feat(server): initial EVM functionality impl

protobufs/evm.proto

@@ -0,0 +1,31 @@
+syntax = "proto3";
+
+package arbiter.evm;
+
+enum EvmError {
+  EVM_ERROR_UNSPECIFIED = 0;
+  EVM_ERROR_VAULT_SEALED = 1;
+  EVM_ERROR_INTERNAL = 2;
+}
+
+message WalletEntry {
+  bytes address = 1; // 20-byte Ethereum address
+}
+
+message WalletList {
+  repeated WalletEntry wallets = 1;
+}
+
+message WalletCreateResponse {
+  oneof result {
+    WalletEntry wallet = 1;
+    EvmError error = 2;
+  }
+}
+
+message WalletListResponse {
+  oneof result {
+    WalletList wallets = 1;
+    EvmError error = 2;
+  }
+}

protobufs/user_agent.proto

@@ -3,6 +3,7 @@ syntax = "proto3";
 package arbiter.user_agent;
 
 import "google/protobuf/empty.proto";
+import "evm.proto";
 
 message AuthChallengeRequest {
   bytes pubkey = 1;
@@ -55,6 +56,8 @@ message UserAgentRequest {
     UnsealStart unseal_start = 3;
     UnsealEncryptedKey unseal_encrypted_key = 4;
     google.protobuf.Empty query_vault_state = 5;
+    google.protobuf.Empty evm_wallet_create = 6;
+    google.protobuf.Empty evm_wallet_list = 7;
   }
 }
 message UserAgentResponse {
@@ -64,5 +67,7 @@ message UserAgentResponse {
     UnsealStartResponse unseal_start_response = 3;
     UnsealResult unseal_result = 4;
     VaultState vault_state = 5;
+    arbiter.evm.WalletCreateResponse evm_wallet_create = 6;
+    arbiter.evm.WalletListResponse evm_wallet_list = 7;
   }
 }