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DH_GENERATE_KEY(3) Library Functions Manual DH_GENERATE_KEY(3)

DH_generate_key, DH_compute_keyperform Diffie-Hellman key exchange

#include <openssl/dh.h>

DH_generate_key(DH *dh);

DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh);

() performs the first step of a Diffie-Hellman key exchange by generating private and public DH values. By calling DH_compute_key(), these are combined with the other party's public value to compute the shared key.

() expects dh to contain the shared parameters and . It generates a random private DH value unless is already set, and computes the corresponding public value , which can then be published.

() computes the shared secret from the private DH value in dh and the other party's public value in pub_key and stores it in key. key must point to (dh) bytes of memory.

DH_generate_key() returns 1 on success, or 0 otherwise.

DH_compute_key() returns the size of the shared secret on success, or -1 on error.

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

DH_get0_key(3), DH_new(3), DH_size(3), ECDH_compute_key(3)

DH_generate_key() and DH_compute_key() first appeared in SSLeay 0.5.1 and have been available since OpenBSD 2.4.

August 19, 2019 OpenBSD-6.7