參數(shù)資料
型號(hào)： DS2432
元件分類： DRAM
英文描述： 1k-Bit Protected 1-Wire EEPROM with SHA-1 Engine
中文描述： 1Kb、保護(hù)型1-Wire EEPROM，帶有SHA-1引擎
文件頁(yè)數(shù)： 16/30頁(yè)
文件大?。?/td> 165K
代理商： DS2432
PRELIMINARY
not write-protected the SHA engine will start and within 2.0
ms compute a new secret that is then
automatically copied to the secrets register. Replacing the secret takes maximum
10 ms. During this time
and the computation of the secret the voltage on the 1-Wire bus must not fall below 2.8V. After copying
is finished the DS2432 fills the scratchpad with AAh bytes. Now a pattern of alternating 1’s and 0’s will
be transmitted until the master issues a reset pulse.
DS2432
16 of 30
Since the content of the scratchpad is used as a partial secret, the master must fill the scratchpad with a
known 8-byte data pattern using the Write Scratchpad command
before
it issues the Compute Next
Secret command. Otherwise the new secret will depend on data that was unintentionally left in the
scratchpad from previous commands.
Copy Scratchpad [55h]
The data memory of the DS2432 can be read without any restrictions. Executing the Copy Scratchpad
command to write new data to the memory or register page, however, requires the knowledge of the
device’s secret and the ability to perform a SHA-1 computation to generate the 160-bit Message
Authentication Code (MAC) to start the data transfer from the scratchpad to the memory. The master may
perform the MAC computation in software or use a DS1963S as a coprocessor. The coprocessor approach
has the benefit that the secret remains hidden in the coprocessor iButton. The sequence in which the
resulting MAC needs to be sent to the DS2432 is shown in Table 2. Table 3 shows how the various data
components are entered into the SHA engine. The SHA computation algorithm is explained later in this
document.
Message Authentication Code Transmission Sequence
Table 2
E[31:24]
E[23:16]
E[15:8]
E[7:0]
D[31:24]
D[23:16]
D[15:8]
D[7:0]
C[31:24]
C[23:16]
C[15:8]
C[7:0]
B[31:24]
B[23:16]
B[15:8]
B[7:0]
A[31:24]
A[23:16]
A[15:8]
A[7:0]
The transmission is least significant bit first starting with Register E.
After issuing the Copy Scratchpad command, the master must provide a 3-byte authorization pattern,
which should have been obtained by an immediately preceding Read Scratchpad command. This 3-byte
pattern must exactly match the data contained in the three address registers (TA1, TA2, E/S, in that
order). If the authorization code matches and the target memory is not write-protected, the DS2432 will
start its SHA engine to compute a 160-bit MAC that is based on the current secret, all of the scratchpad
data, the first 28 bytes of the addressed memory page, and the DS2432's registration number (without the
CRC). Simultaneously the master computes a MAC from the same data and sends it to the DS2432 as
evidence that it is authorized to write to the EEPROM. Now the master waits for 10
ms during which the
voltage on the 1-Wire bus must not fall below 2.8V. If the MAC generated by the DS2432 matches the
MAC that the master computed, the DS2432 will set its AA (Authorization Accepted) flag, and copy the
entire scratchpad contents to the data EEPROM. As indication for a successful copy the master will be
able to read a pattern of alternating 1’s and 0’s until it issues a Reset Pulse. A pattern of all zeros tells the
master that the copy did not take place.
Shift
Direction
相關(guān)PDF資料
PDF描述
DS2432P 1k-Bit Protected 1-Wire EEPROM with SHA-1 Engine
DS2432X 1k-Bit Protected 1-Wire EEPROM with SHA-1 Engine
DS2432 1k-Bit Protected 1-Wire EEPROM with SHA-1 Engine(1K 位具有寫保護(hù)的1線EEPROM（帶SHA-1引擎）)
DS2433 4k-Bit 1-Wire EEPROM
DS2433-Z01 4K-Bit 1-Wire EEPROM
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS2432_12 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:1Kb Protected 1-Wire EEPROM with SHA-1 Engine
DS2432P 功能描述:電可擦除可編程只讀存儲(chǔ)器 RoHS:否 制造商:Atmel 存儲(chǔ)容量:2 Kbit 組織:256 B x 8 數(shù)據(jù)保留:100 yr 最大時(shí)鐘頻率:1000 KHz 最大工作電流:6 uA 工作電源電壓:1.7 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8
DS2432P R 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:1Kb Protected 1-Wire EEPROM with SHA-1 Engine
DS2432P T 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:1Kb Protected 1-Wire EEPROM with SHA-1 Engine
DS2432P/T&R 功能描述:電可擦除可編程只讀存儲(chǔ)器 RoHS:否 制造商:Atmel 存儲(chǔ)容量:2 Kbit 組織:256 B x 8 數(shù)據(jù)保留:100 yr 最大時(shí)鐘頻率:1000 KHz 最大工作電流:6 uA 工作電源電壓:1.7 V to 5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8
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