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Editing: RAND_set_rand_method.3
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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_set_rand_method, RAND_get_rand_method, RAND_SSLeay \- select RAND method .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/rand.h> \& \& void RAND_set_rand_method(const RAND_METHOD *meth); \& \& const RAND_METHOD *RAND_get_rand_method(void); \& \& RAND_METHOD *RAND_SSLeay(void); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" A \fB\s-1RAND_METHOD\s0\fR specifies the functions that OpenSSL uses for random number generation. By modifying the method, alternative implementations such as hardware RNGs may be used. \s-1IMPORTANT:\s0 See the \s-1NOTES\s0 section for important information about how these \s-1RAND API\s0 functions are affected by the use of \&\fB\s-1ENGINE\s0\fR \s-1API\s0 calls. .PP Initially, the default \s-1RAND_METHOD\s0 is the OpenSSL internal implementation, as returned by \fBRAND_SSLeay()\fR. .PP \&\fBRAND_set_default_method()\fR makes \fBmeth\fR the method for \s-1PRNG\s0 use. \fB\s-1NB\s0\fR: This is true only whilst no \s-1ENGINE\s0 has been set as a default for \s-1RAND,\s0 so this function is no longer recommended. .PP \&\fBRAND_get_default_method()\fR returns a pointer to the current \s-1RAND_METHOD.\s0 However, the meaningfulness of this result is dependent on whether the \s-1ENGINE API\s0 is being used, so this function is no longer recommended. .SH "THE RAND_METHOD STRUCTURE" .IX Header "THE RAND_METHOD STRUCTURE" .Vb 9 \& typedef struct rand_meth_st \& { \& void (*seed)(const void *buf, int num); \& int (*bytes)(unsigned char *buf, int num); \& void (*cleanup)(void); \& void (*add)(const void *buf, int num, int entropy); \& int (*pseudorand)(unsigned char *buf, int num); \& int (*status)(void); \& } RAND_METHOD; .Ve .PP The components point to the implementation of \fBRAND_seed()\fR, \&\fBRAND_bytes()\fR, \fBRAND_cleanup()\fR, \fBRAND_add()\fR, \fBRAND_pseudo_rand()\fR and \fBRAND_status()\fR. Each component may be \s-1NULL\s0 if the function is not implemented. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBRAND_set_rand_method()\fR returns no value. \fBRAND_get_rand_method()\fR and \&\fBRAND_SSLeay()\fR return pointers to the respective methods. .SH "NOTES" .IX Header "NOTES" As of version 0.9.7, \s-1RAND_METHOD\s0 implementations are grouped together with other algorithmic APIs (eg. \s-1RSA_METHOD, EVP_CIPHER,\s0 etc) in \fB\s-1ENGINE\s0\fR modules. If a default \s-1ENGINE\s0 is specified for \s-1RAND\s0 functionality using an \s-1ENGINE API\s0 function, that will override any \s-1RAND\s0 defaults set using the \s-1RAND API\s0 (ie. \&\fBRAND_set_rand_method()\fR). For this reason, the \s-1ENGINE API\s0 is the recommended way to control default implementations for use in \s-1RAND\s0 and other cryptographic algorithms. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBrand\fR\|(3), \fBengine\fR\|(3) .SH "HISTORY" .IX Header "HISTORY" \&\fBRAND_set_rand_method()\fR, \fBRAND_get_rand_method()\fR and \fBRAND_SSLeay()\fR are available in all versions of OpenSSL. .PP In the engine version of version 0.9.6, \fBRAND_set_rand_method()\fR was altered to take an \s-1ENGINE\s0 pointer as its argument. As of version 0.9.7, that has been reverted as the \s-1ENGINE API\s0 transparently overrides \s-1RAND\s0 defaults if used, otherwise \s-1RAND API\s0 functions work as before. \fBRAND_set_rand_engine()\fR was also introduced in version 0.9.7.
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