GENRSA(1) OpenSSL GENRSA(1) NNAAMMEE genrsa - generate an RSA private key SSYYNNOOPPSSIISS ooppeennssssll ggeennrrssaa [--oouutt ffiilleennaammee] [--ppaassssoouutt aarrgg] [--aaeess112288] [--aaeess119922] [--aaeess225566] [--ccaammeelllliiaa112288] [--ccaammeelllliiaa119922] [--ccaammeelllliiaa225566] [--ddeess] [--ddeess33] [--iiddeeaa] [--ff44] [--33] [--rraanndd ffiillee((ss))] [--eennggiinnee iidd] [nnuummbbiittss] DDEESSCCRRIIPPTTIIOONN The ggeennrrssaa command generates an RSA private key. OOPPTTIIOONNSS --oouutt ffiilleennaammee the output filename. If this argument is not specified then stan- dard output is used. --ppaassssoouutt aarrgg the output file password source. For more information about the format of aarrgg see the PPAASSSS PPHHRRAASSEE AARRGGUUMMEENNTTSS section in _o_p_e_n_s_s_l(1). --aaeess112288||--aaeess119922||--aaeess225566||--ccaammeelllliiaa112288||--ccaammeelllliiaa119922||--ccaammeell-- lliiaa225566||--ddeess||--ddeess33||--iiddeeaa 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 --ppaassssoouutt argument. --FF44||--33 the public exponent to use, either 65537 or 3. The default is 65537. --rraanndd ffiillee((ss)) a file or files containing random data used to seed the random num- ber generator, or an EGD socket (see _R_A_N_D___e_g_d(3)). Multiple files can be specified separated by a OS-dependent character. The sepa- rator is ;; for MS-Windows, ,, for OpenVMS, and :: for all others. --eennggiinnee iidd specifying an engine (by its unique iidd string) will cause ggeennrrssaa 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. nnuummbbiittss the size of the private key to generate in bits. This must be the last option specified. The default is 512. NNOOTTEESS RSA private key generation essentially involves the generation of two 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. 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. BBUUGGSS A quirk of the prime generation algorithm is that it cannot generate small primes. Therefore the number of bits should not be less that 64. For typical private keys this will not matter because for security rea- sons they will be much larger (typically 1024 bits). SSEEEE AALLSSOO _g_e_n_d_s_a(1) 1.0.1u 2016-09-22 GENRSA(1)