OpenSSL::PKCS7#decrypt

static VALUE
ossl_pkcs7_decrypt(int argc, VALUE *argv, VALUE self)
{
    VALUE pkey, cert, flags;
    EVP_PKEY *key;
    X509 *x509;
    int flg;
    PKCS7 *p7;
    BIO *out;
    VALUE str;

    rb_scan_args(argc, argv, "12", &pkey, &cert, &flags);
    key = GetPrivPKeyPtr(pkey); /* NO NEED TO DUP */
    x509 = NIL_P(cert) ? NULL : GetX509CertPtr(cert); /* NO NEED TO DUP */
    flg = NIL_P(flags) ? 0 : NUM2INT(flags);
    GetPKCS7(self, p7);
    if(!(out = BIO_new(BIO_s_mem())))
        ossl_raise(ePKCS7Error, NULL);
    if(!PKCS7_decrypt(p7, key, x509, out, flg)){
        BIO_free(out);
        ossl_raise(ePKCS7Error, NULL);
    }
    str = ossl_membio2str(out); /* out will be free */

    return str;
}