NAME

       openssl-genrsa - generate an RSA private key

SYNOPSIS

       openssl genrsa [-help] [-out filename] [-passout arg] [-aes128] [-aes192] [-aes256] [-aria128] [-aria192]
       [-aria256] [-camellia128] [-camellia192] [-camellia256] [-des] [-des3] [-idea] [-F4] [-f4] [-3] [-primes
       num] [-verbose] [-traditional] [-rand files] [-writerand file] [-engine id] [-provider name]
       [-provider-path path] [-propquery propq] [numbits]

DESCRIPTION

       This command generates an RSA private key.

OPTIONS

       -help
           Print out a usage message.

       -out filename
           Output the key to the specified file. If this argument is not specified then standard output is used.

       -passout arg
           The    output    file    password    source.    For   more   information   about   the   format   see
           openssl-passphrase-options(1).

       -aes128, -aes192, -aes256, -aria128, -aria192, -aria256, -camellia128, -camellia192, -camellia256, -des,
       -des3, -idea
           These options encrypt the private key with specified cipher before outputting it. If  none  of  these
           options is specified no encryption is used. If encryption is used a pass phrase is prompted for if it
           is not supplied via the -passout argument.

       -F4, -f4, -3
           The  public  exponent  to  use,  either  65537  or  3.  The default is 65537.  The -3 option has been
           deprecated.

       -primes num
           Specify the number of primes to use while generating the  RSA  key.  The  num  parameter  must  be  a
           positive  integer  that  is  greater  than  1  and  less than 16.  If num is greater than 2, then the
           generated key is called a 'multi-prime' RSA key, which is defined in RFC 8017.

       -verbose
           Print extra details about the operations being performed.

       -traditional
           Write the key using the traditional PKCS#1 format instead of the PKCS#8 format.

       -rand files, -writerand file
           See "Random State Options" in openssl(1) for details.

       -engine id
           See "Engine Options" in openssl(1).  This option is deprecated.

       -provider name
       -provider-path path
       -propquery propq
           See "Provider Options" in openssl(1), provider(7), and property(7).

       numbits
           The size of the private key to generate in bits. This must be the last option specified. The  default
           is 2048 and values less than 512 are not allowed.

NOTES

       RSA  private  key  generation  essentially  involves  the  generation  of two or more prime numbers. When
       generating a private key various symbols will be output to indicate the progress of the generation.  A  .
       represents each number which has passed an initial sieve test, + means a number has passed a single round
       of  the Miller-Rabin primality test, * means the current prime starts a regenerating progress due to some
       failed tests. A newline means that the number has passed all the prime tests (the actual  number  depends
       on the key size).

       Because  key  generation  is  a random process the time taken to generate a key may vary somewhat. But in
       general, more primes lead to less generation time of a key.

SEE ALSO

       openssl(1), openssl-genpkey(1), openssl-gendsa(1)

COPYRIGHT

       Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file  except  in  compliance
       with  the  License.   You  can  obtain  a  copy  in  the  file  LICENSE  in the source distribution or at
       <https://www.openssl.org/source/license.html>.

3.0.13                                             2025-02-05                               OPENSSL-GENRSA(1SSL)