mnemonic generation and key derivation follows BIP-0039.
to get started, simply:
git clone https://github.com/leshow/rust_mnemonic
cd rust_mnemonic
cargo build --release
cargo install
Install will provide you with the rust_mnemonic
binary
If no seed is provided the seed string will be "seed". The seed string will be used in conjunction with the mnemonic for generating the pbkdf2 key.
The mnemonic is created exactly the same (to the best of my knowledge) as in python-mnemonic (https://github.com/trezor/python-mnemonic) and to the BIP0039 standard, my code has not been vetted by the bitcoin community or any cryptographers however, so use with your own caution.