Security for smartphones is crucial, now that so many of us use them to make business calls, check work e-mail, and store information. We sampled several apps designed to take the risk out of computing on your phone. Here are the results.

Iris Scanning
To use the eyeD Biometric Password Manager, you take a picture of one eye using the app and your phone's camera. You can then store sensitive data on the app, which will unlock only after you take another photo of the same eye. We tested the app with several people, including siblings, and it blocked out impostors every time. Unfortunately, the camera flash almost blinded us. Cost: $5.99

Voice Encryption
Kryptos uses military-grade 256-bit encryption to scramble smartphone calls, making it difficult for eavesdroppers to listen in. The app, which is available for iPhones and Android phones, provides a separate calling interface that you can use to make secure calls over Wi-Fi. The app was easy to use, and calls sounded mostly clear, though the voices on the other end were a bit distorted. One drawback: The app works only if caller and call recipient have it installed. Cost: $4.99 a month

Search and Retrieval
MobileMe Find My iPhone lets you pinpoint your lost phone's location online and do a remote data wipe. You can set a passcode to lock the device and type a message, such as Return my phone for a reward, that will display on the screen. If you simply misplace your phone nearby, you can command it to make a sound that will override a silent or low ringer setting. MobileMe, available for iPhone 4, iPad, and iPod Touch, located our phone in seconds and responded quickly to remote commands. Cost: Free

Passcode Pattern
An alternative to standard alphanumeric passwords, Android Pattern Lock lets you create a passcode by connecting four to nine dots on your phone's screen. To unlock the device, you must redraw the same pattern. The feature is included on Android phones. To use it, go to Settings, Location & Security, and Set Unlock Pattern. The passcode worked a bit too well for us: We had a hard time remembering our pattern on several occasions. Cost: Free

Remote Lock and Wipe
If a thief tries to swap out your SIM card, McAfee WaveSecure locks your phone, rendering it unusable. You can also log on to the WaveSecure site to locate your lost phone on a map, lock it, and remove contacts, text messages, and media. The app, which is available for Android, BlackBerry, Nokia, and Windows Mobile phones, quickly pinpointed our phone on a map and locked it. Cost: $19.90 a year