Crypto Engine

Overview

The crypto engine (CE) API is a crypto queue manager.

Requirement

You must put, at the start of your transform context your_tfm_ctx, the structure crypto_engine:

struct your_tfm_ctx {
        struct crypto_engine engine;
        ...
};

The crypto engine only manages asynchronous requests in the form of crypto_async_request. It cannot know the underlying request type and thus only has access to the transform structure. It is not possible to access the context using container_of. In addition, the engine knows nothing about your structure “struct your_tfm_ctx”. The engine assumes (requires) the placement of the known member struct crypto_engine at the beginning.

Order of operations

You are required to obtain a struct crypto_engine via crypto_engine_alloc_init(). Start it via crypto_engine_start(). When finished with your work, shut down the engine using crypto_engine_stop() and destroy the engine with crypto_engine_exit().

Before transferring any request, you have to fill the context enginectx by providing functions for the following:

  • prepare_crypt_hardware: Called once before any prepare functions are called.
  • unprepare_crypt_hardware: Called once after all unprepare functions have been called.
  • prepare_cipher_request/prepare_hash_request: Called before each corresponding request is performed. If some processing or other preparatory work is required, do it here.
  • unprepare_cipher_request/unprepare_hash_request: Called after each request is handled. Clean up / undo what was done in the prepare function.
  • cipher_one_request/hash_one_request: Handle the current request by performing the operation.

Note that these functions access the crypto_async_request structure associated with the received request. You are able to retrieve the original request by using:

container_of(areq, struct yourrequesttype_request, base);

When your driver receives a crypto_request, you must to transfer it to the crypto engine via one of:

  • crypto_transfer_aead_request_to_engine()
  • crypto_transfer_akcipher_request_to_engine()
  • crypto_transfer_hash_request_to_engine()
  • crypto_transfer_kpp_request_to_engine()
  • crypto_transfer_skcipher_request_to_engine()

At the end of the request process, a call to one of the following functions is needed:

  • crypto_finalize_aead_request()
  • crypto_finalize_akcipher_request()
  • crypto_finalize_hash_request()
  • crypto_finalize_kpp_request()
  • crypto_finalize_skcipher_request()