ST33TPHF20SPI datasheet(20/47 Pages) STMICROELECTRONICS

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FIPS140-2 SECURITY POLICY

Page 20 of 47

NON-PROPRIETARY DOCUMENT

Control and data inputs are multiplexed over the same physical interface. Control and

data are distinguished by properly parsing input TPM command parameters according

to input structures description, indicated for each command in [TPM2.0 Part3 r1.16]1.

Status and data output are multiplexed over the same physical interface. Status and

data are distinguished by properly setting output TPM response parameters according

to output structures description, indicated for each command in [TPM2.0 Part3 r1.16].

The logical state machine and the command structure parsing of the module prevent

from using input data externally from the “data input path” and prevent from outputting

dat

a externally from the “data output path”.

While performing key generation or key zeroization (no manual key entry on TPM),

the output data path is logically disconnected while the output status path remains

connected to report any possible failure during command processing. Generally, the

output data path is only connected when TPM outputs response containing data.

Plaintext data can be output through usage of:



TPM2_Unseal, TPM2_RSA_Decrypt, TPM2_EncryptDecrypt

To prevent inadvertent release of the plaintext data, command performs:



Check of command input structure



Check of command authorization



Decryption of the input blob with private part of specified key

However an encryption session might be used with these commands to avoid

releasing plaintext data.

The logical state machine and command structure of the module guarantees the

inhibition of all data output via the data output interface whenever an error state exists

and while doing self-tests.

1 Some commands only deal with control input and status output parameters

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