NAME    [Toc]    [Back]

       RSA_generate_key - generate RSA key pair

LIBRARY    [Toc]    [Back]

       libcrypto, -lcrypto

SYNOPSIS    [Toc]    [Back]

        #include <openssl/rsa.h>

        RSA *RSA_generate_key(int num, unsigned long e,
           void (*callback)(int,int,void *), void *cb_arg);

DESCRIPTION    [Toc]    [Back]

       RSA_generate_key() generates a key pair and returns it in
       a newly allocated RSA structure. The pseudo-random number
       generator must be seeded prior to calling RSA_gener-
       ate_key().

       The modulus size will be num bits, and the public exponent
       will be e. Key sizes with num < 1024 should be considered
       insecure.  The exponent is an odd number, typically 3, 17
       or 65537.

       A callback function may be used to provide feedback about
       the progress of the key generation. If callback is not
       NULL, it will be called as follows:

       o   While a random prime number is generated, it is called
           as described in BN_generate_prime(3).

       o   When the n-th randomly generated prime is rejected as
           not suitable for the key, callback(2, n, cb_arg) is
           called.

       o   When a random p has been found with p-1 relatively
           prime to e, it is called as callback(3, 0, cb_arg).

       The process is then repeated for prime q with callback(3,
       1, cb_arg).

RETURN VALUE    [Toc]    [Back]

       If key generation fails, RSA_generate_key() returns NULL;
       the error codes can be obtained by ERR_get_error(3).

BUGS    [Toc]    [Back]

       callback(2, x, cb_arg) is used with two different meanings.


       RSA_generate_key() goes into an infinite loop for illegal
       input values.

SEE ALSO    [Toc]    [Back]

       openssl_err(3), openssl_rand(3), openssl_rsa(3),
       RSA_free(3)

HISTORY    [Toc]    [Back]

       The cb_arg argument was added in SSLeay 0.9.0.



2002-06-10                    0.9.6g          RSA_generate_key(3)