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Diffstat (limited to 'secure/lib/libcrypto/man/RAND_egd.3')
| -rw-r--r-- | secure/lib/libcrypto/man/RAND_egd.3 | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/secure/lib/libcrypto/man/RAND_egd.3 b/secure/lib/libcrypto/man/RAND_egd.3 new file mode 100644 index 0000000..b7304ba --- /dev/null +++ b/secure/lib/libcrypto/man/RAND_egd.3 @@ -0,0 +1,210 @@ +.\" Automatically generated by Pod::Man 2.22 (Pod::Simple 3.07) +.\" +.\" Standard preamble: +.\" ======================================================================== +.de Sp \" Vertical space (when we can't use .PP) +.if t .sp .5v +.if n .sp +.. +.de Vb \" Begin verbatim text +.ft CW +.nf +.ne \\$1 +.. +.de Ve \" End verbatim text +.ft R +.fi +.. +.\" Set up some character translations and predefined strings. \*(-- will +.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left +.\" double quote, and \*(R" will give a right double quote. \*(C+ will +.\" give a nicer C++. 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Always turn off hyphenation; it makes +.\" way too many mistakes in technical documents. +.if n .ad l +.nh +.SH "NAME" +RAND_egd \- query entropy gathering daemon +.SH "SYNOPSIS" +.IX Header "SYNOPSIS" +.Vb 1 +\& #include <openssl/rand.h> +\& +\& int RAND_egd(const char *path); +\& int RAND_egd_bytes(const char *path, int bytes); +\& +\& int RAND_query_egd_bytes(const char *path, unsigned char *buf, int bytes); +.Ve +.SH "DESCRIPTION" +.IX Header "DESCRIPTION" +\&\fIRAND_egd()\fR queries the entropy gathering daemon \s-1EGD\s0 on socket \fBpath\fR. +It queries 255 bytes and uses \fIRAND_add\fR\|(3) to seed the +OpenSSL built-in \s-1PRNG\s0. RAND_egd(path) is a wrapper for +RAND_egd_bytes(path, 255); +.PP +\&\fIRAND_egd_bytes()\fR queries the entropy gathering daemon \s-1EGD\s0 on socket \fBpath\fR. +It queries \fBbytes\fR bytes and uses \fIRAND_add\fR\|(3) to seed the +OpenSSL built-in \s-1PRNG\s0. +This function is more flexible than \fIRAND_egd()\fR. +When only one secret key must +be generated, it is not necessary to request the full amount 255 bytes from +the \s-1EGD\s0 socket. This can be advantageous, since the amount of entropy +that can be retrieved from \s-1EGD\s0 over time is limited. +.PP +\&\fIRAND_query_egd_bytes()\fR performs the actual query of the \s-1EGD\s0 daemon on socket +\&\fBpath\fR. If \fBbuf\fR is given, \fBbytes\fR bytes are queried and written into +\&\fBbuf\fR. If \fBbuf\fR is \s-1NULL\s0, \fBbytes\fR bytes are queried and used to seed the +OpenSSL built-in \s-1PRNG\s0 using \fIRAND_add\fR\|(3). +.SH "NOTES" +.IX Header "NOTES" +On systems without /dev/*random devices providing entropy from the kernel, +the \s-1EGD\s0 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. +.PP +\&\s-1EGD\s0 is available from http://www.lothar.com/tech/crypto/ (\f(CW\*(C`perl +Makefile.PL; make; make install\*(C'\fR to install). It is run as \fBegd\fR +\&\fIpath\fR, where \fIpath\fR is an absolute path designating a socket. When +\&\fIRAND_egd()\fR is called with that path as an argument, it tries to read +random bytes that \s-1EGD\s0 has collected. \fIRAND_egd()\fR retrieves entropy from the +daemon using the daemon's \*(L"non-blocking read\*(R" command which shall +be answered immediately by the daemon without waiting for additional +entropy to be collected. The write and read socket operations in the +communication are blocking. +.PP +Alternatively, the EGD-interface compatible daemon \s-1PRNGD\s0 can be used. It is +available from +http://prngd.sourceforge.net/ . +\&\s-1PRNGD\s0 does employ an internal \s-1PRNG\s0 itself and can therefore never run +out of entropy. +.PP +OpenSSL automatically queries \s-1EGD\s0 when entropy is requested via \fIRAND_bytes()\fR +or the status is checked via \fIRAND_status()\fR for the first time, if the socket +is located at /var/run/egd\-pool, /dev/egd\-pool or /etc/egd\-pool. +.SH "RETURN VALUE" +.IX Header "RETURN VALUE" +\&\fIRAND_egd()\fR and \fIRAND_egd_bytes()\fR 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 \s-1PRNG\s0. +.PP +\&\fIRAND_query_egd_bytes()\fR returns the number of bytes read from the daemon on +success, and \-1 if the connection failed. The \s-1PRNG\s0 state is not considered. +.SH "SEE ALSO" +.IX Header "SEE ALSO" +\&\fIrand\fR\|(3), \fIRAND_add\fR\|(3), +\&\fIRAND_cleanup\fR\|(3) +.SH "HISTORY" +.IX Header "HISTORY" +\&\fIRAND_egd()\fR is available since OpenSSL 0.9.5. +.PP +\&\fIRAND_egd_bytes()\fR is available since OpenSSL 0.9.6. +.PP +\&\fIRAND_query_egd_bytes()\fR is available since OpenSSL 0.9.7. +.PP +The automatic query of /var/run/egd\-pool et al was added in OpenSSL 0.9.7. |
