Encryption support for the statement store (#14440)

* Added ECIES encryption

* tweaks

* fmt

* Make clippy happy

* Use local keystore

* qed

substrate/primitives/core/Cargo.toml

@@ -57,7 +57,6 @@ sp-runtime-interface = { version = "17.0.0", default-features = false, path = ".
 w3f-bls = { version = "0.1.3", default-features = false, optional = true}
 
 [dev-dependencies]
-rand = "0.8.5"
 criterion = "0.4.0"
 serde_json = "1.0"
 sp-core-hashing-proc-macro = { version = "9.0.0", path = "./hashing/proc-macro" }