The generation of random or pseudorandom data, and the use of randomness in security protocols
0
votes
1answer
82 views
is this code valid for securing passwords? [duplicate]
i was wondering if this is a secure method for a hashing password.if it is not secure please tell me what to do in order to make it secure
$pass='test'//the password
...
2
votes
1answer
20 views
bin_random_table and RANDOM_BOOT_ID
The Linux kernel has a few sysctrl's related to random devices packaged in a bin_random_table (http://lxr.free-electrons.com/source/kernel/sysctl_binary.c?v=3.2):
static const struct bin_table ...
17
votes
3answers
612 views
Does (online) poker require cryptographically secure randomness?
Here’s a quote from a reddit discussion:
… for poker [a cryptographically secure RNG] is completely unnecessary.
If you have an appropriate unpredictable seed, and you are throwing away a lot of ...
1
vote
1answer
130 views
How securely random is Oracle's java.security.SecureRandom
There was a lot of news in the past year about exploitable weaknesses in cryptography which originated from weak random number generators. In some cases it was negligence on side of the developers, in ...
8
votes
3answers
746 views
Why doesn't OpenSSL use /dev/random /dev/urandom 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 PRNG.
I can 'understand' why the -rand option can't be used directly for ...
6
votes
6answers
527 views
Testing a hardware random number generator
The Raspberry Pi has a built in hardware random number generator but there doesn't appear to be any public documentation on the hardware, and even if there were it would be questionable (what company ...
5
votes
1answer
127 views
Can the xor of two RNG outputs ever be less secure than one of them?
Suppose I'm suspicious that one or more (pseudo)-random number generators is cryptographically flawed, perhaps even deliberately backdoored. The RNGs in this case might be either PRNG algorithms, ...
5
votes
2answers
67 views
Benefit to using PBKDF2 on key generated by RNGCryptoServiceProvider?
I have a program that generates a fixed-length 32 byte (256-bit) password using RNGCryptoService provider and then uses Rfc2898DeriveBytes on that password to arrive at an encryption key.
However, to ...
12
votes
2answers
333 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
...
0
votes
1answer
129 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 ...
0
votes
1answer
758 views
Generating a TRULY random string in PHP [duplicate]
I need to generate thousands (possibly millions) of unique codes for a client. These codes may have a monetary value, so it's vital that they are TRULY random, and that no pattern could be spotted and ...
2
votes
3answers
199 views
If the code to shuffle an array is known, is it possible for the randomized shuffle to stay secure?
I recently was looking at Poker shuffles that were hacked and made to be guessable within a reasonable degree and this was because of the weakness of the shuffles. Is it possible to make a shuffle ...
2
votes
2answers
316 views
How to generate cryptographically strong pseudorandom data very rapidly?
What's the best way to go about generating a fast stream of cryptographically strong pseudorandom data without installing uncommon packages? Drawing from /dev/urandom is far too slow.
I had an idea ...
2
votes
2answers
134 views
Reducing crypto-random values to a useless entropy
Supposing I have generated random data from CryptGenRandom (or similar PRNG), at what point does futzing with the values make it not-so-random that it's useless? Or is sufficiently random in enough to ...
3
votes
4answers
426 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
98 views
Can the random keys generated during handshake be guessed
During the handshaking of an SSL connection, the server sends its public key, the client generates a random password, encrypts it with the pk, and sends it back, then the server decrypts it and all is ...
24
votes
3answers
1k views
Is generating random numbers using a smartphone camera a good idea?
Forgive my ignorance on the subject, but I wish to know more and asking (stupid) questions are one way. I was reading http://www.random.org/randomness/ and this idea popped into my head (before the ...
8
votes
2answers
531 views
How does a weakness in a random number generator lead to a compromise of the entire cryptographic process?
In the news, there are several articles (here, here, and the technical point of view) which have to do with a weakness in a random number generator.
The question is somewhat twofold. What symptoms do ...
1
vote
2answers
115 views
How many bytes should an authorization token have? [duplicate]
Assuming I generate random bytes with a secure PRNG, how many bytes do I need to make authorization tokens secure?
Specifically, when users log in to a website, a token will be generated and stored ...
7
votes
2answers
563 views
Java SecureRandom doesn't block? How?
I know from experience that reading from /dev/random blocks when the Linux kernel entropy pool runs out of entropy. Also, I've seen many articles and blog entries stating that when running on Linux, ...
3
votes
2answers
311 views
Is mt_rand() suitable for generating a salt?
Assumed I have to following code in order to generate a random blowfish salt for saving a new password:
$blowfishCharacters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789./';
$salt ...
12
votes
2answers
342 views
Correct way to get a number from 0-9 from a random byte?
If I have a good random number generator that gives me a byte of data at a time, and I want to extract a random decimal digit of 0 to 9 from that byte stream, what is the correct way to do that?
At ...
4
votes
2answers
100 views
Understanding PRGs: How can we expand randomness?
I am getting a bit confused with the PRGs employed in cryptography.
Basically, a PRG is used to expand a random sequence (mostly a key) of length s to a length n>s, still looking random. Now while ...
2
votes
2answers
344 views
SJCL : convert ascii to a BitArray & compute random numbers
I am using the Stanford Javascript Crypto library and i'd like more information about it.
1.) I have an ASCII text and a random 128-bit key. I want to concat those two things, so I convert the ASCII ...
15
votes
3answers
3k views
Is it appropriate to use haveged as a source of entropy on virtual machines?
While looking for solutions to entropy pool depletion on virtual machines, I came across an interesting project called haveged, which is based on the HAVEGE algorithm (HArdware Volatile Entropy ...
2
votes
1answer
153 views
isaac random number generator and the type of encryption it is used for (game packet encryption)?
I recently found isaac but I'm not sure what type of encryption is possible using it. Does the random number generator itself become the message somehow or does it get used as a seed for an encryption ...
4
votes
1answer
102 views
Tools and methods for analyzing RNGs
What are the common tools and methods used for analyzing and attacking Random Number Generators?
I know what characteristics make a good RNG and what a good RNG should do but I do not know how to ...
15
votes
2answers
391 views
What statistics can be used to identify pseudorandom data?
I'm working on some code that attempts to identify files whose contents appear to be "random". As such, I'm looking for statistical measures that can be used to identify such randomness.
I've ...
0
votes
1answer
491 views
Java SecureRandom generate secure random number
How to generate a secure random number bit length is 256 bits using Java. What is the different between:
SecureRandom random = new SecureRandom();
and
SecureRandom prng = ...
6
votes
1answer
422 views
How to predict C rand()? [duplicate]
Is there a practical way to predict previous/next C rand() output if i have some of the values? How many values do i need? Do they need to be consequent? If it depends on compiler - for which ...
8
votes
3answers
714 views
Generating random passwords by clicking randomly on the keyboard?
How secure is it to generate random strings/passwords manually for different purposes by just clicking randomly on the keyboard ?
I usually need random strings for salts and for passwords, and I ...
1
vote
2answers
423 views
How to generate a highly unpredictable random bytes
void
vncRandomBytes(unsigned char *bytes)
{
int i;
unsigned int seed = (unsigned int) time(0) + getpid() + rand();
srand(seed);
for (i = 0; i < CHALLENGESIZE; i++) {
bytes[i] = (unsigned ...
5
votes
1answer
143 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 ...
5
votes
3answers
670 views
CSRF Countermeasures
I'm working through a book on web application security and it says that an effective CSRF countermeasure is to assign a temporary pseudo-random token to sensitive actions performed by authenticated ...
6
votes
2answers
470 views
Filling the disk with random data prior to encryption?
Filling the disk with random data prior to encrypting it will supposedly make it harder for the attacker to perform any cryptanalysis. Most sources seem to state this is because it will be harder for ...
2
votes
2answers
2k views
should i use urandom or openssl_random_pseudo_bytes?
I am developing a site in php 5.4 and i was wondering which is better to use to gen a random salt for password security?
$salt = sha1(openssl_random_pseudo_bytes(23));
or
$seed = '';
$a = ...
6
votes
2answers
490 views
How is the available entropy in /dev/random calculated (or estimated)?
It seems (to a non-expert) that /dev/random is acclaimed to be useable as a source of pure random data. However, I am curious as to the analysis of the file /dev/random.
/dev/random is a collection ...
10
votes
3answers
1k views
Is a predictable MAC address a risk?
If you knew from the public internet that a certain IP address belonged to a machine with a certain MAC address, can you see any security exposure associated with that? I know that some software will ...
1
vote
0answers
50 views
Do the popular smartphone operating system have a cryptographically secure random source? [duplicate]
Possible Duplicate:
Do mobile OS’s provide crypto-quality randomness?
Linux and Mac OS X has /dev/urandom, Windows has CryptGenRandom.
Do iOS and Android have a similar way to generate ...
-5
votes
5answers
563 views
create a variants of MD5
I have also asked similar q here :
To create a variants of MD5, I made following changes :
MD5 uses a non-linear sin(i)* pow(2,32) ----> i plane to use cos(i)*pow(2,32)
Instead ...
4
votes
1answer
144 views
Computational Feasibility of finding 'Good Links' of the following format
I recently stumbled upon this and am checking here to see if what I am proposing is indeed feasible and can be considered a breach of privacy.
For obvious reasons I am not revealing the website ...
9
votes
4answers
2k views
Generate cryptographically strong pseudorandom numbers in Javascript?
Is there any good way to generate cryptographically strong pseudorandom (or true random) numbers in Javascript?
The crucial requirement: if a.com's Javascript generates some random numbers, no one ...
3
votes
4answers
467 views
SMS Authentication: random OTP or a cryptographic one
I'm adding two-factor authentication using SMS to enhance an existing login process. Since I'm not working with physical tokens, I was wondering what is considered the safest:
Sending random 8 ...
3
votes
3answers
290 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 ...
3
votes
3answers
2k views
How insecure are PHP's rand functions?
There are some pseudo-random-number generators in PHP: rand(), srand(), mt_rand(), mt_srand(). You can look at their code here.
I understand those functions are insecure, but how insecure are they?
...
8
votes
4answers
855 views
How insecure are non-cryptographic random number generators?
I always hear that C rand() is not secure, but what how many calls would you need to know in order to predict the next value (or at least cut down the possibilities)? Would they have to be sequential? ...
18
votes
5answers
605 views
Hashed password storage with random salt
Ever since I've been making sites that require a user to log in with a username and password I've always kept the passwords somewhat secure by storing them in my database hashed with a salt phrase. ...
9
votes
2answers
490 views
Can I use hardware random number generation on my computer? Am I already using it?
A lot of computer security depends on encryption: SSL connections, TCP packet sequencing, encrypted files, etc. These depend on random number generation to ensure that attackers can't guess the ...
8
votes
1answer
2k views
How to select /dev/random or dev/urandom in the code in Android?
When generating randomness using SecureRandom in Android, I want to select /dev/random or /dev/urandom as the seed source. It can be done in java.security file on Linux and Windows systems but there's ...
7
votes
4answers
3k views
What do I need to configure, to make sure my software uses /dev/urandom?
When setting up a server, what configuration changes do I need to make sure that all of the software uses /dev/urandom instead of /dev/random?
Some servers don't have much entropy in the entropy pool ...
