Add Zephyr support for encrypted images

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/boot/zephyr/CMakeLists.txt b/boot/zephyr/CMakeLists.txt
index 9a69279..15c2ece 100644
--- a/boot/zephyr/CMakeLists.txt
+++ b/boot/zephyr/CMakeLists.txt
@@ -89,6 +89,7 @@
 target_sources(app PRIVATE "${BOOT_DIR}/bootutil/src/loader.c")
 target_sources(app PRIVATE "${BOOT_DIR}/bootutil/src/bootutil_misc.c")
 target_sources(app PRIVATE "${BOOT_DIR}/bootutil/src/image_validate.c")
+target_sources(app PRIVATE "${BOOT_DIR}/bootutil/src/encrypted.c")
 target_sources(app PRIVATE "${BOOT_DIR}/bootutil/src/image_rsa.c")
 target_sources(app PRIVATE "${BOOT_DIR}/bootutil/src/image_ec256.c")
 target_sources(app PRIVATE "${BOOT_DIR}/bootutil/src/caps.c")