SHA is Secure Hash Algorithm, It is used as a unique value of fixed size representing a large amount of data. Hashes of two sets of data should match if and only if the corresponding data also matches. Small changes to the data result in large unpredictable changes in the hash.The hash size for the SHA512 algorithm is 512 bits and hash size for the SHA256 algorithm is 256 bits.

Features Supported

Latest versions of Secure Hash Algorithm SHA-512 and SHA-256
Handles different input buffer lengths.
It used upto 1024 bits blocks.
Accepts 2^128 bits maximum length string.
The initial hash values and round constants are 64 bits in SHA-512 and 32 bits in SHA-256.
No of rounds 80 for SHA-512 and 64 rounds for SHA 256.
Word size 64 bits for SHA-512 and 32 bits for SHA-256.
Supports Hmac Sha-512 and Sha-256.

SysConfig Features

Features NOT Supported

Usage Overview

API Sequence

To use the SHA driver to generate hash for differnt data. Use the following APIs:

Crypto_ShaParams_init() : Call this API to set defaults and then override the fields as needed before calling Crypto_shaOpen.
Crypto_shaOpen() : Initializes a SHA context and gives the configuration based on instance.
Crypto_shaSingleShot() : This function calculates the SHA checksum of a fixed buffer.
Crypto_shaStarts() : Starts a SHA checksum calculation.
Crypto_shaUpdate() : Feeds an input buffer into an ongoing SHA checksum calculation.
Crypto_shaFinish() : Finishes the SHA operation and updates the result to the output buffer.
Crypto_shaClose() : Clears SHA context.

HMAC API Sequence

To use the HMAC SHA driver to generate hash for differnt data. Use the following APIs:

Crypto_ShaParams_init() : Call this API to set defaults and then override the fields as needed before calling Crypto_shaOpen.
Crypto_shaOpen() : Initializes a SHA context and gives the configuration based on instance.
Crypto_hmacSha() : This function calculates the Keyed-Hash Message Authentication Code Secure Hash Algorithm (HMAC-SHA) checksum of a buffer.
Crypto_shaClose() : Clears SHA context.

Initializing the SHA Driver context buffer

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

Generating Hash with SHA Driver

Single Block Hash Computation: Set the input parameters using Crypto_ShaParams structure, all necessary parametets set to Crypto_ShaParams variables and call Crypto_shaOpen() for Initialize the Sha ctx. To compute fixed block hash i.e call Crypto_shaSingleShot() by updating references to input buffer, length and Output buffer. Hash will be available at output buffer on successful computation. Once SHA computation is done for the required data length, reset the SHA ctx buffer using Crypto_shaClose().
Multi Block Hash Computation: Set the input parameters using Crypto_ShaParams structure, all necessary parametets set to Crypto_ShaParams variables and call Crypto_shaOpen() for Initialize the Sha ctx. The initial hash value H(0) will be set using Crypto_shaStarts(). Buffer processing is handled by Crypto_shaUpdate(), use this API for multi buffer processing and extract final hash using Crypto_shaFinish(). Once SHA computation is done for the required data length , reset the SHA ctx buffer using Crypto_shaClose().

Generating HMAC SHA

Set the input parameters using Crypto_ShaParams structure, all necessary parametets set to Crypto_ShaParams variables and call Crypto_shaOpen() for Initialize the Sha ctx. To compute fixed block Hmac hash i.e call Crypto_hmacSha() by updating references to input buffer, length and Output buffer. Hash will be available at output buffer on successful computation. Once SHA computation is done for the required data length, reset the SHA ctx buffer using Crypto_shaClose().

Clearing the SHA Driver context buffer

Crypto_shaClose() clears context buffer data.

Important Usage Guidelines

Example Usage

Include the below file to access the APIs

 
#include<stdio.h>
#include <security/crypto/include/crypto_sha.h>

Hash Example

 
Crypto_ShaParams            params;
Crypto_ShaHandle            shaHandle;
/* Context memory */
static Crypto_ShaContext    gCryptoSha512Context;
uint8_t buf[10]={"abcedfghij"};
int32_t buf_len=10;
uint8_t sha512sum[64];
 
/* Fixed Block SHA512 computation */
shaHandle = Crypto_shaOpen(&gCryptoSha512Context, &params);
Crypto_shaSingleShot(shaHandle, buf, buf_len, sha512sum);
Crypto_shaClose(shaHandle);
 
/*For Multi buffer SHA512 computation */
shaHandle = Crypto_shaOpen(&gCryptoSha512Context, &params);
Crypto_shaStarts(shaHandle);
Crypto_shaUpdate(shaHandle, buf, buf_len);
Crypto_shaFinish(shaHandle, sha512sum );
Crypto_shaClose(shaHandle);
 

API

APIs for CRYPTO SHA

Table of Contents