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4
votes
1answer
44 views

How bad it is to feed /dev/random with /dev/urandom?

I have seen many blog posts, or blog comments which recommends to feed /dev/random entropy using output from /dev/urandom. I'm not a crypto expert, but it looks like a good way to replace ...
4
votes
1answer
249 views

OpenSSL 0.9.6a PRNG algorithm weakness: How to exploit?

I saw an OpenSSL security advisory for Openssl 0.9.6a Recently a cryptographic flaw in OpenSSL's built-in pseudo-random number generator (PRNG) was pointed out to us by Markku-Juhani O. Saarinen ...
3
votes
1answer
47 views

Is this good/secure method for client-server communication encryption?

Something came to my mind, and I wonder if this is proper method for client-server communication, and if this method is wide-used. On connection, client generates seed, encrypts it using asymmetric ...
4
votes
1answer
47 views

Is there a PRNG in Java with a period of at least 256 bits?

From what I can tell, Sun JRE/JDK's are limited to only providing 128-bit strong cryptography without downloading an unlimited strength jurisdiction policy files. My question is, if I install theses ...
1
vote
1answer
44 views

Is reseeding OpenSSL CSPRNG necessary if using RAND_bytes?

I read that cryprographic secure PRNG (CSPRNG) need a random seed to provide random output. Looking at OpenSSL that seems to be archived by RAND_poll() and random data is fetched with RAND_bytes(buf, ...
0
votes
1answer
26 views

Creating secure random output that is repeatable across machines [duplicate]

I'm having trouble figuring out a solution to this problem. Basically what i am trying to do is create random data that can be repeated across multiple machines by a user but is also secure from ...
2
votes
2answers
68 views

Securely generate a rng seed using a small number

I'm trying to figure out a secure method to generate a rng seed to a rng using a small pin number that is 5 digits. The issue that i can see with this is an attacker could very easily just loop ...
0
votes
3answers
96 views

Access Key In URL - Securing The Unsecured!

I'm having some difficulties doing this the right way (as much as it can go). Some time ago, I've asked a question here, asking for help on how to implement sending an access link through email. ...
5
votes
2answers
75 views

Two ways of generating the IV

I'm looking at some code, and in a particular scenario, the code would need to generate two IVs. The second IV-generating code simply uses the C# Rijndael GenerateIV() The first IV-generating code ...
6
votes
2answers
357 views

How much entropy is good enough for seeding a CSPRNG?

I have some fundamental questions on using Cryptographically Secure Pseudorandom Number Generators (CSPRNGs). What should be the size of the seed that I initialize a CSPRNG with? How often should I ...
6
votes
1answer
97 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 ...
4
votes
2answers
146 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 ...
7
votes
2answers
789 views

Linux kernel entropy - does it matter to /dev/urandom and what is a minimum?

This question had been asked several times, but still something's not clearly understood from other answers I have a few servers running with a custom built linux kernel (minimal driver modules etc), ...
4
votes
1answer
70 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 ...
5
votes
2answers
153 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 ...
2
votes
1answer
135 views

Evaluating the Entropy of the PRNG in OpenSSL

I've have a question on the PRNG in OpenSSL. I would like to understand how do you evaluate the diversity/entropy of the PRNG used in the OpenSSL (Cryptographic Library). If this is the wrong ...
15
votes
4answers
10k views

Why OpenSSL can't use /dev/random directly?

I couldn't find the answer for the reason anywhere, even the wiki page doesn't explain it. This seems like using a PRNG for seeding an another PRNG. The first one (/dev/random) may itself be seeded by ...
3
votes
1answer
205 views

Do I need a salt when hashing a randomly generated password?

I have passwords stored in my database that are very long, unique and generated by a CSPRNG. Do I need to use a salt before hashing them? My understanding is that usually you use a hash function in ...
0
votes
1answer
59 views

Secure shuffles and the rand() function

I'm trying to understand one aspect of a secure shuffle using Fisher-Yates. For reference, here is Fisher-Yates to shuffle an array x of n elements (numbered from 0 to n-1) (from Securing a Shuffle ...
2
votes
2answers
302 views

Securing a Shuffle Algorithm

After reading about writing a secure shuffle algorithm, I realized that my module that generates a password is only as strong as my PRNG, which in this case is Math.random(). I'm confused as to how to ...
17
votes
3answers
1k views

Why CSRF Token has to be a Cryptographically Strong Random number, in Double Submit Cookies method?

I was just going through the OWASP's Cheat Sheet for CSRF Prevention. In the Double Submit Cookies method, I saw this the site should generate a (cryptographically strong) pseudorandom value ...
4
votes
2answers
262 views

Reliable random seed for RNG

I want to create my computer passwords with a RNG, but I am thinking about one thing: I would use python to write that script and the RNG is controlled by one seed, most likely the time. If I would ...
10
votes
4answers
1k views

Does hashing a PRNG make it cryptographically secure?

Would hashing the result of a regular random number generator produce a cryptographically secure PRNG? For example, would sha1(rand()) effectively be a secure PRNG? Assuming it doesn't, how would ...
5
votes
2answers
147 views

Does RNG play a role in PGP signing?

We have a Jenkins system that builds and PGP-signs software releases, and we are considering moving the signing component to an isolated VM instead of running it as part of the overall builder ...
2
votes
3answers
586 views

How secure is to seed PRNGs with the sequences from CSPRNG?

Background: Implementing online casino, I would like to use a number of PRNGs with high throughput, like MersenneTwisterFast. I know it is not cryptographically strong, but quite unpredictable when ...
3
votes
4answers
536 views

What are the features of Dual EC DRBG that are lost when using a different cipher?

Due to a potential NSA backdoor, the NIST is now recommending that implementor no longer use ECC-based PRNG Dual EC DRBG. (As described in Wired.com) this PRNG has certain features such as: ...
0
votes
1answer
631 views

Can SHA-1 PRNG still create secure cipher keys?

I am concerned that a SHA-1 PRNG cannot produce an AES-256 cipher key with the expected 256 bits of security, or indeed any secure cipher key where over 165 bits of security are expected. The SHA-1 ...
3
votes
1answer
919 views

What key to use in HMAC

I need to use HMAC on a certain message to guarantee integrity, but I cannot figure out what are the requirements for the key to be given as input to the hashing algorithm. In particular I have to ...
5
votes
1answer
190 views

Detecting PRNG Use from Output

Question: Is there a way to detect the use of a PRNG strictly from observing the output provided by an application? Background: During an audit of a key generating algorithm that I knew was based on ...
3
votes
3answers
371 views

PRNG: Does combining insecure algos help?

Reading about how insecure PHP's rand function is, I was wondering if it helps to combine random functions. The suggested function there, openssl_random_pseudo_bytes, can also be cryptographically ...