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PDF: Check if document is encrypted
Use TElPDFDocument.Encrypted property to check if the document is encrypted or not. Also you can use TElPDFDocument.Decrypted property to check if the document was decrypted.
Note: Usually the Decrypted property is set to true after successful call of Decrypt() method. But if the document contains an encrypted object stream and the document is encrypted with empty password (for example, only the owner password is set for the document, it is usually done to restrict document editing) and the program doesn't handle TElPDFDocument.OnDecryptionInfoNeeded event, then the document could be decrypted automatically, and Encrypted property would be set to false and Decrypted property set to true.
