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random.4: Minor fixes 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2015-02-04 09:48:39 +01:00
parent 17ad768d41
commit 792bb5ad59
1 changed files with 8 additions and 8 deletions
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16
man4/random.4
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@ -37,8 +37,8 @@ The generator also keeps an estimate of the
number of bits of noise in the entropy pool. number of bits of noise in the entropy pool.
From this entropy pool random numbers are created. From this entropy pool random numbers are created.
.LP .LP
When read, the \fI/dev/random\fP device will only return random bytes When read, the \fI/dev/random\fP device will return random bytes
within the estimated number of bits of noise in the entropy only within the estimated number of bits of noise in the entropy
pool. pool.
\fI/dev/random\fP should be suitable for uses that need very \fI/dev/random\fP should be suitable for uses that need very
high quality randomness such as one-time pad or key generation. high quality randomness such as one-time pad or key generation.
@ -48,13 +48,13 @@ If
.BR open (2) .BR open (2)
is called for is called for
.I /dev/random .I /dev/random
with flag with the flag
.BR O_NONBLOCK , .BR O_NONBLOCK ,
a subsequent a subsequent
.BR read (2) .BR read (2)
will not block if the requested number of bytes is not available. will not block if the requested number of bytes is not available.
Instead, the available bytes are returned. Instead, the available bytes are returned.
If no byte is available If no byte is available,
.BR read (2) .BR read (2)
will return -1 and will return -1 and
.I errno .I errno
@ -77,8 +77,8 @@ has no effect when opening
.IR /dev/urandom . .IR /dev/urandom .
When calling When calling
.BR read (2) .BR read (2)
for device for the device
.I /dev/urandom .IR /dev/urandom ,
signals will not be handled until after the requested random bytes signals will not be handled until after the requested random bytes
have been generated. have been generated.
.LP .LP
@ -127,8 +127,8 @@ The amount of seed material required to generate a cryptographic key
equals the effective key size of the key. equals the effective key size of the key.
For example, a 3072-bit RSA For example, a 3072-bit RSA
or Diffie-Hellman private key has an effective key size of 128 bits or Diffie-Hellman private key has an effective key size of 128 bits
(it requires about 2^128 operations to break) so a key generator only (it requires about 2^128 operations to break) so a key generator
needs 128 bits (16 bytes) of seed material from needs only 128 bits (16 bytes) of seed material from
.IR /dev/random . .IR /dev/random .
While some safety margin above that minimum is reasonable, as a guard While some safety margin above that minimum is reasonable, as a guard