PGP DataFormat

Available as of Camel version 2.9

The PGP Data Format integrates the Java Cryptographic Extension into Camel, allowing simple and flexible encryption and decryption of messages using Camel’s familiar marshall and unmarshal formatting mechanism. It assumes marshalling to mean encryption to cyphertext and unmarshalling to mean decryption back to the original plaintext. This data format implements only symmetric (shared-key) encryption and decyption.

PGPDataFormat Options

The PGP dataformat supports 15 options, which are listed below.

Name Default Java Type Description

keyUserid

String

The user ID of the key in the PGP keyring used during encryption. Can also be only a part of a user ID. For example, if the user ID is Test User then you can use the part Test User or to address the user ID.

signatureKeyUserid

String

User ID of the key in the PGP keyring used for signing (during encryption) or signature verification (during decryption). During the signature verification process the specified User ID restricts the public keys from the public keyring which can be used for the verification. If no User ID is specified for the signature verficiation then any public key in the public keyring can be used for the verification. Can also be only a part of a user ID. For example, if the user ID is Test User then you can use the part Test User or to address the User ID.

password

String

Password used when opening the private key (not used for encryption).

signaturePassword

String

Password used when opening the private key used for signing (during encryption).

keyFileName

String

Filename of the keyring; must be accessible as a classpath resource (but you can specify a location in the file system by using the file: prefix).

signatureKeyFileName

String

Filename of the keyring to use for signing (during encryption) or for signature verification (during decryption); must be accessible as a classpath resource (but you can specify a location in the file system by using the file: prefix).

signatureKeyRing

String

Keyring used for signing/verifying as byte array. You can not set the signatureKeyFileName and signatureKeyRing at the same time.

armored

false

Boolean

This option will cause PGP to base64 encode the encrypted text, making it available for copy/paste, etc.

integrity

true

Boolean

Adds an integrity check/sign into the encryption file. The default value is true.

provider

String

Java Cryptography Extension (JCE) provider, default is Bouncy Castle (BC). Alternatively you can use, for example, the IAIK JCE provider; in this case the provider must be registered beforehand and the Bouncy Castle provider must not be registered beforehand. The Sun JCE provider does not work.

algorithm

Integer

Symmetric key encryption algorithm; possible values are defined in org.bouncycastle.bcpg.SymmetricKeyAlgorithmTags; for example 2 (= TRIPLE DES), 3 (= CAST5), 4 (= BLOWFISH), 6 (= DES), 7 (= AES_128). Only relevant for encrypting.

compressionAlgorithm

Integer

Compression algorithm; possible values are defined in org.bouncycastle.bcpg.CompressionAlgorithmTags; for example 0 (= UNCOMPRESSED), 1 (= ZIP), 2 (= ZLIB), 3 (= BZIP2). Only relevant for encrypting.

hashAlgorithm

Integer

Signature hash algorithm; possible values are defined in org.bouncycastle.bcpg.HashAlgorithmTags; for example 2 (= SHA1), 8 (= SHA256), 9 (= SHA384), 10 (= SHA512), 11 (=SHA224). Only relevant for signing.

signatureVerificationOption

String

Controls the behavior for verifying the signature during unmarshaling. There are 4 values possible: optional: The PGP message may or may not contain signatures; if it does contain signatures, then a signature verification is executed. required: The PGP message must contain at least one signature; if this is not the case an exception (PGPException) is thrown. A signature verification is executed. ignore: Contained signatures in the PGP message are ignored; no signature verification is executed. no_signature_allowed: The PGP message must not contain a signature; otherwise an exception (PGPException) is thrown.

contentTypeHeader

false

Boolean

Whether the data format should set the Content-Type header with the type from the data format if the data format is capable of doing so. For example application/xml for data formats marshalling to XML, or application/json for data formats marshalling to JSon etc.

PGPDataFormat Message Headers

You can override the PGPDataFormat options by applying below headers into message dynamically.

Name Type Description

CamelPGPDataFormatKeyFileName

String

filename of the keyring; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatEncryptionKeyRing

byte[]

the encryption keyring; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatKeyUserid

String

the User ID of the key in the PGP keyring; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatKeyUserids

List<String>

the User IDs of the key in the PGP keyring; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatKeyPassword

String

password used when opening the private key; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatSignatureKeyFileName

String

filename of the signature keyring; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatSignatureKeyRing

byte[]

the signature keyring; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatSignatureKeyUserid

String

the User ID of the signature key in the PGP keyring; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatSignatureKeyUserids

List<String>

the User IDs of the signature keys in the PGP keyring; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatSignatureKeyPassword

String

password used when opening the signature private key; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatEncryptionAlgorithm

int

symmetric key encryption algorithm; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatSignatureHashAlgorithm

int

signature hash algorithm; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatCompressionAlgorithm

int

compression algorithm; will override existing setting directly on the PGPDataFormat.

CamelPGPDataFormatNumberOfEncryptionKeys

Integer

number of public keys used for encrypting the symmectric key, set by PGPDataFormat during encryptiion process

CamelPGPDataFormatNumberOfSigningKeys

Integer

number of private keys used for creating signatures, set by PGPDataFormat during signing process

Encrypting with PGPDataFormat

The following sample uses the popular PGP format for encrypting/decrypting files using the Bouncy Castle Java libraries:

The following sample performs signing + encryption, and then signature verification + decryption. It uses the same keyring for both signing and encryption, but you can obviously use different keys:

Or using Spring:

To work with the previous example you need the following

  • A public keyring file which contains the public keys used to encrypt the data

  • A private keyring file which contains the keys used to decrypt the data

  • The keyring password

Managing your keyring

To manage the keyring, I use the command line tools, I find this to be the simplest approach in managing the keys. There are also Java libraries available from http://www.bouncycastle.org/java.html if you would prefer to do it that way.

Install the command line utilities on linux

apt-get install gnupg

Create your keyring, entering a secure password

gpg --gen-key

If you need to import someone elses public key so that you can encrypt a file for them.

gpg --import <filename.key

The following files should now exist and can be used to run the example

ls -l ~/.gnupg/pubring.gpg ~/.gnupg/secring.gpg

[[Crypto-PGPDecrypting/VerifyingofMessagesEncrypted/SignedbyDifferentPrivate/PublicKeys]] PGP Decrypting/Verifying of Messages Encrypted/Signed by Different == Private/Public Keys

A PGP Data Formater can decrypt/verify messages which have been encrypted by different public keys or signed by different private keys. Just, provide the corresponding private keys in the secret keyring, the corresponding public keys in the public keyring, and the passphrases in the passphrase accessor.

Map<String, String> userId2Passphrase = new HashMap<String, String>(2);
// add passphrases of several private keys whose corresponding public keys have been used to encrypt the messages
userId2Passphrase.put("UserIdOfKey1","passphrase1"); // you must specify the exact User ID!
userId2Passphrase.put("UserIdOfKey2","passphrase2");
PGPPassphraseAccessor passphraseAccessor = new PGPPassphraseAccessorDefault(userId2Passphrase);

PGPDataFormat pgpVerifyAndDecrypt = new PGPDataFormat();
pgpVerifyAndDecrypt.setPassphraseAccessor(passphraseAccessor);
// the method getSecKeyRing() provides the secret keyring as byte array containing the private keys
pgpVerifyAndDecrypt.setEncryptionKeyRing(getSecKeyRing()); // alternatively you can use setKeyFileName(keyfileName)
// the method getPublicKeyRing() provides the public keyring as byte array containing the public keys
pgpVerifyAndDecrypt.setSignatureKeyRing((getPublicKeyRing());  // alternatively you can use setSignatureKeyFileName(signatgureKeyfileName)
// it is not necessary to specify the encryption or signer  User Id

from("direct:start")
         ...
        .unmarshal(pgpVerifyAndDecrypt) // can decrypt/verify messages encrypted/signed by different private/public keys
        ...
  • The functionality is especially useful to support the key exchange. If you want to exchange the private key for decrypting you can accept for a period of time messages which are either encrypted with the old or new corresponding public key. Or if the sender wants to exchange his signer private key, you can accept for a period of time, the old or new signer key.

  • Technical background: The PGP encrypted data contains a Key ID of the public key which was used to encrypt the data. This Key ID can be used to locate the private key in the secret keyring to decrypt the data. The same mechanism is also used to locate the public key for verifying a signature. Therefore you no longer must specify User IDs for the unmarshaling.

Restricting the Signer Identities during PGP Signature Verification

If you verify a signature you not only want to verify the correctness of the signature but you also want check that the signature comes from a certain identity or a specific set of identities. Therefore it is possible to restrict the number of public keys from the public keyring which can be used for the verification of a signature.

Signature User IDs

// specify the User IDs of the expected signer identities
 List<String> expectedSigUserIds = new ArrayList<String>();
 expectedSigUserIds.add("Trusted company1");
 expectedSigUserIds.add("Trusted company2");

 PGPDataFormat pgpVerifyWithSpecificKeysAndDecrypt = new PGPDataFormat();
 pgpVerifyWithSpecificKeysAndDecrypt.setPassword("my password"); // for decrypting with private key
 pgpVerifyWithSpecificKeysAndDecrypt.setKeyFileName(keyfileName);
 pgpVerifyWithSpecificKeysAndDecrypt.setSignatureKeyFileName(signatgureKeyfileName);
 pgpVerifyWithSpecificKeysAndDecrypt.setSignatureKeyUserids(expectedSigUserIds); // if you have only one signer identity then you can also use setSignatureKeyUserid("expected Signer")

from("direct:start")
         ...
        .unmarshal(pgpVerifyWithSpecificKeysAndDecrypt)
        ...
  • If the PGP content has several signatures the verification is successful as soon as one signature can be verified.

  • If you do not want to restrict the signer identities for verification then do not specify the signature key User IDs. In this case all public keys in the public keyring are taken into account.

Several Signatures in One PGP Data Format

The PGP specification allows that one PGP data format can contain several signatures from different keys. Since Camel 2.13.3 it is possible to create such kind of PGP content via specifying signature User IDs which relate to several private keys in the secret keyring.

Several Signatures

 PGPDataFormat pgpSignAndEncryptSeveralSignerKeys = new PGPDataFormat();
 pgpSignAndEncryptSeveralSignerKeys.setKeyUserid(keyUserid); // for encrypting, you can also use setKeyUserids if you want to encrypt with several keys
 pgpSignAndEncryptSeveralSignerKeys.setKeyFileName(keyfileName);
 pgpSignAndEncryptSeveralSignerKeys.setSignatureKeyFileName(signatgureKeyfileName);
 pgpSignAndEncryptSeveralSignerKeys.setSignaturePassword("sdude"); // here we assume that all private keys have the same password, if this is not the case then you can use setPassphraseAccessor

 List<String> signerUserIds = new ArrayList<String>();
 signerUserIds.add("company old key");
 signerUserIds.add("company new key");
 pgpSignAndEncryptSeveralSignerKeys.setSignatureKeyUserids(signerUserIds);

from("direct:start")
         ...
        .marshal(pgpSignAndEncryptSeveralSignerKeys)
        ...

Support of Sub-Keys and Key Flags in PGP Data Format Marshaler

*An OpenPGP V4 key can have a primary key and sub-keys. The usage of the keys is indicated by the so called Key Flags. For example, you can have a primary key with two sub-keys; the primary key shall only be used for certifying other keys (Key Flag 0x01), the first sub-key shall only be used for signing (Key Flag 0x02), and the second sub-key shall only be used for encryption (Key Flag 0x04 or 0x08). The PGP Data Format marshaler takes into account these Key Flags of the primary key and sub-keys in order to determine the right key for signing and encryption. This is necessary because the primary key and its sub-keys have the same User IDs.

Support of Custom Key Accessors

*You can implement custom key accessors for encryption/signing. The above PGPDataFormat class selects in a certain predefined way the keys which should be used for signing/encryption or verifying/decryption. If you have special requirements how your keys should be selected you should use the PGPKeyAccessDataFormat class instead and implement the interfaces PGPPublicKeyAccessor and PGPSecretKeyAccessor as beans. There are default implementations DefaultPGPPublicKeyAccessor and DefaultPGPSecretKeyAccessor which cache the keys, so that not every time the keyring is parsed when the processor is called.

PGPKeyAccessDataFormat has the same options as PGPDataFormat except password, keyFileName, encryptionKeyRing, signaturePassword, signatureKeyFileName, and signatureKeyRing.

Dependencies

To use the PGP dataformat in your camel routes you need to add the following dependency to your pom.

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-crypto</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>