The generation of random or pseudorandom data, and the use of randomness in security protocols

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A “hardware” random number generator for mobile phone

I have been trying to write a random number generator using the hardware of the phone. After reading other people's attempts and tried some. I came up with the following to generate the seed: Play ...
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1answer
61 views

Is encrypted data a good random source?

Given that someone needs my encryption key to predict the output, can I encrypt arbitrary data (zeroes, system logs, personal photos) with AES and a secure passphrase, and use the result as a ...
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2answers
58 views

Is it secure to create a Bitcoin address from a private key generated by Rand() instead of cryptographic elliptic curve

I am writing a C++ application that creates a Bitcoin address. I am having a hard time installing openssl for windows and making it work for visual studio. So, I am asking myself, if I create a ...
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0answers
16 views

What is the difference between Shannon entropy and saying that tossing a 6-sided die 100 times has more than 256-bit entropy? [migrated]

I'm confused. I thought that tossing a 6-sided die 100 times had a greater than 256-bit entropy because 6^99 < 2^256 < 6^100. (A similar concept appeared in this XKCD comic, where choosing four ...
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3answers
130 views

Is it worth augmenting /dev/random entropy in software?

Modern Linux systems, especially headless virtuals, often have shallow /dev/random entropy pools, which can cause software to block or fail to run (e.g. Tripwire in FIPS mode) While many agree ...
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11 views

What are the possible issues with generating random numbers in OpenSSL this way [migrated]

My following method is supposed to generate random numbers using OpenSSL. Is this correct and sufficient? Or do you see any issues with it? vector<unsigned char> generateBytes(const unsigned ...
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1answer
29 views

A simple question about entropy and random data

Let's say I roll a 6-sided die 100 times and record the results into a 100 character string, for example: //this is obviously an example (and very unlikely) outcome ...
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2answers
122 views

Why does gpg use /dev/urandom [duplicate]

Looking at the strace output of GPG on my box seems to show that it uses /dev/urandom when encrypting a message without any access to /dev/random even when --no-random-seed-file is specified. Are ...
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1answer
98 views

Attacks on keys generated with low entropy

If I were to give someone a two 4096 bits keys, and say one was generated in a Linux OS with very very low entropy available, and one was generated in a Linux OS with more than enough entropy. Would ...
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2answers
111 views

Token-based authentication - what's a good token length?

What's a good token character length for a token-based login? Currently I'm using the following code: <?php $token = bin2hex(openssl_random_pseudo_bytes(16)); Is 16 sufficient or should ...
4
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1answer
54 views

Law of Large Numbers vs. OpenSSL RAND_bytes

I have a system where tens of thousands of users log in whenever they like and my server has to assign them to one of many databases. I would like to distribute the users evenly amongst the databases. ...
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1answer
585 views

Is Postgres's uuid_generate_v4 securely random?

I'm using Postgres's uuid_generate_v4 in a uuid primary key column to generate secure one-time authentication tokens. Is this okay? Does Postgres use a secure random number source for generating these ...
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2answers
52 views

Calculating the time required to brute force a random code

Say we have amount random entry codes of length characters from an alphabet of size alphabet. The number of possible codes is then easily calculated as keyspace = alphabet ^ length. Now take an ...
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1answer
42 views

Who can certify RNG according NIST SP800-22?

I have written my own random number generator as a C library and I tested it on NIST Statistical Test Suite. Now I would like to get a certification to have a formal proof that my C library generates ...
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0answers
40 views

Using UUIDs for non-guessable URLs [duplicate]

How safe is using UUIDs as URL identifier for non-guessable IDs? Specifically UUIDs generated by Python's uuid4() function, using base64 encoding. E.g. ...
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1answer
40 views

Can a salt maintain pseudo-randomness after being modified?

TL;DR: How much can a function (such as the one below) modify an initially random string before that string becomes useless as a salt for password hashing? Is there a general rule? # Function ...
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1answer
42 views

RDRAND in Intel Celeron CPUs under Linux

Is there any reason to believe that the hardware RNG in an Intel Celeron CPU is more unreliable than in other CPUs? Can someone confirm that what Linus Torvalds says is true, namely that Linux does ...
2
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1answer
62 views

Will two virtual machines running on the same physical host machine get the same value from /dev/random?

Will two virtual machines running on the same physical host machine get the same value from /dev/random if read over the same time period? Say that Virtual-machine-1 wants to generate its ssh host ...
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0answers
19 views

Evaluating a noise source for a RNG - defining a one-paramter family for RNG [closed]

I am trying to evaluate a noise-source as a means of providing entropy to a random number generator. I am running into trouble when it comes to determining the probability distribution that has the ...
2
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2answers
35 views

Which software RNG for linux?

A headless server can suffer from a lack of entropy, which is a problem given that encryption needs random numbers. In the absence of a hardware random number generator (RNG) the numbers must be ...
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1answer
103 views

Managing keys generated with insufficient entropy

Since the Linux RNG which provides /dev/random (and by extension /dev/urandom) is seeded by "mouse and keyboard activity, disk I/O operations, and specific interrupts" (source, PDF) and since virtual ...
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2answers
77 views

Offline RSA strong prime test similar to Phuctor?

One of the ways that RSA keys get consistently owned is when they're generated without enough entropy. Dan Kaminsky refers to a study which found that 1 in 200 RSA keys were badly generated and these ...
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1answer
137 views

What comprises the AIS-31 standard for TRNGs?

I'm researching how my smart card's chipset generates random numbers. According to a source in forums the YubiKey NEO is based on the A700x chipset from NXP. The page for the chipset indicates that ...
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1answer
195 views

Do randomized PID bring more security?

What is the concrete advantage of using random PIDs instead of traditional sequential ones? Some times ago, I've read an article in the french magazine MISC (no. 74 - July/August, 2014) publishing a ...
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1answer
55 views

Is is possible to avoid internal seeding of a RNG and seed the generator manually using OpenSSL's RAND_bytes()?

I'm trying to write a random number generator with the OpenSSL library. The provided RAND_bytes() function is self-seeding with the /dev/urandom. That's why I am only able to reseed with the ...
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2answers
106 views

Should other processes be running while an iPhone or Android is generating a cryptographically random number?

I need to generate a cryptographically secure random number on iOS and Android. I could use a software approach or leverage the built in OS API for this. In each case, is it better to generate a ...
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101 views

Linux random number compliance

Not sure if this is the right forum, and I am pretty sure that his must have been answered before (I searched a lot but I haven't found a definitive answer). Do the Linux random number generators ...
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2answers
197 views

Is `arc4random` secure enough?

I need to generate many many initialization vectors and session keys in C++ code. I am wondering if arc4random is up to the task. Last I heard, there are many weaknesses in the RC4 cipher. Should I ...
3
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1answer
240 views

Predicting Math.random() numbers?

I was reading up on the documentation for Math.random() and I found the note: Math.random() does not provide cryptographically secure random numbers. Do not use them for anything related to ...
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6answers
2k views

What does “random” mean in the context of password creation?

Disclaimer: as you will see from my question I'm a total outsider in this subject, just very curious. I was wondering how easy it would be to crack a password-protected RAR5 file, and I found many ...
8
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1answer
255 views

RSA key generation: gpg vs openssh

When I generate RSA key for ssh (both server-side and client-side): dpkg-reconfigure openssh-server ssh-keygen the key generation is completed instantly. However, when I generate RSA key for gpg, ...
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4answers
499 views

How to check randomness of random number generators?

Assume that I have a smart card that returns an 8 byte (for example) random value on reception of a command. The question is that: How I can check if this value is really random? (I don't have any ...
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1answer
113 views

How to protect against random number generator attacks

I am using custom hardware on which i'm using the random noise from an ADC converter and a few other seeds. I combine these in an algorithm and have tested it against FIPS PUB 140-2 for a random ...
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1answer
108 views

Is it fine to store single-use beta keys plain-text?

Is it okay to store single-use beta keys in plain-text in the database? I'll be pre-generating and storing about 2M keys. The keys get passed around so that people can sign up with it, rather than let ...
3
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1answer
136 views

Ring Oscillator: True Random Number Generator (TRNG) vs Physically Unclonable Function (PUF)

Ring oscillators can be used in hardware true random number generators (TRNG), and also in physically unclonable functions (PUFs). The designs seem fairly similar: TRNG based on ring oscillators: ...
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2answers
251 views

AES encryption on embedded device: Can this be secure?

I plan to create an encryption program for an embedded device with the following characteristics: CPU is Intel 80186 compatible @ ~20 MHz 128 KB RAM, of which I have ~20 KB at my disposal for ...
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3answers
104 views

How to compare passwords with duplicate password

On Steam, the gaming client, I have this habit of creating multiple "smurf" accounts. I have a randomly-generated, unique password, and I decided to use the same password for all of my multiple ...
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2answers
175 views

Initialization of a LUKS encrypted partition with cipher or /dev/urandom

I've created a few encrypted devices with LUKS and cryptsetup on Linux and am pretty comfortable with disk encryption in this regard. I've seen it mentioned in many different places that when setting ...
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0answers
40 views

How is the random string of Thunderbird's profile folder generated? [closed]

As per this link, Thinderbird creates a folder by name in the format ".default” where ”” is an eight digit string randomly generated by Thunderbird. But how is it generated? Which random generator ...
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7answers
681 views

Is it possible to make a more secure random number generator algorithm by XORing two or more less secure random number algorithms?

Is it possible to make a more secure random number generator (e.g. for cryptologic purposes) by combining two or more less secure random number generator algorithms using XOR? Here is an example of ...
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7answers
4k views

Are humans a strong or weak RNG? [duplicate]

Thomas Pornin has stated in the past on multiple occasions (I'm not going to source them, he can argue with me if he wants) that humans are bad RNGs. While I agree that human RNG for password ...
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1answer
195 views

Creating secure PIN in Java

I need to create cryptographically secure PIN number in Java using secret id for each user. This simple approach comes to mind: int getPin(String secretUserIdStr) { String pepper = ...
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2answers
350 views

Including and storing the order of character entry in a password as an enhanced security measure

I'm sure I will be quickly corrected if this is a stupid idea, or if it has already been tried. My question is: has this idea been tried before? If not, are there good reasons it would not work, or ...
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1answer
256 views

Key's random art image is mostly black

I have generated an SSH key on Ubuntu 10.04 with ssh-keygen -t rsa -C "example@example.com" and the key's random art image comes out mostly empty (modified slightly): +--[ RSA 2048]----+ | ...
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1answer
206 views

Where does /dev/random get its entropy?

I read over and over about how /dev/random gets its entropy from "hardware events." What exactly are these hardware events and how can we be sure that it is random enough?
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2answers
185 views

2 way encryption of a string into numerical string using random number

I have a random number like 0.323978544752212. I want to encrypt a string using this random number into to numerical string i.e. final string is like ...
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11answers
5k views

One liner to create passwords in linux?

How do you create a readable password using bash with one line? What if i'm looking for 128 bits of entropy? EDIT By readable I mean the 94 printable ascii characters (without space). It can use ...
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1answer
142 views

Why is using [x] to generate random keypairs a bad idea?

Anyone who has generated large GPG public/private keypairs has come across this annoying message: "Not enough random bytes available. Please do some other work to give the OS a chance to collect more ...
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4answers
638 views

Add a file as entropy source for /dev/random

What I have: A large file containing lots of secret, true-random bytes (yes, I'm sure they're not merely pseudo-random). I'll call it F. What I want to do: Tell Linux that it can use this file as an ...
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2answers
440 views

Can the human brain generate cryptographically secure random numbers?

A security conscious friend of mine was attempting to generate entropy using random dice rolls to generate a random password, and I became curious about the security of random number generators and ...