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.

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

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

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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 way 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.