openssl/doc/man1/openssl-genrsa.pod.in

=pod

=begin comment
{- join("\n", @autowarntext) -}

=end comment

=head1 NAME

openssl-genrsa - generate an RSA private key

=head1 SYNOPSIS

B<openssl> B<genrsa>
[B<-help>]
[B<-out> I<filename>]
[B<-passout> I<arg>]
[B<-aes128>]
[B<-aes192>]
[B<-aes256>]
[B<-aria128>]
[B<-aria192>]
[B<-aria256>]
[B<-camellia128>]
[B<-camellia192>]
[B<-camellia256>]
[B<-des>]
[B<-des3>]
[B<-idea>]
[B<-f4>|B<-3>]
[B<-engine> I<id>]
[B<-primes> I<num>]
[B<-verbose>]
{- $OpenSSL::safe::opt_r_synopsis -}
[B<numbits>]

=for openssl ifdef engine

=head1 DESCRIPTION

This command generates an RSA private key.

=head1 OPTIONS

=over 4

=item B<-help>

Print out a usage message.

=item B<-out> I<filename>

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

=item B<-passout> I<arg>

The output file password source. For more information about the format
see L<openssl(1)/Pass Phrase Options>.

=item B<-aes128>, B<-aes192>, B<-aes256>, B<-aria128>, B<-aria192>, B<-aria256>, B<-camellia128>, B<-camellia192>, B<-camellia256>, B<-des>, B<-des3>, B<-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 B<-passout> argument.

=item B<-F4>|B<-3>

The public exponent to use, either 65537 or 3. The default is 65537.

=item B<-engine> I<id>

Specifying an engine (by its unique I<id> string) will cause this command
to attempt to obtain a functional reference to the specified engine,
thus initialising it if needed. The engine will then be set as the default
for all available algorithms.

=item B<-primes> I<num>

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

=item B<-verbose>

Print extra details about the operations being performed.

{- $OpenSSL::safe::opt_r_item -}

=item B<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.

=back

=head1 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 B<.> represents each number which
has passed an initial sieve test, B<+> means a number has passed a single
round of the Miller-Rabin primality test, B<*> 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.

=head1 SEE ALSO

L<openssl(1)>,
L<openssl-gendsa(1)>

=head1 COPYRIGHT

Copyright 2000-2019 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
L<https://www.openssl.org/source/license.html>.

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