Add 'skip_signer_certification' feature

So we can smoothly migrate the Signers first and then the Aggregator on the preview network,
also the Signer certification is not needed in the protocol demo.

demo/protocol-demo/Cargo.toml

@@ -16,4 +16,6 @@ serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 
 [features]
+default = ["skip_signer_certification"]
 portable = ["mithril-common/portable"]
+skip_signer_certification = ["mithril-common/skip_signer_certification"]

mithril-aggregator/Cargo.toml

@@ -39,5 +39,7 @@ slog-term = "2.9.0"
 tempfile = "3.3.0"
 
 [features]
+default = ["skip_signer_certification"] # TODO: remove 'skip_signer_certification' from default features to activate full signer certification
 portable = ["mithril-common/portable"]
+skip_signer_certification = ["mithril-common/skip_signer_certification"]
 

mithril-common/Cargo.toml

@@ -43,3 +43,4 @@ slog-scope = "4.4.0"
 
 [features]
 portable = ["mithril/portable"]
+skip_signer_certification = []

mithril-common/src/crypto_helper/cardano/key_certification.rs

@@ -183,6 +183,10 @@ impl KeyRegWrapper {
         let cert = OpCert::from_file(opcert_path)?;
 
         cert.validate().map_err(|_| RegisterError::InvalidOpCert)?;
+
+        #[cfg(feature = "skip_signer_certification")]
+        println!("WARNING: Signer certification is skipped!!!");
+        #[cfg(feature = "skip_signer_certification")]
         kes_sig
             .verify(kes_period, &cert.kes_vk, &pk.to_bytes())
             .map_err(|_| RegisterError::KesSignatureInvalid)?;

mithril-signer/Cargo.toml

@@ -33,4 +33,6 @@ mockall = "0.11.0"
 slog-term = "2.9.0"
 
 [features]
+default = ["skip_signer_certification"] # TODO: remove 'skip_signer_certification' from default features to activate full signer certification
 portable = ["mithril-common/portable"]
+skip_signer_certification = ["mithril-common/skip_signer_certification"]