C8051F966-A-GQ Silicon Labs, C8051F966-A-GQ Datasheet - Page 198

• Manufacturer Part Number: C8051F966-A-GQ
• Description: 8-bit Microcontrollers - MCU 32KB DC-DC LCD AES
• Manufacturer: Silicon Labs

Specifications of C8051F966-A-GQ

• Rohs: yes
• Core: 8051
• Processor Series: C8051
• Data Bus Width: 8 bit
• Maximum Clock Frequency: 24.5 MHz
• Program Memory Size: 32 KB
• Data Ram Size: 8 KB
• On-chip Adc: Yes
• Operating Supply Voltage: 1.8 V to 3.8 V
• Operating Temperature Range: - 40 C to + 85 C
• Package / Case: QFP-80
• Mounting Style: SMD/SMT

C8051F96x
14.6.5. Counter Mode
The Counter (CTR) Mode uses a sequential counter which is incremented after each block. This turns the
block cipher into a stream cipher. This algorithm is shown inFigure 14.4. Note that the decryption operation
actually uses the encryption key and encryption block cipher. The XOR operation is always on the output
of the Cipher. The counter is a 16-byte block. Often the several bytes of the counter are initialized to a
nonce (number used once). The last byte of the counter is incremented and propagated. Thus, the counter
is treated as a 16-byte big endian integer.
198
Encryption
Decryption
Encryption Key
Encryption
Key
Ciphertext
Plaintext
Figure 14.7. Counter Mode
Encryption
(0x00...00)
Encryption
(0x00...00)
Ciphertext
Plaintext
Counter
Counter
Cipher
Cipher
XOR
XOR
Rev. 0.5
Encryption Key
Encryption
Key
Ciphertext
Plaintext
Encryption
(0x00...01)
Encryption
(0x00...01)
Ciphertext
Plaintext
Counter
Counter
Cipher
Cipher
XOR
XOR