PGPWriter Class

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The PGPWriter class protects data using PGP keys.

Syntax

secureblackbox.PGPWriter

Remarks

PGPWriter lets you encrypt, sign, armor, and compress files and data in accordance with PGP standard.

PGPWriter supports all modern PGP keys and formats, from last-century PGP 2.6.x to the state-of-the art PGP 6. Single- and multi-file, as well as for-your-eyes-only PGP containers are supported.

Important note. Starting with SecureBlackbox 2024, PGPWriter and PGPReader fully support PGPv6 specification. Introduction of PGPv6 comes with certain upgrade of the default security settings used in these components. Although any projects that rely on earlier SecureBlackbox versions are likely to migrate to SecureBlackbox 2024 without any issues, the mentioned upgrade in security defaults may make protected files that your software produces incompatible with the software on the other end (particularly if that software is on the older scale of age).

While every care was taken to preserve interoperability wherever possible, some security settings could not be upgraded without the risk of affecting it. That said, none of the functionality was removed, so if you start encountering compatibility problems after upgrading to SecureBlackbox 2024, there is always a way back to the 'working' settings.

Please see the section at the end of this topic for the summary of differences between SBB 2022 and SBB 2024 in terms of security settings.

Preparing keys

Encryption and signing in PGP is done with asymmetric keys. Keys are normally stored in files called keyrings. More often that not they consist of a pair of files: a public keyring (e.g pubring.pkr) and a secret keyring (secring.skr), although there are exceptions. Sometimes, recipients provide senders with standalone public keys that they want them to encrypt data with.

Whichever form your keyring takes, use PGPKeyring to load it first. It is recommended to load all the keyring files that you have to make sure you have all the keys loaded. PGPKeyring can detect duplicate keys, so don't worry about loading the same key twice - any duplicates will be neatly merged together into one key object. PGPKeyring keyring = new PGPKeyring(); keyring.ImportFromFile("pubring.pkr"); keyring.ImportFromFile("secring.skr");

Now that you've loaded the keyring files, it is time to identify the key(s) that you need to use and pass them to PGPWriter. The best way to do it may differ between environments. Among the options available are iterating over the whole Keys collection of the PGPKeyring object, using its Select method to filter keys by UserID, or just using the whole set of keys if loading a standalone key.

Whichever way you choose to select the keys, there are a few considerations that need to be taken into account. First, keep in mind that the Keys collection contains both the primary keys and their subkeys. PGP is very flexible on how the 'key trees' can be formed, which means that keys from different vendors may use different key tree patterns.

The most commonly used key tree pattern is where the primary key is sign-only, and its only subkey is encrypt-only. However, there can be different arrangements: for example, there can be more than one subkey in the key tree, or the primary key can be used for encryption alongside the subkey. Please take extra care to figure out what kind of key tree you are dealing with, and select appropriate keys with that structure in mind.

The following properties of the key objects might be helpful in filtering the keys by their purpose:

• CanEncrypt and CanSign properties of the key objects provide information on the key algorithm capabilities. If you are looking to encrypt data, a key or subkey with its CanEncrypt set to false can be safely excluded from the candidate list.
• IsPublic and IsSecret specify whether the key contains the public or private part of the keypair. If you are looking to sign data, keys with their IsSecret set to false can be discarded, as signing can only be done with private keys.
• ValidTo specifies the key's expiration date. Expired keys can be ignored. This is often useful where the vendor updates their keys by issuing fresh subkeys while keeping older ones in the key tree.

Now that you've identified the appropriate keys, you can add them to the respective collections of PGPWriter: EncryptingKeys and SigningKeys. However, there is one important catch that you need to keep in mind.

Private PGP keys are typically protected with passwords. To be able to use them, you need to provide the valid password to the component. You can do that in one of the following two ways:

• By assigning the password to Passphrase property. You can check whether the provided passphrase is valid using the PassphraseValid property.
• By subscribing to KeyPassphraseNeeded event and providing the password from within the event handler. This event will be fired for each private key for which no valid password was provided.

Configuring protection

Protection configuration if quite straightforward and encompasses adjustment of the following settings:

• Provide the input data via the InputFile (or InputBytes) property.
• Provide the destination in OutputFile. If no output destination is provided, the output will be generated in OutputBytes.
• Provide the filename for the file being protected in Filename.
• Set EncryptionAlgorithm and HashAlgorithm, as (and if) required.
• Set Compress to true if you would like the input compressed. You can tune up compression further with CompressionAlgorithm and CompressionLevel settings.
• Set Armor if you would like the output to be base64-armored.

Protecting the file

You are all set now. Call the appropriate protection method to proceed with the file protection:

• Encrypt: encrypt the input data with all the public keys provided in EncryptingKeys.
• Sign: sign the input data with all the private keys provided in SigningKeys.
• EncryptAndSign: encrypt the input data with all the public keys provided in EncryptingKeys and sign it with all the private keys provided in SigningKeys.
• ClearTextSign: sign the input data in email-like way with all the private keys provided in SigningKeys. This method only works with textual ASCII data.

Writer.InputFile = "C:\files\input.txt"; Writer.OutputFile = "C:\files\output.pgp"; Writer.Filename = "input.txt"; Writer.EncryptionAlgorithm = "AES256"; Writer.SigningKeys.Add(Keyring.Keys[0]); Writer.EncryptingKeys.Add(Keyring.Keys[1]); Writer.EncryptAndSign();

Summary of changes in security defaults between SBB 2022 and SBB 2024

Protection type.

While the set of Protection elements stayed the same, the meaning of the elements changed (deflated):

• pptNone: stayed the same
• pptLow in version 2024 corresponds to the protection settings that used to be marked as pptNormal in version 2022.
• pptNormal in version 2024 corresponds to the protection settings that used to be marked as pptHigh in version 2022.
• pptHigh has no equivalent level of protection in version 2022. It corresponds to strong authenticated encryption (AEAD) and KDF introduced in PGP v5 and v6.

Cryptographic algorithms

The default value of HashAlgorithm has changed from SHA1 (SBB 2022) to SHA256 (SBB 2024). The default value of EncryptionAlgorithm changed from CAST5 (SBB 2022) to AES128 (SBB 2024).

This change applies throughout all the PGP components.

UseNewFeatures configuration setting

In SBB 2022 and earlier versions the meaning behind this configuration setting was about enforcing 'new' RFC4880 features, such as MDC packets for authenticated encryption and one-pass signatures.

In SBB 2024, this setting regained its 'new' connotation and applies to PGP v6 features such as AEAD encryption. Use this setting with care as older PGP implementations may struggle to process files protected with PGP v6 features.

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.

Armor Property (PGPWriter Class)

Specifies whether the data should be armored.

Syntax

public boolean isArmor();
public void setArmor(boolean armor);

Default Value

False

Remarks

Switch this property on to armor the protected data by encoding it in base64 and enveloping with BEGIN and END markings.

ArmorBoundary Property (PGPWriter Class)

A boundary to put around the base64 armor.

Syntax

public String getArmorBoundary();
public void setArmorBoundary(String armorBoundary);

Default Value

""

Remarks

Use this property to specify the boundary to put around the base64 armor. If set to 'PGP MESSAGE', the armored data will be enveloped with '-----BEGIN PGP MESSAGE-----' and '-----END PGP MESSAGE-----' lines.

This property only makes sense if Armor is set True.

ArmorHeaders Property (PGPWriter Class)

Additional headers to include with the armored message.

Syntax

public String getArmorHeaders();
public void setArmorHeaders(String armorHeaders);

Default Value

""

Remarks

Use this property to specify additional headers to be included with the armored message.

Assign this property with a multi-line text, with each line being of "header: value" form (without quotes).

Compress Property (PGPWriter Class)

Whether to compress the data before encrypting it.

Syntax

public boolean isCompress();
public void setCompress(boolean compress);

Default Value

False

Remarks

Set this property to True to compress the data before encryption. Use CompressionAlgorithm and CompressionLevel to tune up compression parameters.

CompressionAlgorithm Property (PGPWriter Class)

The compression algorithm to use.

Syntax

public String getCompressionAlgorithm();
public void setCompressionAlgorithm(String compressionAlgorithm);

Default Value

"Uncompressed"

Remarks

Use this property to specify the compression algorithm to use before encrypting the data. This property only makes sense if Compress is True.

CompressionLevel Property (PGPWriter Class)

The compression level to use.

Syntax

public int getCompressionLevel();
public void setCompressionLevel(int compressionLevel);

Default Value

0

Remarks

Use this property to specify the compression level, from 1 (fastest) to 9 (best).

EncryptingKeys Property (PGPWriter Class)

The keys to be used for data encryption.

Syntax

public PGPKeyList getEncryptingKeys();
public void setEncryptingKeys(PGPKeyList encryptingKeys);

Remarks

Use this property to set the keys to encrypt the message for. You only need public keys to encrypt data.

This property is not available at design time.

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

EncryptionAlgorithm Property (PGPWriter Class)

A symmetric algorithm to use for data encryption.

Syntax

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

Default Value

"AES128"

Remarks

Use this property to specify a symmetric algorithm to use for data encryption.

ExternalCrypto Property (PGPWriter 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.

FileName Property (PGPWriter Class)

Specifies the name of the file being protected.

Syntax

public String getFileName();
public void setFileName(String fileName);

Default Value

""

Remarks

Use this property to set the name of the file being protected, such as 'document.txt'. If Filename is empty or its value is "_CONSOLE", the data will be protected for-your-eyes-only, meaning the decryptor will only be able to read it on their screen, but not save.

FIPSMode Property (PGPWriter Class)

Reserved.

Syntax

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

Default Value

False

Remarks

This property is reserved for future use.

HashAlgorithm Property (PGPWriter Class)

The hash algorithm to use for signing.

Syntax

public String getHashAlgorithm();
public void setHashAlgorithm(String hashAlgorithm);

Default Value

""

Remarks

Use this property to specify the hash algorithm to use for calculating signatures.

InputBytes Property (PGPWriter 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 (PGPWriter Class)

Provides a filename of a file to process.

Syntax

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

Default Value

""

Remarks

Use this property to provide a path to the file to be encrypted and/or signed.

If you assign this property with a directory name, all the files contained in the directory will be packed into the resulting protected file.

InputIsText Property (PGPWriter Class)

Whether the input data is text.

Syntax

public boolean isInputIsText();
public void setInputIsText(boolean inputIsText);

Default Value

False

Remarks

Set this property to true to indicate that the supplied data should be treated as text.

InputStream Property (PGPWriter Class)

A stream containing the input to process.

Syntax

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

Default Value

null

Remarks

Use this property to feed the input data to the component from a stream object.

This property is not available at design time.

OutputBytes Property (PGPWriter 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 (PGPWriter Class)

The file where the encrypted and/or signed data will be saved.

Syntax

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

Default Value

""

Remarks

Use this property to provide a path to the file where the class should store the encrypted and/or signed data.

OutputStream Property (PGPWriter Class)

The stream where the encrypted and/or signed data will be saved.

Syntax

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

Default Value

null

Remarks

Use this property to specify the stream to take the resulting encrypted and/or signed data.

This property is not available at design time.

Passphrase Property (PGPWriter Class)

The encryption password.

Syntax

public String getPassphrase();
public void setPassphrase(String passphrase);

Default Value

""

Remarks

Use this property to provide the encryption password. If an encryption password is used, no key will be needed to decrypt the data.

Profile Property (PGPWriter Class)

Specifies a pre-defined profile to apply when creating the signature.

Syntax

public String getProfile();
public void setProfile(String profile);

Default Value

""

Remarks

Advanced signatures come in many variants, which are often defined by parties that needs to process them or by local standards. SecureBlackbox profiles are sets of pre-defined configurations which correspond to particular signature variants. By specifying a profile, you are pre-configuring the component to make it produce the signature that matches the configuration corresponding to that profile.

Protection Property (PGPWriter Class)

Specifies a password protection level.

Syntax

public int getProtection();
public void setProtection(int protection);

Enumerated values:
  public final static int pptNone = 0;
  public final static int pptLow = 1;
  public final static int pptNormal = 2;
  public final static int pptHigh = 3;

Default Value

0

Remarks

This property specifies the complexity of key derivation function for password-protected documents.

Allowed values:

SigningKeys Property (PGPWriter Class)

The keys to be used for signing.

Syntax

public PGPKeyList getSigningKeys();
public void setSigningKeys(PGPKeyList signingKeys);

Remarks

Use this property to set the keys to sign the message with. The keys need to contain their secret compound.

In most cases you will also need to supply a passphrase for the chosen signing keys. Use this by subscribing to KeyPassphraseNeeded event, or setting the Passphrase property of the relevant key object.

This property is not available at design time.

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

Timestamp Property (PGPWriter Class)

The date and time of the last modification of the protected data file (in UTC).

Syntax

public String getTimestamp();
public void setTimestamp(String timestamp);

Default Value

""

Remarks

Use this property to set a timestamp for the data being protected.

ClearTextSign Method (PGPWriter Class)

Creates a cleartext signature over the provided data.

Syntax

public void clearTextSign();

Remarks

Call this method to create a cleartext signature over the provided data buffer (InputBytes). Only textual data can be signed in cleartext.

Pass the signing key(s) via SigningKeys property.

Config Method (PGPWriter 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.

DoAction Method (PGPWriter 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:

Encrypt Method (PGPWriter Class)

Encrypts data.

Syntax

public void encrypt();

Remarks

Use this method to encrypt input data from a byte array (InputBytes), a file (InputFile) or a stream (InputStream) and get the protected message in another byte array (OutputBytes), or another file (OutputFile), or another stream (OutputStream).

Specify encryption keys in EncryptingKeys property, and/or encryption password via Passphrase property.

EncryptAndSign Method (PGPWriter Class)

Encrypts and signs data.

Syntax

public void encryptAndSign();

Remarks

Use this method to encrypt and sign a byte array (InputBytes), a file (InputFile) or a stream (InputStream) and get the protected message in another byte array (OutputBytes), or another file (OutputFile), or another stream (OutputStream).

Specify encryption keys in EncryptingKeys property, and/or encryption password via Passphrase property. Use SigningKeys to provide the signing keys.

Please note that you might need to provide a passphrase to decrypt your signing key. This can be done via KeyPassphraseNeeded event, or by assigning the passphrase to the key object's Passphrase property.

Reset Method (PGPWriter Class)

Resets the class settings.

Syntax

public void reset();

Remarks

Reset is a generic method available in every class.

Sign Method (PGPWriter Class)

Signs data.

Syntax

public void sign(boolean detached);

Remarks

Use this method to sign a byte array (InputBytes), a file (InputFile) or a stream (InputStream) and get the signed message in another byte array (OutputBytes), or another file (OutputFile), or another stream (OutputStream).

Use SigningKeys to provide the signing keys.

Please note that you might need to provide a passphrase to decrypt your signing key. This can be done via KeyPassphraseNeeded event, or by assigning the passphrase to the key object's Passphrase property.

Error Event (PGPWriter Class)

Information about errors during PGP encryption.

Syntax

public class DefaultPGPWriterEventListener implements PGPWriterEventListener {
  ...
  public void error(PGPWriterErrorEvent e) {}
  ...
}

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

Remarks

The event is fired in case of exceptional conditions during data encryption or signing.

ErrorCode contains an error code and Description contains a textual description of the error.

ExternalSign Event (PGPWriter Class)

Handles remote or external signing initiated by the SignExternal method or other source.

Syntax

public class DefaultPGPWriterEventListener implements PGPWriterEventListener {
  ...
  public void externalSign(PGPWriterExternalSignEvent e) {}
  ...
}

public class PGPWriterExternalSignEvent {
  public String operationId;
  public String hashAlgorithm;
  public String pars;
  public String data;
  public String signedData; //read-write
}

Remarks

Assign a handler to this event if you need to delegate a low-level signing operation to an external, remote, or custom signing engine. Depending on the settings, the handler will receive a hashed or unhashed value to be signed.

The event handler must pass the value of Data to the signer, obtain the signature, and pass it back to the class via the SignedData parameter.

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

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

A sample MD5 hash encoded in base16: a0dee2a0382afbb09120ffa7ccd8a152 - lower case base16 A0DEE2A0382AFBB09120FFA7CCD8A152 - upper case base16

A sample event handler that uses the .NET RSACryptoServiceProvider class may look like the following: signer.OnExternalSign += (s, e) => { var cert = new X509Certificate2("cert.pfx", "", X509KeyStorageFlags.Exportable); var key = (RSACryptoServiceProvider)cert.PrivateKey; var dataToSign = e.Data.FromBase16String(); var signedData = key.SignHash(dataToSign, "2.16.840.1.101.3.4.2.1"); e.SignedData = signedData.ToBase16String(); };

KeyPassphraseNeeded Event (PGPWriter Class)

Requests a key protection password from the application.

Syntax

public class DefaultPGPWriterEventListener implements PGPWriterEventListener {
  ...
  public void keyPassphraseNeeded(PGPWriterKeyPassphraseNeededEvent e) {}
  ...
}

public class PGPWriterKeyPassphraseNeededEvent {
  public String keyID;
  public String userID;
  public boolean mainKey;
  public String passphrase; //read-write
  public boolean skip; //read-write
}

Remarks

The class fires this event to request a secret key passphrase from the application. Note that this event asks for a key protection passphrase rather than a message protection passphrase. The class fires it when it attempts to use a secret key to sign the data.

This event is fired for every protected secret key residing in SigningKeys. KeyID specifies the key for which the password is requested, and UserID identifies its user. MainKey tells whether the key is a master key or a subkey.

The handler should provide password via the Passphrase parameter, or set Skip to True to skip this key.

For each key KeyPassphraseNeeded is called in a loop until the correct password is provided or the maximum number of password attempts reached.

Notification Event (PGPWriter Class)

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

Syntax

public class DefaultPGPWriterEventListener implements PGPWriterEventListener {
  ...
  public void notification(PGPWriterNotificationEvent e) {}
  ...
}

public class PGPWriterNotificationEvent {
  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.

Progress Event (PGPWriter Class)

Reports the progress of the decryption operation.

Syntax

public class DefaultPGPWriterEventListener implements PGPWriterEventListener {
  ...
  public void progress(PGPWriterProgressEvent e) {}
  ...
}

public class PGPWriterProgressEvent {
  public long current;
  public long total;
  public boolean cancel; //read-write
}

Remarks

The class fires this event repeatedly to report the progress of the file protection operation.

Current indicates the amount of processed data in bytes, and Total is the total number of bytes to be processed. Use Cancel to terminate the protection process.

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();

PGPKey Type

This container represents a PGP key.

Remarks

OpenPGP standard supports several types of keys. In our days, a typical OpenPGP keypair actually consists of two cryptographic keys: a primary key and a subkey. The primary key is normally used for signing, while the subkey is used for encryption.

While it is typical for PGP environments to use a primary key/subkey bundle, this is not a must. Sometimes you may come across standalone keys (mainly when dealing with older implementations), as well as whole key trees, each of those carrying a bunch of differently-purposed subkeys bound to the same primary key.

Algorithm-wise, OpenPGP keys also differ. Generally speaking, OpenPGP supports the following public key algorithms: RSA, Elgamal (often incorrectly referred to as DH), DSA, ECDH and ECDSA. When it comes to primary key/subkey bundles, DSA/Elgamal, RSA/RSA and ECDSA/ECDH pairs are typically used. Although there's no restriction on algorithm bundles, and, e.g. a ECDSA/Elgamal key bundle is perfectly possible, such combination is rarely used in practice.

A typical OpenPGP key is associated with some kind of user ID (Username). It is normally represented with a user's e-mail address, while in theory can be any piece of text. The secret part of the OpenPGP keypair is protected with a password (Passphrase).

Fields

Constructors

public PGPKey();

public PGPKey( fileName);

Config Settings (PGPWriter 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.

PGPWriter Config Settings

Base Config Settings

Trappable Errors (PGPWriter Class)

PGPWriter Errors