Documentation – Protect or Encrypt a Document in Java

Java: Make a Document Read-Only in Java

Mon, 01 Jan 0001 00:00:00 +0000

Sometimes, you may have a document that needs a review, but you do not want reviewers to randomly modify your content. Aspose.Words allows you to make the permission of your document read-only so that the content can be copied or read, but not modified. This will prevent content from being removed or added to your document.

Applying the read-only option to your document does not prevent someone from creating a new copy of it and saving it with another name.

This article explains how to make a document read-only.

How to Make a Document Read-Only

Aspose.Words has the public class WriteProtection that specifies write protection settings for a document. You do not create instances of this class directly.

Write protection shows whether the author has recommended opening a document as read-only and/or requiring a password to modify the document.

Aspose.Words allows you to make a document read-only to restrict editing by using the ReadOnlyRecommended property and the SetPassword method.

In Microsoft Word, you can create a Read-Only document in a similar way using both:

“Always Open Read-Only” (File → Info → Protect Document)
“Password to modify” (Save As → Tools → General Options → Password)

Users can also restrict document editing by selecting ProtectionType as ReadOnly, but this is another feature that provides more advanced protection capabilities. There is such a function in Microsoft Word, respectively, it is implemented in Aspose.Words.

ProtectionType will be described in detail in one of the following articles – “Restrict Document Editing”.

The ReadOnlyRecommended property is password-secured, so if you do not set a password before applying the ReadOnlyRecommended property, then other users can simply open the document as if it were unprotected. You access the document protection settings and set a write protection password via the SetPassword method.

Note that the password being set is just a property in a document that can be removed if the document properties are accessed. Accordingly, such a password is not a guarantee of the document security.

If you need to check if a document has a write protection password that restricts it from editing, you can use the IsWriteProtected property.

The following code example shows how to make a document read-only:

Remove Read-Only Restriction

If you do not want a user to open your document as read-only, you can simply set the ReadOnlyRecommened property to false or select ProtectionType as NoProtection.

The following code example shows how to remove read-only access for a document:

FAQ

Q: How do I make a document read‑only with Aspose.Words for Java?
A: Load the document, obtain its WriteProtection object via document.getProtection(), set setReadOnlyRecommended(true), optionally call setPassword("yourPassword"), and then save the document. The ReadOnlyRecommended flag tells Word to open the file in read‑only mode.
Q: Can I require a password to modify the document while still allowing read‑only access?
A: Yes. After enabling ReadOnlyRecommended, call writeProtection.setPassword("modifyPassword"). Users can open the file without a password, but any attempt to edit will prompt for the password you supplied.
Q: How can I verify whether a document is write‑protected?
A: Use the WriteProtection object’s isWriteProtected() property. It returns true if a password has been set or if ReadOnlyRecommended is enabled.
Q: How do I remove the read‑only recommendation or any write protection from a document?
A: Set writeProtection.setReadOnlyRecommended(false) and optionally writeProtection.setPassword(null). You can also change the protection type to ProtectionType.NO_PROTECTION before saving. This restores normal editing capabilities.

Java: Encrypt a Document in Java

Mon, 01 Jan 0001 00:00:00 +0000

Encryption is the process that translates readable text to meaningless sequences of bytes so it can only be read by the person who has the decryption key or the secret code. This process plays an important role in securing your content. It helps to encode the content, verify the origin of a document, prove that the content has not been modified after it was sent, and ensure that the data from the document is safe.

This article explains how Aspose.Words allows you to encrypt a document and how to check if a document has encryption or not.

Encrypt with Password

To encrypt a document, use the Password property to provide a password that functions as an encryption key. This will modify the content of your document and make it unreadable. The encrypted document will require to have this password entered before it can be opened.

You can find the appropriate Password property for the required format. Each document save format has a corresponding class containing save options for this format. For example, the Password property in the DocSaveOptions class for DOC, or the Password property in the OoxmlSaveOptions class for DOCX, DOCM, DOTX, DOTM, and FlatOpc.

Note that only certain document formats support encryption. For example, RTF does not support encryption.

The table below lists the formats and encryption algorithms supported by Aspose.Words:

Format	Supported Encryption while Loading	Supported Encryption while Saving
DOC, DOT	XOR encryption40-bit RC4 EncryptionCryptoAPI RC4 Encryption	RC4 Encryption (40-bit)
DOCX, DOTX, DOCM, DOTM, FlatOPC, FlatOpcTemplate, FlatOpcMacroEnabled, FlatOpcTemplateMacroEnabled	ECMA-376 Standard EncryptionECMA-376 Agile Encryption	ECMA-376 Standard Encryption (AES128 + SHA1)
ODT, OTT	ODF Encryption (Blowfish/AES)	ODF Encryption (AES256 + SHA256)
PDF	-	RC4 Encryption (40/128 bit)

The following code example shows how to encrypt a document with a password:

Check If a Document Is Encrypted

In some cases, you may have an unreadable document and want to be sure that the document is encrypted and not corrupted or compressed.

To detect if a document is encrypted and if a password is required, you can use the IsEncrypted property of the FileFormatInfo class. This property will also allow you to perform some action before loading a document, for example, informing a user to provide a password.

The following code example shows how to detect the document encryption:

Open a Document With or Without a Password

When we have made sure that a document is encrypted, we can try to open this document without a password, which should lead to an exception.

The following code example shows how to try opening an encrypted document without a password:

After we have seen that an encrypted document cannot be opened without a password, we can try to open it by entering the password.

The following code example shows how to try opening an encrypted document with a password:

FAQ

Q: How do I encrypt a Word document with a password using Aspose.Words for Java?
A: Use the appropriate save‑options class for the target format (e.g., DocSaveOptions for DOC or OoxmlSaveOptions for DOCX) and set its setPassword("yourPassword") method before calling Document.save. The document will be saved encrypted and will require the password to open.
Q: Which file formats support encryption when saving with Aspose.Words for Java?
A: DOC, DOCX, DOCM, DOTX, DOTM, FlatOPC, ODT, OTT, and PDF support encryption. Formats such as RTF do not support encryption. Each format uses its own set of supported algorithms (e.g., RC4 for DOC, ECMA‑376 AES128 for DOCX, AES256 for ODT, RC4 for PDF).
Q: How can I determine whether a document is encrypted before loading it?
A: Create a FileFormatInfo instance by calling FileFormatUtil.detectFileFormat(filePath). Then check the isEncrypted() property. If it returns true, the document is encrypted and you must supply the password when loading.
Q: What exception is thrown if I try to open an encrypted document without providing a password?
A: Aspose.Words throws a IncorrectPasswordException. Catch this exception to prompt the user for the correct password or to handle the error gracefully.
Q: Can I choose a different encryption algorithm for a specific format?
A: Yes. Each save‑options class exposes algorithm‑specific properties (e.g., setEncryptionAlgorithm(EncryptionAlgorithm.AES256) for ODT or setEncryptionAlgorithm(EncryptionAlgorithm.RC4_128) for PDF). Set the desired algorithm before saving the document.

Java: Restrict Document Editing in Java

Mon, 01 Jan 0001 00:00:00 +0000

Sometimes you may need to limit the ability to edit a document and only allow certain actions with it. This can be useful to prevent other people from editing sensitive and confidential information in your document.

Aspose.Words allows you to restrict editing a document by setting a restriction type. In addition, Aspose.Words also enables you to specify write protection settings for a document.

This article explains how to use Aspose.Words to select a restriction type, how to add or remove protection, and how to make unrestricted editable regions.

Select Editing Restriction Type

Aspose.Words allows you to control the way you restrict the content using the ProtectionType enumeration parameter. This will enable you to select an exact type of protection such as the following:

AllowOnlyComments
AllowOnlyFormFields
AllowOnlyRevisions
ReadOnly
NoProtection

All types are password-secured, and if this password is not entered correctly, a user will not be able to legally change the content of your document. Thus, if your document is returned to you without a requirement to provide the necessary password, this is a sign that something is wrong.

If you did not set a password when choosing the security type, other users can simply ignore the protection of your document.

Add Document Protection

Adding protection to your document is a simple process, as all you need to do is apply one of the protection methods detailed in this section.

Aspose.Words allows you to protect your documents from changes using the Protect method. This method is not a security feature and does not encrypt a document.

In Microsoft Word, you can restrict editing in a similar way using both:

Restrict Editing (File → Info → Protect Document)
Alternative feature – “Restrict Editing” (Review → Protect → Restrict Editing)

The following code example shows how to add password protection to your document:

The following code example shows how to restrict editing in a document so only editing in form fields is possible:

Remove Document Protection

Aspose.Words allows you to remove protection from a document with simple and direct document modification. You can either remove the document protection without knowing the actual password or provide the correct password to unlock the document by using the Unprotect method. Both removing ways have no difference.

The following code example shows how to remove protection from your document:

Specify Unrestricted Editable Regions

You can restrict editing of your document and at the same time allow changes to selected parts of it. So, anyone who opens your document will be able to access these unrestricted parts and make changes to the content.

Aspose.Words allows you to mark the parts that can be changed in your document using the StartEditableRange and EndEditableRange methods.

The following code example shows how to mark the whole document as read-only and specify editable regions in it:

You can also choose different document editing restrictions for different sections.

The following code example shows how to add a restriction for the entire document, and then remove the restriction for one of the sections:

FAQ

Q: How do I apply password protection to a document?
A: Use the Document.protect(ProtectionType, password) method, passing the desired ProtectionType and a string password. The password is stored in the document and is required to remove or change the protection.
Q: Can I remove protection without knowing the password?
A: Yes. Call Document.unprotect() without arguments; this removes protection regardless of the password. Use the overload unprotect(String password) only when you want to verify the password before removing protection.
Q: Which restriction type allows users to fill only form fields?
A: Use ProtectionType.ALLOW_ONLY_FORM_FIELDS when calling Document.protect. This lets users edit form fields while keeping the rest of the document read‑only.
Q: How can I create editable regions inside a read‑only document?
A: With a DocumentBuilder, call startEditableRange() before the region and endEditableRange() after it. Content inside this range can be edited even when the document is protected with ProtectionType.READ_ONLY.
Q: How can I check whether a document is currently protected?
A: Inspect the Document.getProtectionType() property. If it returns ProtectionType.NO_PROTECTION, the document is unprotected; otherwise it returns the active restriction type.

Java: Work with Digital Signatures in Java

Mon, 01 Jan 0001 00:00:00 +0000

A digital signature is a technological implementation of electronic signatures to sign documents and authenticate the signer to guarantee that a document has not been modified since it was signed. Each digital signature is unique for each signer because of following the PKI protocol to generate both public and private keys. Signing a document digitally means creating a signature using the signer’s private key where a mathematical algorithm is used to encrypt the generated hash.

Aspose.Words allows you to detect, count, or verify existing digital signatures, and also add a new signature to your document to find out any tampering in it. You can also remove all digital signatures from a document. Use the DigitalSignatureUtil class to work with digital signatures.

This article explains how to do all of the above to validate the authenticity and integrity of a digital document.

Note that you can access digital signatures of your document only when running the Java 6 version and above.

Try online

You can try this functionality with our Free online signature.

Supported Formats

Aspose.Words allows you to work with digital signatures on DOC, OOXML, and ODT documents and to sign the generated document in PDF or XPS format.

Limitations of Digital Signatures

The table below describes a few limitations that you may face while working with digital signatures through Aspose.Words, as well as some alternative options.

Limitation	Alternative option
Loss of digital signatures on a document after loading and saving it. Therefore, processing a document to a server may cause the loss of all digital signatures without a notice.	Check if a document has digital signatures and take the appropriate action if any are found. For example, send an alert to the clients informing them that the document they are uploading contains digital signatures that will be lost if it is processed.
Aspose.Words supports working with macros in a document. But Aspose.Words does not yet support digital signatures on macros.	Export the document back to any Word format, and use Microsoft Word to add a digital signature to macros.

Detect, Count, and Verify Digital Signatures

Aspose.Words allows you to detect digital signature in a document using the the DetectFileFormat method and the HasDigitalSignature property. It is worth noting that such a check will only detect the fact of the signature, but not its validity.

A document can be signed more than once, and this can be done by different users. To check the validity of digital signatures, you need to load them from the document using the LoadSignatures method and use the IsValid property. Also Aspose.Words allows you to count a set of all digital signatures within a document using the Count property.

All of this provides an efficient and safe way to check a document for signatures before processing it.

The following code example shows how to detect the presence of digital signatures and verify them:

Create a Digital Signature

To create a digital signature, you will require to load a signing certificate that confirms identity. When you send a digitally signed document, you also send your certificate and public key.

Aspose.Words allows you to create X.509 certificate, a digital certificate that uses the internationally accepted X.509 PKI standard to verify that a public key belongs to the signer included inside the certificate. To do this, use the Create method within the CertificateHolder class.

The next sections explain how to add a digital signature, signature line, and how to sign a generated PDF document.

Sign a Document

Aspose.Words allows you to sign a DOC, DOCX, or ODT document digitally using the Sign method and SignOptions properties.

The following code example shows how to sign documents using a certificate holder and sign options:

Add a Signature Line

A signature line is a visual representation of a digital signature in a document. Aspose.Words allows you to insert a signature line using the DocumentBuilder.InsertSignatureLine method. You can also set the parameters for this representation using the SignatureLineOptions class.

For example, the picture below shows how valid and invalid signatures can be displayed.

Also, if a document contains a signature line and no digital signature, there is a feature to ask the user to add a signature.

The following code example shows how to sign a document with a personal certificate and a specific signature line:

Sign a Generated PDF Document

Aspose.Words allows you to sign and get all details of a PDF document using the PdfDigitalSignatureDetails properties.

The following code example shows how to sign a generated PDF:

The picture below demonstrates that the generated PDF document is opened in Adobe Acrobat and the digital signature is verified as present and valid.

Retrieve the Digital Signature Value

Aspose.Words also provides the ability to retrieve the digital signature value from a digitally signed document as a byte array using the SignatureValue property.

The following code example shows how to obtain the digital signature value as a byte array from a document:

Remove Digital Signatures

Aspose.Words allows you to remove all digital signatures from a signed document using the RemoveAllSignatures method.

The following code example shows how to load and remove digital signatures from a document:

Note that you can not remove only one digital signature within your document.

FAQ

Q: Do I need a licensed copy of Aspose.Words to use digital signature features?
A: Yes. Digital signature functionality is fully available only with a valid Aspose.Words license. In evaluation mode the library works, but certain features may be limited or watermarked.
Q: Can I remove a single digital signature from a document?
A: No. Aspose.Words can only remove all signatures at once using RemoveAllSignatures. Individual signature removal is not supported.
Q: Is it possible to sign a PDF that was generated from a Word document?
A: Yes. After generating the PDF, use DigitalSignatureUtil.Sign with a CertificateHolder and appropriate SignOptions to apply a digital signature to the PDF.