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<-aes128>] 13[B<-aes192>] 14[B<-aes256>] 15[B<-camellia128>] 16[B<-camellia192>] 17[B<-camellia256>] 18[B<-des>] 19[B<-des3>] 20[B<-idea>] 21[B<-f4>] 22[B<-3>] 23[B<-rand file(s)>] 24[B<-engine id>] 25[B<numbits>] 26 27=head1 DESCRIPTION 28 29The B<genrsa> command generates an RSA private key. 30 31=head1 OPTIONS 32 33=over 4 34 35=item B<-out filename> 36 37the output filename. If this argument is not specified then standard output is 38used. 39 40=item B<-passout arg> 41 42the output file password source. For more information about the format of B<arg> 43see the B<PASS PHRASE ARGUMENTS> section in L<openssl(1)|openssl(1)>. 44 45=item B<-aes128|-aes192|-aes256|-camellia128|-camellia192|-camellia256|-des|-des3|-idea> 46 47These options encrypt the private key with specified 48cipher before outputting it. If none of these options is 49specified no encryption is used. If encryption is used a pass phrase is prompted 50for if it is not supplied via the B<-passout> argument. 51 52=item B<-F4|-3> 53 54the public exponent to use, either 65537 or 3. The default is 65537. 55 56=item B<-rand file(s)> 57 58a file or files containing random data used to seed the random number 59generator, or an EGD socket (see L<RAND_egd(3)|RAND_egd(3)>). 60Multiple files can be specified separated by a OS-dependent character. 61The separator is B<;> for MS-Windows, B<,> for OpenVMS, and B<:> for 62all others. 63 64=item B<-engine id> 65 66specifying an engine (by its unique B<id> string) will cause B<genrsa> 67to attempt to obtain a functional reference to the specified engine, 68thus initialising it if needed. The engine will then be set as the default 69for all available algorithms. 70 71=item B<numbits> 72 73the size of the private key to generate in bits. This must be the last option 74specified. The default is 512. 75 76=back 77 78=head1 NOTES 79 80RSA private key generation essentially involves the generation of two prime 81numbers. When generating a private key various symbols will be output to 82indicate the progress of the generation. A B<.> represents each number which 83has passed an initial sieve test, B<+> means a number has passed a single 84round of the Miller-Rabin primality test. A newline means that the number has 85passed all the prime tests (the actual number depends on the key size). 86 87Because key generation is a random process the time taken to generate a key 88may vary somewhat. 89 90=head1 BUGS 91 92A quirk of the prime generation algorithm is that it cannot generate small 93primes. Therefore the number of bits should not be less that 64. For typical 94private keys this will not matter because for security reasons they will 95be much larger (typically 1024 bits). 96 97=head1 SEE ALSO 98 99L<gendsa(1)|gendsa(1)> 100 101=cut 102 103