Need to generate a file with random data. /dev/[u]random doesn't exist.
Need to use dd to generate a large file from a sample file of random data. This is because I don't have /dev/urandom.
I create a named pipe then:
but when I cat a file to the fifo that's 1024 random bytes:
the dd command exits writing only 1024 (Likely the EOF thing). so I never get my 1MB file. How do I get around this? How do I ensure it generates the random data file without closing dd? Is there something else I need to pass?
Cheers,
DH
Last edited by Scott; 08-16-2013 at 12:05 PM..
Reason: Code tags, please.
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Give a example in book.
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2 326
123 1256
341 14
3245 645
.
.
.
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Hi,
In our HP-UX B.11.11. I could not find dev/urandom and dev/random
Are all pseudo-devices implemented as device drivers, or in need to run /configure some package to install the package to have dev/urandom.
Please help (4 Replies)
Discussion started by: rashi
4 Replies
LEARN ABOUT OPENSOLARIS
random
random(7D) Devices random(7D)NAME
random, urandom - Strong random number generator device
SYNOPSIS
/dev/random
/dev/urandom
DESCRIPTION
The /dev/random and /dev/urandom files are special files that are a source for random bytes generated by the kernel random number generator
device. The /dev/random and /dev/urandom files are suitable for applications requiring high quality random numbers for cryptographic pur-
poses.
The generator device produces random numbers from data and devices available to the kernel and estimates the amount of randomness (or
"entropy") collected from these sources. The entropy level determines the amount of high quality random numbers that are produced at a
given time.
Applications retrieve random bytes by reading /dev/random or /dev/urandom. The /dev/random interface returns random bytes only when suffi-
cient amount of entropy has been collected. If there is no entropy to produce the requested number of bytes, /dev/random blocks until more
entropy can be obtained. Non-blocking I/O mode can be used to disable the blocking behavior. The /dev/random interface also supports
poll(2). Note that using poll(2) will not increase the speed at which random numbers can be read.
Bytes retrieved from /dev/random provide the highest quality random numbers produced by the generator, and can be used to generate long
term keys and other high value keying material.
The /dev/urandom interface returns bytes regardless of the amount of entropy available. It does not block on a read request due to lack of
entropy. While bytes produced by the /dev/urandom interface are of lower quality than bytes produced by /dev/random, they are nonetheless
suitable for less demanding and shorter term cryptographic uses such as short term session keys, paddings, and challenge strings.
Data can be written to /dev/random and /dev/urandom. Data written to either special file is added to the generator's internal state. Data
that is difficult to predict by other users may contribute randomness to the generator state and help improve the quality of future gener-
ated random numbers.
/dev/random collects entropy from providers that are registered with the kernel-level cryptographic framework and implement random number
generation routines. The cryptoadm(1M) utility allows an administrator to configure which providers will be used with /dev/random.
ERRORS
EAGAIN O_NDELAY or O_NONBLOCK was set and no random bytes are available for reading from /dev/random.
EINTR A signal was caught while reading and no data was transferred.
ENOXIO open(2) request failed on /dev/random because no entropy provider is available.
FILES
/dev/random
/dev/urandom
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability | SUNWcsr |
|Interface Stability |Evolving |
+-----------------------------+-----------------------------+
SEE ALSO cryptoadm(1M), open(2), poll(2), attributes(5)NOTES
/dev/random can be configured to use only the hardware-based providers registered with the kernel-level cryptographic framework by dis-
abling the software-based provider using cryptoadm(1M). You can also use cryptoadm(1M) to obtain the name of the software-based provider.
Because no entropy is available, disabling all randomness providers causes read(2) and poll(2) on /dev/random to block indefinitely and
results in a warning message being logged and displayed on the system console. However, read(2) and poll(2) on /dev/urandom continue to
work in this case.
An implementation of the /dev/random and /dev/urandom kernel-based random number generator first appeared in Linux 1.3.30.
A /dev/random interface for Solaris first appeared as part of the CryptoRand implementation.
SunOS 5.11 1 Sep 2008 random(7D)