CRYPTO AES

Table of Contents

• Features Supported
• SysConfig Features
• Features NOT Supported
• Usage Overview
  • API Sequence
  • Initializing the AES Driver context buffer
  • AES_CBC Encryption and Decryption
  • Clearing the AES Driver context buffer
• Important Usage Guidelines
• Example Usage
• API

Advanced Encryption Standard (AES) is widely adopted symmetric Encrypt/Decrypt algorithm provides information security such as confidentiality ..

Features Supported

• Supports Aes_cbc_256, Aes_cbc_128 and Aes_cbc_192 operations
• Encryption and Decryption
• Symmetric key symmetric block cipher

SysConfig Features

Features NOT Supported

Usage Overview

API Sequence

To use the AES driver to do Encryption and decryption. Use the following APIs:

• Crypto_AesParams_init(): Call this API to set defaults and then override the fields as needed before calling Crypto_aesOpen.
• Crypto_aesOpen() : Initializes a AES context and gives the configuration based on instance.
• Crypto_aesSetKeyEnc() : This function sets the Advance Encryption Standard (AES) encryption key
• Crypto_aesSetKeyDec() : This function sets the Advance Encryption Standard (AES) decryption key
• Crypto_aesCbc() : This function finishes the Advance Encryption Standard (AES) operation, and writes the result to the output buffer.
• Crypto_aesClose() : De-initialize the AES instance and Clears AES context.

Initializing the AES Driver context buffer

• Crypto_aesOpen() must be called before any other AES APIs. This function Initializes a AES context and iterates through the elements of the gCryptoAesConfig[] array. Please note that initializing AES driver is taken care by the SysConfig generated code.

AES_CBC Encryption and Decryption

• AES_CBC Encryption: Set the input parameters using Crypto_AesParams structure, all necessary parametets set to Crypto_AesParams variables and call Crypto_aesOpen() for Initialize the AES ctx, For encryption operation to set the key call Crypto_aesSetKeyEnc(), finally call Crypto_aesCbc() for encryption operation, Aes output will store in output buffer, reset the Aes ctx buffer using Crypto_aesClose().
• AES_CBC Decryption: Set the input parameters using Crypto_AesParams structure, all necessary parametets set to Crypto_AesParams variables and call Crypto_aesOpen() for Initialize the AES ctx, For encryption operation to set the key call Crypto_aesSetKeyDec(), finally call Crypto_aesCbc() for encryption operation, Aes output will store in output buffer, reset the Aes ctx buffer using Crypto_aesClose().

Clearing the AES Driver context buffer

• Crypto_aesClose() clears context buffer data.

Important Usage Guidelines

Example Usage

Include the below file to access the APIs

 
#include <stdio.h>
#include <string.h>
#include <security/crypto/include/crypto_aes.h>
 
#define APP_AES_OUTPUT_LENGTH           (16)
uint8_t gCryptoAesTestBuf[16]={0x81,0xEA,0x5B,0xA4,0x69,0x45,0xC1,0x70,0x5F,0x6F,0x89,0x77,0x88,0x68,0xCC,0x67};
uint8_t gCryptoAesTestKey[32]={0x33,0xA3,0x66,0x46,0xFE,0x56,0xF7,0x0D,0xC0,0xC5,0x1A,0x31,0x17,0xE6,0x39,0xF1,0x82,0xDE,0xF8,0xCA,0xB5,0xC0,0x66,0x71,0xEE,0xA0,0x40,0x7C,0x48,0xA9,0xC7,0x57};
uint8_t gCryptoAesTestIv[16]={0x7C,0xE2,0xAB,0xAF,0x8B,0xEF,0x23,0xC4,0x81,0x6D,0xC8,0xCE,0x84,0x20,0x48,0xA7};

Aes Example

 
Crypto_AesParams            params;
Crypto_AesHandle            aesHandle;
uint8_t                     aesResultBuf[APP_AES_OUTPUT_LENGTH];
int32_t                     status;
/* Context memory */
static Crypto_AesContext    gCryptoAesContext;
 
/* Aes encryption */
memcpy(&params.iv, gCryptoAesTestIv, CRYPTO_AES_IV_LENGTH);
memcpy(&params.key, gCryptoAesTestKey, CRYPTO_AES_KEY_LENGTH);
params.keySizeInBits = 256;
params.type          = CRYPTO_TYPE_SW;
params.algoType      = CRYPTO_AES_ENCRYPT;
                                    
aesHandle = Crypto_aesOpen(&gCryptoAesContext, &params);
status = Crypto_aesSetKeyEnc(aesHandle);
status = Crypto_aesCbc(aesHandle, gCryptoAesTestBuf, sizeof(gCryptoAesTestBuf), aesResultBuf );
status = Crypto_aesClose(aesHandle);
 
/* Aes Decryption */
memcpy(&params.iv, gCryptoAesTestIv, CRYPTO_AES_IV_LENGTH);
memcpy(&params.key, gCryptoAesTestKey, CRYPTO_AES_KEY_LENGTH);
params.keySizeInBits = 256;
params.type          = CRYPTO_TYPE_SW;
params.algoType      = CRYPTO_AES_DECRYPT;
 
aesHandle = Crypto_aesOpen(&gCryptoAesContext, &params);
status = Crypto_aesSetKeyDec(aesHandle);
status = Crypto_aesCbc(aesHandle, gCryptoAesTestBuf, sizeof(gCryptoAesTestBuf), aesResultBuf );
status = Crypto_aesClose(aesHandle);
 
 

API

APIs for CRYPTO AES