Documentation Contents

Java PKCS#11 Reference Guide

1.0 Introduction

2.0 Sun PKCS#11 Provider

2.1 Requirements

2.2 Configuration

2.3 Accessing Network Security Services (NSS)

3.0 Application Developers

3.1 Token Login

3.2 Token Keys

3.3 Delayed Provider Selection

3.4 JAAS KeyStoreLoginModule

3.5 Tokens as JSSE Keystores and Trust Stores

4.0 Tools

4.1 KeyTool and JarSigner

4.2 PolicyTool

5.0 Provider Developers

5.1 Provider Services

5.1.1 Instantiating Engine Classes

5.1.2 Parameter Support

Appendix A Sun PKCS#11 Provider's Supported Algorithms

Appendix B Sun PKCS#11 Provider's KeyStore Restrictions

Appendix C Example Provider

1.0 Introduction

The Java platform defines a set of programming interfaces for performing cryptographic operations. These interfaces are collectively known as the Java Cryptography Architecture (JCA) and the Java Cryptography Extension (JCE). Specifications are available at the Java SE Security Documentation page.

The cryptographic interfaces are provider-based. Specifically, applications talk to Application Programming Interfaces (APIs), and the actual cryptographic operations are performed in configured providers which adhere to a set of Service Provider Interfaces (SPIs). This architecture supports different provider implementations. Some providers may perform cryptographic operations in software; others may perform the operations on a hardware token (for example, on a smartcard device or on a hardware cryptographic accelerator).

The Cryptographic Token Interface Standard, PKCS#11, is produced by RSA Security and defines native programming interfaces to cryptographic tokens, such as hardware cryptographic accelerators and Smartcards. To facilitate the integration of native PKCS#11 tokens into the Java platform, a new cryptographic provider, the Sun PKCS#11 provider, has been introduced into the J2SE 5.0 release. This new provider enables existing applications written to the JCA and JCE APIs to access native PKCS#11 tokens. No modifications to the application are required. The only requirement is the proper configuration of the provider into the Java Runtime.

Although an application can make use of most PKCS#11 features using existing APIs, some applications might need more flexibility and capabilities. For example, an application might want to deal with Smartcards being removed and inserted dynamically more easily. Or, a PKCS#11 token might require authentication for some non-key-related operations and therefore, the application must be able to log into the token without using keystore. In J2SE 5.0, the JCA was enhanced to allow applications greater flexibility in dealing with different providers.

This document describes how native PKCS#11 tokens can be configured into the Java platform for use by Java applications. It also describes the enhancements that were made to the JCA to make it easier for applications to deal with different types of providers, including PKCS#11 providers.

2.0 Sun PKCS#11 Provider

The Sun PKCS#11 provider, in contrast to most other providers, does not implement cryptographic algorithms itself. Instead, it acts as a bridge between the Java JCA and JCE APIs and the native PKCS#11 cryptographic API, translating the calls and conventions between the two. This means that Java applications calling standard JCA and JCE APIs can, without modification, take advantage of algorithms offered by the underlying PKCS#11 implementations, such as, for example,

• Cryptographic Smartcards,
• Hardware cryptographic accelerators, and
• High performance software implementations.

2.1 Requirements

The Sun PKCS#11 provider requires an implementation of PKCS#11 v2.0 or later to be installed on the system. This implementation must take the form of a shared-object library (.so on Solaris and Linux) or dynamic-link library (.dll on Windows). Please consult your vendor documentation to find out if your cryptographic device includes such a PKCS#11 implementation, how to configure it, and what the name of the library file is.

The Sun PKCS#11 provider supports a number of algorithms, provided that the underlying PKCS#11 implementation offers them. The algorithms and their corresponding PKCS#11 mechanisms are listed in the table in Appendix A.

2.2 Configuration

# configuration for security providers 1-6 ommitted
security.provider.7=sun.security.pkcs11.SunPKCS11 /opt/bar/cfg/pkcs11.cfg

String configName = "/opt/bar/cfg/pkcs11.cfg";
Provider p = new sun.security.pkcs11.SunPKCS11(configName);
Security.addProvider(p);

To use more than one slot per PKCS#11 implementation, or to use more than one PKCS#11 implementation, simply repeat the installation for each with the appropriate configuration file. This will result in a Sun PKCS#11 provider instance for each slot of each PKCS#11 implementation.

The configuration file is a text file that contains entries in the following format.

name = FooAccelerator
library = /opt/foo/lib/libpkcs11.so

enabledMechanisms = {
  CKM_RSA_PKCS
  CKM_RSA_PKCS_KEY_PAIR_GEN
}

Attributes Configuration

The attributes option can be used if you do not like the default values your PKCS#11 implementation assigns or if your PKCS#11 implementation does not support defaults and requires a value to be specified explicitly. Note that specifying attributes that your PKCS#11 implementation does not support or that are invalid for the type of key in question may cause the operation to fail at runtime.

The option can be specified zero or more times, the options are processed in the order specified in the configuration file as described below. The attributes option has the format:

attributes(operation, keytype, keyalgorithm) = {
  name1 = value1
  [...]
}

• generate, for keys generated via a KeyPairGenerator or KeyGenerator
• import, for keys created via a KeyFactory or SecretKeyFactory. This also applies to Java software keys automatically converted to PKCS#11 key objects when they are passed to the initialization method of a cryptographic operation, for example Signature.initSign().
• *, for keys created using either a generate or a create operation.

Valid values for keyalgorithm are one of the CKK_xxx constants from the PKCS#11 specification, or * to match keys of any algorithm. The algorithms currently supported by the SunPKCS11 provider are CKK_RSA, CKK_DSA, CKK_DH, CKK_AES, CKK_DES, CKK_DES3, CKK_RC4, CKK_BLOWFISH, and CKK_GENERIC.

The attribute names and values are specified as a list of one or more name-value pairs. name must be a CKA_xxx constant from the PKCS#11 specification, for example CKA_SENSITIVE. value can be one of the following:

• a boolean value, true or false
• an integer, in decimal form (default) or in hexadecimal form if it begins with 0x.
• null, indicating that this attribute should not be specified when creating objects.

attributes(*,CKO_PRIVATE_KEY,*) = {
  CKA_SIGN = true
}

attributes(*,CKO_PRIVATE_KEY,CKK_DH) = {
  CKA_SIGN = null
}

attributes(*,CKO_PRIVATE_KEY,CKK_RSA) = {
  CKA_DECRYPT = true
}

There is also a special form of the attributes option. You can write attributes = compatibility in the configuration file. That is a shortcut for a whole set of attribute statements. They are designed to provider maximum compatibility with existing Java applications, which may expect, for example, all key components to be accessible and secret keys to be useable for both encryption and decryption. The compatibility attributes line can be used together with other attributes lines, in which case the same aggregation and overriding rules apply as described earlier.

2.3 Accessing Network Security Services (NSS)

Network Security Services (NSS) is a set of open source security libraries used by the Mozilla/Firefox browsers, Sun's Java Enterprise System server software, and a number of other products. Its crypto APIs are based on PKCS#11 but it includes special features that are outside of the PKCS#11 standard. The Sun PKCS#11 provider includes code to interact with these NSS specific features, including several NSS specific configuration directives, which are described below.

For best results, we recommend that you use the latest version of NSS available. It should be at least version 3.11.1.

The Sun PKCS#11 provider uses NSS specific code when any of the nss configuration directives described below are used. In that case, the regular configuration commands library, slot, and slotListIndex cannot be used.

Example SunPKCS11 configuration files for NSS

NSS as a pure cryptography provider

name = NSScrypto
nssLibraryDirectory = /opt/tests/nss/lib
nssDbMode = noDb
attributes = compatibility

NSS as a FIPS 140 compliant crypto token:

name = NSSfips
nssLibraryDirectory = /opt/tests/nss/lib
nssSecmodDirectory = /opt/tests/nss/fipsdb
nssModule = fips

3.0 Application Developers

Java applications can use the existing JCA and JCE APIs to access PKCS#11 tokens via the Sun PKCS#11 provider. This is sufficient for many applications but it might be difficult for an application to deal with certain PKCS#11 features, such as unextractable keys and dynamically changing Smartcards. Consequently, a number of enhancements were made to the APIs to better support applications using certain PKCS#11 features. These enhancments are discussed in this section.

3.1 Token Login

Certain PKCS#11 operations, such as accessing private keys, require a login using a Personal Identification Number, or PIN, before the operations can proceed. The most common type of operations that require login are those that deal with keys on the token. In a Java application, such operations often involve first loading the keystore. When accessing the PKCS#11 token as a keystore via the java.security.KeyStore class, you can supply the PIN in the password input parameter to the load method, similar to how applications initialize a keystore prior to J2SE 5.0. The PIN will then be used by the Sun PKCS#11 provider for logging into the token. Here is an example.

char[] pin = ...; 
KeyStore ks = KeyStore.getInstance("PKCS11");
ks.load(null, pin); 

This is fine for an application that treats PKCS#11 tokens as static keystores. For an application that wants to accommodate PKCS#11 tokens more dynamically, such as Smartcards being inserted and removed, you can use the new KeyStore.Builder class. Here is an example of how to initialize the builder for a PKCS#11 keystore with a callback handler.

KeyStore.CallbackHandlerProtection chp =
    new KeyStore.CallbackHandlerProtection(new MyGuiCallbackHandler());
KeyStore.Builder builder =
    KeyStore.Builder.newInstance("PKCS11", null, chp);

For the Sun PKCS#11 provider, the callback handler must be able to satisfy a PasswordCallback, which is used to prompt the user for the PIN. Whenever the application needs access to the keystore, it uses the builder as follows.

KeyStore ks = builder.getKeyStore();
Key key = ks.getKey(alias, null);

The builder will prompt for a password as needed using the previously configured callback handler. The builder will prompt for a password only for the initial access. If the user of the application continues using the same Smartcard, the user will not be prompted again. If the user removes and inserts a different SmartCard, the builder will prompt for a password for the new card.

Depending on the PKCS#11 token, there may be non-key-related operations that also require token login. Applications that use such operations can use the newly introduced java.security.AuthProvider class. The AuthProvider class extends from java.security.Provider and defines methods to perform login and logout operations on a provider, as well as to set a callback handler for the provider to use.

For the Sun PKCS#11 provider, the callback handler must be able to satisfy a PasswordCallback, which is used to prompt the user for the PIN.

Here is an example of how an application might use an AuthProvider to log into the token.

AuthProvider aprov = (AuthProvider)Security.getProvider("SunPKCS11");
aprov.login(subject, new MyGuiCallbackHandler());

3.2 Token Keys

Java Key objects may or may not contain actual key material.

• A software Key object does contain the actual key material and allows access to that material.
• An unextractable key on a secure token (such as a Smartcard) is represented by a Java Key object that does not contain the actual key material. The Key object only contains a reference to the actual key.

Applications and providers must use the correct interfaces to represent these different types of Key objects. Software Key objects (or any Key object that has access to the actual key material) should implement the interfaces in the java.security.interfaces and javax.crypto.interfaces packages (such as DSAPrivateKey). Key objects representing unextractable token keys should only implement the relevant generic interfaces in the java.security and javax.crypto packages (PrivateKey, PublicKey, or SecretKey). Identification of the algorithm of a key should be performed using the Key.getAlgorithm() method.

Applications should note that a Key object for an unextractable token key can only be used by the provider associated with that token.

3.3 Delayed Provider Selection

Prior to J2SE 5.0, the Java cryptography getInstance() methods, such as Cipher.getInstance("DES"), returned the implementation from the first provider that implemented the requested algorithm. This is problematic if an application attempts to use a Key object for an unextractable token key with a provider that only accepts software key objects. In such a case, the provider would throw an InvalidKeyException. This is an issue for the Cipher, KeyAgreement, Mac, and Signature classes.

J2SE 5.0, addresses this issue by delaying the selection of the provider until the relevant initialization method is called. The initialization method accepts a Key object and can determine at that point which provider can accept the specified Key object. This ensures that the selected provider can use the specified Key object. The following represents the affected initialization methods.

• Cipher.init(..., Key key, ...)
• KeyAgreement.init(Key key, ...)
• Mac.init(Key key, ...)
• Signature.initSign(PrivateKey privateKey)

Although this delayed provider selection is hidden from the application, it does affect the behavior of the getProvider() method for Cipher, KeyAgreement, Mac, and Signature. If getProvider() is called before the initialization operation has occurred (and therefore before provider selection has occurred), then the first provider that supports the requested algorithm is returned. This may not be the same provider as the one selected after the initialization method is called. If getProvider() is called after the initialization operation has occurred, then the actual selected provider is returned. It is recommended that applications only call getProvider() after they have called the relevant initialization method.

In addition to getProvider(), the following additional methods are similarly affected.

• Cipher.getBlockSize
• Cipher.getExcemptionMechanism
• Cipher.getIV
• Cipher.getOutputSize
• Cipher.getParameters
• Mac.getMacLength
• Signature.getParameters
• Signature.setParameter

3.4 JAAS KeyStoreLoginModule

Use the following options to configure the KeyStoreLoginModule to use a PKCS#11 token as the keystore.

• keyStoreURL="NONE"
• keyStoreType="PKCS11"
• keyStorePasswordURL=some_pin_url

other {
    com.sun.security.auth.module.KeyStoreLoginModule required
        keyStoreURL="NONE"
  keyStoreType="PKCS11"
  keyStorePasswordURL="file:/home/joe/scpin";
};

If more than one Sun PKCS#11 provider has been configured dynamically or in the java.security security properties file, you can use the keyStoreProvider option to target a specific provider instance. The argument to this option is the name of the provider. For the Sun PKCS#11 provider, the provider name is of the form SunPKCS11-TokenName, where TokenName is the name suffix that the provider instance has been configured with, as detailed in the configuration attributes table. For example, the following configuration file names the PKCS#11 provider instance with name suffix SmartCard.

other {
    com.sun.security.auth.module.KeyStoreLoginModule required
        keyStoreURL="NONE"
  keyStoreType="PKCS11"
  keyStorePasswordURL="file:/home/joe/scpin"
  keyStoreProvider="SunPKCS11-SmartCard";
};

Some PKCS#11 tokens support login via a protected authentication path. For example, a Smartcard may have a dedicated PIN-pad to enter the pin. Biometric devices will also have their own means to obtain authentication information. If the PKCS#11 token has a protected authentication path, then use the protected=true option and omit the keyStorePasswordURL option. Here is an example of a configuration file for such a token.

other {
    com.sun.security.auth.module.KeyStoreLoginModule required
        keyStoreURL="NONE"
  keyStoreType="PKCS11"
  protected=true;
};

3.5 Tokens as JSSE Keystore and Trust Stores

JSSE also supports configuring the use of keystores and trust stores via system properties, as described in the JSSE Reference Guide. To use a PKCS#11 token as a keystore or trust store, set the javax.net.ssl.keyStoreType and javax.net.ssl.trustStoreType system properties, respectively, to "PKCS11", and set the javax.net.ssl.keyStore and javax.net.ssl.trustStore system properties, respectively, to NONE. To specify the use of a specific provider instance, use the javax.net.ssl.keyStoreProvider and javax.net.ssl.trustStoreProvider system properties (e.g., "SunPKCS11-SmartCard").

4.0 Tools

In J2SE 5.0, the security tools were updated to support operations using the new Sun PKCS#11 provider. The changes are discussed below.

4.1 KeyTool and JarSigner

If the Sun PKCS#11 provider has been configured in the java.security security properties file (located in the $JAVA_HOME/lib/security directory of the Java runtime), then keytool and jarsigner can be used to operate on the PKCS#11 token by specifying the following options.

• -keystore NONE
• -storetype PKCS11

keytool -keystore NONE -storetype PKCS11 -list

If more than one Sun PKCS#11 provider has been configured in the java.security security properties file, you can use the -providerName option to target a specific provider instance. The argument to this option is the name of the provider.

• -providerName providerName

keytool -keystore NONE -storetype PKCS11 \
        -providerName SunPKCS11-SmartCard \
        -list

If the Sun PKCS#11 provider has not been configured in the java.security security properties file, you can use the following options to instruct keytool and jarsigner to install the provider dynamically.

• -providerClass sun.security.pkcs11.SunPKCS11
• -providerArg ConfigFilePath

keytool -keystore NONE -storetype PKCS11 \
        -providerClass sun.security.pkcs11.SunPKCS11 \
        -providerArg /foo/bar/token.config \
        -list

4.2 PolicyTool

Prior to J2SE 5.0, the keystore entry in the default policy implementation had the following syntax.

keystore "some_keystore_url", "keystore_type";

keystore "some_keystore_url", "keystore_type", "keystore_provider";
keystorePasswordURL "some_password_url";

The following is an example keystore policy entry for a PKCS#11 token.

keystore "NONE", "PKCS11", "SunPKCS11-SmartCard";
keystorePasswordURL "file:/foo/bar/passwordFile";

5.0 Provider Developers

J2SE 5.0 introduces new facilities in the java.security.Provider class for provider implementations to more easily support PKCS#11 tokens and cryptographic services in general. These new facilities are discussed below.

See Appendix C for an example of a simple provider designed to demonstrate the new facilties.

5.1 Provider Services

As described in the above provider documentation, prior to J2SE 5.0, providers were required to create java.util.Property entries describing the services they supported. For each service implemented by the provider, there must be a property whose name is the type of service (Cipher, Signature, etc), followed by a period and the name of the algorithm to which the service applies. The property value must specify the fully qualified name of the class implementing the service. Here is an example of a provider setting KeyAgreement.DiffieHellman property to have the value com.sun.crypto.provider.DHKeyAgreement.

put("KeyAgreement.DiffieHellman", 
      "com.sun.crypto.provider.DHKeyAgreement")

J2SE 5.0 introduces a new public static nested class, Provider.Service, to help better encapsulate the properties of a provider service (including its type, attributes, algorithm name, and algorithm aliases). Providers can instantiate Provider.Service objects and register them by calling the Provider.putService() method. This is equivalent to creating a Property entry and calling the Provider.put() method (as was done prior to J2SE 5.0). Note that legacy Property entries registered via Provider.put are still supported.

Here is an example of a provider creating a Service object with the KeyAgreement type, for the DiffieHellman algorithm, implemented by the class com.sun.crypto.provider.DHKeyAgreement.

Service s = new Service(this, "KeyAgreement", "DiffieHellman",
    "com.sun.crypto.provider.DHKeyAgreement", null, null);
putService(s);

Using Provider.Servicee objects instead of legacy Property entries has a couple of major benefits. One benefit is that it allows the provider to have greater flexibility when instantiating engine classes. Another benefit is that it allows the provider to test parameter validity. These features are discussed in detail next.

5.1.1 Instantiating Engine Classes

Prior to J2SE 5.0, the Java Cryptography framework looked up the provider property for a particular service and directly instantiated the engine class registered for that property. J2SE 5.0, has the same behavior by default, but allows the provider to override this behavior and instantiate the engine class for the requested service itself.

To override the default behavior, the provider overrides the Provider.Service.newInstance() method to add its customer behavior. For example, the provider might call a custom constructor, or might perform initialization using information not accessible outside the provider (or that are only known by the provider).

5.1.2 Parameter Support

The Java Cryptography framework may attempt a fast check to determine whether a provider's service implementation can use an application-specified parameter. To perform this fast check, the framework calls Provider.Service.supportsParameter().

In J2SE 5.0, the framework relies on this fast test during delayed provider selection. When an application invokes an initialization method and passes it a Key object, the framework asks an underlying provider whether it supports the object by calling its Service.supportsParameter() method. If supportsParameter() returns false, the framework can immediately remove that provider from consideration. If supportsParameter() returns true, the framework passes the Key object to that provider's initialization engine class implementation. A provider that requires software Key objects should override this method to return false when it is passed non-software keys. Likewise, a provider for a PKCS#11 token that contains unextractable keys should only return true for Key objects that it created, and which therefore correspond to the Keys on its respective token.

Note that the default implementation of supportsParameter() returns true. This allows existing providers to work without modification. However, because of this lenient default implementation, the framework must be prepared to catch exceptions thrown by providers that reject the Key object inside their initialization engine class implementations. The framework treats these cases the same as when supportsParameter() returns false.

Appendix A: Sun PKCS#11 Provider's Supported Algorithms

For Elliptic Curve mechanisms, SunPKCS11 will only use keys that use the namedCurve choice as encoding for the parameters and only allow the uncompressed point format. The Sun PKCS#11 provider assumes that a token supports all standard named domain parameters.

Appendix B: Sun PKCS#11 provider's KeyStore Requirements

The following describes the requirements placed by the Sun PKCS#11 Provider's KeyStore implementation on the underlying native PKCS#11 library. Note that changes may be made in future releases to maximize interoperability with as many existing PKCS#11 libraries as possible.

Read-Only Access

To map existing objects stored on a PKCS#11 token to KeyStore entries, the Sun PKCS#11 Provider's KeyStore implementation performs the following operations.

1. A search for all private key objects on the token is performed by calling C_FindObjects[Init|Final]. The search template includes the following attributes:
   • CKA_TOKEN = true
   • CKA_CLASS = CKO_PRIVATE_KEY
2. A search for all certificate objects on the token is performed by calling C_FindObjects[Init|Final]. The search template includes the following attributes:
   • CKA_TOKEN = true
   • CKA_CLASS = CKO_CERTIFICATE
3. Each private key object is matched with its corresponding certificate by retrieving their respective CKA_ID attributes. A matching pair must share the same unique CKA_ID.

   For each matching pair, the certificate chain is built by following the issuer->subject path. From the end entity certificate, a call fo C_FindObjects[Init|Final] is made with a search template that includes the following attributes:

   • CKA_TOKEN = true
   • CKA_CLASS = CKO_CERTIFICATE
   • CKA_SUBJECT = [DN of certificate issuer]

   This search is continued until either no certificate for the issuer is found, or until a self-signed certificate is found. If more than one certificate is found the first one is used.

   Once a private key and certificate have been matched (and its certificate chain built), the information is stored in a private key entry with the CKA_LABEL value from end entity certificate as the KeyStore alias.

   If the end entity certificate has no CKA_LABEL, then the alias is derived from the CKA_ID. If the CKA_ID can be determined to consist exclusively of printable characters, then a String alias is created by decoding the CKA_ID bytes using the UTF-8 charset. Otherwise, a hex String alias is created from the CKA_ID bytes ("0xFFFF...", for example).

   If multiple certificates share the same CKA_LABEL, then the alias is derived from the CKA_LABEL plus the end entity certificate issuer and serial number ("MyCert/CN=foobar/1234", for example).

4. Each certificate not part of a private key entry (as the end entity certificate) is checked whether it is trusted. If the CKA_TRUSTED attribute is true, then a KeyStore trusted certificate entry is created with the CKA_LABEL value as the KeyStore alias. If the certificate has no CKA_LABEL, or if multiple certificates share the same CKA_LABEL, then the alias is derived as described above.

   If the CKA_TRUSTED attribute is not supported then no trusted certificate entries are created.

5. Any private key or certificate object not part of a private key entry or trusted certificate entry is ignored.
6. A search for all secret key objects on the token is performed by calling C_FindObjects[Init|Final]. The search template includes the following attributes:
   • CKA_TOKEN = true
   • CKA_CLASS = CKO_SECRET_KEY

   A KeyStore secret key entry is created for each secret key object, with the CKA_LABEL value as the KeyStore alias. Each secret key object must have a unique CKA_LABEL.

Write Access

To create new KeyStore entries on a PKCS#11 token to KeyStore entries, the Sun PKCS#11 Provider's KeyStore implementation performs the following operations.

1. When creating a KeyStore entry (during KeyStore.setEntry, for example), C_CreateObject is called with CKA_TOKEN=true to create token objects for the respective entry contents.

   Private key objects are stored with CKA_PRIVATE=true. The KeyStore alias (UTF8-encoded) is set as the CKA_ID for both the private key and the corresponding end entity certificate. The KeyStore alias is also set as the CKA_LABEL for the end entity certificate object.

   Each certificate in a private key entry's chain is also stored. The CKA_LABEL is not set for CA certificates. If a CA certificate is already in the token, a duplicate is not stored.

   Secret key objects are stored with CKA_PRIVATE=true. The KeyStore alias is set as the CKA_LABEL.

2. If an attempt is made to convert a session object to a token object (for example, if KeyStore.setEntry is called and the private key object in the specified entry is a session ojbect), then C_CopyObject is called with CKA_TOKEN=true.
3. If multiple certificates in the token are found to share the same CKA_LABEL, then the write capabilities to the token are disabled.
4. Since the PKCS#11 specification does not allow regular applications to set CKA_TRUSTED=true (only token initialization applications may do so), trusted certificate entries can not be created.

Miscellaneous

In addition to the searches listed above, the following searches may be used by the Sun PKCS#11 provider's KeyStore implementation to perform internal functions. Specifically, C_FindObjects[Init|Final] may be called with any of the following attribute templates:

•     CKA_TOKEN    true
      CKA_CLASS    CKO_CERTIFICATE
      CKA_SUBJECT  [subject DN]
      
  

•     CKA_TOKEN    true
      CKA_CLASS    CKO_SECRET_KEY
      CKA_LABEL    [label]
      
  

•     CKA_TOKEN    true
      CKA_CLASS    CKO_CERTIFICATE or CKO_PRIVATE_KEY
      CKA_ID       [cka_id] 
      
  

Appendix C: Example Provider

package com.foo;

import java.io.*;
import java.lang.reflect.*;
import java.security.*;
import javax.crypto.*;

/**
 * Example provider that demonstrates some of the new API features.
 *
 *  . implement multiple different algorithms in a single class.
 *    Previously each algorithm needed to be implemented in a separate class
 *    (e.g. one for MD5, one for SHA-1, etc.)
 *
 *  . multiple concurrent instances of the provider frontend class each
 *    associated with a different backend.
 *
 *  . it uses "unextractable" keys and lets the framework know which key
 *    objects it can and cannot support
 *
 * Note that this is only a simple example provider designed to demonstrate
 * several of the new features.  It is not explicitly designed for efficiency.
 */
public final class ExampleProvider extends Provider {

    // reference to the crypto backend that implements all the algorithms
    final CryptoBackend cryptoBackend;

    public ExampleProvider(String name, CryptoBackend cryptoBackend) {
        super(name, 1.0, "JCA/JCE provider for " + name);
        this.cryptoBackend = cryptoBackend;
        // register the algorithms we support (MD5, SHA1, DES, and AES)
        putService(new MyService
            (this, "MessageDigest", "MD5", "com.foo.ExampleProvider$MyMessageDigest"));
        putService(new MyService
            (this, "MessageDigest", "SHA1", "com.foo.ExampleProvider$MyMessageDigest"));
        putService(new MyCipherService
            (this, "Cipher", "DES", "com.foo.ExampleProvider$MyCipher"));
        putService(new MyCipherService
            (this, "Cipher", "AES", "com.foo.ExampleProvider$MyCipher"));
    }

    // the API of our fictitious crypto backend
    static abstract class CryptoBackend {
        abstract byte[] digest(String algorithm, byte[] data);
        abstract byte[] encrypt(String algorithm, KeyHandle key, byte[] data);
        abstract byte[] decrypt(String algorithm, KeyHandle key, byte[] data);
        abstract KeyHandle createKey(String algorithm, byte[] keyData);
    }

    // the shell of the representation the crypto backend uses for keys
    private static final class KeyHandle {
        // fill in code
    }

    // we have our own ServiceDescription implementation that overrides newInstance()
    // that calls the (Provider, String) constructor instead of the no-args constructor
    private static class MyService extends Service {

        private static final Class[] paramTypes = {Provider.class, String.class};

        MyService(Provider provider, String type, String algorithm,
                String className) {
            super(provider, type, algorithm, className, null, null);
        }

        public Object newInstance(Object param) throws NoSuchAlgorithmException {
            try {
                // get the Class object for the implementation class
                Class clazz;
                Provider provider = getProvider();
                ClassLoader loader = provider.getClass().getClassLoader();
                if (loader == null) {
                    clazz = Class.forName(getClassName());
                } else {
                    clazz = loader.loadClass(getClassName());
                }
                // fetch the (Provider, String) constructor
                Constructor cons = clazz.getConstructor(paramTypes);
                // invoke constructor and return the SPI object
                Object obj = cons.newInstance(new Object[] {provider, getAlgorithm()});
                return obj;
            } catch (Exception e) {
                throw new NoSuchAlgorithmException("Could not instantiate service", e);
            }
        }
    }

    // custom ServiceDescription class for Cipher objects. See supportsParameter() below
    private static class MyCipherService extends MyService {
        MyCipherService(Provider provider, String type, String algorithm,
                String className) {
            super(provider, type, algorithm, className);
        }
        // we override supportsParameter() to let the framework know which
        // keys we can support. We support instances of MySecretKey, if they
        // are stored in our provider backend, plus SecretKeys with a RAW encoding.
        public boolean supportsParameter(Object obj) {
            if (obj instanceof SecretKey == false) {
                return false;
            }
            SecretKey key = (SecretKey)obj;
            if (key.getAlgorithm().equals(getAlgorithm()) == false) {
                return false;
            }
            if (key instanceof MySecretKey) {
                MySecretKey myKey = (MySecretKey)key;
                return myKey.provider == getProvider();
            } else {
                return "RAW".equals(key.getFormat());
            }
        }
    }

    // our generic MessageDigest implementation. It implements all digest
    // algorithms in a single class. We only implement the bare minimum
    // of MessageDigestSpi methods
    private static final class MyMessageDigest extends MessageDigestSpi {
        private final ExampleProvider provider;
        private final String algorithm;
        private ByteArrayOutputStream buffer;
        MyMessageDigest(Provider provider, String algorithm) {
            super();
            this.provider = (ExampleProvider)provider;
            this.algorithm = algorithm;
            engineReset();
        }
        protected void engineReset() {
            buffer = new ByteArrayOutputStream();
        }
        protected void engineUpdate(byte b) {
            buffer.write(b);
        }
        protected void engineUpdate(byte[] b, int ofs, int len) {
            buffer.write(b, ofs, len);
        }
        protected byte[] engineDigest() {
            byte[] data = buffer.toByteArray();
            byte[] digest = provider.cryptoBackend.digest(algorithm, data);
            engineReset();
            return digest;
        }
    }

    // our generic Cipher implementation, only partially complete. It implements
    // all cipher algorithms in a single class. We implement only as many of the
    // CipherSpi methods as required to show how it could work
    private static abstract class MyCipher extends CipherSpi {
        private final ExampleProvider provider;
        private final String algorithm;
        private int opmode;
        private MySecretKey myKey;
        private ByteArrayOutputStream buffer;
        MyCipher(Provider provider, String algorithm) {
            super();
            this.provider = (ExampleProvider)provider;
            this.algorithm = algorithm;
        }
        protected void engineInit(int opmode, Key key, SecureRandom random)
                throws InvalidKeyException {
            this.opmode = opmode;
            myKey = MySecretKey.getKey(provider, algorithm, key);
            if (myKey == null) {
                throw new InvalidKeyException();
            }
            buffer = new ByteArrayOutputStream();
        }
        protected byte[] engineUpdate(byte[] b, int ofs, int len) {
            buffer.write(b, ofs, len);
            return new byte[0];
        }
        protected int engineUpdate(byte[] b, int ofs, int len, byte[] out, int outOfs) {
            buffer.write(b, ofs, len);
            return 0;
        }
        protected byte[] engineDoFinal(byte[] b, int ofs, int len) {
            buffer.write(b, ofs, len);
            byte[] in = buffer.toByteArray();
            byte[] out;
            if (opmode == Cipher.ENCRYPT_MODE) {
                out = provider.cryptoBackend.encrypt(algorithm, myKey.handle, in);
            } else {
                out = provider.cryptoBackend.decrypt(algorithm, myKey.handle, in);
            }
            buffer = new ByteArrayOutputStream();
            return out;
        }
        // code for remaining CipherSpi methods goes here
    }

    // our SecretKey implementation. All our keys are stored in our crypto
    // backend, we only have an opaque handle available. There is no
    // encoded form of these keys.
    private static final class MySecretKey implements SecretKey {

        final String algorithm;
        final Provider provider;
        final KeyHandle handle;

        MySecretKey(Provider provider, String algorithm, KeyHandle handle) {
            super();
            this.provider = provider;
            this.algorithm = algorithm;
            this.handle = handle;
        }
        public String getAlgorithm() {
            return algorithm;
        }
        public String getFormat() {
            return null; // this key has no encoded form
        }
        public byte[] getEncoded() {
            return null; // this key has no encoded form
        }
        // Convert the given key to a key of the specified provider, if possible
        static MySecretKey getKey(ExampleProvider provider, String algorithm, Key key) {
            if (key instanceof SecretKey == false) {
                return null;
            }
            // algorithm name must match
            if (!key.getAlgorithm().equals(algorithm)) {
                return null;
            }
            // if key is already an instance of MySecretKey and is stored
            // on this provider, return it right away
            if (key instanceof MySecretKey) {
                MySecretKey myKey = (MySecretKey)key;
                if (myKey.provider == provider) {
                    return myKey;
                }
            }
            // otherwise, if the input key has a RAW encoding, convert it
            if (!"RAW".equals(key.getFormat())) {
                return null;
            }
            byte[] encoded = key.getEncoded();
            KeyHandle handle = provider.cryptoBackend.createKey(algorithm, encoded);
            return new MySecretKey(provider, algorithm, handle);
        }
    }
}

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