NAME

       RSA_generate_key_ex, RSA_generate_key - generate RSA key pair

SYNOPSIS

        #include <openssl/rsa.h>

        int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);

       Deprecated:

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

DESCRIPTION

       RSA_generate_key_ex() generates a key pair and stores it in the RSA structure provided in
       rsa. The pseudo-random number generator must be seeded prior to calling
       RSA_generate_key_ex().

       The modulus size will be of length 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 cb is not NULL, it will be called as follows using the BN_GENCB_call()
       function described on the BN_generate_prime(3) page.

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

       •   When the n-th randomly generated prime is rejected as not suitable for the key,
           BN_GENCB_call(cb, 2, n) is called.

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

       The process is then repeated for prime q with BN_GENCB_call(cb, 3, 1).

       RSA_generate_key is deprecated (new applications should use RSA_generate_key_ex instead).
       RSA_generate_key works in the same was as RSA_generate_key_ex except it uses "old style"
       call backs. See BN_generate_prime(3) for further details.

RETURN VALUE

       If key generation fails, RSA_generate_key() returns NULL.

       The error codes can be obtained by ERR_get_error(3).

BUGS

       BN_GENCB_call(cb, 2, x) is used with two different meanings.

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

SEE ALSO

       ERR_get_error(3), rand(3), rsa(3), RSA_free(3), BN_generate_prime(3)

HISTORY

       The cb_arg argument was added in SSLeay 0.9.0.