Texas Instruments SHA-1/HMAC BASED SECURITY AND AUTHENTICATION IC BQ26100EVM BQ26100EVM 데이터 시트
제품 코드
BQ26100EVM
www.ti.com
Communicating with the bq26100
SLUS696A – JUNE 2006 – REVISED FEBRUARY 2007
writes a random 20-byte message to the bq26100 and sets the AUTH bit in the CTRL register. The bq26100
calculates the HMAC digest in less than 500
calculates the HMAC digest in less than 500
µ
s, replacing the random message sent by the host with the HMAC
result. To complete the authentication process, the host computes the HMAC function with the same 20-byte
random message originally written to the bq26100. The result is compared to the HMAC result computed by the
bq26100. If the values match, the pack is authenticated.
random message originally written to the bq26100. The result is compared to the HMAC result computed by the
bq26100. If the values match, the pack is authenticated.
The key is separated into two 64-bit spaces, allowing multiple parties to program separate portions of the key
and providing an added level of security. Programming a key utilizes the SHA-1 algorithm to provide a mix from
the values used to program the device to the actual key stored on the device. When put into key programming
mode, the device combines the 160-bit message space with a pad as required to get the minimum 512-bit
SHA-1 block, and run through the SHA-1 engine once. The 160-bit output is truncated to the lower 64 bits,
scrambled internally, and then written to the appropriate non-volatile memory key space. The key can only be
read and descrambled by the authentication engine, not by the communication engine, of the bq26100.
and providing an added level of security. Programming a key utilizes the SHA-1 algorithm to provide a mix from
the values used to program the device to the actual key stored on the device. When put into key programming
mode, the device combines the 160-bit message space with a pad as required to get the minimum 512-bit
SHA-1 block, and run through the SHA-1 engine once. The 160-bit output is truncated to the lower 64 bits,
scrambled internally, and then written to the appropriate non-volatile memory key space. The key can only be
read and descrambled by the authentication engine, not by the communication engine, of the bq26100.
The bq26100 communication protocol starts when the host pulls the bus low for reset time. All devices on the
bus are to respond with a presence pulse, which is active low. The host can then transmit the ROM Function
command, which is used to address the devices on the bus. The ROM functions include Match ID, Skip ID,
Read ID, and Search ID.
bus are to respond with a presence pulse, which is active low. The host can then transmit the ROM Function
command, which is used to address the devices on the bus. The ROM functions include Match ID, Skip ID,
Read ID, and Search ID.
Match ID
The host transmits the 64-bit ID of the 1-wire based device to communicate.
Skip ID
No ID is necessary for communication. Used only if one device is connected to the host.
Read ID
The 1-wire slave transmits its 64 bit address. This command is only useful if there is only one
device connected to the host.
device connected to the host.
Search ID
Useful if there are multiple devices on the bus. This command initiates a communication with a
single device, but it is more useful in allowing the host to determine the address of every device
on the bus. The Match ID can then be used to communicate with a specific addressed device.
single device, but it is more useful in allowing the host to determine the address of every device
on the bus. The Match ID can then be used to communicate with a specific addressed device.
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