MCIMX286CVM4B Freescale Semiconductor, MCIMX286CVM4B Datasheet - Page 1004

• Manufacturer Part Number: MCIMX286CVM4B
• Description: IC MPU I.MX286 289MAPBGA
• Manufacturer: Freescale Semiconductor
• Series: i.MX28r

Specifications of MCIMX286CVM4B

• Core Processor: ARM9
• Core Size: 32-Bit
• Speed: 454MHz
• Connectivity: CAN, EBI/EMI, Ethernet, I²C, MMC, SmartCard, SPI, SSI, UART/USART, USB OTG
• Peripherals: DMA, I²S, LCD, POR, PWM, WDT
• Program Memory Size: 128KB (32K x 32)
• Program Memory Type: Mask ROM
• Ram Size: 32K x 32
• Voltage - Supply (vcc/vdd): 1.25 V ~ 5.25 V
• Data Converters: A/D 17x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 289-LFBGA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of I /o: -
• Eeprom Size: -
• Lead Free Status / Rohs Status: Compliant

Operation
13.2.2.3 Encryption Modes
The most basic form of encryption is the Electronic Code Book (ECB) mode. In this mode,
the encryption output is a function only of the key and the plaintext, therefore, it can be
visualized as a giant lookup table. While this provides a great deal of security, there are a
few limitations. For instance, if the same plaintext appears more than once in a block of
data, the same ciphertext will also appear. This can be very evident if the plaintext contains
large blocks of constant data (0s for example) and can be used to formulate attacks against
a key.
In order to make ciphers stronger, several modes of operation can be implemented around
the basic ECB cipher to provide additional security. One such mode is CBC mode (Cipher
Block Chaining), which takes the previous encrypted data and logically XORs it with the
next incoming plaintext before performing the encryption. During decryption, the process
is reversed and the previous encrypted data is XORed with the decrypted ECB data to
provide the plaintext again.
The AES engine supports handling the various modes of operation. The core AES block
supports ECB mode and other algorithms are handled in the wrapper around the encryption
blocks. The DCP module supports Cipher Block Chaining (CBC), which chains the data
blocks by XORing the previously encrypted data with the plaintext before encryption. Cipher
block chaining encryption is illustrated in
Decryption (shown in the following figure) works in a similar manner, where the cipher
text is first decrypted and then XORed with the previous ciphertext. For the first
encryption/decryption operation, an initialization vector (IV) is used to seed the operation.
The IV must be the same for both the encryption and decryption steps; otherwise, decrypted
data will not match the original plaintext.
1004
Initialization Vector (IV)
Figure 13-7. Cipher Block Chaining (CBC) Mode Encryption
Key
i.MX28 Applications Processor Reference Manual, Rev. 1, 2010
Block Cipher
Encryption
Ciphertext
Plaintext
Key
Figure
Block Cipher
Encryption
Ciphertext
Plaintext
13-7.
Key
Block Cipher
Encryption
Freescale Semiconductor, Inc.
Ciphertext
Plaintext