PDFEncrypt Class

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The PDFEncrypt class encrypts PDF documents.

Syntax

securepdf.PDFEncrypt

Remarks

As with signing, PDF encryption is part of the PDF format itself. It is used to prevent unauthorized access to documents and is performed using either an encryption password (known as password-based or symmetric encryption) or the intended document recipient's public X.509 certificate (known as certificate-based or asymmetric encryption). The PDFEncrypt class supports both encryption types.

The benefit of this encryption scheme as defined in the standard is that encrypted PDF documents are still valid PDF documents and can be handled by almost any PDF reader. Of course, this software will need to be able to decrypt such documents, but it can always reach the metadata (information about the document) and document structure.

Password-Based Encryption

In password-based encryption, the publishers and intended users of the document must know some secret key (a password), which is used both to protect the document and access the protected data. Once the document has been protected (encrypted), the password is required to get access to the document's contents. Although this method is straightforward and widely used for protecting PDF documents, the password must be passed from the publisher to the intended users, which presents a significant disadvantage.

The following code shows how to encrypt a PDF document with a user password: pdfencrypt.InputFile = "input.pdf"; pdfencrypt.OutputFile = "password_encrypted.pdf"; pdfencrypt.Password = "password"; pdfencrypt.Encrypt(); Owner passwords are also supported. Compared to user passwords, these passwords are used to protect the permissions (set via the Permissions property) that will be embedded into the document. For example, you may want to prevent the recipient from printing or editing the document. You can encrypt the document with an owner password by specifying the OwnerPassword configuration setting before calling the Encrypt method.

Certificate-Based Encryption

Certificate-based encryption uses X.509 digital certificates to encrypt data. This encryption type provides a higher level of security compared to password-based encryption, as it relies on cryptographic key pairs, making it more difficult for unauthorized users to gain access. It is often used in environments where secure and authenticated document exchange is critical. Encrypting with a certificate (as opposed to a password) ensures that only the intended recipient who possesses the corresponding private key can decrypt the PDF document.

The following code shows how to encrypt a PDF document with a certificate: pdfencrypt.InputFile = "input.pdf"; pdfencrypt.OutputFile = "cert_encrypted.pdf"; pdfencrypt.EncryptionCert = new Certificate(CertStoreTypes.cstPublicKeyFile, "C:/MyCerts/cert.cer", "", "*"); pdfencrypt.Encrypt(); When encrypting using either a password or certificate, set the EncryptionAlgorithm property to the desired encryption algorithm. As additional encryption options, you can also decide whether the document metadata will be encrypted and embed permissions into the document via the EncryptMetadata and Permissions properties respectively.

Property List

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The following is the full list of the properties of the class with short descriptions. Click on the links for further details.

Method List

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The following is the full list of the methods of the class with short descriptions. Click on the links for further details.

Event List

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The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.

Config Settings

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The following is a list of config settings for the class with short descriptions. Click on the links for further details.

EncryptionAlgorithm Property (PDFEncrypt Class)

The encryption algorithm to encrypt the PDF document with.

Syntax

public String getEncryptionAlgorithm();
public void setEncryptionAlgorithm(String encryptionAlgorithm);

Default Value

"AES256"

Remarks

This property is used to specify the encryption algorithm to encrypt the document with.

Possible values are:

• RC4
• AES128
• AES256

EncryptionCert Property (PDFEncrypt Class)

The encryption certificate.

Syntax

public Certificate getEncryptionCert();
public void setEncryptionCert(Certificate encryptionCert);

Remarks

This property is used to provide the certificate used for encryption. Note that this certificate need not have a private key associated with it, but the intended recipient of the encrypted document does.

Note: Encryption for multiple recipients is currently unsupported.

This property is not available at design time.

Please refer to the Certificate type for a complete list of fields.

EncryptMetadata Property (PDFEncrypt Class)

Whether to encrypt the document metadata.

Syntax

public boolean isEncryptMetadata();
public void setEncryptMetadata(boolean encryptMetadata);

Default Value

True

Remarks

This property indicates whether the document metadata will be encrypted when the Encrypt method is called. Metadata contains additional information about the document, such as its name and author.

InputData Property (PDFEncrypt Class)

A byte array containing the PDF document to process.

Syntax

public byte[] getInputData();
public void setInputData(byte[] inputData);

Remarks

This property is used to assign a byte array containing the PDF document to be processed.

This property is not available at design time.

InputFile Property (PDFEncrypt Class)

The PDF file to process.

Syntax

public String getInputFile();
public void setInputFile(String inputFile);

Default Value

""

Remarks

This property is used to provide a path to the PDF document to be processed.

OutputData Property (PDFEncrypt Class)

A byte array containing the PDF document after processing.

Syntax

public byte[] getOutputData();

Remarks

This property is used to read the byte array containing the produced output after the operation has completed. It will only be set if an output file and output stream have not been assigned via OutputFile and SetOutputStream respectively.

This property is read-only and not available at design time.

OutputFile Property (PDFEncrypt Class)

The path to a local file where the output will be written.

Syntax

public String getOutputFile();
public void setOutputFile(String outputFile);

Default Value

""

Remarks

This property is used to provide a path where the resulting PDF document will be saved after the operation has completed.

Overwrite Property (PDFEncrypt Class)

Whether or not the class should overwrite files.

Syntax

public boolean isOverwrite();
public void setOverwrite(boolean overwrite);

Default Value

False

Remarks

This property indicates whether or not the class will overwrite OutputFile, OutputData, or the stream set in SetOutputStream. If set to false, an error will be thrown whenever OutputFile, OutputData, or the stream set in SetOutputStream exists before an operation.

Password Property (PDFEncrypt Class)

The password to encrypt the document with.

Syntax

public String getPassword();
public void setPassword(String password);

Default Value

""

Remarks

This property is used to provide the user password for encryption. Though it may be different from OwnerPassword, most implementations use the same value for both.

Permissions Property (PDFEncrypt Class)

The document permissions associated with the encryption.

Syntax

public int getPermissions();
public void setPermissions(int permissions);

Default Value

0

Remarks

This property is used to specify the permissions protected by this encryption. The PDF specification expects applications to comply with these permissions when handling encrypted documents, but note that it is a policy-like requirement rather than an enforcement.

Its value should be provided as a bitmask of the following flags:

This property is not available at design time.

Close Method (PDFEncrypt Class)

Closes an opened PDF document.

Syntax

public void close();

Remarks

This method is used to close the previously opened document specified in InputFile, InputData, or SetInputStream. It should always be preceded by a call to the Open method.

Example: component.InputFile = "input.pdf"; component.Open(); // Some operation component.Close();

If any changes are made to the document, they will be saved automatically to OutputFile, OutputData, or the stream set in SetOutputStream when this method is called. To configure this saving behavior, set the SaveChanges configuration setting.

Config Method (PDFEncrypt Class)

Sets or retrieves a configuration setting.

Syntax

public String config(String configurationString);

Remarks

Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Encrypt Method (PDFEncrypt Class)

Encrypts a PDF document.

Syntax

public void encrypt();

Remarks

This method is used to encrypt the PDF document specified in InputFile, InputData, or SetInputStream. The document will be encrypted using EncryptionAlgorithm and either Password (for password-based encryption) or EncryptionCert (for certificate-based encryption), then saved in OutputFile, OutputData, or the stream set in SetOutputStream.

Example: pdfencrypt.InputFile = "input.pdf"; pdfencrypt.OutputFile = "encrypted.pdf"; pdfencrypt.Password = "password"; pdfencrypt.EncryptionAlgorithm = "AES256"; pdfencrypt.Encrypt(); Note: If the document is not already opened, this method will open it, perform the operation, then close it.

Encrypted Method (PDFEncrypt Class)

Checks whether a PDF document is encrypted.

Syntax

public boolean encrypted();

Remarks

This method is used to determine whether or not the document specified in InputFile, InputData, or SetInputStream is encrypted. It will return false if the document is pseudo-encrypted with an empty password.

Example: pdfencrypt.InputFile = "input.pdf"; if (!pdfencrypt.Encrypted()) { pdfencrypt.OutputFile = "encrypted.pdf"; // Set Password or EncryptionCert pdfencrypt.Encrypt(); } Note: If the document is not already opened, this method will open it, perform the operation, then close it.

Open Method (PDFEncrypt Class)

Opens a PDF document for processing.

Syntax

public void open();

Remarks

This method is used to open the document specified in InputFile, InputData, or SetInputStream before performing some operation on it, such as signing, updating, verifying signatures, or removing signatures. When finished, call Close to complete or discard the operation.

It is recommended to use this method (alongside Close) when performing multiple operations on the document at once.

Automatic Decryption Functionality

If this method is called on an encrypted document, the Password or RecipientInfo event will fire (depending on the encryption type) as a notification that the document must be decrypted before processing can continue.

Once the correct decryption material is supplied, the class will then attempt to decrypt the document automatically within this method. When this occurs, the decrypted content is kept in memory so that the document's encrypted status is preserved when it is saved later. Use the Decrypt method to save a decrypted copy of the document instead.

Reset Method (PDFEncrypt Class)

Resets the class.

Syntax

public void reset();

Remarks

This method is used to reset the class's properties and configuration settings to their default values.

SetInputStream Method (PDFEncrypt Class)

Sets the stream containing the PDF document to process.

Syntax

public void setInputStream(java.io.InputStream inputStream);

Remarks

This method is used to set the stream from which the class will read the PDF document to be processed. If an input stream is set before the class attempts to perform operations on the document, the class will read the data from the input stream instead of from the InputFile or InputData properties.

Note: It may be useful to additionally set the CloseInputStreamAfterProcessing configuration setting to true when using input streams.

SetOutputStream Method (PDFEncrypt Class)

Sets the stream to write the processed document to.

Syntax

public void setOutputStream(java.io.OutputStream outputStream);

Remarks

This method is used to set the stream to which the class will write the resulting PDF document. If an output stream is set before the class attempts to perform operations on the document, the class will write the data to the output stream instead of writing to OutputFile or populating OutputData.

Note: It may be useful to additionally set the CloseOutputStreamAfterProcessing configuration setting to true when using output streams.

Error Event (PDFEncrypt Class)

Fired when information is available about errors during data delivery.

Syntax

public class DefaultPDFEncryptEventListener implements PDFEncryptEventListener {
  ...
  public void error(PDFEncryptErrorEvent e) {}
  ...
}

public class PDFEncryptErrorEvent {
  public int errorCode;
  public String description;
}

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class throws an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Log Event (PDFEncrypt Class)

Fired once for each log message.

Syntax

public class DefaultPDFEncryptEventListener implements PDFEncryptEventListener {
  ...
  public void log(PDFEncryptLogEvent e) {}
  ...
}

public class PDFEncryptLogEvent {
  public int logLevel;
  public String message;
  public String logType;
}

Remarks

This event is fired once for each log message generated by the class. The verbosity is controlled by the LogLevel configuration setting.

The LogLevel parameter indicates the detail level of the message. Possible values are:

The Message parameter is the log message.

The LogType parameter identifies the type of log entry. Possible values are:

• CertValidator
• Font
• HTTP
• PDFInvalidSignature
• PDFRevocationInfo
• Timestamp
• TSL

Password Event (PDFEncrypt Class)

Fired when the class detects that the PDF document is encrypted with a password.

Syntax

public class DefaultPDFEncryptEventListener implements PDFEncryptEventListener {
  ...
  public void password(PDFEncryptPasswordEvent e) {}
  ...
}

public class PDFEncryptPasswordEvent {
  public boolean available;
  public boolean cancel; //read-write
}

Remarks

This event is fired during document processing to report that the document is encrypted with a password. It may be used to supply the correct decryption password to the Password property.

The Available parameter indicates whether the decryption password is already available to the class or still needs to be set. If this parameter is set to false, the correct password must be provided for the decryption attempt to succeed.

The Cancel parameter determines whether the class will stop firing this event to request a password.

RecipientInfo Event (PDFEncrypt Class)

Fired for each recipient certificate of the encrypted PDF document.

Syntax

public class DefaultPDFEncryptEventListener implements PDFEncryptEventListener {
  ...
  public void recipientInfo(PDFEncryptRecipientInfoEvent e) {}
  ...
}

public class PDFEncryptRecipientInfoEvent {
  public String issuer;
  public String serialNumber;
  public String subjectKeyIdentifier;
  public boolean available;
  public boolean cancel; //read-write
}

Remarks

This event is fired during document processing for each recipient certificate that the document has been encrypted for (if applicable). It may be used to identify the certificate(s) to load and supply to the DecryptionCert property.

The Issuer parameter specifies the subject of the issuer certificate.

The SerialNumber parameter specifies the serial number of the encryption certificate.

The SubjectKeyIdentifier parameter specifies the X.509 subjectKeyIdentifier extension value of the encryption certificate, encoded as a hex string.

The Available parameter indicates whether the decryption certificate is already available to the class or still needs to be set. If this parameter is set to false, the correct certificate must be provided for the decryption attempt to succeed.

The Cancel parameter determines whether the class will stop firing this event to request a certificate.

Note: The document may be encrypted with more than one certificate (or have "more than one recipient"), in which case each certificate will cause its own invocation of this event.

Certificate Type

This is the digital certificate being used.

Remarks

This type describes the current digital certificate. The certificate may be a public or private key. The fields are used to identify or select certificates.

Fields

Constructors

public Certificate();

public Certificate( certificateFile);

public Certificate( encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

Config Settings (PDFEncrypt Class)

The class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

PDFEncrypt Config Settings

Base Config Settings

Trappable Errors (PDFEncrypt Class)

PDFEncrypt Errors

PDF Errors

Parsing Errors