src/core/crypto/hmac_sha256.hpp

/*
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/**
 * @file
 *   This file includes definitions for performing HMAC SHA-256 computations.
 */

#ifndef HMAC_SHA256_HPP_
#define HMAC_SHA256_HPP_

#include "utils/wrap_stdint.h"

#include <mbedtls/md.h>

namespace ot {
namespace Crypto {

/**
 * @addtogroup core-security
 *
 * @{
 *
 */

/**
 * This class implements HMAC SHA-256 computation.
 *
 */
class HmacSha256
{
public:
    enum
    {
        kHashSize = 32,  ///< SHA-256 hash size (bytes)
    };

    /**
     * Constructor for initialization of mbedtls_md_context_t.
     *
     */
    HmacSha256();

    /**
     * Destructor for freeing of mbedtls_md_context_t.
     *
     */
    ~HmacSha256();

    /**
     * This method sets the key.
     *
     * @param[in]  aKey        A pointer to the key.
     * @param[in]  aKeyLength  The key length in bytes.
     *
     */
    void Start(const uint8_t *aKey, uint16_t aKeyLength);

    /**
     * This method inputs bytes into the HMAC computation.
     *
     * @param[in]  aBuf        A pointer to the input buffer.
     * @param[in]  aBufLength  The length of @p aBuf in bytes.
     *
     */
    void Update(const uint8_t *aBuf, uint16_t aBufLength);

    /**
     * This method finalizes the hash computation.
     *
     * @param[out]  aHash  A pointer to the output buffer.
     *
     */
    void Finish(uint8_t aHash[kHashSize]);

private:
    mbedtls_md_context_t mContext;
};

/**
 * @}
 *
 */

}  // namespace Crypto
}  // namespace ot

#endif  // HMAC_SHA256_HPP_