Device libraries for the Tillitis TKey

• C runtime: libcrt0.
• Common C functions including protocol calls: libcommon.
• Cryptographic functions: libmonocypher. Based on monocypher version 4.0.2 https://github.com/LoupVaillant/Monocypher

Release notes in RELEASE.md.

Licenses and SPDX tags

Unless otherwise noted, the project sources are copyright Tillitis AB, licensed under the terms and conditions of the "BSD-2-Clause" license. See LICENSE for the full license text.

Until Oct 8, 2024, the license was GPL-2.0 Only.

External source code we have imported are isolated in their own directories. They may be released under other licenses. This is noted with a similar LICENSE file in every directory containing imported sources.

The project uses single-line references to Unique License Identifiers as defined by the Linux Foundation's SPDX project on its own source files, but not necessarily imported files. The line in each individual source file identifies the license applicable to that file.

The current set of valid, predefined SPDX identifiers can be found on the SPDX License List at:

https://spdx.org/licenses/

We attempt to follow the REUSE specification.

Hardware support

Bellatrix and earlier

Please note that you need to use uart_write() and uart_read() for I/O.

If you want debug prints in QEMU you can still use write(IO_QEMU, ...). Avoid using write() in other cases.

Building

In order to build, you must have the make, clang, llvm, and lld packages installed.

Version 15 or higher of LLVM/Clang is necessary for the RV32IC_Zmmul architecture we are using. For more detailed information on the supported build and development environment, please refer to the Developer Handbook.

Building using Podman

You can also build the libraries with our OCI image ghcr.io/tillitis/tkey-builder.

The easiest way to build this is if you have make installed:

make podman

You can also specify a different image by using IMAGE=localhost/tkey-builder-local.

Or use Podman directly:

podman run --rm --mount type=bind,source=.,target=/src -w /src -it ghcr.io/tillitis/tkey-builder:4 make -j

Minimal application build

You will typically need to link at least the libcrt0 C runtime otherwise your program won't even reach main().

We provide a linker script in apps.lds which shows the linker the memory layout.

Minimal compilation would look something like:

clang -target riscv32-unknown-none-elf -march=rv32iczmmul -mabi=ilp32 \
  -mcmodel=medany -static -std=gnu99 -O2 -ffast-math -fno-common \
  -fno-builtin-printf -fno-builtin-putchar -nostdlib -mno-relax -flto \
  -Wall -Werror=implicit-function-declaration \
  -I ../tkey-libs/include \
  -I ../tkey-libs -c -o foo.o foo.c

clang -target riscv32-unknown-none-elf -march=rv32iczmmul -mabi=ilp32 \
  -mcmodel=medany -static -ffast-math -fno-common -nostdlib \
  -T ../tkey-libs/app.lds \
  -L ../tkey-libs -lcrt0 \
  -I ../tkey-libs -o foo.elf foo.o

Makefile example

See example-app/Makefile for an example Makefile for a simple device application.

Debug output

If you want to have debug prints in your program you can use the debug_putchar(), debug_puts(), debug_putinthex(), debug_hexdump() and friends. See include/tkey/debug.h for list of functions.

These functions will be turned on if you define either of these when compiling your program and linking with libcommon:

• QEMU_DEBUG: Uses the special debug port only available in qemu to print to the qemu console.
• TKEY_DEBUG: Uses the extra HID device.

Note that if you use TKEY_DEBUG you must have something listening on the corresponding HID device. It's usually the last HID device created. On Linux, for instance, this means the last reported hidraw in dmesg is the one you should do cat /dev/hidrawX on.