RSA_generate_key − generate RSA key pair |
#include <openssl/rsa.h> RSA *RSA_generate_key(int num, unsigned long e, void (*callback)(int,int,void *), void *cb_arg); |
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 or 65535. 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: |
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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, callback(2, n, cb_arg) is called. |
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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). |
If key generation fails, RSA_generate_key() returns NULL; the error codes can be obtained by ERR_get_error(3). |
callback(2, x, cb_arg) is used with two different meanings. RSA_generate_key() goes into an infinite loop for illegal input values. |
err(3), rand(3), rsa(3), RSA_free(3) |
The cb_arg argument was added in SSLeay 0.9.0. |