EIP-2335: Keystore (#1071)

* Add test to understand flow of key storage

* First commit

* Committing to save trait stuff

* Working naive design

* Add keystore struct

* Move keystore files into their own module

* Add serde (de)serialize_with magic

* Add keystore test

* Fix tests

* Add comments and minor fixes

* Pass optional params to `to_keystore` function

* Add `path` field to keystore

* Add function to read Keystore from file

* Add test vectors and fix Version serialization

* Checksum params is empty object

* Add public key to Keystore

* Add function for saving keystore into file

* Deleted account_manager main.rs

* Move keystore module to validator_client

* Add save_keystore method to validator_directory

* Add load_keystore function. Minor refactorings

* Fixed dependencies

* Address some review comments

* Add Password newtype; derive Zeroize

* Fix test

* Move keystore into own crate

* Remove padding

* Add error enum, zeroize more things

* Fix comment

* Add keystore builder

* Remove keystore stuff from val client

* Add more tests, comments

* Add more comments, test vectors

* Progress on improving JSON validation

* More JSON verification

* Start moving JSON into own mod

* Remove old code

* Add more tests, reader/writers

* Tidy

* Move keystore into own file

* Move more logic into keystore file

* Tidy

* Tidy

* Allow for odd-character hex

* Add more json missing field checks

* Use scrypt by default

* Tidy, address comments

* Test path and uuid in vectors

* Fix comment

* Add checks for kdf params

* Enforce empty kdf message

* Expose json_keystore mod

* Split out encrypt/decrypt

* Replace some password usage with slice

* Expose PlainText struct

* Expose consts, remove Password

* Expose SALT_SIZE

* Move dbg assert statement

* Fix dodgy json test

* Protect against n == 1

* Return error if n is not power of 2

* Add dklen checks

* Add note about panics

Co-authored-by: pawan <pawandhananjay@gmail.com>

eth2/utils/eth2_keystore/src/lib.rs

@@ -0,0 +1,15 @@
+//! Provides a JSON keystore for a BLS keypair, as specified by
+//! [EIP-2335](https://eips.ethereum.org/EIPS/eip-2335).
+
+mod derived_key;
+mod keystore;
+mod plain_text;
+
+pub mod json_keystore;
+
+pub use keystore::{
+    decrypt, default_kdf, encrypt, Error, Keystore, KeystoreBuilder, DKLEN, HASH_SIZE, IV_SIZE,
+    SALT_SIZE,
+};
+pub use plain_text::PlainText;
+pub use uuid::Uuid;