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review.trustedfirmware.org / mirror / mbed-tls.git / bdf309ccdb51255a39abd1d29bbf19539263813b
commitbdf309ccdb51255a39abd1d29bbf19539263813b[log] [tgz]
authorGilles Peskine <Gilles.Peskine@arm.com>Mon Dec 03 15:36:32 2018 +0100
committerGilles Peskine <Gilles.Peskine@arm.com>Tue Dec 11 16:48:13 2018 +0100
treeee850b094c2784af2752be669630788c8bd7103e
parenta8860b2990be9a1380a6bf1ca4072850e247c870 [diff]
Convert the PSA crypto cryptography tests to the new handle API

Switch from the direct use of slot numbers to handles allocated by
psa_allocate_key.

This commit does not affect persistent key tests except for the one
test function in test_suite_psa_crypto that uses persistent keys
(persistent_key_load_key_from_storage).

The general principle for each function is:
* Change `psa_key_slot_t slot` to `psa_key_handle_t handle`.
* Call psa_allocate_key() before setting the policy of the slot,
  or before creating key material in functions that don't set a policy.
* Some PSA_ERROR_EMPTY_SLOT errors become PSA_ERROR_INVALID_HANDLE
  because there is now a distinction between not having a valid
  handle, and having a valid handle to a slot that doesn't contain key
  material.
* In tests that use symmetric keys, calculate the max_bits parameters
  of psa_allocate_key() from the key data size. In tests where the key
  may be asymmetric, call an auxiliary macro KEY_BITS_FROM_DATA which
  returns an overapproximation. There's no good way to find a good
  value for max_bits with the API, I think the API should be tweaked.
2 files changed
tree: ee850b094c2784af2752be669630788c8bd7103e
  1. .github/
  2. configs/
  3. docs/
  4. doxygen/
  5. include/
  6. library/
  7. programs/
  8. scripts/
  9. tests/
  10. visualc/
  11. .gitignore
  12. .pylint
  13. .travis.yml
  14. apache-2.0.txt
  15. ChangeLog
  16. circle.yml
  17. CMakeLists.txt
  18. CONTRIBUTING.md
  19. DartConfiguration.tcl
  20. LICENSE
  21. Makefile
  22. README.md
README.md

Mbed Crypto library

The Mbed cryptography library is a reference implementation of the cryptography interface of the Arm Platform Security Architecture (PSA). This is a preview release of Mbed Crypto, provided for evaluation purposes only.

Mbed Crypto is distributed under the Apache License, version 2.0. See the LICENSE file for the full text of the license.

PSA cryptography API

Arm's Platform Security Architecture (PSA) is a holistic set of threat models, security analyses, hardware and firmware architecture specifications, and an open source firmware reference implementation. PSA provides a recipe, based on industry best practice, that allows security to be consistently designed in, at both a hardware and firmware level.

The PSA cryptography API provides access to a set of cryptographic primitives. It has a dual purpose. First, it can be used in a PSA-compliant platform to build services, such as secure boot, secure storage and secure communication. Second, it can also be used independently of other PSA components on any platform.

The design goals of the PSA cryptography API include:

  • The API distinguishes caller memory from internal memory, which allows the library to be implemented in an isolated space for additional security. Library calls can be implemented as direct function calls if isolation is not desired, and as remote procedure calls if isolation is desired.
  • The structure of internal data is hidden to the application, which allows substituting alternative implementations at build time or run time, for example, in order to take advantage of hardware accelerators.
  • All access to the keys happens through handles, which allows support for external cryptoprocessors that is transparent to applications.
  • The interface to algorithms is generic, favoring algorithm agility.
  • The interface is designed to be easy to use and hard to accidentally misuse.

Mbed Crypto implementation

Mbed Crypto is a reference implementation of the PSA cryptography API. It is written in portable C.

Documentation

Since the Mbed Crypto library is a reference implementation of the PSA cryptography API, the library's API documentation is the PSA cryptography API specification. The PSA cryptography API specification consists of the following documents:

Compiling

You need the following tools to build the library with the provided makefiles:

  • GNU Make or a build tool that CMake supports.
  • A C99 toolchain (compiler, linker, archiver).
  • Python 2 or Python 3 (either will work) to generate the test code.
  • Perl to run the tests.

If you have a C compiler, such as GCC or Clang, just run make in the top-level directory to build the library, a set of unit tests and some sample programs.

To select a different compiler, set the CC variable to the name or path of the compiler and linker (default: cc), and set AR to a compatible archiver (default: ar). For example:

make CC=arm-linux-gnueabi-gcc AR=arm-linux-gnueabi-ar

The provided makefiles pass options to the compiler that assume a GCC-like command-line syntax. To use a different compiler, you may need to pass different values for CFLAGS, WARNINGS_CFLAGS and LDFLAGS.

To run the unit tests on the host machine, run make test from the top-level directory. If you are cross-compiling, copy the test executable from the tests directory to the target machine.

Compiling as a subproject

Mbed Crypto supports being built as a subproject of Mbed TLS. Mbed TLS can use Mbed Crypto for its cryptography implementation by using Mbed Crypto as a subproject.

From the Mbed TLS project repository, CMake can be invoked as follows to build Mbed TLS using Mbed Crypto's libmbedcrypto.

mkdir cmake
cd cmake
cmake .. -DUSE_CRYPTO_SUBMODULE=1
make -j
make test

When building Mbed Crypto as a subproject of Mbed TLS, the Mbed TLS configuration file (config.h) is used, and not the Mbed Crypto configuration file.

Example programs

The programs/ subdirectory contains sample programs that use the library. Please note that the goal of these sample programs is to demonstrate specific features of the library, and the code may need to be adapted to build a real-world application.

Upcoming features

Future releases of this library will include:

  • A driver programming interface, which makes it possible to use hardware accelerators instead of the default software implementation for chosen algorithms.
  • Support for external keys to be stored and manipulated exclusively in a separate cryptoprocessor.
  • A configuration mechanism to compile only the algorithms you need for your application.
  • A wider set of cryptographic algorithms.

Feedback welcome

Arm welcomes feedback on the design of the API. If you think something could be improved, please open an issue on our Github repository. Alternatively, if you prefer to provide your feedback privately, please email us at mbed-crypto@arm.com. All feedback received by email is treated confidentially.