Ok, so just another sanity check. Is the TZ implementation purely software
based, or does it make use of any rng's or anything like that for seeding
the keygeneration, etc.

On Tue, Mar 3, 2015 at 7:35 PM, Shawn Willden <[email protected]> wrote:

> "Hardware-backed" means "in ARM TrustZone" on all existing devices. Since
> TrustZone isn't separate hardware but a secure mode of the main CPU, key
> generation should be almost exactly as fast as a software key, since the
> only additional cost is the context switches in and out of secure mode. If
> KeyChain.isAlgorithmSupported returns true for an algorithm, that means
> that algorithm is supported in secure hardware (actually, TrustZone) on
> your device.
>
> On Nexus 5, keystore.msm8974.so is the HAL module that talks to the
> Qualcomm trusted OS.
>
> On Tue, Mar 3, 2015 at 8:25 PM William Roberts <[email protected]>
> wrote:
>
>> Without rooting an image, is there a way to test if AKS is hardware
>> backed? KeyChain.isKeyAlgorithmSupported("RSA")) returns true, but others
>> suspect the generation times are too fast (1.2-1.7 seconds).
>>
>> On Kitkat Nexus 5, I see /system/lib/hw contains 2 keymaster
>> implementations:
>>
>> keystore.default.so
>> keystore.msm8974.so
>>
>> I initially was going to look at the memmap of keystored to see what was
>> loaded. Any comments, much appreciated.
>>
>> Thanks.
>>
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-- 
Respectfully,

William C Roberts

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