zSeries doesn't support Protected Key. Oh, wait,you probably *really* meant
System z. It's been eight years, time to upgrade your terminology, eh?


On Fri, Apr 26, 2013 at 10:52 PM, Tim Henness <[email protected]> wrote:

> It is *theoretically* possible for someone with physical access to the
> zSeries processor to open it up and install some customized hardware that
> could intercept the clear key.  Is that a reasonable risk for the dats you
> need to protect, when weighed against the improved performance?  For most
> customers I would think so.  But that is something customers have to weigh
> for themselves - with the assistance of their friendly neighborhood auditor!
>
> Tim
>
>
> On 4/26/2013 8:58 AM, Todd Arnold wrote:
>
>> So.. even though the protected key starts with the Crypto Express, it
>>> wouldn't pass an audit for protection of card data?
>>>
>>
>> Yes, it STARTS with the Crypto Express, but then the cleartext key is
>> protected by the fact that it is buried in the inaccessible System z
>> hardware which cannot be seen or probed by applications, the O/S, debug
>> tools, etc.  However, regardless of the fact that the key is inaccessible,
>> it does not meet the strict requirements as defined by the standards.  As
>> an example, here is a piece of the ANSI X9.24 Part 1 standard, which
>> defines requirements for handling and managing symmetric cryptographic keys
>> in banking applications:
>>
>> -------------- begin text from X9.24.1 ---------------
>> a) Cryptographic keys SHALL only exist in one or more of the following
>> forms:
>>    1) In a Tamper-Resistant Security Module (TRSM) as specified in
>> Section 7.2 below.
>>    2) If outside a TRSM, as a cryptogram that SHALL have been created
>> inside a TRSM by
>>        TDEA using a Key Encrypting Key.
>>    3) If non-encrypted and outside of a TRSM, a key SHALL exist only in
>> one of the following
>>         forms:
>>      i) as two or more key components as defined in Section 7.5,
>> employing dual control
>>         and split knowledge or
>>      ii) as a cleartext key while being transferred from a Key Loading
>> Device (KLD) to a
>>         directly connected TRSM
>> -------------- end text from X9.24.1 ---------------
>>
>> Some clarification of terms in this...
>>    - A TRSM is a physically secure device which detects any attempt to
>> tamper with it and automatically clears all secret data (like keys)
>>    - TDEA is a synonym for TDES, Triple-DES, which is the only symmetric
>> crypto algorithm currently approved for banking applications.
>>    - "cryptogram" is just a fancy word for a piece of data that is in
>> encrypted form.
>>    - "key components" are values that are combined together to form the
>> actual key, such that no component by itself can be
>>       used to learn anything about the value of the key.  (typically,
>> components are exclusive-ored together to create the key.)
>>    - A KLD is a very specialized secure device that can be connected to
>> an HSM, Point of Sale terminal, etc. to load keys into it.
>>    - In standards, the word SHALL means that something is absolutely
>> mandatory.
>>
>> So, this says that any complete key that is not encrypted MUST ONLY exist
>> inside a TRSM, which means a physically secure, tamper-detecteing device
>> like the Crypto Express.  This is what the auditors are measuring the
>> systems against.
>>
>> Todd Arnold
>>
>
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-- 
zMan -- "I've got a mainframe and I'm not afraid to use it"

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