MessageDecryptor Class

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The MessageDecryptor class decrypts data that is stored in the PKCS#7 format.

Syntax

secureblackbox.MessageDecryptor

Remarks

PKCS#7 (Public Key Cryptography Standard #7) is a common format used to store encrypted and signed data. It is used by a variety of protocols, including S/MIME and CMS.

MessageDecryptor is capable of decrypting encrypted PKCS#7 data stored in EnvelopedData (asymmetric encryption) and EncryptedData (symmetric encryption) subformats. RSA and ECDH key wrapping and all popular symmetric encryption algorithms are supported.

Setting up and using MessageDecryptor is easy:

• Set up your source and destination via InputFile (InputBytes) and OutputFile (OutputBytes) properties.
• For certificate-based (asymmetric) encryption, put the decryption certificate (with its private key included) to the Certificates collection.
• For key-based (symmetric) encryption, assign the symmetric key to Key property. Note: you can find out whether asymmetric or symmetric encryption was used on the input message using the CheckEncryptionType method.
• Call Decrypt to execute the operation.

Note that MessageDecryptor only works with binary PKCS#7-compliant encrypted messages. For processing encrypted S/MIME emails, see MailReader. For decrypting PGP messages, see PGPReader. For raw symmetric encryption, see SymmetricCrypto. For processing XML-ENC messages, see XMLDecryptor. MessageDecryptor decryptor = new MessageDecryptor(); // Select the file which contains the message that will be decrypted decryptor.setInputFile("encryptedMessage.bin"); // Select the file where the decrypted message will be written decryptor.setOutputFile("decryptedMessage.txt"); // Providing the certificate with its private key to decrypt data CertificateList certificateList = new CertificateList(); certificateList.add(new Certificate("cert.pfx","password")); decryptor.setCertificates(certificateList); decryptor.decrypt(); // Decrypt

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.

CertificateIndex Property (MessageDecryptor Class)

The index of certificate that was used to decrypt the message.

Syntax

public int getCertificateIndex();

Default Value

-1

Remarks

This property contains the index of certificate (one of those residing in Certificates collection) that was used to decrypt the message.

This property is read-only.

Certificates Property (MessageDecryptor Class)

A collection of certificates that can be used for message decryption.

Syntax

public CertificateList getCertificates();
public void setCertificates(CertificateList certificates);

Remarks

Use this collection to provide certificates that should be attempted to decrypt the message. The certificates can be provided before calling the Decrypt method, or later from RecipientFound event handler.

Note that the certificates need to have a private key associated with them to be usable for decryption.

This property is not available at design time.

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

EncryptionAlgorithm Property (MessageDecryptor Class)

The symmetric cipher that was used to encrypt the data.

Syntax

public String getEncryptionAlgorithm();

Default Value

""

Remarks

This property contains the symmetric algorithm that the creator had used to encrypt the message.

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

EncryptionType Property (MessageDecryptor Class)

Specifies the kind of encrypted message to create.

Syntax

public int getEncryptionType();

Enumerated values:
  public final static int metUnknown = 0;
  public final static int metCertEncrypted = 1;
  public final static int metKeyEncrypted = 2;
  public final static int metCertEncryptedAndAuthenticated = 3;

Default Value

0

Remarks

Possible values:

This property is read-only.

ExternalCrypto Property (MessageDecryptor Class)

Provides access to external signing and DC parameters.

Syntax

public ExternalCrypto getExternalCrypto();

Remarks

Use this property to tune-up remote cryptography settings. SecureBlackbox supports two independent types of external cryptography: synchronous (based on the ExternalSign event) and asynchronous (based on the DC protocol and the DCAuth signing component).

This property is read-only.

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

FIPSMode Property (MessageDecryptor Class)

Reserved.

Syntax

public boolean isFIPSMode();
public void setFIPSMode(boolean FIPSMode);

Default Value

False

Remarks

This property is reserved for future use.

InputBytes Property (MessageDecryptor Class)

Use this property to pass the input to class in byte array form.

Syntax

public byte[] getInputBytes();
public void setInputBytes(byte[] inputBytes);

Remarks

Assign a byte array containing the data to be processed to this property.

This property is not available at design time.

InputFile Property (MessageDecryptor Class)

Path to the file containing the encrypted message.

Syntax

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

Default Value

""

Remarks

Use this property to provide a file containing the encrypted data.

InputStream Property (MessageDecryptor Class)

The stream containing the encrypted message.

Syntax

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

Default Value

null

Remarks

Use this property to provide a stream containing the encrypted message.

This property is not available at design time.

Key Property (MessageDecryptor Class)

The symmetric key to use for decryption.

Syntax

public byte[] getKey();
public void setKey(byte[] key);

Remarks

Use this property to provide the symmetric key to decrypt the data. This property is only applicable for processing data of EncryptedData subtype.

Assign this property before calling Decrypt.

This property is not available at design time.

OutputBytes Property (MessageDecryptor Class)

Use this property to read the output the class object has produced.

Syntax

public byte[] getOutputBytes();

Remarks

Read the contents of this property after the operation has completed to read the produced output. This property will only be set if the OutputFile and OutputStream properties had not been assigned.

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

OutputFile Property (MessageDecryptor Class)

Path to the file to save the decrypted data to.

Syntax

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

Default Value

""

Remarks

Use this property to specify the output file where the decrypted message should be saved.

OutputStream Property (MessageDecryptor Class)

The stream to save the decrypted data to.

Syntax

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

Default Value

null

Remarks

Use this property to provide the stream to save the decrypted message to.

This property is not available at design time.

SignedAttributes Property (MessageDecryptor Class)

Custom signature attributes that are covered by the electronic signature.

Syntax

public SignatureAttributeList getSignedAttributes();

Remarks

Signature attributes are used to store auxiliary information in the signature. Values included as signed attributes are covered by the signature.

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

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

UnsignedAttributes Property (MessageDecryptor Class)

Custom unsigned attributes included in the electronic signature.

Syntax

public SignatureAttributeList getUnsignedAttributes();

Remarks

Signature attributes are used to store auxiliary information in the signature. Values included as unsigned attributes are not covered by the signature and can be changed or removed without affecting the signature.

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

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

CheckEncryptionType Method (MessageDecryptor Class)

Determines the type of encrypted message in the supplied file.

Syntax

public int checkEncryptionType();

Remarks

Use this method to determine the kind of the signature stored in InputFile (InputStream).

Config Method (MessageDecryptor 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.

Decrypt Method (MessageDecryptor Class)

Attempts to decrypt an encrypted PKCS#7 message.

Syntax

public void decrypt();

Remarks

Call this method to attempt to decrypt the PKCS#7 encrypted data. This call supports EnvelopedData and EncryptedData subtypes on input.

Use InputFile or InputStream property to provide the data, and either Certificates or Key to supply the decryption key material.

When processing enveloped data, the class may fire RecipientFound event to report recipient information.

DoAction Method (MessageDecryptor Class)

Performs an additional action.

Syntax

public String doAction(String actionID, String actionParams);

Remarks

DoAction is a generic method available in every class. It is used to perform an additional action introduced after the product major release. The list of actions is not fixed, and may be flexibly extended over time.

The unique identifier (case insensitive) of the action is provided in the ActionID parameter.

ActionParams contains the value of a single parameter, or a list of multiple parameters for the action in the form of PARAM1=VALUE1;PARAM2=VALUE2;....

Common ActionIDs:

Reset Method (MessageDecryptor Class)

Resets the class settings.

Syntax

public void reset();

Remarks

Reset is a generic method available in every class.

Error Event (MessageDecryptor Class)

Information about errors during PKCS#7 message decryption.

Syntax

public class DefaultMessageDecryptorEventListener implements MessageDecryptorEventListener {
  ...
  public void error(MessageDecryptorErrorEvent e) {}
  ...
}

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

Remarks

The event is fired in case of exceptional conditions during message processing.

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

ExternalDecrypt Event (MessageDecryptor Class)

Handles remote or external decryption.

Syntax

public class DefaultMessageDecryptorEventListener implements MessageDecryptorEventListener {
  ...
  public void externalDecrypt(MessageDecryptorExternalDecryptEvent e) {}
  ...
}

public class MessageDecryptorExternalDecryptEvent {
  public String operationId;
  public String algorithm;
  public String pars;
  public String encryptedData;
  public String data; //read-write
}

Remarks

Assign a handler to this event if you need to delegate a low-level decryption operation to an external, remote, or custom decryption engine. The handler receives an encrypted value in the EncryptedData parameter, and is expected to decrypt it and place the decrypted value into the Data parameter.

OperationId provides a comment about the operation and its origin. It depends on the exact class being used, and may be empty. Algorithm specifies the encryption algorithm being used, and Pars contains algorithm-dependent parameters.

The class uses base16 (hex) encoding for the EncryptedData, Data, and Pars parameters. If your decryption engine uses a different input and output encoding, you may need to decode and/or encode the data before and/or after the decryption.

Sample data encoded in base16: a0dee2a0382afbb09120ffa7ccd8a152 - lower case base16 A0DEE2A0382AFBB09120FFA7CCD8A152 - upper case base16

Notification Event (MessageDecryptor Class)

This event notifies the application about an underlying control flow event.

Syntax

public class DefaultMessageDecryptorEventListener implements MessageDecryptorEventListener {
  ...
  public void notification(MessageDecryptorNotificationEvent e) {}
  ...
}

public class MessageDecryptorNotificationEvent {
  public String eventID;
  public String eventParam;
}

Remarks

The class fires this event to let the application know about some event, occurrence, or milestone in the class. For example, it may fire to report completion of the document processing. The list of events being reported is not fixed, and may be flexibly extended over time.

The unique identifier of the event is provided in the EventID parameter. EventParam contains any parameters accompanying the occurrence. Depending on the type of the class, the exact action it is performing, or the document being processed, one or both may be omitted.

RecipientFound Event (MessageDecryptor Class)

Fires to report a message addressee parameters.

Syntax

public class DefaultMessageDecryptorEventListener implements MessageDecryptorEventListener {
  ...
  public void recipientFound(MessageDecryptorRecipientFoundEvent e) {}
  ...
}

public class MessageDecryptorRecipientFoundEvent {
  public String issuerRDN;
  public byte[] serialNumber;
  public byte[] subjectKeyID;
  public boolean certFound;
}

Remarks

This event is fired for each addressee the message is encrypted for. It may fire several times in a row if the message is encrypted for more than one recipient.

The IssuerRDN, SerialNumber, and SubjectKeyID parameters to identify the recipient's certificate. CertFound indicates if the specified certificate has been located in Certificates collection. If it wasn't, you might want to look up the certificate manually, and add it to the collection inside the event handler.

Certificate Type

Encapsulates an individual X.509 certificate.

Remarks

This type keeps and provides access to X.509 certificate details.

Fields

Constructors

public Certificate( bytes,  startIndex,  count,  password);

public Certificate( certBytes,  certStartIndex,  certCount,  keyBytes,  keyStartIndex,  keyCount,  password);

public Certificate( bytes,  startIndex,  count);

public Certificate( path,  password);

public Certificate( certPath,  keyPath,  password);

public Certificate( path);

public Certificate( stream);

public Certificate( stream,  password);

public Certificate( certStream,  keyStream,  password);

public Certificate();

ExternalCrypto Type

Specifies the parameters of external cryptographic calls.

Remarks

External cryptocalls are used in a Distributed Cryptography (DC) subsystem, which allows the delegation of security operations to the remote agent. For instance, it can be used to compute the signature value on the server, while retaining the client's private key locally.

Fields

Constructors

public ExternalCrypto();

SignatureAttribute Type

Represents an attribute of a digital PKCS#7/CMS signature.

Remarks

Attributes store auxiliary information about the signed message, the signature, or the owner. Each attribute is a OID=Value pair.

Common attributes are signing time, a content type, a policy identifier, and a signature timestamp.

Fields

Constructors

public SignatureAttribute();

Config Settings (MessageDecryptor 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.

MessageDecryptor Config Settings

Base Config Settings

Trappable Errors (MessageDecryptor Class)

MessageDecryptor Errors