ica_aes_ofb

Purpose

Encrypt or decrypt data with an AES key using Output Feedback (OFB) mode, as described in NIST Special Publication 800-38A Chapter 6.4.

Required hardware support

KMO-AES-128, KMO-AES-192, or KMO-AES-256

Parameters

const unsigned char *in_data

Pointer to a readable buffer that contains the message to be encrypted or decrypted. The size of the message in bytes is data_length. The size of this buffer must be at least as large as data_length.

unsigned char *out_data

Pointer to a writable buffer that to contain the resulting encrypted or decrypted message. The size of this buffer in bytes must be at least as large as data_length.

unsigned long data_length

Length in bytes of the message to be encrypted or decrypted, which resides at the beginning of in_data.

const unsigned char *key

Pointer to a valid AES key.

unsigned int key_length

Length in bytes of the AES key. Supported sizes are 16, 24, and 32 for AES-128, AES-192, and AES-256 respectively. Therefore, you can use the definitions: AES_KEY_LEN128, AES_KEY_LEN192, and AES_KEY_LEN256.

unsigned char *iv

Pointer to a valid initialization vector of the same size as the cipher block, in bytes (16 bytes for AES). This vector is overwritten during the function. If data_length is a multiple of the cipher block size (16 bytes for AES), the result value in iv can be used as the initialization vector for a chained ica_aes_ofb call with the same key.

unsigned int direction

0

Use the decrypt function.

1

Use the encrypt function.

Return codes

0

Success

For return codes indicating exceptions, see Return codes.