pkcs7.c

X509_STORE *store;

// set up the store

X509_VERIFY_PARAM *param = X509_VERIFY_PARAM_new();
X509_VERIFY_PARAM_set_time(param, time_from_receipt); // option 1: verify using a specific time
//X509_VERIFY_PARAM_set_flags(param, X509_V_FLAG_NO_CHECK_TIME); // option 2: relatively new option to disable time checking
X509_STORE_set1_param(store, param);
X509_VERIFY_PARAM_free(param);

// call PKCS7_verify() using configured store