The PDF specification defines different algorithms to be used to encrypt and/or decrypt a PDF document's content: RC4 40 bits, RC4 128 bits, AES 128 bits, AES 256 bits.
'DeclarationPublic Function GetEncryptionScheme() As PdfEncryption
public PdfEncryption GetEncryptionScheme()
public function GetEncryptionScheme(): PdfEncryption;
public function GetEncryptionScheme() : PdfEncryption;
public: PdfEncryption GetEncryptionScheme();
public: PdfEncryption GetEncryptionScheme();
You need to decrypt the PDF document at first using the GdPicturePDF.SetPassword method with specifyting either the correct user password or the owner password.
Dim caption As String = "Example: GetEncryptionScheme" Dim gdpicturePDF As New GdPicturePDF() 'Please see the example in the SetPassword method for creating this file. Dim status As GdPictureStatus = gdpicturePDF.LoadFromFile("encrypted.pdf", False) If status = GdPictureStatus.OK Then Dim encryption As PdfEncryption = PdfEncryption.PdfEncryptionUnknown Dim encrypted As Boolean = gdpicturePDF.IsEncrypted() status = gdpicturePDF.GetStat() If status = GdPictureStatus.OK Then If encrypted Then 'This is incorrect usage. encryption = gdpicturePDF.GetEncryptionScheme() If gdpicturePDF.GetStat() = GdPictureStatus.OK Then MessageBox.Show("This PDF document is encrypted, the encryption scheme is: " + encryption.ToString() + vbCrLf + "Please use SetPassword to decrypt your document.", caption) End If 'You need to provide the correct password here. status = gdpicturePDF.SetPassword("user") If status = GdPictureStatus.OK Then 'The correct usage. encryption = gdpicturePDF.GetEncryptionScheme() ' correct use If gdpicturePDF.GetStat() = GdPictureStatus.OK Then MessageBox.Show("This PDF document is decrypted, the encryption scheme is: " + encryption.ToString(), caption) End If Else MessageBox.Show("The SetPassword() method has failed with the status: " + status.ToString(), caption) End If Else encryption = gdpicturePDF.GetEncryptionScheme() If gdpicturePDF.GetStat() = GdPictureStatus.OK Then MessageBox.Show("The PDF document is not encrypted, the encryption scheme is: " + encryption.ToString(), caption) End If End If Else MessageBox.Show("The IsEncrypted() method has failed with the status: " + status.ToString(), caption) End If Else MessageBox.Show("The file can't be loaded.", caption) End If gdpicturePDF.Dispose()
string caption = "Example: GetEncryptionScheme"; GdPicturePDF gdpicturePDF = new GdPicturePDF(); //Please see the example in the SetPassword method for creating this file. GdPictureStatus status = gdpicturePDF.LoadFromFile("encrypted.pdf", false); if (status == GdPictureStatus.OK) { PdfEncryption encryption = PdfEncryption.PdfEncryptionUnknown; bool encrypted = gdpicturePDF.IsEncrypted(); status = gdpicturePDF.GetStat(); if (status == GdPictureStatus.OK) { if (encrypted) { //This is incorrect usage. encryption = gdpicturePDF.GetEncryptionScheme(); if (gdpicturePDF.GetStat() == GdPictureStatus.OK) MessageBox.Show("This PDF document is encrypted, the encryption scheme is: " + encryption.ToString() + "\nPlease use SetPassword to decrypt your document.", caption); //You need to provide the correct password here. status = gdpicturePDF.SetPassword("user"); if (status == GdPictureStatus.OK) { //The correct usage. encryption = gdpicturePDF.GetEncryptionScheme(); if (gdpicturePDF.GetStat() == GdPictureStatus.OK) MessageBox.Show("This PDF document is decrypted, the encryption scheme is: " + encryption.ToString(), caption); } else { MessageBox.Show("The SetPassword() method has failed with the status: " + status.ToString(), caption); } } else { encryption = gdpicturePDF.GetEncryptionScheme(); if (gdpicturePDF.GetStat() == GdPictureStatus.OK) MessageBox.Show("The PDF document is not encrypted, the encryption scheme is: " + encryption.ToString(), caption); } } else { MessageBox.Show("The IsEncrypted() method has failed with the status: " + status.ToString(), caption); } } else { MessageBox.Show("The file can't be loaded.", caption); } gdpicturePDF.Dispose();