src/core/crypto/aes_ccm.hpp

/*
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 *     derived from this software without specific prior written permission.
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 */

/**
 * @file
 *   This file includes definitions for performing AES-CCM computations.
 */

#ifndef AES_CCM_HPP_
#define AES_CCM_HPP_

#include "openthread-core-config.h"

#include <stdint.h>

#include <openthread/platform/crypto.h>
#include "common/error.hpp"
#include "common/message.hpp"
#include "common/type_traits.hpp"
#include "crypto/aes_ecb.hpp"
#include "crypto/storage.hpp"
#include "mac/mac_types.hpp"

namespace ot {
namespace Crypto {

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

/**
 * This class implements AES CCM computation.
 *
 */
class AesCcm
{
public:
    static constexpr uint8_t kMinTagLength = 4;                  ///< Minimum tag length (in bytes).
    static constexpr uint8_t kMaxTagLength = AesEcb::kBlockSize; ///< Maximum tag length (in bytes).
    static constexpr uint8_t kNonceSize    = 13;                 ///< Size of IEEE 802.15.4 Nonce (in bytes).

    /**
     * This enumeration type represent the encryption vs decryption mode.
     *
     */
    enum Mode : uint8_t
    {
        kEncrypt, // Encryption mode.
        kDecrypt, // Decryption mode.
    };

    /**
     * This method sets the key.
     *
     * @param[in]  aKey    Crypto Key used in AES operation
     *
     */
    void SetKey(const Key &aKey) { mEcb.SetKey(aKey); }

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

    /**
     * This method sets the key.
     *
     * @param[in]  aMacKey        Key Material for AES operation.
     *
     */
    void SetKey(const Mac::KeyMaterial &aMacKey);

    /**
     * This method initializes the AES CCM computation.
     *
     * @param[in]  aHeaderLength     Length of header in bytes.
     * @param[in]  aPlainTextLength  Length of plaintext in bytes.
     * @param[in]  aTagLength        Length of tag in bytes (must be even and in `[kMinTagLength, kMaxTagLength]`).
     * @param[in]  aNonce            A pointer to the nonce.
     * @param[in]  aNonceLength      Length of nonce in bytes.
     *
     */
    void Init(uint32_t    aHeaderLength,
              uint32_t    aPlainTextLength,
              uint8_t     aTagLength,
              const void *aNonce,
              uint8_t     aNonceLength);

    /**
     * This method processes the header.
     *
     * @param[in]  aHeader        A pointer to the header.
     * @param[in]  aHeaderLength  Length of header in bytes.
     *
     */
    void Header(const void *aHeader, uint32_t aHeaderLength);

    /**
     * This method processes the header.
     *
     * @tparam    ObjectType   The object type.
     *
     * @param[in] aObject      A reference to the object to add to header.
     *
     */
    template <typename ObjectType> void Header(const ObjectType &aObject)
    {
        static_assert(!TypeTraits::IsPointer<ObjectType>::kValue, "ObjectType must not be a pointer");

        Header(&aObject, sizeof(ObjectType));
    }

    /**
     * This method processes the payload.
     *
     * @param[in,out]  aPlainText   A pointer to the plaintext.
     * @param[in,out]  aCipherText  A pointer to the ciphertext.
     * @param[in]      aLength      Payload length in bytes.
     * @param[in]      aMode        Mode to indicate whether to encrypt (`kEncrypt`) or decrypt (`kDecrypt`).
     *
     */
    void Payload(void *aPlainText, void *aCipherText, uint32_t aLength, Mode aMode);

#if !OPENTHREAD_RADIO
    /**
     * This method processes the payload within a given message.
     *
     * This method encrypts/decrypts the payload content in place within the @p aMessage.
     *
     * @param[in,out]  aMessage     The message to read from and update.
     * @param[in]      aOffset      The offset in @p aMessage to start of payload.
     * @param[in]      aLength      Payload length in bytes.
     * @param[in]      aMode        Mode to indicate whether to encrypt (`kEncrypt`) or decrypt (`kDecrypt`).
     *
     */
    void Payload(Message &aMessage, uint16_t aOffset, uint16_t aLength, Mode aMode);
#endif

    /**
     * This method returns the tag length in bytes.
     *
     * @returns The tag length in bytes.
     *
     */
    uint8_t GetTagLength(void) const { return mTagLength; }

    /**
     * This method generates the tag.
     *
     * @param[out]  aTag        A pointer to the tag (must have `GetTagLength()` bytes).
     *
     */
    void Finalize(void *aTag);

    /**
     * This static method generates IEEE 802.15.4 nonce byte sequence.
     *
     * @param[in]  aAddress        An extended address.
     * @param[in]  aFrameCounter   A frame counter.
     * @param[in]  aSecurityLevel  A security level.
     * @param[out] aNonce          A buffer (with `kNonceSize` bytes) to place the generated nonce.
     *
     */
    static void GenerateNonce(const Mac::ExtAddress &aAddress,
                              uint32_t               aFrameCounter,
                              uint8_t                aSecurityLevel,
                              uint8_t *              aNonce);

private:
    AesEcb   mEcb;
    uint8_t  mBlock[AesEcb::kBlockSize];
    uint8_t  mCtr[AesEcb::kBlockSize];
    uint8_t  mCtrPad[AesEcb::kBlockSize];
    uint32_t mHeaderLength;
    uint32_t mHeaderCur;
    uint32_t mPlainTextLength;
    uint32_t mPlainTextCur;
    uint16_t mBlockLength;
    uint16_t mCtrLength;
    uint8_t  mNonceLength;
    uint8_t  mTagLength;
};

/**
 * @}
 *
 */

} // namespace Crypto
} // namespace ot

#endif // AES_CCM_HPP_