diff --git a/.github/workflows/security.yml b/.github/workflows/security.yml
index e6d1b83..026b5b1 100644
--- a/.github/workflows/security.yml
+++ b/.github/workflows/security.yml
@@ -62,3 +62,12 @@ jobs:
     steps:
       - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
       - uses: actions/dependency-review-action@72eb423297a7cc29376c3e0026574f1a203f9052 # v4.5.0
+
+  cargo-deny:
+    name: Cargo Deny (Licenses & Bans)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
+      - uses: EmbarkStudios/cargo-deny-action@v2
+        with:
+          command: check licenses bans sources
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 468efa5..7053e87 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- `ci`: Add `deny.toml` and `cargo-deny` check in `.github/workflows/security.yml` to enforce license compliance (Apache-2.0, MIT, BSD) and deny unknown registries (#91).
 - Stage 1 developer-experience tooling:
   - `.gitattributes` normalizing all tracked text to LF (`*.sh`, `*.rs`, `*.ts`, `*.md`, and the other text formats in the tree) and marking `Cargo.lock` and `package-lock.json` as generated. The tree was re-normalized once, and a new **Line Endings** workflow fails any pull request that reintroduces CRLF into the index (#85).
   - A **Commitlint** workflow and `commitlint.config.cjs` enforcing the Conventional Commits style documented in `CONTRIBUTING.md`; a pull request with a non-conforming commit now fails the check. Allowed scopes are documented and now include the `vault` and `common` crates (#90).
diff --git a/deny.toml b/deny.toml
new file mode 100644
index 0000000..0bafb02
--- /dev/null
+++ b/deny.toml
@@ -0,0 +1,32 @@
+# Configuration for cargo-deny (Issue #91)
+
+[graph]
+targets = []
+all-features = false
+no-default-features = false
+
+[licenses]
+unlicensed = "deny"
+allow = [
+    "Apache-2.0",
+    "MIT",
+    "BSD-2-Clause",
+    "BSD-3-Clause",
+    "ISC",
+    "Unicode-DFS-2016",
+    "CC0-1.0",
+]
+confidence-threshold = 0.8
+
+[licenses.private]
+ignore = true
+
+[bans]
+multiple-versions = "warn"
+wildcards = "deny"
+highlight = "all"
+
+[sources]
+unknown-registries = "deny"
+unknown-git = "deny"
+allow-registry = ["https://github.com/rust-lang/crates.io-index"]