NAME¶
RSA_generate_key - generate RSA key pair
SYNOPSIS¶
#include <openssl/rsa.h>
RSA *RSA_generate_key(int num, unsigned long e,
void (*callback)(int,int,void *), void *cb_arg);
DESCRIPTION¶
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_generate_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:
- •
- 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, callback(2, n, cb_arg) is called.
- •
- 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¶
If key generation fails,
RSA_generate_key() returns
NULL; the
error codes can be obtained by
ERR_get_error(3).
BUGS¶
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¶
ERR_get_error(3),
rand(3),
rsa(3),
RSA_free(3)
HISTORY¶
The
cb_arg argument was added in SSLeay 0.9.0.