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RAND_egd(3)
NAME
  RAND_egd - Query entropy gathering daemon

SYNOPSIS
  #include <openssl/rand.h>

  int RAND_egd(
	  const char *path );

  int RAND_egd_bytes(
	  const char *path, int bytes );

DESCRIPTION
  The RAND_egd() function queries the entropy gathering daemon EGD on socket
  path. It queries 255 bytes and uses RAND_add() to seed the OpenSSL built-in
  PRNG. The RAND_egd(path) is a wrapper for RAND_egd_bytes(path, 255).

  The RAND_egd_bytes() function queries the entropy gathering daemon EGD on
  socket path. It queries bytes and uses RAND_add() to seed the OpenSSL
  built-in PRNG. This function is more flexible than the RAND_egd() function
  . When only one secret key must be generated, it is not necessary to
  request the full amount 255 bytes from the EGD socket. This can be
  advantageous, since the amount of entropy that can be retrieved from EGD
  over time is limited.

NOTES
  On systems without /dev/*random devices providing entropy from the kernel,
  the EGD entropy gathering daemon can be used to collect entropy. It
  provides a socket interface through which entropy can be gathered in chunks
  up to 255 bytes. Several chunks can be queried during one connection.

  EGD is available from http://www.lothar.com/tech/crypto/ (perl Makefile.PL;
  make; make install to install). It is run as egd path, where path is an
  absolute path designating a socket. When the RAND_egd() function is called
  with that path as an argument, it tries to read random bytes that EGD
  collected.  The read is performed in non-blocking mode.

  Alternatively, the EGD-interface compatible daemon PRNGD can be used.	 It
  is available from http://www.aet.tu-
  cottbus.de/personen/jaenicke/postfix_tls/prngd.html.	PRNGD does employ an
  internal PRNG itself and can therefore never run out of entropy.

RETURN VALUE
  The RAND_egd() and RAND_egd_bytes() functions return the number of bytes
  read from the daemon on success, and -1 if the connection failed or the
  daemon did not return enough data to fully seed the PRNG.

HISTORY
  The RAND_egd() function is available since OpenSSL 0.9.5.

  The RAND_egd_bytes() function is available since OpenSSL 0.9.6.

SEE ALSO
  Functions: rand_ssl(3), RAND_add(3), RAND_cleanup(3)

Index for Section 3

Alphabetical listing for R

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