diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 1719ab8c..a990ad5b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -58,6 +58,9 @@ jobs:
     name: Build ${{ matrix.package }} (${{ matrix.build.target }})
     permissions:
       contents: read
+      # Required by actions/attest for keyless Sigstore signing.
+      id-token: write
+      attestations: write
     needs: [parse-tag]
     runs-on: ${{ matrix.build.os }}
     strategy:
@@ -93,13 +96,63 @@ jobs:
       - name: Configure git auth
         run: git config --global url."https://x-access-token:${{ secrets.GH_PAT }}@github.com/".insteadOf "https://github.com/"
       - name: Build release binary
-        run: cargo build --release --target ${{ matrix.build.target }} -p ${{ env.PACKAGE }}
+        run: cargo build --locked --release --target ${{ matrix.build.target }} -p ${{ env.PACKAGE }}
       - run: strip target/${{ matrix.build.target }}/release/${{ env.PACKAGE }}
       - run: mv target/${{ matrix.build.target }}/release/${{ env.PACKAGE }} ${{ env.PACKAGE }}-${{ matrix.build.suffix }}
+
+      - name: Generate sha256
+        shell: bash
+        run: |
+          set -euo pipefail
+          BIN="${PACKAGE}-${{ matrix.build.suffix }}"
+          if command -v sha256sum >/dev/null 2>&1; then
+            sha256sum "$BIN" > "$BIN.sha256"
+          else
+            shasum -a 256 "$BIN" > "$BIN.sha256"
+          fi
+          cat "$BIN.sha256"
+
+      - name: Generate SBOM (SPDX-JSON)
+        uses: anchore/sbom-action@e22c389904149dbc22b58101806040fa8d37a610 # v0.24.0
+        with:
+          file: ${{ env.PACKAGE }}-${{ matrix.build.suffix }}
+          format: spdx-json
+          output-file: ${{ env.PACKAGE }}-${{ matrix.build.suffix }}.spdx.json
+          upload-artifact: false
+          upload-release-assets: false
+
+      - name: Attest SBOM
+        uses: actions/attest@59d89421af93a897026c735860bf21b6eb4f7b26 # v4.1.0
+        with:
+          subject-path: ${{ env.PACKAGE }}-${{ matrix.build.suffix }}
+          sbom-path: ${{ env.PACKAGE }}-${{ matrix.build.suffix }}.spdx.json
+
+      - name: Attest build provenance (SLSA v1)
+        uses: actions/attest@59d89421af93a897026c735860bf21b6eb4f7b26 # v4.1.0
+        with:
+          subject-path: ${{ env.PACKAGE }}-${{ matrix.build.suffix }}
+
+      - name: Install cosign
+        uses: sigstore/cosign-installer@cad07c2e89fa2edd6e2d7bab4c1aa38e53f76003 # v4.1.1
+
+      - name: Sign binary with cosign (keyless)
+        shell: bash
+        run: |
+          set -euo pipefail
+          BIN="${PACKAGE}-${{ matrix.build.suffix }}"
+          cosign sign-blob --yes \
+            --bundle "${BIN}.sigstore.json" \
+            "$BIN"
+
       - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           name: ${{ env.PACKAGE }}-${{ matrix.build.suffix }}
-          path: ${{ env.PACKAGE }}-${{ matrix.build.suffix }}
+          path: |
+            ${{ env.PACKAGE }}-${{ matrix.build.suffix }}
+            ${{ env.PACKAGE }}-${{ matrix.build.suffix }}.sha256
+            ${{ env.PACKAGE }}-${{ matrix.build.suffix }}.spdx.json
+            ${{ env.PACKAGE }}-${{ matrix.build.suffix }}.sigstore.json
+          if-no-files-found: error
 
   publish:
     name: Publish ${{ matrix.package }}
diff --git a/README.md b/README.md
index a807c67b..40de695b 100644
--- a/README.md
+++ b/README.md
@@ -120,7 +120,7 @@ The Minimum Supported Rust Version (MSRV) is specified in [`Cargo.toml`](Cargo.t
 
 ## Security
 
-See [SECURITY.md](SECURITY.md) for vulnerability reporting.
+See [SECURITY.md](SECURITY.md) for vulnerability reporting and for instructions on [verifying release binaries](SECURITY.md#verifying-releases) (SLSA provenance, SBOM, Sigstore signatures, and SHA-256 checksums).
 
 ## License
 
diff --git a/SECURITY.md b/SECURITY.md
index 08a6f7df..197c20df 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -4,3 +4,52 @@
 
 If you believe you've found a security vulnerability, please do not report it via GitHub issues.
 Instead, email `security@tempo.xyz` and we will acknowledge your report within 5 days and provide a more detailed follow-up within 10 days.
+
+## Verifying Releases
+
+Each binary ships with three sidecars: `.sha256` (checksum), `.sigstore.json`
+(cosign keyless bundle), and `.spdx.json` (SBOM). GitHub also stores SLSA v1
+provenance and SBOM attestations against the binary's digest. Signing identity
+is the OIDC token of [`build.yml`](./.github/workflows/build.yml).
+
+```bash
+TAG=v1.0.0
+PKG=tempo-wallet
+BIN=${PKG}-linux-amd64
+```
+
+### From GitHub Releases
+
+```bash
+gh release download "$TAG" --repo tempoxyz/wallet \
+  -p "$BIN" -p "$BIN.sha256" -p "$BIN.sigstore.json" -p "$BIN.spdx.json"
+
+sha256sum -c "$BIN.sha256"
+
+gh attestation verify "$BIN" --repo tempoxyz/wallet \
+  --signer-workflow tempoxyz/wallet/.github/workflows/build.yml \
+  --source-ref "refs/tags/${TAG}" \
+  --predicate-type https://slsa.dev/provenance/v1
+
+gh attestation verify "$BIN" --repo tempoxyz/wallet \
+  --signer-workflow tempoxyz/wallet/.github/workflows/build.yml \
+  --source-ref "refs/tags/${TAG}" \
+  --predicate-type https://spdx.dev/Document/v2.3
+```
+
+### From cli.tempo.xyz (offline-friendly)
+
+```bash
+BASE=https://cli.tempo.xyz/extensions/${PKG}
+curl -fsSL -O "${BASE}/${BIN}"
+curl -fsSL -O "${BASE}/${BIN}.sha256"
+curl -fsSL -O "${BASE}/${BIN}.sigstore.json"
+
+sha256sum -c "${BIN}.sha256"
+
+cosign verify-blob \
+  --bundle "${BIN}.sigstore.json" \
+  --certificate-identity "https://github.com/tempoxyz/wallet/.github/workflows/build.yml@refs/tags/${TAG}" \
+  --certificate-oidc-issuer 'https://token.actions.githubusercontent.com' \
+  "$BIN"
+```
diff --git a/crates/tempo-sign/src/sign.rs b/crates/tempo-sign/src/sign.rs
index 5122c977..620aafcc 100644
--- a/crates/tempo-sign/src/sign.rs
+++ b/crates/tempo-sign/src/sign.rs
@@ -10,7 +10,7 @@ use sha2::{Digest, Sha256};
 use crate::error::SignError;
 
 /// Skip non-binary artifacts when building a release manifest.
-pub const SKIP_EXTENSIONS: &[&str] = &[".json", ".md", ".sh", ".txt", ".py"];
+pub const SKIP_EXTENSIONS: &[&str] = &[".json", ".md", ".sh", ".txt", ".py", ".sha256"];
 
 /// Compute SHA-256 for a file.
 pub fn sha256_file(path: &Path) -> Result<String, SignError> {