption for storing encrypted data on the server. A user-specific master key would be used, so to easily share it between devices a encrypted version of ...
3
votes
1answer
59 views

Public SRP verifiers or public hash chain “public keys” when secret is low entropy password

I want to set up the following: An untrusted server should host user sessions and authenticate users without knowing their passwords or being capable of creating a fake user session in the user's ...
2
votes
1answer
78 views

How does the small n attack work?

I'm studying the Lamport's Hash one-time password scheme. This is the scheme: Alice wants to authenticate herself to Bob from a workstation that knows nothing about her. Alice only knows her ...
4
votes
1answer
94 views

Are shorter password hashes safe?

How much can I shorten a password hash before it begins to impact security? Suppose that I use PBKDF2 (correctly salted) with HMAC-SHA256 as the PRF. From what I've seen, it's typical to use 256 ...
3
votes
1answer
119 views

Is it possible to reverse the birthday attack calculation?

I find that for every 100 password salts in our database, we only average 94.73 distinct salt values (averaged over a total of around 18 million). Is there a way to take that observation and calculate ...
3
votes
1answer
46 views

Attacks on WinRAR volumes reusing same password?

I have quite a few WinRAR volumes that are all encrypted with the same password. The password is long and unbruteforceable, but I recently read that WinRAR uses PBDKF2 as its key-derivation function ...
2
votes
1answer
244 views

XTEA: patterns in plain text

I'm using XTEA to encrypt passwords that I store in a database. (I need to be able to decrypt these passwords later to log in on another system.) But now I have noticed something: if I decrypt a ...
1
vote
1answer
91 views

Value of S and r in Fiat-Shamir Protocol

In the book Cryptography and Network Security by Forouzan,in chapter 14, Fiat-Shamir protocol, its mentioned that two large prime numbers p and q are chosen and kept secret. However n=p*q is made ...
0
votes
1answer
195 views

How long does it take to brute force a Wordpress password?

I'm not a cryptograhpy expert, I am a web developer trying to determine the origin of a Wordpress blog hack, and how likely it is that it was brute forced. The administrator account username had been ...
2
votes
1answer
192 views

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 ...
4
votes
1answer
286 views

PBKDF2-SHA512 - Does a Big Salt Decrease Security?

I use PBKDF2-SHA512 with an iteration count of 128,000 to hash my passwords. I use a CSPRNG to generate a salt per password. However, I am unsure about the ideal size of the salt. I have read a lot of ...
1
vote
2answers
142 views

What are the required security properties for salts?

I was recently thinking about password hashing (maybe caused by the PHC progression). I started to think a little more about it and got stuck at this question: What security properties do ...
2
votes
2answers
98 views

Client login without sending a password

I would love to have a system where the password is never send in plaintext (even with TLS) to authenticate a user. I've come up with this protocol, but I'd rather use something proven. Registration: ...
3
votes
1answer
329 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 ...
28
votes
6answers
4k views

Is there a secure cryptosystem that can be performed mentally?

I, myself, do not plan on getting into a situation where I would be unable to use a computer in order to communicate securely. However, I can think of many practical situations in which mental ...
2
votes
1answer
139 views

Extension of a password hashing algorithm using Fibonacci

I am right now taking a class named Applied Cryptography and our final project is to create a password hashing method using at least one existing algorithm and then add additional steps to make it ...
3
votes
1answer
122 views

How can I generate a good password from a SHA512 hash?

I have to change local administrator passwords on machines. I don't want to store password in a database. I have to generate a password that I can find later to connect to the machine again. So I ...
5
votes
2answers
504 views

SHA-256 exhaustive search

How do I calculate the number of computations needed to break SHA256 in case we are using it for safely storing passwords (together with a salt)? Are there any formulas that can be employed? For ...
2
votes
1answer
54 views

Salting in asp.net?

I have spent the past hour reading up on salting and still don't understand how it is achieved. Forgive me if im wrong, but the way I am thinking of salting is, storing an ArrayList of random strings ...
0
votes
0answers
51 views

one complex password as a “seed” for localy generated per-service passwords

I've stumbled upon a project that suggests a way of having to remember one password, from which a “per-service password” could be generated by salting the service name using scrypt. What could be a ...
1
vote
1answer
49 views

About DH-EKE and ECDHE_PSK (PSK versus Pasword)

I am currently having a look at J-PAKE , so learning about Authenticated Key Exchange : Reading 2.2.2 E.K.E from this paper https://people.kth.se/~maguire/Erik_Ehrlund_Literature_Study_report_v1.2.pdf ...
1
vote
2answers
92 views

How much pre-hashing a password increase security against brute force attack?

I am wondering how much hashing a password used as key for a symmetric key algorithm helps preventing brute force attack on crypted text. Let's assume I want to crypt text A using key B using ...
1
vote
2answers
85 views