v0.2.0

This library is a forked version of bls_key_derivation, containing a straightforward interface to BLS12-381 key derivation in complete compliance with EIP2333.

Since EIP2333 only proposes the hardened key derivation, this library has also implemented a method of non-hardened key derivation inspired by BIP32 to support the current application scenarios.

Changes

Differences with the original library (https://github.com/ChainSafe/rust-bls-derivation) lie in the following:

1. removing the dependency on the unmaintained-for-over-6-years crate rust-crypto;
2. adding the active crate curv-kzen to support non-hardened BLS key derivation beyond EIP233;
3. changing the lower limit of the seed entropy from 16 bytes to 32 bytes to be consistent with the current EIP2333 and draft-irtf-cfrg-bls-signature-05;
4. particularly modifying the function hkdf_mod_r in the following 5 parts to be in complete compliance with both EIP2333 and KeyGen in Section 2.3 of draft-irtf-cfrg-bls-signature-05:
   1. IKM -> IMK || I20SP(0, 1);
   2. keyinfo -> keyinfo || I20SP(L, 2);
   3. salt -> H(salt);
   4. add a loop with the zero private key check;
   5. add an input parameter key_info to support user-customized key info strings instead of fixing as a default empty string "".