Some of the users who updated to iOS 6.0.1 firmware are getting the error where redsn0w says “Missing Keys.plist data for this build” while trying to jailbreak or boot tethered. In error details, it mentions the build as 10A523. As an example, here is the screenshot of the error that appears for iPhone 3GS users:

As you can guess, redsn0w seems to be unable to identify the iOS build that your device is running. So, either you are using and older version of redsn0w or the latest version as not yet been updated to add support for that build. Here is what I was using:
Device: iPhone 3GS
OS: iOS 6.0.1 (iPhone2,1_6.0.1_10A523)
Redsn0w version: 0.9.15 beta 3
How to Fix Redsn0w Missing Keys.plist Error
First, download latest version of redsn0w. At current, the latest version is Redsn0w 0.9.15b3 and it does not support iOS 6.0.1. This was the reason I received the error. In order to jailbreak iOS 6.0.1 with redsn0w 0.9.15 beta 3, you need to point redsn0w to iOS 6.0 instead of 6.0.1 IPSW. Follow the steps below:
Step 1: When you receive this error, click “Back” button to navigate back to Redsn0w main screen.
Or simply launch redsn0w. Windows users should run redsn0w.exe as administrator. OSX Mountain Lion users should Ctrl-Click->Open the redsn0w.
Step 2: Click on “Extras” button and then click on “Select IPSW”.
Step 3: Browse and select the iOS 6.0 firmware IPSW.
Step 4: After selecting the IPSW, navigate back to redsn0w main screen and click on “Jailbreak” button. Or if you were trying to boot tethered, navigate to “Extras” and click on “Just Boot” button.
This should resolve the issue in most cases.
The issue is that you are trying to use redsn0w for a version iOS that it does not currently support. So, you just need to select an older version that it supports.
Still facing the error? Let us know in comments, we’d be glad to help.
_kev