TRUSTED SEND(5Eh) - ATA Trusted Commands

TRUSTED SEND(5Eh) PIO Data-Out

This 28-bit command is mandatory for devices implementing the Trusted Computing feature set.

The TRUSTED SEND command is used to send data to the device. The data sent contains one or more Security Protocol specific instructions to be performed by the device. The host uses TRUSTED RECEIVE commands to retrieve any data resulting from these instructions.

Any association between a TRUSTED SEND command and a subsequent TRUSTED RECEIVE command depends on the protocol specified by the Security Protocol field.  Each protocol shall specify whether:

A.        the device shall complete the command with normal status as soon as it determines the data has been received without error. An indication that the data has been processed is obtained by sending a TRUSTED RECEIVE command and receiving the results in the associated data transfer; or

B.        the device shall complete the command with normal status only after the data has been processed without error and an associated TRUSTED RECEIVE command is not required.

There may be intentional side effects, depending on the trusted operation requested. Most trusted operations have no side effects, but there may be some allowable exceptions. For example, a request to lock the device is expected to cause subsequent reads or writes to fail.

The completion of background activity resulting from a trusted command shall not return command aborted for any outstanding queued commands.

The format of the data and some of the parameters depends on the protocol specified by the Security Protocol field.

Inputs:

Register	7	6	5	4	3	2	1	0
Feature	Security Protocol
Sector Count	Transfer Length (7:0)
LBA Low(7:0)	Transfer Length (15:8)
LBA Mid(15:8)	SP Specific(7:0) - Security Protocol Specific
LBA High(23:16)	SP Specific(15:8) - Security Protocol Specific
Device	obs	N/A	obs	TD	LBA(27:24) Reserved
Command	5Eh

Transfer Length:The Transfer Length is security protocol specific

TD: Transport Dependent - All bits and fields that are labelled transport dependent are defined in the transport standards.

Security Protocol

The Security Protocol field identifies which security protocol is being used. This determines the format of the parameters and of the data that is transferred. If the Security Protocol field is set to a reserved value, the device shall return command aborted.

Value	Description
00h	Reserved
01h – 06h	Defined by TCG
07h – 1Fh	Reserved
20h	Reserved for T10
21h-EDh	Reserved
EEh	Defined by IEEE 1667
EFh	Reserved for T10
F0h – FFh	Vendor Specific.

The meaning of the security protocol-specific fields are defined by each security protocol.

Parameters for Security Protocol 01h - 06h

The Transfer Length Field contains the number of 512-byte blocks of data to be transferred (e.g., one means 512 bytes, two means 1,024 bytes, etc.). Pad bytes are appended to the valid data as needed to meet this requirement.  ad bytes shall have a value of 00h. A transfer length of zero is invalid.

The SP Specific field provides Security Protocol field specific information. The meaning of this field is defined by each security protocol.