1=pod 2 3=head1 NAME 4 5genrsa - generate an RSA private key 6 7=head1 SYNOPSIS 8 9B<openssl> B<genrsa> 10[B<-out filename>] 11[B<-passout arg>] 12[B<-des>] 13[B<-des3>] 14[B<-idea>] 15[B<-f4>] 16[B<-3>] 17[B<-rand file(s)>] 18[B<-engine id>] 19[B<numbits>] 20 21=head1 DESCRIPTION 22 23The B<genrsa> command generates an RSA private key. 24 25=head1 OPTIONS 26 27=over 4 28 29=item B<-out filename> 30 31the output filename. If this argument is not specified then standard output is 32used. 33 34=item B<-passout arg> 35 36the output file password source. For more information about the format of B<arg> 37see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 38 39=item B<-des|-des3|-idea> 40 41These options encrypt the private key with the DES, triple DES, or the 42IDEA ciphers respectively before outputting it. If none of these options is 43specified no encryption is used. If encryption is used a pass phrase is prompted 44for if it is not supplied via the B<-passout> argument. 45 46=item B<-F4|-3> 47 48the public exponent to use, either 65537 or 3. The default is 65537. 49 50=item B<-rand file(s)> 51 52a file or files containing random data used to seed the random number 53generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>). 54Multiple files can be specified separated by a OS-dependent character. 55The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for 56all others. 57 58=item B<-engine id> 59 60specifying an engine (by it's unique B<id> string) will cause B<req> 61to attempt to obtain a functional reference to the specified engine, 62thus initialising it if needed. The engine will then be set as the default 63for all available algorithms. 64 65=item B<numbits> 66 67the size of the private key to generate in bits. This must be the last option 68specified. The default is 512. 69 70=back 71 72=head1 NOTES 73 74RSA private key generation essentially involves the generation of two prime 75numbers. When generating a private key various symbols will be output to 76indicate the progress of the generation. A B<.> represents each number which 77has passed an initial sieve test, B<+> means a number has passed a single 78round of the Miller-Rabin primality test. A newline means that the number has 79passed all the prime tests (the actual number depends on the key size). 80 81Because key generation is a random process the time taken to generate a key 82may vary somewhat. 83 84=head1 BUGS 85 86A quirk of the prime generation algorithm is that it cannot generate small 87primes. Therefore the number of bits should not be less that 64. For typical 88private keys this will not matter because for security reasons they will 89be much larger (typically 1024 bits). 90 91=head1 SEE ALSO 92 93L<gendsa(1)|gendsa(1)> 94 95=cut 96 97