diff --git a/CHANGES.rst b/CHANGES.rst
index 84c598d..913affb 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -4,6 +4,34 @@ Changes
 Unreleased
 ----------
 
+Version 3.1.0
+-------------
+
+Released 2025-07-21
+
+- Add alg validation for fully-specified algs. `#621 <https://github.com/dajiaji/python-cwt/pull/621>`__
+- Update supported algorithms and specs. `#620 <https://github.com/dajiaji/python-cwt/pull/620>`__
+- Fix post_install in readthedocs config. `#616 <https://github.com/dajiaji/python-cwt/pull/616>`__
+- Add fully specified algorithms. `#612 <https://github.com/dajiaji/python-cwt/pull/612>`__
+- Refine pyproject.toml to use poetry groups. `#595 <https://github.com/dajiaji/python-cwt/pull/595>`__
+- Update dependencies.
+    - Bump cryptography to 44.0.3. `#602 <https://github.com/dajiaji/python-cwt/pull/602>`__
+- Update dev dependencies.
+    - Bump certifi to 2025.7.14. `#622 <https://github.com/dajiaji/python-cwt/pull/622>`__
+    - Bump coverage to 7.9.2. `#622 <https://github.com/dajiaji/python-cwt/pull/622>`__
+    - Bump tox to 4.28.0. `#622 <https://github.com/dajiaji/python-cwt/pull/622>`__
+    - Bump urllib3 to 2.5.0. `#611 <https://github.com/dajiaji/python-cwt/pull/611>`__
+    - Bump pytest to 8.4.1. `#610 <https://github.com/dajiaji/python-cwt/pull/610>`__
+    - Bump pytest-cov to 6.2.1. `#608 <https://github.com/dajiaji/python-cwt/pull/608>`__
+    - Bump requests to 2.32.4. `#606 <https://github.com/dajiaji/python-cwt/pull/606>`__
+    - Bump pre-commit/black to 25.1.0. `#599 <https://github.com/dajiaji/python-cwt/pull/599>`__
+    - Bump pre-commit/blacken-docs to 1.19.1. `#599 <https://github.com/dajiaji/python-cwt/pull/599>`__
+    - Bump pre-commit/flake8 to 7.2.0. `#599 <https://github.com/dajiaji/python-cwt/pull/599>`__
+    - Bump pre-commit/isort to 6.0.1. `#599 <https://github.com/dajiaji/python-cwt/pull/599>`__
+    - Bump pre-commit/mirrors-mypy to 1.15.0. `#599 <https://github.com/dajiaji/python-cwt/pull/599>`__
+    - Bump pre-commit to 4.2.0. `#597 <https://github.com/dajiaji/python-cwt/pull/597>`__
+
+
 Version 3.0.0
 -------------
 
diff --git a/SECURITY.md b/SECURITY.md
index 7cfc244..db41463 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -4,8 +4,8 @@
 
 | Version | Supported          |
 | ------- | ------------------ |
-| 3.0.x   | :white_check_mark: |
-| < 3     | :x:                |
+| 3.1.x   | :white_check_mark: |
+| < 3.1   | :x:                |
 
 ## Reporting a Vulnerability
 
diff --git a/cwt/__init__.py b/cwt/__init__.py
index c04dce7..f22fba0 100644
--- a/cwt/__init__.py
+++ b/cwt/__init__.py
@@ -27,7 +27,7 @@
 from .recipient import Recipient
 from .signer import Signer
 
-__version__ = "3.0.0"
+__version__ = "3.1.0"
 __title__ = "cwt"
 __description__ = "A Python implementation of CWT/COSE"
 __url__ = "https://python-cwt.readthedocs.io"
diff --git a/pyproject.toml b/pyproject.toml
index 792c413..14b3ef4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "poetry.core.masonry.api"
 
 [tool.poetry]
 name = "cwt"
-version = "3.0.0"
+version = "3.1.0"
 description = "A Python implementation of CWT/COSE."
 authors = ["Ajitomi Daisuke <dajiaji@gmail.com>"]
 license = "MIT"