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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_DRBG_new, RAND_DRBG_secure_new, RAND_DRBG_set, RAND_DRBG_set_defaults, RAND_DRBG_instantiate, RAND_DRBG_uninstantiate, RAND_DRBG_free \&\- initialize and cleanup a RAND_DRBG instance .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/rand_drbg.h> \& \& \& RAND_DRBG *RAND_DRBG_new(int type, \& unsigned int flags, \& RAND_DRBG *parent); \& \& RAND_DRBG *RAND_DRBG_secure_new(int type, \& unsigned int flags, \& RAND_DRBG *parent); \& \& int RAND_DRBG_set(RAND_DRBG *drbg, \& int type, unsigned int flags); \& \& int RAND_DRBG_set_defaults(int type, unsigned int flags); \& \& int RAND_DRBG_instantiate(RAND_DRBG *drbg, \& const unsigned char *pers, size_t perslen); \& \& int RAND_DRBG_uninstantiate(RAND_DRBG *drbg); \& \& void RAND_DRBG_free(RAND_DRBG *drbg); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\fBRAND_DRBG_new()\fR and \fBRAND_DRBG_secure_new()\fR create a new \s-1DRBG\s0 instance of the given \fBtype\fR, allocated from the heap resp. the secure heap (using \fBOPENSSL_zalloc()\fR resp. \fBOPENSSL_secure_zalloc()\fR). .PP \&\fBRAND_DRBG_set()\fR initializes the \fBdrbg\fR with the given \fBtype\fR and \fBflags\fR. .PP \&\fBRAND_DRBG_set_defaults()\fR sets the default \fBtype\fR and \fBflags\fR for new \s-1DRBG\s0 instances. .PP Currently, all \s-1DRBG\s0 types are based on AES-CTR, so \fBtype\fR can be one of the following values: NID_aes_128_ctr, NID_aes_192_ctr, NID_aes_256_ctr. Before the \s-1DRBG\s0 can be used to generate random bits, it is necessary to set its type and to instantiate it. .PP The optional \fBflags\fR argument specifies a set of bit flags which can be joined using the | operator. Currently, the only flag is \&\s-1RAND_DRBG_FLAG_CTR_NO_DF,\s0 which disables the use of the derivation function ctr_df. For an explanation, see [\s-1NIST SP 800\-90A\s0 Rev. 1]. .PP If a \fBparent\fR instance is specified then this will be used instead of the default entropy source for reseeding the \fBdrbg\fR. It is said that the \&\fBdrbg\fR is \fIchained\fR to its \fBparent\fR. For more information, see the \s-1NOTES\s0 section. .PP \&\fBRAND_DRBG_instantiate()\fR seeds the \fBdrbg\fR instance using random input from trusted entropy sources. Optionally, a personalization string \fBpers\fR of length \fBperslen\fR can be specified. To omit the personalization string, set \fBpers\fR=NULL and \fBperslen\fR=0; .PP \&\fBRAND_DRBG_uninstantiate()\fR clears the internal state of the \fBdrbg\fR and puts it back in the uninstantiated state. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBRAND_DRBG_new()\fR and \fBRAND_DRBG_secure_new()\fR return a pointer to a \s-1DRBG\s0 instance allocated on the heap, resp. secure heap. .PP \&\fBRAND_DRBG_set()\fR, \&\fBRAND_DRBG_instantiate()\fR, and \&\fBRAND_DRBG_uninstantiate()\fR return 1 on success, and 0 on failure. .PP \&\fBRAND_DRBG_free()\fR does not return a value. .SH "NOTES" .IX Header "NOTES" The \s-1DRBG\s0 design supports \fIchaining\fR, which means that a \s-1DRBG\s0 instance can use another \fBparent\fR \s-1DRBG\s0 instance instead of the default entropy source to obtain fresh random input for reseeding, provided that \fBparent\fR \s-1DRBG\s0 instance was properly instantiated, either from a trusted entropy source, or from yet another parent \s-1DRBG\s0 instance. For a detailed description of the reseeding process, see \s-1\fBRAND_DRBG\s0\fR\|(7). .PP The default \s-1DRBG\s0 type and flags are applied only during creation of a \s-1DRBG\s0 instance. To ensure that they are applied to the global and thread-local \s-1DRBG\s0 instances (<master>, resp. <public> and <private>), it is necessary to call \&\fBRAND_DRBG_set_defaults()\fR before creating any thread and before calling any cryptographic routines that obtain random data directly or indirectly. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBOPENSSL_zalloc\fR\|(3), \&\fBOPENSSL_secure_zalloc\fR\|(3), \&\fBRAND_DRBG_generate\fR\|(3), \&\s-1\fBRAND_DRBG\s0\fR\|(7) .SH "HISTORY" .IX Header "HISTORY" The \s-1RAND_DRBG\s0 functions were added in OpenSSL 1.1.1. .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright 2017\-2020 The OpenSSL Project Authors. All Rights Reserved. .PP Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.