AT88SC0104CA_11 ATMEL [ATMEL Corporation], AT88SC0104CA_11 Datasheet - Page 14

• Manufacturer Part Number: AT88SC0104CA_11
• Description: Atmel CryptoMemory Specification Datasheet
• Manufacturer: ATMEL [ATMEL Corporation]

6.
6.1
6.1.1
Communication Security Modes
Communication between the device and host operates in three basic modes. Standard mode is the default mode for the
device after power-up. Authentication mode is activated by a successful authentication sequence. Encryption mode is
activated by a successful encryption activation following a successful authentication. Data transferred to and from the device is
handled per the following table.
Table 6-1.
Note:
Security Operations
Password Verification
The use of passwords protects read and write accesses to the user zones. Any one of eight password sets is available for
assignment to any user zone through configuration of access registers. CryptoMemory provides separate 24-bit passwords for
read and write operations. Read passwords grant only read accesses to zones under password protection, while write
passwords grant both read and write accesses. Successful presentation of any password renders the verify password
command active until the presentation of another password or device reset. Only one password may be active at a time.
Presenting incorrect passwords decrements the value of the corresponding password attempts counter (PAC). Decrementing
the PAC to $00 permanently disables the corresponding password and permanently renders the corresponding user zone(s)
under protection inaccessible. Operation in authentication or encryption modes requires encryption of passwords for all
password transactions.
Figure 6-1. Password Verification
Mode
Standard/Password
Authentication
Encryption
CryptoMemory Device
1.
Communication Security Modes
Configuration data includes the entire configuration memory except the passwords


VERIFY Password
MDC: Modification Detection Code
MAC: Message Authentication Code
Allow Access
Configuration Data
clear
clear
clear
Command/Communications
Atmel AT88SC0104CA/0204CA/0404CA/0808CA [Datasheet]
Verify Password
User Data
encrypted
clear
clear
Passwords
encrypted
encrypted
Send Password
clear
encrypted if performed after
Mutual Authentication
Host Logic
8664E−CRYPTO−12/11
Data Integrity Check
MDC
MAC
MAC
14