store map of provider pks

contracts/contracts/coordination/Coordinator.sol

@@ -40,7 +40,6 @@ contract Coordinator is Ownable {
         bool aggregated;
         bytes transcript;  // TODO: Consider event processing complexity vs storage cost
         bytes decryptionRequestStaticKey;
-        bytes publicKey;  // TODO: Consider event processing complexity vs storage cost
     }
 
     // TODO: Optimize layout
@@ -58,6 +57,8 @@ contract Coordinator is Ownable {
 
     Ritual[] public rituals;
 
+    mapping(address => bytes) public providerPublicKey;
+
     IAccessControlApplication public immutable application;
     uint32 public timeout;
     uint32 public maxDkgSize;
@@ -96,6 +97,11 @@ contract Coordinator is Ownable {
         }
     }
 
+    function setProviderPublicKey(bytes calldata publicKey) external {
+        // TODO: Verify public key length
+        require(publicKey.length == 48, "Invalid public key length");
+        providerPublicKey[msg.sender] = publicKey;
+    }
 
     function setTimeout(uint32 newTimeout) external onlyOwner {
         emit TimeoutChanged(timeout, newTimeout);
@@ -131,6 +137,11 @@ contract Coordinator is Ownable {
         for(uint256 i=0; i < length; i++){
             Participant storage newParticipant = ritual.participant.push();
             address current = providers[i];
+            // Make sure that current provider has already set their public key
+            require(
+                providerPublicKey[current].length > 0,
+                "Provider has not set their public key"
+            );
             require(previous < current, "Providers must be sorted");
             // TODO: Improve check for eligible nodes (staking, etc) - nucypher#3109
             // TODO: Change check to isAuthorized(), without amount