fund raising with an android enigma machine simulator

Franklin Heath Ltd 02 June 2012

Fund Raising with an Android Enigma Machine Simulator

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What Shall We Talk About?

How the World War II Enigma machine works

Potential for mobile apps to raise money for charities

How bad is Android fragmentation and how best to deal with it

What mechanical cryptography can teach us about today's security software

02 June 2012 2 © Franklin Heath Ltd

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Android Enigma Simulator: Why?

2012 is Alan Turing’s centenary year One of Bletchley Park’s “Wicked Uncles” working on Enigma

Real WWII Enigma machines can cost > $200,000 Touch screen animation gives an idea of the real thing

Education Strong cryptography existed before computers

Fund raising Bletchley Park Trust needs matching funds to restore the site

Experiment in Android development and monetisation


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Bletchley Park’s “Wicked Uncles”

Senior codebreakers recruited in 1939 Introduced mathematical and mechanised methods

1941 memo delivered to P.M Winston Churchill Response: “Make sure they have all they want on extreme

priority and report to me that this had been done.”


Alan Turing 1912-1954

Gordon Welchman 1906-1985 Hugh Alexander 1909-1974 Stuart Milner-Barry 1906-1995

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Enigma Machine Components


Scrambler Rotors and reflector

Output Battery-powered lamps

Input Keys (switch and lever)

Plug Board Static, swaps letters

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Enigma Machine Components


Scrambler Rotors and reflector

Output Battery-powered lamps

Input Keys (switch and lever)

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Fully Functional Paper Model


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Enigma Simulator App Demo


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Google Play International Reach

Finland 27 Indonesia 30 Hungary 33 Mexico 35 Turkey 39 India 41 Sweden 43 Croatia 44 Brazil 45 Czech Republic 46 Canada 47

France 59 Australia 61 Netherlands 63

Poland 111 Italy 112

Spain 151 Germany 264

UK 450 USA 670

0% 5% 10% 15% 20% 25% 30%

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Top

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of 9

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Revenue Stats (by 2012 Week Nos.)

£0.00

£2.50

£5.00

£7.50

£10.00

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alls

In-App. Payments Advert. Revenue Nook Sales


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How the Revenue Divides Up

Google Play (user charged £1) 17p to Her Majesty’s Revenue and Customs (V.A.T.) 25p to Google (30% Android billing fee) 29p to us (until development costs covered) 29p to the Bletchley Park Trust

AdMob (variable rates per click) Remitted in $US so no V.A.T. due 50% to the Bletchley Park Trust

Nook sales (user charged $2.49) $0.75 to Barnes & Noble (30% transaction fee) $0.87 to us $0.87 to the Bletchley Park Trust


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Fundraising: What Have We Learned? People will donate using in-app billing ~ 2% of ~2,700 installs so far

People do click on in-app advertisements ~ 0.8% of ~36,000 impressions so far

Revenue so far is low Street corner tin rattling could have been more productive! BUT software revenue scales effortlessly, so good potential

What we need to do better Marketing (increase awareness and donations) Continuing user engagement (increase ad revenue)


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Android Testing Strategy

448 different device models in 2864 installs! Clearly impossible to test on every device

What is the best mix of devices to test on?

Use Android resource qualifiers to identify categories “small” → “xlarge”, “ldpi” → “xhdpi”

Using Android’s layout engine to adapt to different screens

Also need to cover all supported Android API levels We don’t support Android 1.5

0.23% of category, mandates extra permissions for compatibility


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Android Device Variability: Screen Size and Density

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0 0 26 129

359

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335

1

1370

4 0 16 120

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small normal large xlarge

Perc

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gmaS

im in

stal

ls ldpi

mdpi hdpi xhdpi


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Android Device Variability: API Level / Android Version

27 0 0

195

424

19

1308

2 49

159

48

383

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API level: Version: 1.6 2.0 2.1 2.2 2.3 3.0 3.1 3.2 4.0

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Device-Specific Android Issues

Samsung Galaxy S app data directory bug

Android 4 XT9 soft keyb. ignores “no suggestion” flag

Android 1.6 ghost status bar on resume

System font changed in Android 4 (size changes)

Nook default dialog title colour different

Android 1.6 in-app billing hangs

Samsung Galaxy Note pixel density


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Most popular devices in the commonly used categories

How to avoid having to buy all these devices? Remote access testing services (DeviceAnywhere, TestDroid)

Android Testing Strategy: Representative Devices

normal-hdpi 51.0% Samsung Galaxy S2 normal-mdpi 13.4% Samsung Galaxy Ace xlarge-mdpi 12.5% Asus EeePad Transformer TF101 small-ldpi 5.3% Samsung Galaxy Mini

small-mdpi 4.8% Sony Ericsson Xperia X10 Mini Pro normal-xhdpi 4.5% Samsung Galaxy Nexus

large-mdpi 4.4% Samsung Galaxy Tab large-xhdpi 2.5% Samsung Galaxy Note


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Android Fragmentation: What Have We Learned?

Support for all versions/screens took 80% of our effort But 70% installed on Android 2.x, 51% on “normal-hdpi” Best strategy to release on a limited subset, at least initially?

Automated tests are essential Overnight tests on 15 different emulated devices Android extensions to JUnit are extremely flaky

Unpredictable data corruption caused by test framework,we gave up

MonkeyRunner is usable but still unreliable We will be looking at Robotium in future

Remote access could help with device-specific issues


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The Crypto Lessons that Enigma and Bletchley Park Can Teach Us

Don’t assume that key length is equivalent to security

User-selected passwords may be the weakest link

Plan for your keys to be compromised

Use really random numbers, not random-looking ones

Don't underestimate the attacker


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Enigma Machine Key Length

4-rotor Enigma M4 2 possible reflectors 672 possible rotor choices 676 possible notch positions 532,985,208,200,576 possible combinations of plugs 456,976 possible starting positions = 221,286,292,668,406,558,235,295,744 possible keys Log2 gives equivalent binary key length: ~88 bits This is still export-controlled!

Yet it could be broken with 70-year old mechanical technology

Key length isn’t the most important factor 02 June 2012 20 © Franklin Heath Ltd

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Users Pick Poor Passwords

Many Enigma messages were read by guessing the message key that the operator chose (“Cillies”) AAA BBB, QWE ASD, BER LIN, etc.

This was addressed later in the war by operational procedures Daily settings used as a pseudo-random generator

Cryptographic keys need more entropy than users can supply in the form of a password Salts, nonces, etc.


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Plan for Key Compromise

“Pinches” were an important way into new Enigma networks 1941 HMS Tartar: code books from weather ship Lauenberg 1942 HMS Petard: machine and code books from U-559 1940 HMS Gleaner: rotors VI and VII from U-33 1941 HMS Somali: rotors and code books from armed trawler Krebs 1940 HMS Griffin: settings and cribs from armed trawler Polares 1941 HMS Somali: code books from weather ship München 1941 HMS Bulldog: machine and code books from U-110

They had emergency procedures to switch to other settings Modern security systems need to have “renewability” too


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Use Really Random Numbers

Don’t be tempted to interfere to make it look random

German cipher staff had rules for not repeating rotor order and not plugging adjacent letters

This significantly reduced the number of possible settings that needed to be tried on the Bombe

Many security vulnerabilities in modern systems are due to poor randomness

e.g. Debian OpenSSL vulnerability in 2008


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Don’t Underestimate the Enemy

German high command told Enigma was “unbreakable”

German cryptographers knew it was theoretically breakable, but thought no one would put in that much effort

Bletchley Park’s mathematical approach and production line methods led to industrial-scale cryptanalysis

Today: it only needs a handful of bright and bored attackers to find a “class break” and then millions of “script kiddies” can use it.


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Questions?

If we have time!


fund raising with an android enigma machine simulator

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