MessageDecryptor Component

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

Syntax

TsbxMessageDecryptor

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 component 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 component 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 component 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 component with short descriptions. Click on the links for further details.

CertificateIndex Property (MessageDecryptor Component)

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

Syntax

property CertificateIndex: Integer read get_CertificateIndex;

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 Component)

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

Syntax

property Certificates: TsbxCertificateList read get_Certificates write set_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 Component)

The symmetric cipher that was used to encrypt the data.

Syntax

property EncryptionAlgorithm: String read get_EncryptionAlgorithm;

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 Component)

Specifies the kind of encrypted message to create.

Syntax

property EncryptionType: TsbxMessageEncryptionTypes read get_EncryptionType;

TsbxMessageEncryptionTypes = (
  metUnknown,
  metCertEncrypted,
  metKeyEncrypted,
  metCertEncryptedAndAuthenticated
);

Default Value

metUnknown

Remarks

Possible values:

This property is read-only.

ExternalCrypto Property (MessageDecryptor Component)

Provides access to external signing and DC parameters.

Syntax

property ExternalCrypto: TsbxExternalCrypto read get_ExternalCrypto;

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 Component)

Reserved.

Syntax

property FIPSMode: Boolean read get_FIPSMode write set_FIPSMode;

Default Value

false

Remarks

This property is reserved for future use.

InputBytes Property (MessageDecryptor Component)

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

Syntax

property InputBytes: TBytes read get_InputBytes write set_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 Component)

Path to the file containing the encrypted message.

Syntax

property InputFile: String read get_InputFile write set_InputFile;

Default Value

''

Remarks

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

Key Property (MessageDecryptor Component)

The symmetric key to use for decryption.

Syntax

property Key: TBytes read get_Key write set_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 Component)

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

Syntax

property OutputBytes: TBytes read get_OutputBytes;

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 Component)

Path to the file to save the decrypted data to.

Syntax

property OutputFile: String read get_OutputFile write set_OutputFile;

Default Value

''

Remarks

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

SignedAttributes Property (MessageDecryptor Component)

Custom signature attributes that are covered by the electronic signature.

Syntax

property SignedAttributes: TsbxSignatureAttributeList read get_SignedAttributes;

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 Component)

Custom unsigned attributes included in the electronic signature.

Syntax

property UnsignedAttributes: TsbxSignatureAttributeList read get_UnsignedAttributes;

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 Component)

Determines the type of encrypted message in the supplied file.

Syntax

function CheckEncryptionType(): Integer;

Remarks

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

Config Method (MessageDecryptor Component)

Sets or retrieves a configuration setting.

Syntax

function Config(ConfigurationString: String): String;

Remarks

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

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, 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 Component)

Attempts to decrypt an encrypted PKCS#7 message.

Syntax

procedure 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 component may fire RecipientFound event to report recipient information.

DoAction Method (MessageDecryptor Component)

Performs an additional action.

Syntax

function DoAction(ActionID: String; ActionParams: String): String;

Remarks

DoAction is a generic method available in every component. 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 Component)

Resets the component settings.

Syntax

procedure Reset();

Remarks

Reset is a generic method available in every component.

Error Event (MessageDecryptor Component)

Information about errors during PKCS#7 message decryption.

Syntax

type TErrorEvent = procedure (
  Sender: TObject;
  ErrorCode: Integer;
  const Description: String
) of Object;

property OnError: TErrorEvent read FOnError write FOnError;

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 Component)

Handles remote or external decryption.

Syntax

type TExternalDecryptEvent = procedure (
  Sender: TObject;
  const OperationId: String;
  const Algorithm: String;
  const Pars: String;
  const EncryptedData: String;
  var Data: String
) of Object;

property OnExternalDecrypt: TExternalDecryptEvent read FOnExternalDecrypt write FOnExternalDecrypt;

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 component being used, and may be empty. Algorithm specifies the encryption algorithm being used, and Pars contains algorithm-dependent parameters.

The component 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 Component)

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

Syntax

type TNotificationEvent = procedure (
  Sender: TObject;
  const EventID: String;
  const EventParam: String
) of Object;

property OnNotification: TNotificationEvent read FOnNotification write FOnNotification;

Remarks

The component fires this event to let the application know about some event, occurrence, or milestone in the component. 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 component, the exact action it is performing, or the document being processed, one or both may be omitted.

RecipientFound Event (MessageDecryptor Component)

Fires to report a message addressee parameters.

Syntax

type TRecipientFoundEvent = procedure (
  Sender: TObject;
  const IssuerRDN: String;
  const SerialNumber: TBytes;
  const SubjectKeyID: TBytes;
  CertFound: Boolean
) of Object;

property OnRecipientFound: TRecipientFoundEvent read FOnRecipientFound write FOnRecipientFound;

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

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constructor Create();

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

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constructor Create();

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

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constructor Create();

Config Settings (MessageDecryptor Component)

The component 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 component, access to these internal properties is provided through the Config method.

MessageDecryptor Config Settings

Base Config Settings

Trappable Errors (MessageDecryptor Component)

MessageDecryptor Errors