This repository includes scripts and code to evaluate the memory footprint of some libraries implementing ECC and SHA-256 functions.
The comparison considers just the secp256r1 curve, that is implemented by all this libraries:
The difference in size is mainly related to the complexity and the set of features present in the libraries.
The goal of this comparison is to find the smallest library to implement ECDSA validation inside a bootloader that must be as small as possible. For this reason the set of features included in many libraries are not needed in this application.
The result of this comparison for Posix systems can be seen in the table below. This size includes also the size of the main;
| Library | SHA2 | ECC | ECDSA |
|---|---|---|---|
| tinydtls | 3800 | 7531 | 9888 |
| polarssl | 6056 | 23046 | 27735 |
| matrixssl | 3864 | 29103 | 34022 |
| micro-ecc | / | 8970 | / |
| tinycrypt | 3656 | 8968 | 11241 |
| wolfssl | 4592 | 31443 | 34777 |
| libtomcrypt | 4354 | 35959 | 38256 |
- micro-ecc does not includes the digest calculation;
- libtomcrypt does not contains all the symbols of libtommath that is loaded at runtime;
The build system has been tested with an Ubuntu Trusty machine. I'm providing
a reproducible environment using Vagrant. Type vagrant up and vagrant ssh
to open a shell into the VM and then run the ./run.sh script located
in the shared /vagrant folder. If everything was successfull at the end of the
build you should seen a table containing the various memory footprint.