DS1205S 데이터 시트보기 (PDF) - Dallas Semiconductor -> Maxim Integrated

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DS1205S

MultiKey Chip

Dallas Semiconductor -> Maxim Integrated 

DS1205S

SET SECURITY MATCH

The Set Security Match command is used to enter data

into the I.D. and security match fields of the selected se-

cure partition. The DS1205S will respond to the com-

mand by outputting the 64-bit I.D. field of the selected

secure partition. The next 64 clock cycles are used to

echo the I.D. field back to the DS1205S. Upon receipt of

the correct I.D., the DS1205S MultiKey will erase the

contents of the selected secure partition. The part is

then ready to receive the the new 64-bit I.D. and the

64-bit security match code. The flow sequence is

shown in Figure 5.

SET SECURE DATA

The Set Secure Data command is used to write data into

the selected secure partition. After the command is re-

ceived by the DS1205S, the 64-bit I.D. field of the se-

lected secure partition is output. The next 64 bits of in-

put comprise a password that must match the security

match code of the selected secure partition. If the pass-

word and the security match are identical, data is written

to the secure data field starting at the address specified

in the command word. If the password and the security

match code are not identical, the DS1205S will termi-

nate the transaction immediately. The flow sequence is

shown in Figure 6.

GET SECURE DATA

The Get Secure Data command is used to retrieve data

from the selected secure partition. After the command

word is received by the DS1205S, the 64-bit I.D. field of

the selected secure partition is returned. The next 64

bits are the password being written to the DS1205S. If

the presented password and the security match code of

the selected secure partition are identical, the DS1205S

will output the contents of the secure data field starting

from the byte specified in the command word. If the

presented password is not identical to the security

match code, the DS1205S MultiKey will use the pass-

word as a “seed” for its internal random number genera-

tor. This results in a repeatable, seemingly valid yet

false response to the invalid password. The flow se-

quence is shown in Figure 7.

partition is byte addressable. The scratchpad can be

used to store unsecured data or it can act as a staging

area to build and verify data structures to be transferred

to a secure partition. The three commands that operate

on the read/write scratchpad are:

1. Set Scratchpad Data

2. Get Scratchpad Data

3. Move Block

SET SCRATCHPAD DATA

The Set Scratchpad Data command is used to enter

data into the DS1205S MultiKey scratchpad. The com-

mand word must specify the starting byte address for

the data transfer. Valid byte addresses are 0 through 63.

The DS1205S MultiKey will write data to the scratchpad

until byte 63 has been written or until the RST line goes

to a logic low level. The flow sequence is shown in

Figure 8.

GET SCRATCHPAD DATA

The Get Scratchpad data command is used to retrieve

data from the 512-bit scratchpad. The command word

must specify the starting byte address for the data re-

trieval. Valid byte addresses are 0 through 63. The

DS1205S MultiKey will retrieve data from the scratch-

pad until byte 63 has been read or the RST line goes to a

logic low level. The flow sequence is shown in Figure 9.

MOVE BLOCK

The Move Block command is used to transfer data,

which has been previously entered into the scratchpad

and verified, to one of the three secure subkeys. Data

can be transferred as one large block of 512 bits or it can

be transferred in blocks of 64 bits each (Figure 10).

There are nine valid block selectors which are used to

specify which block or blocks are to be transferred

(Figure 11). As a further precaution against accidental

erasure of a secure subkey, the 64-bit password of the

destination subkey must be entered and match the des-

tination subkey. If the passwords fail to match, the oper-

ation is terminated. The flow sequence is shown in

Figure 12.

SCRATCHPAD READ/WRITE COMMANDS

The 512-bit read/write scratchpad of the DS1205S Mul-

tiKey is not protected by a security match code. This

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