diff --git a/apkverify/src/lib.rs b/apkverify/src/lib.rs
index 9930099..869431e 100644
--- a/apkverify/src/lib.rs
+++ b/apkverify/src/lib.rs
@@ -18,6 +18,7 @@
 
 mod bytes_ext;
 mod sigutil;
+mod testing;
 mod v3;
 mod ziputil;
 
diff --git a/apkverify/src/testing.rs b/apkverify/src/testing.rs
new file mode 100644
index 0000000..777afb8
--- /dev/null
+++ b/apkverify/src/testing.rs
@@ -0,0 +1,34 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+//! A collection of utilities for testing
+
+/// Asserts if `haystack.contains(needed)`
+#[macro_export]
+macro_rules! assert_contains {
+    ($haystack:expr,$needle:expr $(,)?) => {
+        match (&$haystack, &$needle) {
+            (haystack_value, needle_value) => {
+                assert!(
+                    haystack_value.contains(needle_value),
+                    "{} is not found in {}",
+                    needle_value,
+                    haystack_value
+                );
+            }
+        }
+    };
+}
diff --git a/apkverify/src/ziputil.rs b/apkverify/src/ziputil.rs
index dbf5131..bfb1c01 100644
--- a/apkverify/src/ziputil.rs
+++ b/apkverify/src/ziputil.rs
@@ -22,8 +22,10 @@
 use zip::ZipArchive;
 
 const EOCD_MIN_SIZE: usize = 22;
+const EOCD_CENTRAL_DIRECTORY_SIZE_FIELD_OFFSET: usize = 12;
 const EOCD_CENTRAL_DIRECTORY_OFFSET_FIELD_OFFSET: usize = 16;
 const EOCD_MAGIC: u32 = 0x06054b50;
+const ZIP64_MARK: u32 = 0xffffffff;
 
 #[derive(Debug, PartialEq)]
 pub struct ZipSections {
@@ -44,30 +46,39 @@
     // retrieve reader back
     reader = archive.into_inner();
     // the current position should point EOCD offset
-    let eocd_offset = reader.seek(SeekFrom::Current(0))?;
+    let eocd_offset = reader.seek(SeekFrom::Current(0))? as u32;
     let mut eocd = vec![0u8; eocd_size as usize];
     reader.read_exact(&mut eocd)?;
     if (&eocd[0..]).get_u32_le() != EOCD_MAGIC {
         bail!("Invalid ZIP: ZipArchive::new() should point EOCD after reading.");
     }
-    let central_directory_offset = get_central_directory_offset(&eocd)?;
-    let central_directory_size = eocd_offset as u32 - central_directory_offset;
+    let (central_directory_size, central_directory_offset) = get_central_directory(&eocd)?;
+    if central_directory_offset == ZIP64_MARK || central_directory_size == ZIP64_MARK {
+        bail!("Unsupported ZIP: ZIP64 is not supported.");
+    }
+    if central_directory_offset + central_directory_size != eocd_offset {
+        bail!("Invalid ZIP: EOCD should follow CD with no extra data or overlap.");
+    }
+
     Ok((
         reader,
         ZipSections {
             central_directory_offset,
             central_directory_size,
-            eocd_offset: eocd_offset as u32,
+            eocd_offset,
             eocd_size: eocd_size as u32,
         },
     ))
 }
 
-fn get_central_directory_offset(buf: &[u8]) -> Result<u32> {
+fn get_central_directory(buf: &[u8]) -> Result<(u32, u32)> {
     if buf.len() < EOCD_MIN_SIZE {
         bail!("Invalid EOCD size: {}", buf.len());
     }
-    Ok((&buf[EOCD_CENTRAL_DIRECTORY_OFFSET_FIELD_OFFSET..]).get_u32_le())
+    let mut buf = &buf[EOCD_CENTRAL_DIRECTORY_SIZE_FIELD_OFFSET..];
+    let size = buf.get_u32_le();
+    let offset = buf.get_u32_le();
+    Ok((size, offset))
 }
 
 /// Update EOCD's central_directory_offset field.
@@ -78,3 +89,42 @@
     (&mut buf[EOCD_CENTRAL_DIRECTORY_OFFSET_FIELD_OFFSET..]).put_u32_le(value);
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::assert_contains;
+    use std::io::{Cursor, Write};
+    use zip::{write::FileOptions, ZipWriter};
+
+    fn create_test_zip() -> Cursor<Vec<u8>> {
+        let mut writer = ZipWriter::new(Cursor::new(Vec::new()));
+        writer.start_file("testfile", FileOptions::default()).unwrap();
+        writer.write_all(b"testcontent").unwrap();
+        writer.finish().unwrap()
+    }
+
+    #[test]
+    fn test_zip_sections() {
+        let (cursor, sections) = zip_sections(create_test_zip()).unwrap();
+        assert_eq!(sections.eocd_offset, (cursor.get_ref().len() - EOCD_MIN_SIZE) as u32);
+    }
+
+    #[test]
+    fn test_reject_if_extra_data_between_cd_and_eocd() {
+        // prepare normal zip
+        let buf = create_test_zip().into_inner();
+
+        // insert garbage between CD and EOCD.
+        // by the way, to mock zip-rs, use CD as garbage. This is implementation detail of zip-rs,
+        // which reads CD at (eocd_offset - cd_size) instead of at cd_offset from EOCD.
+        let (pre_eocd, eocd) = buf.split_at(buf.len() - EOCD_MIN_SIZE);
+        let (_, cd_offset) = get_central_directory(eocd).unwrap();
+        let cd = &pre_eocd[cd_offset as usize..];
+
+        // ZipArchive::new() succeeds, but we should reject
+        let res = zip_sections(Cursor::new([pre_eocd, cd, eocd].concat()));
+        assert!(res.is_err());
+        assert_contains!(res.err().unwrap().to_string(), "Invalid ZIP: offset should be 0");
+    }
+}