On 06/08/2019 17:16, Matt Caswell wrote: > sig->r = BN_bin2bn(r, rlen, NULL); > sig->s = BN_bin2bn(s, slen, NULL); As a slight amendment to my earlier answer - a better way to do the above two lines would be to use the ECDSA_SIG_set0() function to set the r and s components rather than diving into the internals of the ECDSA_SIG structure. Matt