feat(cli): introduce planet key derive

CHANGES.md

@@ -155,6 +155,8 @@ To be released.
     specific peer. [[#1240]]
  -  Added the option `--no-passphrase` to `planet key remove` command to remove
     key without asking passphrase.  [[#1213], [#1265]]
+ -  Added `planet key derive` subcommand to derive the address or
+    public key from a private.  [[#1268]]
 
 [#1192]: https://github.com/planetarium/libplanet/issues/1192
 [#1197]: https://github.com/planetarium/libplanet/pull/1197
@@ -165,6 +167,7 @@ To be released.
 [#1235]: https://github.com/planetarium/libplanet/pull/1235
 [#1240]: https://github.com/planetarium/libplanet/pull/1240
 [#1265]: https://github.com/planetarium/libplanet/pull/1265
+[#1268]: https://github.com/planetarium/libplanet/pull/1268
 
 
 Version 0.11.1

Libplanet.Extensions.Cocona/Commands/Key/DerivationCommand.cs

@@ -0,0 +1,47 @@
+using System;
+using global::Cocona;
+using Libplanet.Crypto;
+
+namespace Libplanet.Extensions.Cocona.Commands.Key
+{
+    public class DerivationCommand
+    {
+        public void PrivateKey(
+            [Argument(
+                "PRIVATE-KEY",
+                Description = "A private key that the address/public key are derived from."
+            )]
+            string privateKeyHex,
+            [Option('p', Description = "Derives the public key.")]
+            bool publicKey = false,
+            [Option('a', Description = "Derives the address.")]
+            bool address = false)
+        {
+            if (publicKey && address)
+            {
+                throw new CommandExitedException(
+                   "--public-key and --address are mutually exclusive; turn on one at a time.",
+                   -1
+                );
+            }
+            else if (!publicKey && !address)
+            {
+                 throw new CommandExitedException(
+                    "One of --public-key and --address should be turned on.",
+                    -1
+                 );
+            }
+
+            var privateKey = new PrivateKey(ByteUtil.ParseHex(privateKeyHex));
+            if (address)
+            {
+                Console.Out.WriteLine(privateKey.ToAddress());
+            }
+
+            if (publicKey)
+            {
+                Console.Out.WriteLine(ByteUtil.Hex(privateKey.PublicKey.Format(true)));
+            }
+        }
+    }
+}

Libplanet.Extensions.Cocona/Commands/KeyCommand.cs

@@ -4,10 +4,16 @@
 using System.Linq;
 using global::Cocona;
 using Libplanet.Crypto;
+using Libplanet.Extensions.Cocona.Commands.Key;
 using Libplanet.KeyStore;
 
 namespace Libplanet.Extensions.Cocona.Commands
 {
+    [HasSubCommands(
+        typeof(DerivationCommand),
+        "derive",
+        Description = "Derive the address or public key from private key."
+    )]
     public class KeyCommand
     {
         public KeyCommand()