RSA_GENERATE_KEY(3)

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 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.