diff --git a/.gitignore b/.gitignore
index 505a3b1..ddaec25 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,3 +8,9 @@ wheels/
 
 # Virtual environments
 .venv
+
+# Terraform/Tofu
+examples/tofu/**/.terraform
+examples/tofu/**/.terraform.lock.hcl
+examples/tofu/**/.terraform.tfstate
+examples/tofu/**/.terraform.tfstate.backup
diff --git a/examples/tofu/main.tf b/examples/tofu/main.tf
new file mode 100644
index 0000000..e6e772f
--- /dev/null
+++ b/examples/tofu/main.tf
@@ -0,0 +1,22 @@
+terraform {
+  required_providers {
+    aws = {
+      source = "hashicorp/aws"
+      version = "~> 5.0"
+    }
+  }
+}
+
+provider "aws" {
+  region = "eu-west-1"
+}
+
+resource "aws_instance" "test-instance" {
+  ami = "0c4dcaafb6a14dbb93b402f1fd6a9dfb"
+  instance_type = "micro"
+  availability_zone = "az-1"
+
+  tags = {
+    TestTag = "TestValue"
+  }
+}
diff --git a/examples/tofu/terraform.tfstate b/examples/tofu/terraform.tfstate
new file mode 100644
index 0000000..da837b1
--- /dev/null
+++ b/examples/tofu/terraform.tfstate
@@ -0,0 +1 @@
+{"version":4,"terraform_version":"1.9.0","serial":8,"lineage":"a013da38-6954-7573-33dd-c05f6b0ec61f","outputs":{},"resources":[{"mode":"managed","type":"aws_instance","name":"test-instance","provider":"provider[\"registry.opentofu.org/hashicorp/aws\"]","instances":[{"schema_version":1,"attributes":{"ami":"0c4dcaafb6a14dbb93b402f1fd6a9dfb","arn":"arn:aws:ec2:eu-west-1:1:instance/19b606d3c0b543c991f2b0cd632013a2","associate_public_ip_address":false,"availability_zone":"az-1","capacity_reservation_specification":[],"cpu_core_count":null,"cpu_options":[],"cpu_threads_per_core":null,"credit_specification":[],"disable_api_stop":false,"disable_api_termination":false,"ebs_block_device":[],"ebs_optimized":false,"enable_primary_ipv6":null,"enclave_options":[],"ephemeral_block_device":[],"get_password_data":false,"hibernation":null,"host_id":null,"host_resource_group_arn":null,"iam_instance_profile":"","id":"19b606d3c0b543c991f2b0cd632013a2","instance_initiated_shutdown_behavior":null,"instance_lifecycle":"","instance_market_options":[],"instance_state":"running","instance_type":"","ipv6_address_count":0,"ipv6_addresses":[],"key_name":"","launch_template":[],"maintenance_options":[],"metadata_options":[],"monitoring":null,"network_interface":[],"outpost_arn":"","password_data":"","placement_group":null,"placement_partition_number":null,"primary_network_interface_id":"","private_dns":"","private_dns_name_options":[],"private_ip":"","public_dns":"","public_ip":"","root_block_device":[],"secondary_private_ips":[],"security_groups":[],"source_dest_check":true,"spot_instance_request_id":"","subnet_id":"","tags":{"TestTag":"TestValue"},"tags_all":{"TestTag":"TestValue"},"tenancy":null,"timeouts":null,"user_data":null,"user_data_base64":null,"user_data_replace_on_change":false,"volume_tags":null,"vpc_security_group_ids":[]},"sensitive_attributes":[],"private":"eyJlMmJmYjczMC1lY2FhLTExZTYtOGY4OC0zNDM2M2JjN2M0YzAiOnsiY3JlYXRlIjo2MDAwMDAwMDAwMDAsImRlbGV0ZSI6MTIwMDAwMDAwMDAwMCwicmVhZCI6OTAwMDAwMDAwMDAwLCJ1cGRhdGUiOjYwMDAwMDAwMDAwMH0sInNjaGVtYV92ZXJzaW9uIjoiMSJ9"}]}],"check_results":null}
diff --git a/examples/tofu/terraform.tfstate.backup b/examples/tofu/terraform.tfstate.backup
new file mode 100644
index 0000000..a71968e
--- /dev/null
+++ b/examples/tofu/terraform.tfstate.backup
@@ -0,0 +1 @@
+{"version":4,"terraform_version":"1.9.0","serial":7,"lineage":"a013da38-6954-7573-33dd-c05f6b0ec61f","outputs":{},"resources":[],"check_results":null}
diff --git a/src/openec2/actions/create_tags.py b/src/openec2/actions/create_tags.py
new file mode 100644
index 0000000..decf99e
--- /dev/null
+++ b/src/openec2/actions/create_tags.py
@@ -0,0 +1,51 @@
+from dataclasses import dataclass
+from typing import cast
+import uuid
+
+from fastapi import Response
+from fastapi.datastructures import QueryParams
+from sqlmodel import select
+
+from openec2.config import OpenEC2Config
+from openec2.db import DatabaseDep
+from openec2.db.user import User
+from openec2.db.instance import Instance
+from openec2.utils.array import parse_array_objects, parse_array_plain
+from openec2.api.create_tags import CreateTagsResponse
+
+
+@dataclass
+class Tag:
+    key: str
+    value: str
+
+
+def create_tags(
+    params: QueryParams,
+    config: OpenEC2Config,
+    db: DatabaseDep,
+    user: User,
+):
+    tags: dict[str, str] = {}
+    for tag in parse_array_objects("Tag", cast(dict, params)):
+        tags[tag["Key"]] = tag["Value"]
+
+    for instance_id in parse_array_plain("ResourceId", cast(dict, params)):
+        instance = db.exec(select(Instance).where(Instance.id == instance_id, Instance.owner_id == user.id)).first()
+        if instance is None:
+            print(f"Unknown instance {instance_id}")
+            continue
+        instance.tags = {
+            **instance.tags,
+            **tags,
+        }
+        print(instance)
+
+    db.commit()
+    return Response(
+        CreateTagsResponse(
+            requestId=uuid.uuid4().hex,
+            return_=True,
+        ).to_xml(),
+        media_type="application/xml",
+    )
diff --git a/src/openec2/actions/create_vpc.py b/src/openec2/actions/create_vpc.py
new file mode 100644
index 0000000..f4b5935
--- /dev/null
+++ b/src/openec2/actions/create_vpc.py
@@ -0,0 +1,17 @@
+from fastapi import Response, HTTPException
+from fastapi.datastructures import QueryParams
+from sqlmodel import select
+
+from openec2.db.user import User
+from openec2.config import OpenEC2Config
+from openec2.db import DatabaseDep
+from openec2.db.vpc import VPC
+
+
+def create_vpc(
+    params: QueryParams,
+    config: OpenEC2Config,
+    db: DatabaseDep,
+    user: User,
+):
+    cidr_block = params["CidrBlock"]
diff --git a/src/openec2/actions/describe_instance_attribute.py b/src/openec2/actions/describe_instance_attribute.py
new file mode 100644
index 0000000..03dca47
--- /dev/null
+++ b/src/openec2/actions/describe_instance_attribute.py
@@ -0,0 +1,43 @@
+import uuid
+
+from fastapi import Response, HTTPException
+from fastapi.datastructures import QueryParams
+from sqlmodel import select
+
+from openec2.config import OpenEC2Config
+from openec2.db import DatabaseDep
+from openec2.db.user import User
+from openec2.db.instance import Instance
+from openec2.api.describe_instance_attribute import DescribeInstanceAttributeResponse, InstanceInitiatedShutdownBehaviour, DisableApiTermination, DisableApiStop
+
+
+def describe_instance_attribute(
+    params: QueryParams,
+    config: OpenEC2Config,
+    db: DatabaseDep,
+    user: User,
+):
+    instance_id = params["InstanceId"]
+    attribute = params["Attribute"]
+    instance = db.exec(select(Instance).where(Instance.id == instance_id, Instance.owner_id == user.id)).first()
+    if instance is None:
+        raise HTTPException(
+            status_code=404,
+        )
+
+    return Response(
+        DescribeInstanceAttributeResponse(
+            requestId=uuid.uuid4().hex,
+            instanceId=instance.id,
+            instanceInitiatedShutdownBehaviour=InstanceInitiatedShutdownBehaviour(
+                value="stop",
+            ) if attribute == "instanceInitiatedShutdownBehaviour" else None,
+            disableApiTermination=DisableApiTermination(
+                value="false",
+            ) if attribute == "disableApiTermination" else None,
+            disableApiStop=DisableApiStop(
+                value="false",
+            ) if attribute == "disableApiStop" else None,
+        ).to_xml(),
+        media_type="application/xml",
+    )
diff --git a/src/openec2/actions/describe_instance_types.py b/src/openec2/actions/describe_instance_types.py
new file mode 100644
index 0000000..33820cc
--- /dev/null
+++ b/src/openec2/actions/describe_instance_types.py
@@ -0,0 +1,36 @@
+import uuid
+
+from fastapi import Response
+from fastapi.datastructures import QueryParams
+from sqlmodel import select
+
+from openec2.config import OpenEC2Config
+from openec2.db import DatabaseDep
+from openec2.db.user import User
+from openec2.db.instance import Instance
+from openec2.api.describe_instance_types import DescribeInstanceTypesResponse, InstanceTypeInfo
+
+
+def describe_instance_types(
+    params: QueryParams,
+    config: OpenEC2Config,
+    db: DatabaseDep,
+    user: User,
+):
+    response: list[InstanceTypeInfo] = []
+    instances = db.exec(select(Instance).where(Instance.owner_id == user.id)).all()
+    for instance in instances:
+        response.append(
+            InstanceTypeInfo(
+                instanceType=instance.instanceType,
+            ),
+        )
+
+    return Response(
+        DescribeInstanceTypesResponse(
+            requestId=uuid.uuid4().hex,
+            instanceTypeSet=response,
+            nextToken=None,
+        ).to_xml(),
+        media_type="application/xml",
+    )
diff --git a/src/openec2/actions/describe_tags.py b/src/openec2/actions/describe_tags.py
new file mode 100644
index 0000000..2dc8d44
--- /dev/null
+++ b/src/openec2/actions/describe_tags.py
@@ -0,0 +1,99 @@
+from typing import Literal, cast
+from dataclasses import dataclass
+import uuid
+
+from fastapi import Response
+from fastapi.datastructures import QueryParams
+from sqlmodel import select
+
+from openec2.config import OpenEC2Config
+from openec2.db import DatabaseDep
+from openec2.db.user import User
+from openec2.db.instance import Instance
+from openec2.api.describe_tags import DescribeTagsResponse, TagDescription
+from openec2.utils.array import parse_array_objects, parse_array_plain, find
+
+
+@dataclass
+class Filter:
+    name: Literal["resource-id"] | Literal["resource-type"] | Literal["key"] | str
+    values: list[str]
+
+    def match(self, instance: Instance) -> bool:
+        if self.name not in instance.tags:
+            return False
+
+        value: str | None
+        if self.name == "resource-type":
+            value = "instance"
+        elif self.name == "resource-id":
+            value = instance.id
+        elif self.name == "key":
+            return any(key in instance.tags for key in self.values)
+        elif self.name.startswith("tag:"):
+            value = instance.tags.get(self.name.replace("tag:", ""))
+        else:
+            raise Exception(f"Unknown filter name {self.name}")
+
+        return value in self.values
+
+    def value(self, instance: Instance) -> TagDescription:
+        if self.name == "resource-type":
+            return TagDescription(resourceType="instance")
+        elif self.name == "resource-id":
+            return TagDescription(resourceId=instance.id)
+        elif self.name == "key":
+            key_name = find(
+                self.values,
+                lambda x: x in instance.tags,
+            )
+            assert key_name is not None
+
+            key_value = instance.tags[key_name]
+
+            return TagDescription(
+                key=key_name,
+                value=key_value,
+            )
+        elif self.name.startswith("tag:"):
+            tag = self.name.replace("tag:", "")
+            return TagDescription(
+                key=tag,
+                value=instance.tags[tag],
+            )
+        else:
+            raise Exception(f"Unknown filter name {self.name}")
+
+def describe_tags(
+    params: QueryParams,
+    config: OpenEC2Config,
+    db: DatabaseDep,
+    user: User,
+):
+    filters: list[Filter] = []
+    for filter in parse_array_objects("Filter", cast(dict, params)):
+        filters.append(
+            Filter(
+                name=filter["Name"],
+                values=parse_array_plain("Values", filter),
+            )
+        )
+
+    response: list[TagDescription] = []
+    for instance in db.exec(select(Instance).where(Instance.owner_id == user.id)).all():
+        filter = find(
+            filters,
+            lambda f: f.match(instance),
+        )
+        if filter is None:
+            continue
+        response.append(filter.value(instance))
+
+    return Response(
+        DescribeTagsResponse(
+            requestId=uuid.uuid4().hex,
+            nextToken=None,
+            tagSet=response,
+        ).to_xml(),
+        media_type="application/xml",
+    )
diff --git a/src/openec2/actions/get_caller_identity.py b/src/openec2/actions/get_caller_identity.py
new file mode 100644
index 0000000..976e438
--- /dev/null
+++ b/src/openec2/actions/get_caller_identity.py
@@ -0,0 +1,30 @@
+import uuid
+
+from fastapi import Response
+from fastapi.datastructures import QueryParams
+
+from openec2.config import OpenEC2Config
+from openec2.db import DatabaseDep
+from openec2.db.user import User
+from openec2.api.get_caller_identity import GetCallerIdentityResponse, GetCallerIdentityResult, ResponseMetadata
+
+
+def get_caller_identity(
+    params: QueryParams,
+    config: OpenEC2Config,
+    db: DatabaseDep,
+    user: User,
+):
+    return Response(
+        GetCallerIdentityResponse(
+            result=GetCallerIdentityResult(
+                arn=f"arn:aws:iam::{user.id}:user/{user.name}",
+                user_id=str(user.id),
+                account=str(user.id),
+            ),
+            metadata=ResponseMetadata(
+                request_id=uuid.uuid4().hex,
+            ),
+        ).to_xml(),
+        media_type="application/xml",
+    )
diff --git a/src/openec2/actions/run_instances.py b/src/openec2/actions/run_instances.py
index 6c23824..14c30f3 100644
--- a/src/openec2/actions/run_instances.py
+++ b/src/openec2/actions/run_instances.py
@@ -115,11 +115,11 @@ def run_instances(
         )
 
     # Parse tags
-    # TODO: broken
     tags: dict[str, str] = {}
     for spec in parse_array_objects("TagSpecification", cast(dict, params)):
         for raw_tag in parse_array_objects("Tag", spec):
             tags[raw_tag["Key"]] = raw_tag["Value"]
+    print(f"Creating with tags {tags}")
 
     # Get a private IPv4
     instance_id = uuid.uuid4().hex
@@ -176,7 +176,7 @@ def run_instances(
     return Response(
         RunInstanceResponse(
             request_id=uuid.uuid4().hex,
-            instance_set=RunInstanceInstanceSet(
+            instancesSet=RunInstanceInstanceSet(
                 item=[description],
             ),
         ).to_xml(),
diff --git a/src/openec2/api/create_tags.py b/src/openec2/api/create_tags.py
new file mode 100644
index 0000000..4597325
--- /dev/null
+++ b/src/openec2/api/create_tags.py
@@ -0,0 +1,10 @@
+from pydantic_xml import BaseXmlModel, element
+
+
+class CreateTagsResponse(
+    BaseXmlModel,
+    nsmap={"": ""},
+):
+    requestId: str = element()
+
+    return_: bool = element(tag="return")
diff --git a/src/openec2/api/describe_instance_attribute.py b/src/openec2/api/describe_instance_attribute.py
new file mode 100644
index 0000000..7c4ef40
--- /dev/null
+++ b/src/openec2/api/describe_instance_attribute.py
@@ -0,0 +1,26 @@
+from pydantic_xml import BaseXmlModel, element
+
+
+class InstanceInitiatedShutdownBehaviour(BaseXmlModel):
+    value: str = element()
+
+class DisableApiTermination(BaseXmlModel):
+    value: str = element()
+
+class DisableApiStop(BaseXmlModel):
+    value: str = element()
+
+class DescribeInstanceAttributeResponse(
+    BaseXmlModel,
+    tag="DescribeInstanceAttributeResponse",
+    nsmap={"": "http://ec2.amazonaws.com/doc/2016-11-15/"},
+):
+    requestId: str = element()
+
+    instanceId: str = element()
+
+    instanceInitiatedShutdownBehaviour: InstanceInitiatedShutdownBehaviour | None = element(defaut=None)
+
+    disableApiTermination: DisableApiTermination | None = element(default=None)
+
+    disableApiStop: DisableApiStop | None = element(default=None)
diff --git a/src/openec2/api/describe_instance_types.py b/src/openec2/api/describe_instance_types.py
new file mode 100644
index 0000000..d4f5508
--- /dev/null
+++ b/src/openec2/api/describe_instance_types.py
@@ -0,0 +1,18 @@
+from pydantic_xml import BaseXmlModel, element, wrapped
+
+
+class InstanceTypeInfo(BaseXmlModel, tag="item"):
+    instanceType: str = element()
+
+class DescribeInstanceTypesResponse(
+    BaseXmlModel,
+    nsmap={"": "http://ec2.amazonaws.com/doc/2016-11-15/"},
+):
+    requestId: str = element()
+
+    instanceTypeSet: list[InstanceTypeInfo] = wrapped(
+        "instanceTypeSet",
+        element(tag="item"),
+    )
+
+    nextToken: str | None = element()
diff --git a/src/openec2/api/describe_instances.py b/src/openec2/api/describe_instances.py
index 3633664..e259a5e 100644
--- a/src/openec2/api/describe_instances.py
+++ b/src/openec2/api/describe_instances.py
@@ -1,4 +1,4 @@
-from pydantic_xml import BaseXmlModel, element
+from pydantic_xml import BaseXmlModel, wrapped, element
 import libvirt
 
 from openec2.db.instance import Instance
@@ -21,7 +21,7 @@ class InstanceDescription(
     instance_id: str = element(tag="instanceId")
     image_id: str = element(tag="imageId")
     instance_state: InstanceState = element(tag="instanceState")
-    tag_set: InstanceTagSet = element(tag="tagSet")
+    tagSet: list[InstanceTag] = wrapped("tagSet", element(tag="item"))
 
 
 class ReservationSetInstancesSet(BaseXmlModel):
@@ -64,13 +64,11 @@ def describe_instance(
         instance_id=instance.id,
         image_id=instance.imageId,
         instance_state=describe_instance_state(domain),
-        tag_set=InstanceTagSet(
-            item=[
-                InstanceTag(
-                    key=key,
-                    value=value,
-                )
-                for key, value in instance.tags.items()
-            ],
-        ),
+        tagSet=[
+            InstanceTag(
+                key=key,
+                value=value,
+            )
+            for key, value in instance.tags.items()
+        ],
     )
diff --git a/src/openec2/api/describe_tags.py b/src/openec2/api/describe_tags.py
new file mode 100644
index 0000000..4d02a96
--- /dev/null
+++ b/src/openec2/api/describe_tags.py
@@ -0,0 +1,22 @@
+from pydantic_xml import BaseXmlModel, wrapped, element
+
+
+class TagDescription(BaseXmlModel):
+    key: str | None = element(default=None)
+
+    resourceId: str | None = element(default=None)
+
+    resourceType: str | None = element(default=None)
+
+    value: str | None = element(default=None)
+
+
+class DescribeTagsResponse(
+    BaseXmlModel,
+    nsmap={"": "http://ec2.amazonaws.com/doc/2016-11-15/"}
+):
+    requestId: str = element()
+
+    nextToken: str | None = element()
+
+    tagSet: list[TagDescription] = wrapped("tagSet", element(tag="item"))
diff --git a/src/openec2/api/get_caller_identity.py b/src/openec2/api/get_caller_identity.py
new file mode 100644
index 0000000..ea92364
--- /dev/null
+++ b/src/openec2/api/get_caller_identity.py
@@ -0,0 +1,18 @@
+from pydantic_xml import BaseXmlModel, element
+
+
+class GetCallerIdentityResult(BaseXmlModel):
+    arn: str = element(tag="Arn")
+    user_id: str = element(tag="UserId")
+    account: str = element(tag="Account")
+
+class ResponseMetadata(BaseXmlModel):
+   request_id: str = element(tag="RequestId")
+
+class GetCallerIdentityResponse(
+    BaseXmlModel,
+    nsmap={"": "https://sts.amazonaws.com/doc/2011-06-15/"}
+):
+    result: GetCallerIdentityResult = element(tag="GetCallerIdentityResult")
+
+    metadata: ResponseMetadata = element()
diff --git a/src/openec2/api/run_instances.py b/src/openec2/api/run_instances.py
index 5e37066..97ae48f 100644
--- a/src/openec2/api/run_instances.py
+++ b/src/openec2/api/run_instances.py
@@ -10,4 +10,4 @@ class RunInstanceInstanceSet(BaseXmlModel):
 class RunInstanceResponse(BaseXmlModel):
     request_id: str = element(tag="requestId")
 
-    instance_set: RunInstanceInstanceSet = element(tag="instanceSet")
+    instancesSet: RunInstanceInstanceSet = element(tag="instancesSet")
diff --git a/src/openec2/config.py b/src/openec2/config.py
index 0557413..092ff85 100644
--- a/src/openec2/config.py
+++ b/src/openec2/config.py
@@ -59,7 +59,7 @@ def _get_config() -> _OpenEC2Config:
         insecure=False,
         database=_OpenEC2DatabaseConfig(
             url="sqlite:////home/alexander/openec2/db2.sqlite3",
-            debug=True,
+            debug=False,
         ),
     )
 
diff --git a/src/openec2/db/vpc.py b/src/openec2/db/vpc.py
index 478f60b..b913e90 100644
--- a/src/openec2/db/vpc.py
+++ b/src/openec2/db/vpc.py
@@ -1,12 +1,12 @@
-from sqlmodel import SQLModel, Field, PrimaryKeyConstraint
+from sqlmodel import SQLModel, Field
 
 
 class VPC(SQLModel, table=True):
     # ID of the VPC
     id: str = Field(default=None, primary_key=True)
 
-    # Subnet mask
-    subnet: str
-
     # Base IPv4
-    ipv4_base: str
+    cidr: str
+
+    # Owning user
+    owner_id: int = Field(foreign_key="user.id")
diff --git a/src/openec2/main.py b/src/openec2/main.py
index 6838532..0af39a2 100644
--- a/src/openec2/main.py
+++ b/src/openec2/main.py
@@ -23,6 +23,12 @@ from openec2.actions.attach_volume import attach_volume
 from openec2.actions.describe_volumes import describe_volumes
 from openec2.actions.detach_volume import detach_volume
 from openec2.db.instance import Instance
+from openec2.actions.get_caller_identity import get_caller_identity
+from openec2.actions.describe_instance_types import describe_instance_types
+from openec2.actions.describe_tags import describe_tags
+from openec2.actions.create_tags import create_tags
+from openec2.actions.describe_instance_attribute import describe_instance_attribute
+
 
 app = FastAPI()
 
@@ -43,6 +49,7 @@ def healthz():
 def get_action(
     request: Request, config: OpenEC2Config, db: DatabaseDep, user: AWSSignature
 ):
+    print("GET Action")
     return run_action(
         request,
         config,
@@ -56,9 +63,13 @@ def get_action(
 async def post_action(
     request: Request, config: OpenEC2Config, db: DatabaseDep, user: AWSSignature
 ):
+    print("POST Action")
+
+    body = (await request.body()).decode()
+    print(f"--> {body}")
     query_params = {
         key: value[0]
-        for key, value in parse_qs((await request.body()).decode()).items()
+        for key, value in parse_qs(body).items()
     }
     return run_action(
         request,
@@ -76,9 +87,8 @@ def run_action(
     query_params: dict[str, str],
     user: User,
 ):
-    print(query_params)
     action = query_params["Action"]
-    return {
+    action_function = {
         "ImportImage": import_image,
         "DescribeImages": describe_images,
         "RunInstances": run_instances,
@@ -91,7 +101,21 @@ def run_action(
         "AttachVolume": attach_volume,
         "DescribeVolumes": describe_volumes,
         "DetachVolume": detach_volume,
-    }[action](query_params, config, db, user)
+        "GetCallerIdentity": get_caller_identity,
+        "DescribeInstanceTypes": describe_instance_types,
+        "DescribeTags": describe_tags,
+        "CreateTags": create_tags,
+        "DescribeInstanceAttribute": describe_instance_attribute,
+    }.get(action)
+    if action_function is None:
+        print(f"Unknown action: '{action}'")
+        raise HTTPException(
+            status_code=404,
+            detail="Unknown action",
+        )
+
+    return action_function(query_params, config, db, user)
+
 
 
 @app.get("/private/cloudinit/{instance_id}/{entry}")
diff --git a/src/openec2/security/aws.py b/src/openec2/security/aws.py
index 25128a7..034b50f 100644
--- a/src/openec2/security/aws.py
+++ b/src/openec2/security/aws.py
@@ -2,7 +2,7 @@ from typing import Annotated, cast
 from dataclasses import dataclass
 import datetime
 from hashlib import sha256
-from urllib.parse import quote, parse_qs
+from urllib.parse import parse_qs
 
 from sqlmodel import select
 from fastapi import Request, HTTPException, Depends
@@ -37,13 +37,20 @@ class AWSRequest:
     # The payload, if we used a POST/PUT
     payload: str | None
 
+    # List of headers that were signed
+    signed_headers: list[str]
+
+    def include_in_canonical_string(self, name: str) -> bool:
+        return name.lower() in self.signed_headers
+
+    # TODO: Probably vulnerable against a replay because we never get the current date ourselves
     def sign(
         self, secret_access_key: str, region: str, product: str, credential_scope: str
     ) -> str:
         dt = datetime.datetime.fromisoformat(self.headers["X-Amz-Date"])
 
         canonical_header_string_keys = sorted(
-            [name for name in self.headers.keys() if include_in_canonical_string(name)]
+            [name for name in self.headers.keys() if self.include_in_canonical_string(name)]
         )
         canonical_header_string = (
             "\n".join(
@@ -67,8 +74,6 @@ class AWSRequest:
                 hashed_payload,
             ]
         )
-        print("Canonical request")
-        print(canonical_request)
 
         hashed_canonical_request = sha256(canonical_request.encode()).hexdigest()
         date = dt.strftime("%Y%m%d")
@@ -81,9 +86,6 @@ class AWSRequest:
             ]
         )
 
-        print("String to sign")
-        print(string_to_sign)
-
         date_key = _hmac_sha256(f"AWS4{secret_access_key}".encode(), date.encode())
         date_region_key = _hmac_sha256(date_key, region.encode())
         date_region_service_key = _hmac_sha256(date_region_key, product.encode())
@@ -99,10 +101,7 @@ class AWSAuthentication:
 
     x_amz_signature: str
 
-
-def include_in_canonical_string(name: str) -> bool:
-    lower = name.lower()
-    return lower in ("host", "content-type") or lower.startswith("x-amz")
+    signed_headers: str
 
 
 def get_authentication_info(request: Request) -> AWSAuthentication:
@@ -117,12 +116,14 @@ def get_authentication_info(request: Request) -> AWSAuthentication:
             x_amz_algorithm=algorithm,
             x_amz_credential=auth["Credential"],
             x_amz_signature=auth["Signature"],
+            signed_headers=auth["SignedHeaders"],
         )
 
     return AWSAuthentication(
         "",
         "",
         "",
+        "",
     )
 
 
@@ -142,7 +143,7 @@ async def check_request_signature(request: Request, db: DatabaseDep):
 
     if auth_info.x_amz_algorithm != "AWS4-HMAC-SHA256":
         raise HTTPException(
-            status_code=400,
+            status_code=403,
             detail=f"Invalid signature algorithm: {auth_info.x_amz_algorithm}",
         )
 
@@ -154,6 +155,16 @@ async def check_request_signature(request: Request, db: DatabaseDep):
     if user is None:
         raise HTTPException(status_code=403)
 
+    # Validate the signed headers
+    signed_headers = auth_info.signed_headers.split(";")
+    if any(header not in signed_headers for header in [
+        "host",
+        "content-type",
+    ]):
+        print("Validation of signed headers failed!")
+        raise HTTPException(status_code=403)
+
+    print(auth_info.x_amz_credential)
     x_amz_signature = auth_info.x_amz_signature
     signature = AWSRequest(
         url=request.url,
@@ -161,6 +172,7 @@ async def check_request_signature(request: Request, db: DatabaseDep):
         params=query_params,
         headers=request.headers,
         payload=body,
+        signed_headers=signed_headers,
     ).sign(
         user.secret_access_key,
         region,
@@ -168,9 +180,11 @@ async def check_request_signature(request: Request, db: DatabaseDep):
         "/".join([date, region, service, key]),
     )
 
-    print(x_amz_signature, signature)
     if x_amz_signature != signature:
-        raise HTTPException(status_code=401)
+        print("Signature mismatch!")
+        print(f"Expected: {signature}")
+        print(f"Got:      {x_amz_signature}")
+        raise HTTPException(status_code=403)
 
     return user
 
diff --git a/src/openec2/utils/array.py b/src/openec2/utils/array.py
index 60ab58a..cab6a6a 100644
--- a/src/openec2/utils/array.py
+++ b/src/openec2/utils/array.py
@@ -1,3 +1,6 @@
+from typing import Callable
+
+
 def parse_array_objects(prefix: str, params: dict) -> list[dict[str, str]]:
     items: dict[str, dict[str, str]] = {}
     for key, value in params.items():
@@ -25,3 +28,10 @@ def parse_array_plain(prefix: str, params: dict[str, str]) -> list[str]:
 
     indices = sorted(list(items.keys()))
     return [items[key] for key in indices]
+
+
+def find[T](l: list[T], pred: Callable[[T], bool]) -> T | None:
+    for item in l:
+        if pred(item):
+            return item
+    return None