I wanted to distribute the desktop client I made for https://cryptabyte.com/ as a single .exe, without any install or additional DLL’s. I used ILMerge, a tool from Microsoft Research to merge all the assemblies into one DLL. (If you have the .Net 4.5 beta installed like me, read this to target .Net 4.0.) I merged the assemblies with ILMerge:
ILMerge.exe /target:CryptAByte /out:Crypt.exe /targetplatform:"v4,C:Program Files (x86)Reference AssembliesMicrosoftFramework.NETFrameworkv4.0" CryptAByte.exe CryptAByte.CryptoLibrary.dll CryptAByte.Domain.dll Ionic.Zip.dll
ILMerge has the added benefit of making the merged DLL slightly smaller that than the sum of its parts.
I wanted my app to run on OS X too. After I stripped out the Entity Framework Code First data annotations from my data structures, it compiled and ran smoothly on OS X:
Actually, that doesn’t look very good at all. The Mono WinForms color scheme has some kind of sickly yellow tinge to it. I want to distribute this without requiring Mono to be installed, so I used macpack:
macpack -m:2 -o:. -r:/Library/Frameworks/Mono.framework/Versions/Current/lib/ CryptAByte.Domain.dll CryptAByte.CryptoLibrary.dll Ionic.Zip.dll -n:CryptAByte -a:CryptAByte.exe
The resulting .app was over 300MB! Looks like I’m going to have to write a native client for OS X.
Speaking of power usage, there are two nice apps to help monitor battery usage in OS X. CoconutBattery is mostly useful for checking the health of the battery.
MiniBatteryLogger is a more advanced tool that monitors power consumption and levels over time. You can use it to see how particular configurations are consuming power.
Another, slightly related app is fseventer. fseventer shows filesystem access in real time and provides nice insight into what apps are using the hard drive.
There is some confusion about the impact of background apps on iOS on battery life. Some prominent sources advise “quitting” all background apps to maximize batter life while others say that background apps are suspended and use no battery.
Actually, both statements are true. The confusing part is that iOS does not visually indicate suspended versus running background apps. Some apps are will obviously use power in the background – GPS navigation, instant messaging, or a music player. In other cases, it is not clear.
While there are many apps in the App Store that claim to help “improve” battery life, Apple does not allow access to any API which can have any impact on battery life. The only way to do so is to jailbreak your iPhone/iPad and install an app like BatteryDetective, which can measure how much power background apps and services actually use. (It also the only app which can tell you how much charge your iPhone battery can retain.)
In my brief testing, I made a few surprises. When an iPhone is not actively being used (the screen is off), the biggest power drain are the various radios: WiFi, 3G and Bluetooth. So first tip is to turn off any service you don’t need. SBSettings is useful in doing so with one tap:
Here are some sample measurements (not intended to be typical) in milli-amp drain in the background: iPod: 50mA, Gmail App: 185mA, Skype: 265mA. I found that some apps are seeming unnecessary energy-hogs: why does Skype use so much power in idle mode? I also found that the built-in Messages app was using way too much power – which went down after I deleted some of four years of received SMS and MMS messages.
BatteryMeter has a manual mode so you can take samples when toggling background services:
Unfortunately, measuring the power usage of apps and services is not practical for most users. So if you want to maximize battery life, just (1) turn off any function/service you don’t need and (2) remember that when and only when an app is doing anything in the background, it will drain the battery.
I recently gave a presentation/tutorial on information security for the Shanghai Rationalist group. Here are the PowerPoint slides with links (1MB).
Part 1: Secure Web Browsing
Part 2: Secure Networks
Part 3: Secure Email and IM
Part 4: Securing Operating Systems & mobile devices
Part 5: Secure Organizations
Conclusion: Limitations of Security Measures