Managarm's Library of Freestanding Cryptographic Algorithms

This library implements freestanding versions of various cryptographic primitives. As of now, AES256 and SHA256 are implemented.

We do not aim to provide original implementations the afforementioned primitives as implementing cryptographic algorithms is non-trivial (e.g., to defend against sidechannel attacks) and requires great care and frequent maintainance. Instead, we borrow our implementations from the excellent Botan library and adopt them to be freestanding. As far as possible, the original source code is kept intact such that merging improvements and fixes from upstream remains possible.

Note that since this library is freestanding, it is less intuitive to use than a general-purpose library (such as Botan) and requires even more care. Compared to Botan, notable differences in the security model include:

• Users need to ensure that secrets do not leak into swap files and/or core dumps. Users are responsible for putting secret keys and other state into non-swapable memory.

All non-trivial changes compared to Botan are annotated by [cralgo] comments in the source. Other, more trivial changes include:

• The compiler is assumed to be GCC or GCC-compatible (e.g., Clang).
• Botan-specific macros are replaced by generic macros. For example, BOTAN_ASSERT is replaced by assert and BOTAN_TARGET_CPU_HAS_NATIVE_64BIT is replaced by __LP64__.
• Annotations for sanitizers such as CT::{poison,unpoison} are removed.

This library uses code from Botan. The latter is developed by Jack Lloyd and contributors and is available under a 2-clause BSD license (just like this project), see LICENSE.