Questions tagged [passwords]

Passwords are secret keys which human beings can memorize.

Filter by
Sorted by
Tagged with
1
vote
0answers
25 views

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 ...
8
votes
4answers
7k views

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 ...
1
vote
0answers
47 views

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 ...
1
vote
2answers
67 views

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 ...
1
vote
3answers
42 views

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 ...
1
vote
1answer
59 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 ...
5
votes
2answers
2k views

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 ...
0
votes
0answers
9 views

How do I store Argon2 passwords in my database? [migrated]

I'm trying to store user passwords in my DB using Argon2 algorithm. This is what I obtain by using it: ...
0
votes
1answer
78 views

migrate bcrypt -> argon2

We want to migrate our userbase from bcrypt to argon2. I was planning on an approach that migrates all hashes immediately to argon2; "old" users would have an argon2'd hash of their bcrypt hash of ...
1
vote
1answer
95 views

XChacha20poly1305 vulnerability to known plaintext attacks

During a security audit, the guy said our cryptosystem is vulnerable to known-plaintext attacks. He said that's because «the implementation uses a crypto_stream_xor() approach» (from libsodium). That'...
0
votes
1answer
59 views

Password to password mapping

DISCLAIMER: I understand the question might be a bit amateurish due to my limited knowledge of cryptography but, please, bear with me for a minute. QUESTION: Suppose a user Alice generates a pass ...
0
votes
1answer
75 views

Generating nicer diceware passwords without losing entropy

Yes, another one of those "I have found a great password-generation strategy" waiting to be shot down! It seems that although diceware aims to be a secure and user-friendly password generation ...
-3
votes
1answer
32 views

just a question regarding passwords .computing the possibilities for a numerical PIN [closed]

How many possibilities for a numerical PIN with exactly 9 digits? How about a PIN with no more than 9 digits?
2
votes
3answers
198 views

Does the use of English words weaken diceware passphrases [duplicate]

A Diceware passphrase is constructed from a set of words chosen from a 7776-word database, using five dice throws to choose each word. The argument is that each word in the phrase adds about 12.92 ...
2
votes
5answers
258 views

Why are password database breaches bad if cryptographic hashes can't be reversed?

If companies such as Facebook store our passwords as hashes, when they are leaked how can this be a threat to the users? I thought of it because nowadays we do not have computational power to break ...
2
votes
1answer
104 views

pwd-hash like algorithm which can be computed on paper

"Common password problem" is well known problem, when user uses one password for many resources (web sites, logins to computers, etc...) For example, if one web site loses it' database, which contains ...
2
votes
1answer
49 views

About the security of GnuPG private key on-disk storage

GnuPG on-disk storage of secret key material is encrypted with AES-128, with an encryption key generated via an iterated and salted SHA-1 hash of the given passphrase. Is this usage of the SHA-1 hash ...
0
votes
0answers
80 views

Digital Signature Password verification

I currently have this TOFU protocol: First connection: Client generates salt and inputs a password Client saves salt Client hashes password with argon2 and salt Client generates Ed25519 keys Client ...
2
votes
2answers
360 views

Is using quantum computing to break passwords non-sense?

I understand the concept of 'trying all possibilities at once' but can anyone explain this with respect to the fact that my PC only accepts one password at a time? There's no input field that accepts ...
0
votes
2answers
571 views

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: ...
2
votes
2answers
155 views

PBKDF and Entropy

We all regularly use password based, key derivation functions, however something that strikes me as counter intuitive is how PBKDF can somehow "stretch" the entropy of a supplied password to generate ...
2
votes
1answer
80 views

I don't want to store passwords, can I use them as an encryption key for another field?

I'm not a 'cryptographic' anything, so if this is a super-dumb question please let me know (politely). So here's the deal, say I don't want to store passwords because that opens me up to all sorts of ...
0
votes
2answers
128 views

Can an attacker exploit the nonuniform distribution of letters in a diceware password to improve a brute force search?

I use some diceware pass phrases in some places but I have one question that I can't find the answer to. Let's say I roll the dice and get $N$ words with a total of $M$ letters and that I don't put ...
-1
votes
1answer
86 views

Brute forcing/hacking Secure passphrases - difficulty for random strings vs real words

I was wondering about this topic of brute forcing passwords,or ANY other way to deriving them - and asking myself whats more secure (relatively): A Password which includes A) 30 digits length- a ...
0
votes
0answers
57 views

Time-based decryption service

i am thinking about building a public crypto service, yet at the same time, I am still quite new to crypto and therefore prone to snake-oil inventions I guess. My plan is to build a website which ...
-1
votes
2answers
128 views

Can you encrypt a 256bit password with a 256bit key so that it cannot be bruteforced?

Lets say we have an arbitrary but dictionary attackable password that is less than 256bit. (Lets just say the password is '1234Password'). We encrypt this password with a securely random 256bit key ...
0
votes
1answer
109 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, ...
2
votes
2answers
102 views

Authentication without decrypting the password?

To my knowledge it works like this: The server receives the username-password values over a secure & encrypted channel. The username-password values are decrypted in the server and are present as ...
0
votes
2answers
319 views

Best practices for saving encrypted user data without a database

We are setting up a web application which requires users to submit sensitive data. Since entering all the required data may take a long amount of time, we want to give them the option to save their ...
3
votes
1answer
145 views

What is the most secure way to check that a given masterkey is valid?

For the purposes of learning, I'm writing a small utility that allows encrypting a list of passwords using a single master key (using AES-256 and PBKDF2) Before encrypting or decrypting any password ...
-1
votes
1answer
84 views

How many bits should I request from PBKDF2 to create a strong password?

I'm building a tool which generates passwords by hashing a service name with a master key. PBKDF2 was primarily chosen due to availability in the Web Crypto API. What would be a secure value for the ...
4
votes
0answers
114 views

Can “OPAQUE-over-TLS” authentication be optimized?

So while discussing the issues of password-hashing off-loading in our chat I noticed that it's easy to extend OPAQUE (CFRG draft) to essentially be a better standard password based authentication when ...
1
vote
2answers
81 views

Possible combinations of 8 digits, 6 upper case letters, 2 distinct numbers

Assume I want to find out how many combinations there are for a 8 digit word with 6 uppercase letters and 2 distinct numbers, e.g. A7BC9DEF, 1A0CRDEF, ... how many ...
3
votes
2answers
36 views

Mutual keys protection/wrapping

Is there a known risk in having two keys wrapping each other? Let's say, an adversary has access to both AESkey1(key2) and AESkey2(key1). Does it make it much easier for him to recover the keys?
0
votes
2answers
120 views

Where is the password hash calculated, locally on or the server?

My computer security professor uses the following notation, where S denotes a server and A denoted Alice. Alice wants to authenticate herself to the server. The hash function is a hash chain where $h^...
1
vote
2answers
650 views

64 bits password = 13 characters?

If we use upper and lower case letters, and 10 digits, we get approximately 6 bits per character. Then, strings of 13 characters should work. I saw above explanation in the material, but I cannot ...
2
votes
1answer
2k 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 ...
1
vote
3answers
326 views

Password re-use by another person or on another service

How does having the same password in different services make it less secure? How does having the same password as someone else make it less secure? Very basic question that I've always wondered about; ...
2
votes
2answers
90 views

How may passwords are available to use in this scenario?

Password string consisting of one or more of the 26 characters A..Z and can be of any length from $1$ to $8$ characters. How may password available to use this scenario? As my calculation, it should ...
-2
votes
1answer
3k 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 ...
2
votes
1answer
223 views

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 ...
15
votes
2answers
6k views

Calculating entropy within xkcd 936: Password Strength

When I calculate entropy for the xkcd Password Strength (comic 936) I don't get nearly the amount of entropy stated in the comic. So why doesn't the the first password "Tr0ub4dor&3" have an ...
3
votes
1answer
140 views

Secure password-authenticated key exchange that allows for passwords to be stored as hashes, but does not make the hashes password-equivalent

Are there any secure password-authenticated key exchange that allows for passwords to be stored as hashes, but does not make the hashes password-equivalent? This would be useful for many ...
3
votes
1answer
118 views

Does it make sense to have long SSH Key with shorter Passphrase?

If we encrypt our data with a longer SSH key which is protected by a shorter passphrase (with a decent entropy), then the limiting factor is entropy of the passphrase. So why do we use a longer key at ...
0
votes
1answer
472 views

Having trouble understanding reduction functions in rainbow tables

I'm continuing doing some personal research on rainbow tables, but forsome reason I cannot understand how to choose the correct reduction function. Wikipedia states that "Only when the attacker has ...
1
vote
1answer
182 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 ...
3
votes
1answer
272 views

Is using a smart card and password two-factor authentication?

I use a smart card - as read only device - for user identity as well as a password: The smart card (holds the user ID) is something I have; The password is something I know. Is this still two-factor ...
0
votes
1answer
292 views

Avoid decrypting every password in a password manager

The Setup I'm making a password manager for fun. It stores a random encryption key, encrypted with a key derived from the master password, and then it stores the data, which is a list of (site, ...
0
votes
3answers
828 views

Recommended minimum entropy for online passwords in 2018

Assume a simple case, that an attacker knows the password creation scheme, and that we're not dealing with state actors, nor with sites which keep passwords in plain text. We're trying to defend ...
0
votes
2answers
106 views

Client-side password stretching - danger of the salt being public?

In case of using client-side password stretching (plus a single hash on the server) - the server would need to send the salt before authentication, of course. Though the salt is not considered a real ...