The article said ... “It is not clear how the NSA may have obtained the hard drives’ source code. Western Digital spokesman Steve Shattuck said the company ‘has not provided its source code to government agencies.’ The other hard drive makers would not say if they had shared their source code with the NSA.”
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WELL ... a boatload of money from one of these agencies to someone on the inside would “shake loose” the source code! ... :-) ...
I wouldn’t think it would be that hard.
I could imagine a number of ways they could compromise a developer so the he would share the source code: money, amnesty from prosecution (legal blackmail), offers of employment, etc. When you print the money and run the prisons all doors are open.