GPS satnavs and interactive web maps

  1. If you use a motor vehicle (private or commercial) to travel to your meeting place, remember that the increasingly common Global Positioning Satellite in-vehicle navigation units ("satnavs") are electronic devices just like mobile phones etc, which contain flash memory which can be read under forensic examination, even when the data is nominally erased. This could betray your movement patterns and give intelligence about, or hard evidence of the time and location of your secret meeting.

  2. Some units also synchronise with your mobile phone, via BlueTooth, in order to download the latest traffic information or map updates etc, and that could leave a trace of whose mobile phone was present in the vehicle at a particular time and location. - See this New Scientist article Why satnavs are a detective's best friend.

  3. One of the features of such satnav devices is the convenience of setting up pre-set destinations e.g. "Home", something which can be exploited e.g. there have been warnings from the Police about gangs of thieves, who have burgled an obviously empty property, after discovering its location (and route directions) from a stolen satnav. Such pre-set navigation data could also be used by snoopers to track your movements retroactively, and possibly therby betray your meetings with anonymous sources or friends. Sometimes it may be worthwhile not to store very precise navigation endpoint data in such satnav devices e.g. instead of the precise post code or ordnance survey map coordinates or latitude and longitude for "Home" or for "Secret Meeting Location", you could only store the nearest landmark which puts you on the same page of the map e.g. a local railway or bus station or tourist attraction.

  4. Further research needs to be done, on particular models of satnav devices (including mobile phones with built in GPS chips), to determine if the device actually keeps a logfile of the searches for particular locations, e.g. the file names names and last displayed time and date data, of the individual graphics files used to display a particular grid square on the interactive map display, or if such data is only held transiently in the memory of the device.

    Such graphical file data is defiantly logged by online web sites which offer interactive maps, so you need to take anonymous web browsing precautions (e.g. clearing the browsing history and cached data, using Tor etc.) if you are using such general mapping (e.g. Google Maps,, Multimap etc) or public or commercial transport time table web sites (e.g. Transport for London, Tube, Rail or Bus timetable systems, RAC Routefinder etc.) to plan a route to a secret meeting.

    N.B. trying to erase such data from, for example, an Apple iPhone's Safari web browser, which takes snapshot images of the web pages which have been visited, as part of the clever / fiddly touch screen system, is almost impossible, short of re-flashing the whole device (this is a separate issue from the more general one of the easy recoverability of a a lot of supposedly erased data on flash memory devices).

About this blog

We know that there are decent, honest, trustworthy individual politicians, civil servants, law enforcement, intelligence agency personnel and broadcast, print and internet journalists etc., who often feel powerless or trapped in the system. They need the assistance of external, detailed, informed, public scrutiny to help them to resist deliberate or unthinking policies, which erode our freedoms and liberties.

Some of these people will, in the public interest, act as whistleblowers, and may try to leak documents or information to the mainstream media, or to political blog websites etc.

Here are some Spy Blog "Hints and Tips", giving some basic preecautions, and some more obscure technical tips, which both whistleblowers, journalists, and bloggers need to be aware of, in order to help preserve the anonymity of whisteleblowing or other journalistic sources, especially in the United Kingdom, but applicable in other countries as well.

Whistleblower anonymity may not always be possible, or even necessary, forever into the future, but it is usuially crucial during at least the early stages of a "leak", whilst it is being evaluated by others, to see if it merits wider publication and publicity.

Email & PGP Contact

Please feel free to email your views about this blog, or news about the issues it tries to comment on.


Our PGP public encryption key is available for those correspondents who wish to send us news or information in confidence, and also for those of you who value your privacy, even if you have got nothing to hide.

You can download a free copy of the PGP encryption software from
(available for most of the common computer operating systems, and also in various Open Source versions like GPG).

We look forward to the day when UK Government Legislation, Press Releases and Emails etc. are Digitally Signed so that we can be assured that they are not fakes. Trusting that the digitally signed content makes any sense, is another matter entirely.


Tag Cloud

CryptoParty London

CryptoParty London

Most months there is a CryptoParty London event. where some of these Hints and Tips and other techniques are demonstrated and taught.

Usually at:

Juju's Bar and Stage 15 Hanbury St, E1 6QR, London

Follow on Twitter: @CryptoPartyLDN

Syndicate this site (XML):


Campaign Button Links

Watching Them, Watching Us, UK Public CCTV Surveillance Regulation Campaign
UK Public CCTV Surveillance Regulation Campaign

NO2ID Campaign - cross party opposition to the NuLabour Compulsory Biometric ID Card
NO2ID Campaign - cross party opposition to the NuLabour Compulsory Biometric ID Card and National Identity Register centralised database.

Gary McKinnon is facing extradition to the USA under the controversial Extradition Act 2003, without any prima facie evidence or charges brought against him in a UK court. Try him here in the UK, under UK law.
Gary McKinnon is facing extradition to the USA under the controversial Extradition Act 2003, without any prima facie evidence or charges brought against him in a UK court. Try him here in the UK, under UK law.

FreeFarid_150.jpg - Kafkaesque extradition of Farid Hilali under the European Arrest Warrant to Spain

Peaceful resistance to the curtailment of our rights to Free Assembly and Free Speech in the SOCPA Designated Area around Parliament Square and beyond

Parliament Protest blog - resistance to the Designated Area restricting peaceful demonstrations or lobbying in the vicinity of Parliament.

Petition to the European Commission and European Parliament against their vague Data Retention plans
Data Retention is No Solution Petition to the European Commission and European Parliament against their vague Data Retention plans.

Open Rights Group

renew for freedom - renew your passport in 2006
Renew For Freedom - renew your Passport in the Summer Autumn of 2006.

The Big Opt Out Campaign - opt out of having your NHS Care Record medical records and personal details stored insecurely on a massive national centralised database.

Tor - the onion routing network
Tor - the onion routing network - "Tor aims to defend against traffic analysis, a form of network surveillance that threatens personal anonymity and privacy, confidential business activities and relationships, and state security. Communications are bounced around a distributed network of servers called onion routers, protecting you from websites that build profiles of your interests, local eavesdroppers that read your data or learn what sites you visit, and even the onion routers themselves."

Tor - the onion routing network
Anonymous Blogging with Wordpress and Tor - useful Guide published by Global Voices Advocacy with step by step software configuration screenshots (updated March 10th 2009).

Amnesty International's campaign

BlogSafer - wiki with multilingual guides to anonymous blogging

NGO in a box - Security Edition privacy and security software tools

Home Office Watch blog, "a single repository of all the shambolic errors and mistakes made by the British Home Office compiled from Parliamentary Questions, news reports, and tip-offs by the Liberal Democrat Home Affairs team."

Reporters Without Borders - Reporters Sans Frontières - campaign for journalists 'and bloggers' freedom in repressive countries and war zones.

Committee to Protect Bloggers - "devoted to the protection of bloggers worldwide with a focus on highlighting the plight of bloggers threatened and imprisoned by their government."

wikileaks_logo_low.jpg - the controversial "uncensorable, anonymous whistleblowing" website based currently in Sweden.

Public Concern at Work - "(PCaW) is the independent authority on public interest whistleblowing. Established as a charity in 1993 following a series of scandals and disasters, PCaW has played a leading role in putting whistleblowing on the governance agenda and in developing legislation in the UK and abroad. All our work is informed by the free advice we offer to people with whistleblowing dilemmas and the professional support we provide to enlightened organisations."