(C#) Determine if a Zip is Encrypted or Password-Protected

Determins whether or not a zip archive is AES encrypted or password-protected.

Download: Chilkat .NET Assemblies

Chilkat.Zip zip = new Chilkat.Zip();

bool success;

//  Any string unlocks the component for the 1st 30-days.
success = zip.UnlockComponent("Anything for 30-day trial");
if (success != true) {
    textBox1.Text += zip.LastErrorText + "\r\n";
    return;
}

//  An encrypted or password-protected zip can be opened
//  without specifying the password.  However, the contents
//  of the files cannot be unzipped without providing the correct
//  password.

success = zip.OpenZip("something.zip");
if (success != true) {
    textBox1.Text += zip.LastErrorText + "\r\n";
    return;
}

//  If the zip is password-protected, meaning that it uses
//  the old (insecure) Zip 2.0 encryption, then the
//  PasswordProtect property will be true
bool bPwdProt;
bPwdProt = zip.PasswordProtect;
if (bPwdProt) {
    textBox1.Text += "This zip is password-protected." + "\r\n";
}

//  If the zip is AES encrypted (WinZip compatible) then
//  the Encryption property will be equal to 4.
int encValue;
encValue = zip.Encryption;
if (encValue == 4) {
    textBox1.Text += "This zip is AES encrypted." + "\r\n";
}

//  If the Encryption property = 0, then the zip is NOT
//  strong encrypted, and is either password-protected or
//  entirely unencrypted, depending on the value of the
//  PasswordProtect property.

//  If the Encryption property = 1, 2, or 3, then the zip was
//  encrypted using AES, Blowfish, or Twofish using a
//  Chilkat-specific encryption format that was implemented
//  prior to the publication of the Zip AES standard.

zip.CloseZip();