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Password Protection

This chapter introduces how to read and write password-protected Excel files.

Overview​

Apache Fesod (Incubating) supports Excel's built-in password protection for both reading and writing. Use .password("xxx") on the builder to configure the password. Successfully completed .xlsx output with a non-empty password uses Apache POI's encryption (AES-based), which can be memory-intensive for large workbooks. Legacy .xls protection differs from .xlsx encryption and must not be assumed to provide equivalent confidentiality.

Writing with Password​

Code Example​

@Test
public void passwordWrite() {
    String fileName = "passwordWrite" + System.currentTimeMillis() + ".xlsx";

    FesodSheet.write(fileName)
        .password("your_password")
        .head(DemoData.class)
        .sheet("PasswordSheet")
        .doWrite(data());
}

Reading with Password​

Code Example​

@Test
public void passwordRead() {
    String fileName = "path/to/encrypted.xlsx";

    FesodSheet.read(fileName, DemoData.class, new DemoDataListener())
        .password("your_password")
        .sheet()
        .doRead();
}

Security Notes​

  • XLSX password protection applies to successfully completed output; it does not encrypt all temporary files, caches, or JVM memory used during processing.
  • Protect temporary and output directories from untrusted access. File output may contain plaintext during processing; publish results only after the entire write succeeds.
  • Treat output from a failed write or encryption operation as incomplete and sensitive, and do not deliver it.
  • Without the correct password, reading will throw an EncryptedDocumentException.
  • In production, avoid hardcoding passwords — use configuration files or secrets management.

See the Security Model for encryption boundaries, temporary-file requirements, and Apache POI's role and limitations.