EVP_DecodeFinal
int EVP_DecodeFinal(EVP_ENCODE_CTX *ctx, unsigned char *out, int *outl);
LCRYPTO_ALIAS(EVP_DecodeFinal);
LCRYPTO_USED(EVP_DecodeFinal);
i = EVP_DecodeFinal(&ctx, (unsigned char *)&(dataB->data[bl]), &k);
if (EVP_DecodeFinal(ctx, to + evplen, &evplen) == -1)