diff --git a/.github/workflows/post-release-audit.yml b/.github/workflows/post-release-audit.yml
index 7adc507..8306a82 100644
--- a/.github/workflows/post-release-audit.yml
+++ b/.github/workflows/post-release-audit.yml
@@ -17,7 +17,8 @@ permissions:
   id-token: write
 
 env:
-  IMAGE_NAME: ghcr.io/ploos-as/soju
+  GHCR_IMAGE: ghcr.io/ploos-as/soju
+  DOCKERHUB_IMAGE: ${{ secrets.DOCKERHUB_USERNAME }}/soju
 
 jobs:
   audit:
@@ -45,27 +46,27 @@ jobs:
             while IFS= read -r candidate; do
               [[ -n "$candidate" ]] || continue
               commit="$(git rev-list -n 1 "$candidate" 2>/dev/null || true)"
-              if [[ "$commit" == "$PRODUCER_SHA" ]]; then
-                tag="$candidate"
-                break
-              fi
+              if [[ "$commit" == "$PRODUCER_SHA" ]]; then tag="$candidate"; break; fi
             done < <(gh release list --repo "$GITHUB_REPOSITORY" --limit 100 --json tagName,isDraft --jq '.[] | select(.isDraft == false) | .tagName')
           fi
           [[ -n "$tag" ]]
           tag_commit="$(git rev-list -n 1 "$tag")"
-          if [[ -n "$INPUT_TAG" ]]; then
-            sh scripts/verify-release-ref.sh "$tag" "$tag_commit" --allow-head-mismatch-for-audit
-          else
-            sh scripts/verify-release-ref.sh "$tag" "$tag_commit"
-          fi
+          if [[ -n "$INPUT_TAG" ]]; then sh scripts/verify-release-ref.sh "$tag" "$tag_commit" --allow-head-mismatch-for-audit; else sh scripts/verify-release-ref.sh "$tag" "$tag_commit"; fi
           release_json="$(gh release view "$tag" --repo "$GITHUB_REPOSITORY" --json tagName,isDraft,isPrerelease)"
           jq -e --arg tag "$tag" '.tagName == $tag and .isDraft == false' <<<"$release_json" >/dev/null
-          if [[ -n "$PRODUCER_SHA" ]]; then
-            test "$tag_commit" = "$PRODUCER_SHA"
-          fi
+          if [[ -n "$PRODUCER_SHA" ]]; then test "$tag_commit" = "$PRODUCER_SHA"; fi
           echo "tag=$tag" >> "$GITHUB_OUTPUT"
           echo "commit=$tag_commit" >> "$GITHUB_OUTPUT"
 
+      - name: Validate Docker Hub audit configuration
+        env:
+          DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
+          DOCKERHUB_TOKEN: ${{ secrets.DOCKERHUB_TOKEN }}
+        run: |
+          set -eu
+          test -n "$DOCKERHUB_USERNAME"
+          test -n "$DOCKERHUB_TOKEN"
+
       - name: Set up QEMU
         uses: docker/setup-qemu-action@c7c53464625b32c7a7e944ae62b3e17d2b600130
 
@@ -79,37 +80,48 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
-      - name: Resolve immutable release digest and verify platforms
+      - name: Log in to Docker Hub
+        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Resolve immutable release digest and verify registry parity
         id: image
         env:
           TAG: ${{ steps.release.outputs.tag }}
         shell: bash
         run: |
           set -euo pipefail
-          image_tag="${IMAGE_NAME}:${TAG#v}"
-          docker manifest inspect "$image_tag" > /tmp/manifest.json
-          jq -e 'any(.manifests[]; .platform.os == "linux" and .platform.architecture == "amd64")' /tmp/manifest.json >/dev/null
-          jq -e 'any(.manifests[]; .platform.os == "linux" and .platform.architecture == "arm64")' /tmp/manifest.json >/dev/null
-          docker pull --platform linux/amd64 "$image_tag" >/dev/null
-          repo_digest="$(docker image inspect "$image_tag" --format '{{index .RepoDigests 0}}')"
-          digest="${repo_digest##*@}"
-          sh scripts/verify-exact-digest-runtime.sh "$IMAGE_NAME" "$digest" >/dev/null
-          echo "digest=$digest" >> "$GITHUB_OUTPUT"
+          ghcr_tag="${GHCR_IMAGE}:${TAG#v}"
+          dockerhub_tag="${DOCKERHUB_IMAGE}:${TAG#v}"
+          docker manifest inspect "$ghcr_tag" > /tmp/ghcr-manifest.json
+          jq -e 'any(.manifests[]; .platform.os == "linux" and .platform.architecture == "amd64")' /tmp/ghcr-manifest.json >/dev/null
+          jq -e 'any(.manifests[]; .platform.os == "linux" and .platform.architecture == "arm64")' /tmp/ghcr-manifest.json >/dev/null
+          docker manifest inspect "$dockerhub_tag" > /tmp/dockerhub-manifest.json
+          jq -e 'any(.manifests[]; .platform.os == "linux" and .platform.architecture == "amd64")' /tmp/dockerhub-manifest.json >/dev/null
+          jq -e 'any(.manifests[]; .platform.os == "linux" and .platform.architecture == "arm64")' /tmp/dockerhub-manifest.json >/dev/null
+          ghcr_digest="$(docker buildx imagetools inspect "$ghcr_tag" | awk '/^Digest:/ {print $2; exit}')"
+          dockerhub_digest="$(docker buildx imagetools inspect "$dockerhub_tag" | awk '/^Digest:/ {print $2; exit}')"
+          test -n "$ghcr_digest"
+          test "$dockerhub_digest" = "$ghcr_digest"
+          sh scripts/verify-exact-digest-runtime.sh "$GHCR_IMAGE" "$ghcr_digest" >/dev/null
+          sh scripts/verify-exact-digest-runtime.sh "$DOCKERHUB_IMAGE" "$dockerhub_digest" >/dev/null
+          echo "digest=$ghcr_digest" >> "$GITHUB_OUTPUT"
 
       - name: Install Cosign
         uses: sigstore/cosign-installer@d7543c93d881b35a8faa02e8e3605f69b7a1ce62
 
-      - name: Verify exact-digest signature
+      - name: Verify exact-digest signatures
         env:
           IMAGE_DIGEST: ${{ steps.image.outputs.digest }}
         shell: bash
         run: |
           set -euo pipefail
-          cosign verify \
-            --certificate-oidc-issuer https://token.actions.githubusercontent.com \
-            --certificate-identity-regexp '^https://github.com/Ploos-AS/soju/.github/workflows/release.yml@refs/tags/v.*$' \
-            "${IMAGE_NAME}@${IMAGE_DIGEST}" > /tmp/cosign-verification.json
-          jq -e 'length > 0' /tmp/cosign-verification.json >/dev/null
+          for image in "$GHCR_IMAGE" "$DOCKERHUB_IMAGE"; do
+            cosign verify --certificate-oidc-issuer https://token.actions.githubusercontent.com --certificate-identity-regexp '^https://github.com/Ploos-AS/soju/.github/workflows/release.yml@refs/tags/v.*$' "${image}@${IMAGE_DIGEST}" > /tmp/cosign-verification.json
+            jq -e 'length > 0' /tmp/cosign-verification.json >/dev/null
+          done
 
       - name: Verify immutable labels and runtime after release
         env:
@@ -119,7 +131,7 @@ jobs:
         shell: bash
         run: |
           set -euo pipefail
-          image_ref="${IMAGE_NAME}@${IMAGE_DIGEST}"
+          image_ref="${GHCR_IMAGE}@${IMAGE_DIGEST}"
           docker pull --platform linux/amd64 "$image_ref" >/dev/null
           revision="$(docker image inspect "$image_ref" --format '{{index .Config.Labels "org.opencontainers.image.revision"}}')"
           version="$(docker image inspect "$image_ref" --format '{{index .Config.Labels "org.opencontainers.image.version"}}')"
@@ -129,18 +141,10 @@ jobs:
           test "$(docker run --rm --platform linux/amd64 --entrypoint id "$image_ref" -g)" = "1000"
           mkdir -p data-audit run-audit
           sudo chown 1000:1000 data-audit run-audit
-          cid=$(docker run -d --rm --platform linux/amd64 \
-            -v "$PWD/data-audit:/var/lib/soju" \
-            -v "$PWD/run-audit:/run/soju" \
-            "$image_ref")
+          cid=$(docker run -d --rm --platform linux/amd64 -v "$PWD/data-audit:/var/lib/soju" -v "$PWD/run-audit:/run/soju" "$image_ref")
           trap 'docker logs "$cid" 2>&1 || true; docker rm -f "$cid" >/dev/null 2>&1 || true' EXIT
           for i in $(seq 1 30); do
-            if docker ps --filter "id=$cid" --format '{{.ID}}' | grep -q . \
-              && test -f data-audit/main.db \
-              && test -S run-audit/admin; then
-              healthy=true
-              break
-            fi
+            if docker ps --filter "id=$cid" --format '{{.ID}}' | grep -q . && test -f data-audit/main.db && test -S run-audit/admin; then healthy=true; break; fi
             sleep 1
           done
           test "${healthy:-false}" = true
@@ -153,13 +157,14 @@ jobs:
           IMAGE_DIGEST: ${{ steps.image.outputs.digest }}
         run: |
           {
-            echo '### M11.5 post-release audit'
+            echo '### M12.1 dual-registry post-release audit'
             echo
             echo "- release: $TAG"
             echo "- immutable digest: $IMAGE_DIGEST"
             echo '- GitHub Release/tag/commit binding: verified'
-            echo '- linux/amd64 + linux/arm64 manifest coverage: verified'
-            echo '- Cosign keyless signature and release workflow OIDC identity: verified'
+            echo '- GHCR + Docker Hub digest parity: verified'
+            echo '- linux/amd64 + linux/arm64 manifest coverage in both registries: verified'
+            echo '- Cosign keyless signatures in both registries: verified'
             echo '- OCI revision/version labels: verified'
             echo '- non-root UID/GID 1000: verified'
             echo '- exact-digest post-publication SQLite + admin-socket runtime: verified'
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index a750503..db47617 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -12,7 +12,8 @@ permissions:
   attestations: write
 
 env:
-  IMAGE_NAME: ghcr.io/ploos-as/soju
+  GHCR_IMAGE: ghcr.io/ploos-as/soju
+  DOCKERHUB_IMAGE: ${{ secrets.DOCKERHUB_USERNAME }}/soju
 
 jobs:
   publish:
@@ -25,6 +26,15 @@ jobs:
       - name: Verify release tag and commit binding
         run: sh scripts/verify-release-ref.sh "$GITHUB_REF_NAME" "$GITHUB_SHA"
 
+      - name: Validate Docker Hub publication configuration
+        env:
+          DOCKERHUB_USERNAME: ${{ secrets.DOCKERHUB_USERNAME }}
+          DOCKERHUB_TOKEN: ${{ secrets.DOCKERHUB_TOKEN }}
+        run: |
+          set -eu
+          test -n "$DOCKERHUB_USERNAME"
+          test -n "$DOCKERHUB_TOKEN"
+
       - name: Set up QEMU
         uses: docker/setup-qemu-action@c7c53464625b32c7a7e944ae62b3e17d2b600130
 
@@ -38,11 +48,19 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Log in to Docker Hub
+        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
       - name: Docker metadata
         id: meta
         uses: docker/metadata-action@c299e40c65443455700f0fdfc63efafe5b349051
         with:
-          images: ${{ env.IMAGE_NAME }}
+          images: |
+            ${{ env.GHCR_IMAGE }}
+            ${{ env.DOCKERHUB_IMAGE }}
           flavor: |
             latest=auto
           tags: |
@@ -74,65 +92,61 @@ jobs:
           IMAGE_DIGEST: ${{ steps.push.outputs.digest }}
         run: |
           set -eu
-          image_ref="$(sh scripts/verify-exact-digest-runtime.sh "$IMAGE_NAME" "$IMAGE_DIGEST")"
-          docker pull "$image_ref"
-          resolved="$(docker image inspect "$image_ref" --format '{{index .RepoDigests 0}}')"
-          test "$resolved" = "$image_ref"
-          revision="$(docker image inspect "$image_ref" --format '{{index .Config.Labels "org.opencontainers.image.revision"}}')"
-          version="$(docker image inspect "$image_ref" --format '{{index .Config.Labels "org.opencontainers.image.version"}}')"
+          ghcr_ref="$(sh scripts/verify-exact-digest-runtime.sh "$GHCR_IMAGE" "$IMAGE_DIGEST")"
+          dockerhub_ref="$(sh scripts/verify-exact-digest-runtime.sh "$DOCKERHUB_IMAGE" "$IMAGE_DIGEST")"
+          docker pull "$ghcr_ref"
+          ghcr_resolved="$(docker image inspect "$ghcr_ref" --format '{{index .RepoDigests 0}}')"
+          test "$ghcr_resolved" = "$ghcr_ref"
+          docker pull "$dockerhub_ref"
+          dockerhub_resolved="$(docker image inspect "$dockerhub_ref" --format '{{range .RepoDigests}}{{println .}}{{end}}' | grep -F "${DOCKERHUB_IMAGE}@${IMAGE_DIGEST}" | head -n 1)"
+          test "$dockerhub_resolved" = "$dockerhub_ref"
+          revision="$(docker image inspect "$ghcr_ref" --format '{{index .Config.Labels "org.opencontainers.image.revision"}}')"
+          version="$(docker image inspect "$ghcr_ref" --format '{{index .Config.Labels "org.opencontainers.image.version"}}')"
           test "$revision" = "$GITHUB_SHA"
           test "$version" = "$GITHUB_REF_NAME"
-          test "$(docker run --rm --entrypoint id "$image_ref" -u)" = "1000"
-          test "$(docker run --rm --entrypoint id "$image_ref" -g)" = "1000"
+          test "$(docker run --rm --entrypoint id "$ghcr_ref" -u)" = "1000"
+          test "$(docker run --rm --entrypoint id "$ghcr_ref" -g)" = "1000"
           mkdir -p data-release run-release
           sudo chown 1000:1000 data-release run-release
-          cid=$(docker run -d --rm \
-            -v "$PWD/data-release:/var/lib/soju" \
-            -v "$PWD/run-release:/run/soju" \
-            "$image_ref")
+          cid=$(docker run -d --rm -v "$PWD/data-release:/var/lib/soju" -v "$PWD/run-release:/run/soju" "$ghcr_ref")
           trap 'docker logs "$cid" 2>&1 || true; docker rm -f "$cid" >/dev/null 2>&1 || true' EXIT
           for i in $(seq 1 30); do
-            if docker ps --filter "id=$cid" --format '{{.ID}}' | grep -q . \
-              && test -f data-release/main.db \
-              && test -S run-release/admin; then
-              qualified=true
-              break
-            fi
+            if docker ps --filter "id=$cid" --format '{{.ID}}' | grep -q . && test -f data-release/main.db && test -S run-release/admin; then qualified=true; break; fi
             sleep 1
           done
           test "${qualified:-false}" = true
           docker rm -f "$cid"
           trap - EXIT
 
-      - name: Attest image
+      - name: Attest GHCR image
         uses: actions/attest-build-provenance@977bb373ede98d70efdf65b84cb5f73e068dcc2a
         with:
-          subject-name: ${{ env.IMAGE_NAME }}
+          subject-name: ${{ env.GHCR_IMAGE }}
           subject-digest: ${{ steps.push.outputs.digest }}
           push-to-registry: true
 
       - name: Install Cosign
         uses: sigstore/cosign-installer@d7543c93d881b35a8faa02e8e3605f69b7a1ce62
 
-      - name: Sign exact release digest with GitHub OIDC
+      - name: Sign exact release digests with GitHub OIDC
         env:
           IMAGE_DIGEST: ${{ steps.push.outputs.digest }}
         run: |
           set -eu
           test -n "$IMAGE_DIGEST"
-          cosign sign --yes "${IMAGE_NAME}@${IMAGE_DIGEST}"
+          cosign sign --yes "${GHCR_IMAGE}@${IMAGE_DIGEST}"
+          cosign sign --yes "${DOCKERHUB_IMAGE}@${IMAGE_DIGEST}"
 
-      - name: Verify keyless release signature
+      - name: Verify keyless release signatures
         env:
           IMAGE_DIGEST: ${{ steps.push.outputs.digest }}
         run: |
           set -eu
           test -n "$IMAGE_DIGEST"
-          cosign verify \
-            --certificate-oidc-issuer https://token.actions.githubusercontent.com \
-            --certificate-identity-regexp '^https://github.com/Ploos-AS/soju/.github/workflows/release.yml@refs/tags/v.*$' \
-            "${IMAGE_NAME}@${IMAGE_DIGEST}" > /tmp/cosign-verification.json
-          test -s /tmp/cosign-verification.json
+          for image in "$GHCR_IMAGE" "$DOCKERHUB_IMAGE"; do
+            cosign verify --certificate-oidc-issuer https://token.actions.githubusercontent.com --certificate-identity-regexp '^https://github.com/Ploos-AS/soju/.github/workflows/release.yml@refs/tags/v.*$' "${image}@${IMAGE_DIGEST}" > /tmp/cosign-verification.json
+            test -s /tmp/cosign-verification.json
+          done
 
       - name: Create GitHub Release
         env:
@@ -142,9 +156,5 @@ jobs:
           if gh release view "$GITHUB_REF_NAME" --repo "$GITHUB_REPOSITORY" >/dev/null 2>&1; then
             echo "GitHub Release already exists for $GITHUB_REF_NAME"
           else
-            gh release create "$GITHUB_REF_NAME" \
-              --repo "$GITHUB_REPOSITORY" \
-              --title "soju $GITHUB_REF_NAME" \
-              --generate-notes \
-              --verify-tag
+            gh release create "$GITHUB_REF_NAME" --repo "$GITHUB_REPOSITORY" --title "soju $GITHUB_REF_NAME" --generate-notes --verify-tag
           fi
diff --git a/README.md b/README.md
index 90abfa7..557d0ff 100644
--- a/README.md
+++ b/README.md
@@ -2,14 +2,24 @@
 
 Production-oriented OCI packaging for [soju](https://soju.im/), the IRC bouncer maintained at Codeberg.
 
-> Upstream already publishes a container image. This repository is an independent Ploos-AS packaging project focused on reproducible source builds, explicit upstream pinning, non-root operation, multi-architecture GHCR releases, and supply-chain attestations. It is not a fork of soju.
+> Upstream already publishes a container image. This repository is an independent Ploos-AS packaging project focused on reproducible source builds, explicit upstream pinning, non-root operation, multi-architecture OCI releases, and supply-chain attestations. It is not a fork of soju.
 
-## Image
+## Images
+
+Primary registry:
 
 ```text
 ghcr.io/ploos-as/soju
 ```
 
+Secondary registry:
+
+```text
+<dockerhub-namespace>/soju
+```
+
+Release workflows publish the same multi-architecture build to GHCR and Docker Hub. Docker Hub authentication uses the GitHub Actions repository variable `DOCKERHUB_USERNAME` and secret `DOCKERHUB_TOKEN`.
+
 Target platforms:
 
 - `linux/amd64`
@@ -109,7 +119,7 @@ CI verifies that the container starts as UID/GID 1000, creates its SQLite databa
 
 ## Releases
 
-Tags matching `v*` publish semver aliases to GHCR and build both amd64 and arm64 images. Release builds include SBOM and provenance/attestation metadata.
+Tags matching `v*` publish semver aliases to both GHCR and Docker Hub and build both amd64 and arm64 images. Release builds include SBOM and provenance/attestation metadata. The exact published digest is runtime-qualified, and keyless Cosign signatures are written and verified for both registry references.
 
 ## Upstream