var
  hCertStore: Pointer;
  pCertContext, pSignerCert: PCCERT_CONTEXT;
  FStoreName: string;

function CertNameToWideString: WideString;
begin
  if (len = 0) then
  begin
    Result := '';
    Exit;
  end;

  SetLength(Result, len div 2);
  System.Move(CertName^, Pointer(Result)^, len);
  len := Length(Result);
  if (Result[len] = #0) then
  begin
    Dec(len);
    SetLength(Result, len);
  end;
end;

begin
  FStoreName := 'MY';
  hStoreHandle := CertOpenStore(CERT_STORE_PROV_SYSTEM, X509_ASN_ENCODING or PKCS_7_ASN_ENCODING, nil, $00010000, PWideChar(WideString(FStoreName)));

  if hCertStore <> nil
  then Log('Store open: Success')
  else log('Store open: Fail');

  pCertContext := nil;
  repeat
    pCertContext := CertEnumCertificatesInStore(hStoreHandle, pCertContext);
    if (pCertContext <> nil) then
    begin
      pSignerCert := CertDuplicateCertificateContext(pCertContext);
      len := CertGetNameString(pSignerCert, CERT_NAME_SIMPLE_DISPLAY_TYPE, 0, nil, nil, 0);
      if len > 0 then
      begin
        len := len*2;
        GetMem(CertName, len);
        CertGetNameString(pSignerCert, CERT_NAME_SIMPLE_DISPLAY_TYPE, 0, nil, PWideChar(CertName), len);
        CrtName := CertNameToWideString;
        if CrtName = 'subj' then
        // делаем, что надо
      end;
    end;
  until (pCertContext = nil);

end;