Questions tagged [passwords]

Passwords are secret keys which human beings can memorize.

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10
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4answers
1k views

What is the best-practice for encrypting small files?

I would like to know how to store a sensitive file; a credential of sorts. I want to password-protect it, obviously. It would be appropriate - in my application - to prompt the user for the password ...
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1answer
159 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 ...
-1
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1answer
800 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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0answers
106 views

How can I encrypt a password for storage without having to remember another password? [migrated]

I've recently started using a password manager (1Password). I have a really good master password (using diceware) but I'm worried that if I forget it then I can't access 1P and all my passwords. One ...
0
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0answers
35 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 ...
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1answer
29 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?
14
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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 ...
2
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2answers
989 views

How do I calculate a password space if the password only has eight alphabetic characters (not case sensitive)

I read this wiki article and saw this formula for random password's information entropy. Also the wiki article mention that the symbol count for non case sensitive is 36. Is there a way I can ...
12
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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
89 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 ...
0
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2answers
3k views

How many attempts does it take to crack a 32-bit password hash with this scenario?

How many attempts does it take to crack (match) a 32-bit password hash from a database of 4 million password hashes? Correct me if I'm wrong, but to crack a 32-bit password hash would take roughly 2^...
0
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3answers
598 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 ...
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5answers
190 views

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

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
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3answers
170 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 ...
0
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2answers
229 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: ...
6
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1answer
2k views

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 (...
2
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2answers
2k 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 bcrypt(...
2
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1answer
44 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
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0answers
71 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 ...
3
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1answer
127 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 ...
4
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5answers
7k views

Why don’t all AES encryption tools produce the same key from the same password?

Alice and Bob meet regularly. They have agreed face-to-face a 128 bit password which they want use to encrypt/decrypt emails written between them. They decide to use 256-bit AES. Alice wrote her ...
2
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1answer
117 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 ...
6
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2answers
783 views

Is my password entropy calculation correct?

I have a password with a prescribed format: 111 + (2 Random lowercase letters) + (random digit) As you can see, it starts with a fixed value of ...
2
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2answers
97 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 ...
98
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4answers
61k views

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, ...
0
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2answers
108 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 ...
2
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1answer
76 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 ...
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1answer
65 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 ...
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0answers
49 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 ...
6
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3answers
292 views

Bounding security of password authentication given entropy

An adversary Craig tries to log-in as Alice on a system that will only accept the right password, leaks (only) if an attempt succeeds, and allows many attempts. Alice's password choice is modeled as ...
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2answers
122 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 ...
3
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2answers
405 views

KDF followed by a Hash?

It is my understanding that a KDF adds entropy, whereas a hash loses information. I've read that KDF should be used to store passwords. I don't understand why we don't use a KDF and then a hash, so ...
0
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1answer
91 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
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2answers
93 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
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2answers
138 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 ...
8
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3answers
1k 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 ...
2
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2answers
82 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 ...
17
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2answers
2k views

Is bcrypt better than GnuPG's iterated+salted hashing method?

GnuPG has slow hash built-in in form of iterated+salted S2K. Does it have disadvantages in comparison with bcrypt or scrypt? Is GnuPG's slow hash method easily automated in GPUs?
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1answer
71 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 ...
12
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3answers
6k views

Is there a way to make RC4 (ARCFOUR) secure, or is it completely broken?

I need a method to authenticate a process with another in order to establish interprocess communication between them, to prevent malicious processes from trying to hook onto the system. Currently I ...
3
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2answers
26 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?
4
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0answers
84 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
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1answer
317 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 ...
4
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2answers
238 views

On the security definition of password-authenticated key exchange

I found in all PAKE papers, the security is defined as something like this: Let $Succ(A)$ be the probability that an attacker $A$ successfully distinguished the session key from a random string. Then ...
3
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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 ...
1
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2answers
74 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
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1answer
98 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 ...
0
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2answers
89 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
427 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
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1answer
1k 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 ...