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Encrypting / Decrypting PDFs

These examples were written in answer to questions such as:

DecryptPdf.java
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/*
    This file is part of the iText (R) project.
    Copyright (c) 1998-2020 iText Group NV
    Authors: iText Software.
 
    For more information, please contact iText Software at this address:
    sales@itextpdf.com
 */
/**
 * Example written by Bruno Lowagie in answer to:
 * http://stackoverflow.com/questions/27867868/how-can-i-decrypt-a-pdf-document-with-the-owner-password
 */
package com.itextpdf.samples.sandbox.security;
 
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.ReaderProperties;
 
import java.io.File;
 
public class DecryptPdf {
    public static final String DEST = "./target/sandbox/security/decrypt_pdf.pdf";
    public static final String SRC = "./src/test/resources/pdfs/hello_encrypted.pdf";
 
    public static final String OWNER_PASSWORD = "World";
 
    public static void main(String[] args) throws Exception {
        File file = new File(DEST);
        file.getParentFile().mkdirs();
 
        new DecryptPdf().manipulatePdf(DEST);
    }
 
    protected void manipulatePdf(String dest) throws Exception {
        try (PdfDocument document = new PdfDocument(
                new PdfReader(SRC, new ReaderProperties().setPassword(OWNER_PASSWORD.getBytes())),
                new PdfWriter(dest)
        )) {
            byte[] userPasswordBytes = document.getReader().computeUserPassword();
 
            // The result of user password computation logic can be null in case of
            // AES256 password encryption or non password encryption algorithm
            String userPassword = userPasswordBytes == null ? null : new String(userPasswordBytes);
            System.out.println(userPassword);
        }
    }
}
DecryptPdf2.java
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/*
    This file is part of the iText (R) project.
    Copyright (c) 1998-2020 iText Group NV
    Authors: iText Software.
 
    For more information, please contact iText Software at this address:
    sales@itextpdf.com
 */
/**
 * Example written by Bruno Lowagie in answer to:
 * http://stackoverflow.com/questions/27867868/how-can-i-decrypt-a-pdf-document-with-the-owner-password
 */
package com.itextpdf.samples.sandbox.security;
 
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.StampingProperties;
 
import java.io.File;
 
public class DecryptPdf2 {
    public static final String DEST = "./target/sandbox/security/decrypt_pdf2.pdf";
    public static final String SRC = "./src/test/resources/pdfs/encrypt_pdf_without_user_password.pdf";
 
    public static void main(String[] args) throws Exception {
        File file = new File(DEST);
        file.getParentFile().mkdirs();
 
        new DecryptPdf2().manipulatePdf(DEST);
    }
 
    protected void manipulatePdf(String dest) throws Exception {
        // This is not actually a decrypt example.
        // The old iText5 test shows how to open an encrypted pdf document
        // without user password for modifying with preserving an old owner password
        try (PdfDocument document = new PdfDocument(
                new PdfReader(SRC).setUnethicalReading(true),
                new PdfWriter(dest),
                new StampingProperties().preserveEncryption()
        )) {
            // here we can modify the document
        }
    }
}
DecryptPdf3.java
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/*
    This file is part of the iText (R) project.
    Copyright (c) 1998-2020 iText Group NV
    Authors: iText Software.
 
    For more information, please contact iText Software at this address:
    sales@itextpdf.com
 */
/**
 * Example written by Bruno Lowagie in answer to:
 * http://stackoverflow.com/questions/27867868/how-can-i-decrypt-a-pdf-document-with-the-owner-password
 */
package com.itextpdf.samples.sandbox.security;
 
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfWriter;
 
import java.io.File;
 
public class DecryptPdf3 {
    public static final String DEST = "./target/sandbox/security/decrypt_pdf3.pdf";
    public static final String SRC = "./src/test/resources/pdfs/encrypt_pdf_without_user_password.pdf";
 
    public static void main(String[] args) throws Exception {
        File file = new File(DEST);
        file.getParentFile().mkdirs();
 
        new DecryptPdf3().manipulatePdf(DEST);
    }
 
    protected void manipulatePdf(String dest) throws Exception {
        PdfDocument pdfDoc = new PdfDocument(new PdfReader(SRC).setUnethicalReading(true), new PdfWriter(dest));
        pdfDoc.close();
    }
}
EncryptPdf.java
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/*
    This file is part of the iText (R) project.
    Copyright (c) 1998-2020 iText Group NV
    Authors: iText Software.
 
    For more information, please contact iText Software at this address:
    sales@itextpdf.com
 */
/**
 * Example written by Bruno Lowagie in answer to:
 * http://stackoverflow.com/questions/27867868/how-can-i-decrypt-a-pdf-document-with-the-owner-password
 */
package com.itextpdf.samples.sandbox.security;
 
import com.itextpdf.kernel.pdf.EncryptionConstants;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.WriterProperties;
 
import java.io.File;
 
public class EncryptPdf {
    public static final String DEST = "./target/sandbox/security/encrypt_pdf.pdf";
    public static final String SRC = "./src/test/resources/pdfs/hello.pdf";
 
    public static final String OWNER_PASSWORD = "World";
    public static final String USER_PASSWORD = "Hello";
 
    public static void main(String[] args) throws Exception {
        File file = new File(DEST);
        file.getParentFile().mkdirs();
 
        new EncryptPdf().manipulatePdf(DEST);
    }
 
    protected void manipulatePdf(String dest) throws Exception {
        PdfDocument pdfDoc = new PdfDocument(
                new PdfReader(SRC),
                new PdfWriter(dest, new WriterProperties().setStandardEncryption(
                        USER_PASSWORD.getBytes(),
                        OWNER_PASSWORD.getBytes(),
                        EncryptionConstants.ALLOW_PRINTING,
                        EncryptionConstants.ENCRYPTION_AES_128 | EncryptionConstants.DO_NOT_ENCRYPT_METADATA))
        );
        pdfDoc.close();
    }
}
EncryptPdfWithoutUserPassword.java
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/*
    This file is part of the iText (R) project.
    Copyright (c) 1998-2020 iText Group NV
    Authors: iText Software.
 
    For more information, please contact iText Software at this address:
    sales@itextpdf.com
 */
/**
 * Example written by Bruno Lowagie in answer to:
 * http://stackoverflow.com/questions/27867868/how-can-i-decrypt-a-pdf-document-with-the-owner-password
 */
package com.itextpdf.samples.sandbox.security;
 
import com.itextpdf.kernel.pdf.EncryptionConstants;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.WriterProperties;
 
import java.io.File;
 
public class EncryptPdfWithoutUserPassword {
    public static final String DEST = "./target/sandbox/security/encrypt_pdf_without_user_password.pdf";
    public static final String SRC = "./src/test/resources/pdfs/hello.pdf";
 
    public static final String OWNER_PASSWORD = "World";
 
    public static void main(String[] args) throws Exception {
        File file = new File(DEST);
        file.getParentFile().mkdirs();
 
        new EncryptPdfWithoutUserPassword().manipulatePdf(DEST);
    }
 
    protected void manipulatePdf(String dest) throws Exception {
        PdfDocument pdfDoc = new PdfDocument(
                new PdfReader(SRC),
                new PdfWriter(dest, new WriterProperties().setStandardEncryption(
                        // null user password argument is equal to empty string,
                        // this means that no user password required
                        null,
                        OWNER_PASSWORD.getBytes(),
                        EncryptionConstants.ALLOW_PRINTING,
                        EncryptionConstants.ENCRYPTION_AES_128 | EncryptionConstants.DO_NOT_ENCRYPT_METADATA))
        );
        pdfDoc.close();
    }
}

Click the following link to see the legacy example for iText 5. Except for security fixes, iText 5 is no longer being developed.



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