diff --git a/.github/workflows/android-apk-tag.yml b/.github/workflows/android-apk-tag.yml
index 1a85b707..b93fdb03 100644
--- a/.github/workflows/android-apk-tag.yml
+++ b/.github/workflows/android-apk-tag.yml
@@ -190,6 +190,7 @@ jobs:
                       "anyio-*-py3-none-any.whl"
                       "hpack-*-py3-none-any.whl"
                       "hyperframe-*-py3-none-any.whl"
+                      "altcha-2.0.2-py3-none-any.whl"
                   )
                   missing=0
                   for pattern in "${required[@]}"; do
diff --git a/.github/workflows/android-build.yml b/.github/workflows/android-build.yml
index f959eff0..4247ac39 100644
--- a/.github/workflows/android-build.yml
+++ b/.github/workflows/android-build.yml
@@ -218,6 +218,7 @@ jobs:
                       "anyio-*-py3-none-any.whl"
                       "hpack-*-py3-none-any.whl"
                       "hyperframe-*-py3-none-any.whl"
+                      "altcha-2.0.2-py3-none-any.whl"
                   )
                   missing=0
                   for pattern in "${required[@]}"; do
diff --git a/android/app/build.gradle b/android/app/build.gradle
index 8b8b7054..a9538231 100644
--- a/android/app/build.gradle
+++ b/android/app/build.gradle
@@ -384,6 +384,7 @@ chaquopy {
             // Pure-python; wheels are vendored by scripts/build-android-wheels-local.sh
             // for offline/find-links installs (HTTPInterface / RNS-over-HTTP).
             install "httpx[http2]==0.28.1"
+            install "altcha==2.0.2"
         }
     }
 }
diff --git a/meshchatx.rsm b/meshchatx.rsm
index 5a0c3488..4dd5f0a3 100644
Binary files a/meshchatx.rsm and b/meshchatx.rsm differ
diff --git a/scripts/build-android-wheels-local.sh b/scripts/build-android-wheels-local.sh
index 7a6fc0b6..eb578669 100755
--- a/scripts/build-android-wheels-local.sh
+++ b/scripts/build-android-wheels-local.sh
@@ -64,6 +64,7 @@ NUMPY_VERSION="1.26.2"
 LXST_VERSION="0.5.1"
 BLEAK_VERSION="3.0.2"
 HTTPX_VERSION="0.28.1"
+ALTCHA_VERSION="2.0.2"
 RNS_VERSION="1.4.2"
 PATCH_LXST="1"
 PATCH_RNS="1"
@@ -881,6 +882,21 @@ PY
             exit 1
         fi
     done
+
+    echo "Fetching altcha ${ALTCHA_VERSION} pure-python wheel"
+    ALTCHA_TMP_DIR="$(mktemp -d)"
+    "${VENV_DIR}/bin/pip" download \
+        --only-binary=:all: \
+        --no-deps \
+        "altcha==${ALTCHA_VERSION}" \
+        --dest "${ALTCHA_TMP_DIR}" \
+        --index-url https://pypi.org/simple
+    cp -f "${ALTCHA_TMP_DIR}"/altcha-"${ALTCHA_VERSION}"-py3-none-any.whl "${OUT_DIR}/"
+    rm -rf "${ALTCHA_TMP_DIR}"
+    if ! ls "${OUT_DIR}/altcha-${ALTCHA_VERSION}-py3-none-any.whl" >/dev/null 2>&1; then
+        echo "Expected altcha-${ALTCHA_VERSION}-py3-none-any.whl in ${OUT_DIR}" >&2
+        exit 1
+    fi
 fi
 
 if [[ "${PATCH_RNS}" == "1" && -z "${ONLY_RECIPES}" ]]; then