Secretstore over network (#4974)

* ECDKG protocol prototype

* added test for enc/dec math

* get rid of decryption_session

* added licenses

* fix after merge

* get rid of unused serde dependency

* doc

* decryption session [without commutative enc]

* failed_dec_session

* fixed tests

* added commen

* added more decryption session tests

* helper to localize an issue

* more computations to localize error

* decryption_session::SessionParams

* added tests for EC math to localize problem

* secretstore network transport

* encryption_session_works_over_network

* network errors processing

* connecting to KeyServer

* licenses

* get rid of debug println-s

* fixed secretstore args

* encryption results are stored in KS database

* decryption protocol works over network

* enc/dec Session traits

* fixing warnings

* fix after merge

* finally fixed <odd>-of-N-scheme

* temporary commented test

* 1-of-N works in math

* scheme 1-of-N works

* remove unnecessary unsafety

* fixed grumbles

* fix grumbles

* lost files

ethcrypto/src/lib.rs

@@ -78,6 +78,12 @@ impl fmt::Display for Error {
 	}
 }
 
+impl Into<String> for Error {
+	fn into(self) -> String {
+		format!("{}", self)
+	}
+}
+
 impl From<SecpError> for Error {
 	fn from(e: SecpError) -> Self {
 		Error::Secp(e)