wrote first script/validator (smart contract) and build blueprint

plutus.json

@@ -0,0 +1,69 @@
+{
+  "preamble": {
+    "title": "aiken-lang/hello-world",
+    "description": "Aiken contracts for project 'aiken-lang/hello-world'",
+    "version": "0.0.0",
+    "plutusVersion": "v2",
+    "compiler": {
+      "name": "Aiken",
+      "version": "v1.0.26-alpha+unknown"
+    },
+    "license": "Apache-2.0"
+  },
+  "validators": [
+    {
+      "title": "hello_world.hello_world",
+      "datum": {
+        "title": "datum",
+        "schema": {
+          "$ref": "#/definitions/hello_world~1Datum"
+        }
+      },
+      "redeemer": {
+        "title": "redeemer",
+        "schema": {
+          "$ref": "#/definitions/hello_world~1Redeemer"
+        }
+      },
+      "compiledCode": "58e901000032323232323223223225333006323253330083371e6eb8c008c028dd5002a4410d48656c6c6f2c20576f726c642100100114a06644646600200200644a66601c00229404c94ccc030cdc79bae301000200414a226600600600260200026eb0c02cc030c030c030c030c030c030c030c030c024dd5180098049baa002375c600260126ea80188c02c0045261365653330043370e900018029baa001132325333009300b002149858dd7180480098031baa0011653330023370e900018019baa0011323253330073009002149858dd7180380098021baa001165734aae7555cf2ab9f5742ae881",
+      "hash": "c1fe430f19ac248a8a7ea47db106002c4327e542c3fdc60ad6481103"
+    }
+  ],
+  "definitions": {
+    "ByteArray": {
+      "dataType": "bytes"
+    },
+    "hello_world/Datum": {
+      "title": "Datum",
+      "anyOf": [
+        {
+          "title": "Datum",
+          "dataType": "constructor",
+          "index": 0,
+          "fields": [
+            {
+              "title": "owner",
+              "$ref": "#/definitions/ByteArray"
+            }
+          ]
+        }
+      ]
+    },
+    "hello_world/Redeemer": {
+      "title": "Redeemer",
+      "anyOf": [
+        {
+          "title": "Redeemer",
+          "dataType": "constructor",
+          "index": 0,
+          "fields": [
+            {
+              "title": "msg",
+              "$ref": "#/definitions/ByteArray"
+            }
+          ]
+        }
+      ]
+    }
+  }
+}

validators/hello-world.ak

@@ -0,0 +1,27 @@
+use aiken/hash.{Blake2b_224, Hash}
+use aiken/list
+use aiken/string
+use aiken/transaction.{OutputReference, ScriptContext, Spend, TransactionId}
+use aiken/transaction/credential.{VerificationKey}
+
+
+type Datum {
+    owner: Hash<Blake2b_224, VerificationKey>,
+}
+
+type Redeemer {
+    msg: ByteArray,
+}
+
+validator {
+    fn hello_world(datum: Datum, redeemer: Redeemer, context: ScriptContext) -> Bool {
+
+        trace string.from_bytearray(redeemer.msg)
+
+        let must_say_hello = redeemer.msg == "Hello, World!"
+
+        let must_be_signed = list.has(context.transaction.extra_signatories, datum.owner)
+
+        must_say_hello? && must_be_signed? 
+    }
+}