OpenSSL::PKCS7::SignerInfo.new

static VALUE
ossl_pkcs7si_initialize(VALUE self, VALUE cert, VALUE key, VALUE digest)
{
    PKCS7_SIGNER_INFO *p7si;
    EVP_PKEY *pkey;
    X509 *x509;
    const EVP_MD *md;

    pkey = GetPrivPKeyPtr(key); /* NO NEED TO DUP */
    x509 = GetX509CertPtr(cert); /* NO NEED TO DUP */
    md = ossl_evp_get_digestbyname(digest);
    GetPKCS7si(self, p7si);
    if (!(PKCS7_SIGNER_INFO_set(p7si, x509, pkey, (EVP_MD*)md))) {
        ossl_raise(ePKCS7Error, NULL);
    }

    return self;
}