ci: drop dpkg-sig per-deb signing (broken on modern .debs); rely on Nexus repo signing for apt trust chain

.gitea/workflows/build-publish.yml

@@ -85,11 +85,8 @@ jobs:
           ls -la "${DEB_FILE}"
           sha256sum "${DEB_FILE}"
 
-      - name: Sign and publish to Nexus
+      - name: Publish to Nexus
         env:
-          GPG_PRIVATE_KEY: ${{ secrets.GPG_PRIVATE_KEY }}
-          GPG_PASSPHRASE:  ${{ secrets.GPG_PASSPHRASE }}
-          GPG_KEY_ID:      ${{ secrets.GPG_KEY_ID }}
           NEXUS_USER: ${{ secrets.NEXUS_USER }}
           NEXUS_PASS: ${{ secrets.NEXUS_PASS }}
           NEXUS_URL:  ${{ secrets.NEXUS_URL }}
@@ -100,43 +97,19 @@ jobs:
           set -euo pipefail
           umask 077
 
-          # Tmpfs (RAM-only) scratch for every byte of secret material.
+          # All secret material lives in tmpfs (RAM); shredded on exit either way.
-          # Falls back to /tmp if /dev/shm is absent.
           SECDIR="$(mktemp -d -p /dev/shm raweb-XXXXXXXX 2>/dev/null \
                     || mktemp -d -t raweb-XXXXXXXX)"
           chmod 700 "$SECDIR"
-          export GNUPGHOME="$SECDIR/gnupg"
+          trap 'find "$SECDIR" -type f -exec shred -uz {} + 2>/dev/null || true; rm -rf "$SECDIR"' EXIT
 
-          cleanup() {
+          # Auth via netrc file — never via -u user:pass on the command line,
-            (gpg --batch --yes --quiet \
+          # which would be visible to anything that can read /proc.
-                  --delete-secret-and-public-key "$GPG_KEY_ID" 2>/dev/null) || true
-            (gpgconf --kill all 2>/dev/null) || true
-            find "$SECDIR" -type f -exec shred -uz {} + 2>/dev/null || true
-            rm -rf "$SECDIR"
-          }
-          trap cleanup EXIT
-
-          # Materialise secrets to in-memory files. After this, drop them from env
-          # so any subprocess (or accidental `env`) cannot read them.
-          printf '%s' "$GPG_PRIVATE_KEY" > "$SECDIR/key.asc"
-          printf '%s' "$GPG_PASSPHRASE"  > "$SECDIR/pp"
           printf 'machine apt.julio.al login %s password %s\n' \
                  "$NEXUS_USER" "$NEXUS_PASS" > "$SECDIR/netrc"
-          unset GPG_PRIVATE_KEY GPG_PASSPHRASE NEXUS_PASS NEXUS_USER
+          unset NEXUS_USER NEXUS_PASS
 
-          # Ephemeral keyring on tmpfs.
+          # Replace prior component of the same name, if any (best-effort).
-          mkdir -p "$GNUPGHOME"; chmod 700 "$GNUPGHOME"
-          printf 'allow-loopback-pinentry\n' > "$GNUPGHOME/gpg-agent.conf"
-          printf 'pinentry-mode loopback\n'  > "$GNUPGHOME/gpg.conf"
-          gpg --batch --import "$SECDIR/key.asc"
-
-          # Sign the .deb. Passphrase passed via FILE — never argv, never env.
-          dpkg-sig -k "$GPG_KEY_ID" \
-                   -g "--batch --pinentry-mode loopback --passphrase-file $SECDIR/pp" \
-                   --sign builder "$DEB_FILE"
-          dpkg-sig --verify "$DEB_FILE"
-
-          # Replace any prior component of the same name (best-effort).
           OLD_ID="$(curl -fsS --netrc-file "$SECDIR/netrc" \
                     "$NEXUS_URL/service/rest/v1/components?repository=$NEXUS_REPO" \
                     | PKG_NAME="$PKG_NAME" python3 -c '
@@ -150,7 +123,6 @@ jobs:
                  "$NEXUS_URL/service/rest/v1/components/$OLD_ID" -o /dev/null
           fi
 
-          # Upload — auth via netrc (not -u, not query string).
           HTTP="$(curl -sS --netrc-file "$SECDIR/netrc" \
                   -o "$SECDIR/upload.body" -w '%{http_code}' \
                   -X POST -F "apt.asset=@$DEB_FILE" \
@@ -159,3 +131,8 @@ jobs:
             201|204) echo "Uploaded $(basename "$DEB_FILE") to $NEXUS_URL/repository/$NEXUS_REPO/" ;;
             *) echo "Upload failed (HTTP $HTTP)"; head -c 400 "$SECDIR/upload.body"; exit 1 ;;
           esac
+
+          # Note: per-.deb signing intentionally not performed here. apt's trust
+          # chain is Release.gpg → Packages SHA256 → .deb SHA256, and Nexus signs
+          # the Release file on every upload using the key bound at repo creation.
+          # The private key never leaves the Nexus host.