random.4: ffix

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man4/random.4

@@ -44,14 +44,14 @@ interface which requires no special files;
 see the
 .BR getrandom (2)
 manual page for details.
-
+.PP
 When read, the
 .I /dev/urandom
 device returns random bytes using a pseudorandom
 number generator seeded from the entropy pool.
 Reads from this device do not block (i.e., the CPU is not yielded),
 but can incur an appreciable delay when requesting large amounts of data.
-
+.PP
 When read during early boot time,
 .IR /dev/urandom
 may return data prior to the entropy pool being initialized.
@@ -60,7 +60,7 @@ may return data prior to the entropy pool being initialized.
 If this is of concern in your application, use
 .BR getrandom (2)
 or \fI/dev/random\fP instead.
-
+.PP
 The \fI/dev/random\fP device is a legacy interface which dates back to
 a time where the cryptographic primitives used in the implementation
 of \fI/dev/urandom\fP were not widely trusted.
@@ -68,7 +68,7 @@ It will return random bytes only within the estimated number of
 bits of fresh noise in the entropy pool, blocking if necessary.
 \fI/dev/random\fP is suitable for applications that need
 high quality randomness, and can afford indeterminate delays.
-
+.PP
 When the entropy pool is empty, reads from \fI/dev/random\fP will block
 until additional environmental noise is gathered.
 If
@@ -87,7 +87,7 @@ will return -1 and
 .I errno
 will be set to
 .BR EAGAIN .
-
+.PP
 The
 .B O_NONBLOCK
 flag has no effect when opening
@@ -102,7 +102,7 @@ Reads with a buffer over this limit may return less than the
 requested number of bytes or fail with the error
 .BR EINTR ,
 if interrupted by a signal handler.
-
+.PP
 Since Linux 3.16,
 .\" commit 79a8468747c5f95ed3d5ce8376a3e82e0c5857fc
 a
@@ -117,7 +117,7 @@ from
 will return at most 512 bytes
 .\" SEC_XFER_SIZE in drivers/char/random.c
 (340 bytes on Linux kernels before version 2.6.12).
-
+.PP
 Writing to \fI/dev/random\fP or \fI/dev/urandom\fP will update the
 entropy pool with the data written, but this will not result in a
 higher entropy count.
@@ -135,7 +135,7 @@ these applications,
 .BR getrandom (2)
 must be used instead,
 because it will block until the entropy pool is initialized.
-
+.PP
 If a seed file is saved across reboots as recommended below (all major
 Linux distributions have done this since 2000 at least), the output is
 cryptographically secure against attackers without local root access as
@@ -152,13 +152,13 @@ entropy is not immediately available.
 If your system does not have
 \fI/dev/random\fP and \fI/dev/urandom\fP created already, they
 can be created with the following commands:
-
+.PP
 .nf
     mknod \-m 666 /dev/random c 1 8
     mknod \-m 666 /dev/urandom c 1 9
     chown root:root /dev/random /dev/urandom
 .fi
-
+.PP
 When a Linux system starts up without much operator interaction,
 the entropy pool may be in a fairly predictable state.
 This reduces the actual amount of noise in the entropy pool
@@ -167,7 +167,7 @@ In order to counteract this effect, it helps to carry
 entropy pool information across shut-downs and start-ups.
 To do this, add the lines to an appropriate script
 which is run during the Linux system start-up sequence:
-
+.PP
 .nf
     echo "Initializing random number generator..."
     random_seed=/var/run/random-seed
@@ -184,10 +184,10 @@ which is run during the Linux system start-up sequence:
     bytes=$(expr $bits / 8)
     dd if=/dev/urandom of=$random_seed count=1 bs=$bytes
 .fi
-
+.PP
 Also, add the following lines in an appropriate script which is
 run during the Linux system shutdown:
-
+.PP
 .nf
     # Carry a random seed from shut-down to start-up
     # Save the whole entropy pool
@@ -200,7 +200,7 @@ run during the Linux system shutdown:
     bytes=$(expr $bits / 8)
     dd if=/dev/urandom of=$random_seed count=1 bs=$bytes
 .fi
-
+.PP
 In the above examples, we assume Linux 2.6.0 or later, where
 .IR /proc/sys/kernel/random/poolsize
 returns the size of the entropy pool in bits (see below).
@@ -331,5 +331,5 @@ may return data prior to the entropy pool being initialized.
 .BR mknod (1),
 .BR getrandom (2),
 .BR random (7)
-
+.PP
 RFC\ 1750, "Randomness Recommendations for Security"