diff --git a/Dockerfile b/Dockerfile
index 1b751de..92b6708 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -8,6 +8,8 @@ ENV SRC_DIR /srv/src
 ENV CCACHE_DIR /srv/ccache
 ENV ZIP_DIR /srv/zips
 ENV LMANIFEST_DIR /srv/local_manifests
+ENV DELTA_DIR /srv/delta
+ENV KEYS_DIR /srv/keys
 ENV DEBIAN_FRONTEND noninteractive
 ENV USER root
 
@@ -61,7 +63,7 @@ ENV ANDROID_JACK_VM_ARGS "-Dfile.encoding=UTF-8 -XX:+TieredCompilation -Xmx4G"
 ENV CUSTOM_PACKAGES ''
 
 # Key path (from the root of the android source)
-ENV KEYS_DIR ''
+ENV SIGN_BUILDS false
 
 # Move the resulting zips to $ZIP_DIR/$codename instead of $ZIP_DIR/
 ENV ZIP_SUBDIR false
@@ -71,6 +73,9 @@ ENV ZIP_SUBDIR false
 # permission only to the privileged apps)
 ENV SIGNATURE_SPOOFING "no"
 
+# Generate delta files (saved in $ZIP_DIR/delta)
+ENV BUILD_DELTA false
+
 # Create Volume entry points
 ############################
 
@@ -78,6 +83,8 @@ VOLUME $SRC_DIR
 VOLUME $CCACHE_DIR
 VOLUME $ZIP_DIR
 VOLUME $LMANIFEST_DIR
+VOLUME $DELTA_DIR
+VOLUME $KEYS_DIR
 
 # Copy required files and fix permissions
 #####################
@@ -91,11 +98,8 @@ RUN mkdir -p $SRC_DIR
 RUN mkdir -p $CCACHE_DIR
 RUN mkdir -p $ZIP_DIR
 RUN mkdir -p $LMANIFEST_DIR
-
-# Set the work directory
-########################
-
-WORKDIR $SRC_DIR
+RUN mkdir -p $DELTA_DIR
+RUN mkdir -p $KEYS_DIR
 
 # Fix permissions
 #################
@@ -119,6 +123,32 @@ RUN apt-get install -y bc bison build-essential ccache cron curl flex \
 RUN curl https://storage.googleapis.com/git-repo-downloads/repo > /usr/local/bin/repo
 RUN chmod a+x /usr/local/bin/repo
 
+# Download and build delta tools
+################################
+RUN cd /root/ && \
+        mkdir delta && \
+        git clone https://github.com/omnirom/android_packages_apps_OpenDelta.git OpenDelta && \
+        cd OpenDelta/jni && \
+        gcc -o /root/delta/zipadjust zipadjust.c zipadjust_run.c -lz && \
+        cd xdelta3* && \
+        chmod +x configure && \
+        ./configure && \
+        make && \
+        cp xdelta3 /root/OpenDelta/server/minsignapk.jar /root/OpenDelta/server/opendelta.sh /root/delta/ && \
+        rm -rf /root/OpenDelta && \
+        chmod +x /root/delta/opendelta.sh && \
+        sed -i -e 's/^\s*HOME=.*/HOME=\/root/' /root/delta/opendelta.sh && \
+        sed -i -e 's/^\s*FILE_MATCH=.*/FILE_MATCH=lineage-\*.zip/' /root/delta/opendelta.sh && \
+        sed -i -e 's/^\s*PATH_CURRENT=.*/PATH_CURRENT=$SRC_DIR\/out\/target\/product\/$DEVICE/' /root/delta/opendelta.sh && \
+        sed -i -e 's/^\s*PATH_LAST=.*/PATH_LAST=$SRC_DIR\/delta_last\/$DEVICE/' /root/delta/opendelta.sh && \
+        sed -i -e 's/^\s*KEY_X509=.*/KEY_X509=$KEYS_DIR\/releasekey.x509.pem/' /root/delta/opendelta.sh && \
+        sed -i -e 's/^\s*KEY_PK8=.*/KEY_PK8=$KEYS_DIR\/releasekey.pk8/' /root/delta/opendelta.sh && \
+        sed -i -e 's/publish/$DELTA_DIR/g' /root/delta/opendelta.sh
+
+# Set the work directory
+########################
+WORKDIR $SRC_DIR
+
 # Allow redirection of stdout to docker logs
 ############################################
 
diff --git a/src/build.sh b/src/build.sh
index 19afef4..d6d3d13 100644
--- a/src/build.sh
+++ b/src/build.sh
@@ -82,6 +82,11 @@ if ! [ -z "$DEVICE_LIST" ]; then
     sed -i "1s;^;PRODUCT_PACKAGES += $CUSTOM_PACKAGES\n\n;" vendor/cm/config/common.mk
   fi
 
+  if [ "$SIGN_BUILDS" = true ]; then
+    echo ">> [$(date)] Adding keys path ($KEYS_DIR)" >> $DOCKER_LOG
+    sed -i "1s;^;PRODUCT_DEFAULT_DEV_CERTIFICATE := $KEYS_DIR/releasekey\nPRODUCT_OTA_PUBLIC_KEYS := $KEYS_DIR/releasekey\n\n;" vendor/cm/config/common.mk
+  fi
+
   # Cycle DEVICE_LIST environment variable, to know which one may be executed next
   IFS=','
   for codename in $DEVICE_LIST; do
@@ -93,41 +98,31 @@ if ! [ -z "$DEVICE_LIST" ]; then
         zipsubdir=
       fi
       # Start the build
-      if [ -z "$KEYS_DIR" ]; then
-        echo ">> [$(date)] Starting build for $codename" >> $DOCKER_LOG
-        if brunch $codename 2>&1 >&$DEBUG_LOG; then
-          # Move produced ZIP files to the main OUT directory
-          echo ">> [$(date)] Moving build artifacts for $codename to '$ZIP_DIR/$zipsubdir'" >> $DOCKER_LOG
-          cd $SRC_DIR
-          find out/target/product/$codename -name '*UNOFFICIAL*.zip*' -exec sh -c 'sha256sum {} > $ZIP_DIR/$zipsubdir/{}.sha256sum && mv {} $ZIP_DIR/$zipsubdir/' \; >&$DEBUG_LOG
-        else
-          echo ">> [$(date)] Failed build for $codename" >> $DOCKER_LOG
-        fi
-      else
-        echo ">> [$(date)] Starting build for $codename" >> $DOCKER_LOG
-        if breakfast $codename 2>&1 >&$DEBUG_LOG && \
-             mka target-files-package dist 2>&1 >&$DEBUG_LOG; then
-          echo ">> [$(date)] Signing build output for $codename" >> $DOCKER_LOG
-          build_number=$(<$SRC_DIR/out/build_number.txt)
-          if $SRC_DIR/build/tools/releasetools/sign_target_files_apks -o -d $SRC_DIR/$KEYS_DIR \
-               $SRC_DIR/out/dist/lineage_$codename-target_files-$build_number.zip \
-               $SRC_DIR/out/dist/lineage_$codename-signed_target_files-$build_number.zip 2>&1 >&$DEBUG_LOG && \
-             $SRC_DIR/build/tools/releasetools/ota_from_target_files -k $SRC_DIR/$KEYS_DIR/releasekey --block --backup=true \
-               $SRC_DIR/out/dist/lineage_$codename-signed_target_files-$build_number.zip \
-               $ZIP_DIR/$zipsubdir/lineage-14.1-$builddate-UNOFFICIAL-$codename-signed.zip 2>&1 >&$DEBUG_LOG; then
-            cd $ZIP_DIR/$zipsubdir
-            md5sum lineage-14.1-$builddate-UNOFFICIAL-$codename-signed.zip > lineage-14.1-$builddate-UNOFFICIAL-$codename-signed.zip.md5sum
-            sha256sum lineage-14.1-$builddate-UNOFFICIAL-$codename-signed.zip > lineage-14.1-$builddate-UNOFFICIAL-$codename-signed.zip.sha256sum
-            cd $SRC_DIR
-            echo ">> [$(date)] Build completed for $codename" >> $DOCKER_LOG
+      echo ">> [$(date)] Starting build for $codename" >> $DOCKER_LOG
+      if brunch $codename 2>&1 >&$DEBUG_LOG; then
+        if [ "$BUILD_DELTA" = true ]; then
+          if [ -d "$SRC_DIR/delta_last/$codename/" ]; then
+            # If not the first build, create delta files
+            echo ">> [$(date)] Generating delta files for $codename" >> $DOCKER_LOG
+            cd /root/delta
+            if ./opendelta.sh $codename >&$DEBUG_LOG; then
+              echo ">> [$(date)] Delta generation for $codename completed" >> $DOCKER_LOG
+            else
+              echo ">> [$(date)] Delta generation for $codename failed" >> $DOCKER_LOG
+            fi
           else
-            echo ">> [$(date)] Failed signing for $codename" >> $DOCKER_LOG
+            # If the first build, copy the current full zip in $SRC_DIR/delta_last/$codename/
+            echo ">> [$(date)] No previous build for $codename; using current build as base for the next delta" >> $DOCKER_LOG
+            mkdir -p $SRC_DIR/delta_last/$codename/
+            find out/target/product/$codename -name '*UNOFFICIAL*.zip*' -exec cp {} $SRC_DIR/delta_last/$codename/ \;
           fi
-          rm -f $SRC_DIR/out/dist/lineage_$codename-target_files-$build_number.zip
-          rm -f $SRC_DIR/out/dist/lineage_$codename-signed_target_files-$build_number.zip
-        else
-          echo ">> [$(date)] Failed build for $codename" >> $DOCKER_LOG
         fi
+        # Move produced ZIP files to the main OUT directory
+        echo ">> [$(date)] Moving build artifacts for $codename to '$ZIP_DIR/$zipsubdir'" >> $DOCKER_LOG
+        cd $SRC_DIR
+        find out/target/product/$codename -name '*UNOFFICIAL*.zip*' -exec mv {} $ZIP_DIR/$zipsubdir/ \; >&$DEBUG_LOG
+      else
+        echo ">> [$(date)] Failed build for $codename" >> $DOCKER_LOG
       fi
       # Clean everything, in order to start fresh on next build
       if [ "$CLEAN_AFTER_BUILD" = true ]; then