The Mozilla-JSS JCA Provider

Newsgroup: mozilla.dev.tech.crypto

Overview

This document describes the JCA Provider shipped with JSS. The provider's name is "Mozilla-JSS". It implements cryptographic operations in native code using the NSS libraries.

Contents

• Signed JAR file
• Installing the Provider
• Specifying the CryptoToken
• Supported Classes
• What's Not Supported

Signed JAR file

• JSS 3.2 implements several JCE (Java Cryptography Extension) algorithms. These algorithms have at various times been export-controlled by the US government. Sun therefore requires that JAR files implementing JCE algorithms be digitally signed by an approved organization. Netscape has this approval and signs the official builds of jss32.jar. At runtime, the JRE automatically verifies this signature whenever a JSS class is loaded that implements a JCE algorithm. The verification is transparent to the application (unless it fails and throws an exception). If you are curious, you can verify the signature on the JAR file using the jarsigner tool, which is distributed with the JDK.

  If you build JSS yourself from source instead of using binaries downloaded from mozilla.org, your JAR file will not have a valid signature. This means you will not be able to use the JSS provider for JCE algorithms. You have two choices.

  1. Use the binary release of JSS from mozilla.org.
  2. Apply for your own JCE code-signing certificate following the procedure at How to Implement a Provider for the Java^TM Cryptography Extension. Then you can sign your own JSS JAR file.

Installing the Provider

• In order to use any part of JSS, including the JCA provider, you must first call CryptoManager.initialize(). By default, the JCA provider will be installed in the list of providers maintained by the java.security.Security class. If you do not wish the provider to be installed, create a CryptoManager.InitializationValues object, set its installJSSProvider field to false, and pass the InitializationValues object to CryptoManager.initialize().

Specifying the CryptoToken

• All cryptographic operations in JSS and NSS occur on a particular PKCS #11 token, implemented in software or hardware. There is no clean way to specify this token through the JCA API. By default, the JSS provider carries out all operations except MessageDigest on the Internal Key Storage Token, a software token included in JSS/NSS. MessageDigest operations take place by default on the Internal Crypto Token, another internal software token in JSS/NSS. There is no good design reason for this difference, but it is necessitated by a quirk in the NSS implementation.

  In order to use a different token, use CryptoManager.setThreadToken(). This sets the token to be used by the JSS JCA provider in the current thread. When you call getInstance() on a JCA class, the JSS provider checks the current per-thread default token (by calling CryptoManager.getThreadToken()) and instructs the new object to use that token for cryptographic operations. The per-thread default token setting is only consulted inside getInstance(). Once a JCA object has been created it will continue to use the same token, even if the application later changes the per-thread default token.

  Whenever a new thread is created, its token is initialized to the default, the Internal Key Storage Token. Thus, the thread token is not inherited from the parent thread.

  The following example shows how you can specify which token is used for various JCA operations:

  
  // Lookup PKCS #11 tokens
  CryptoManager manager = CryptoManager.getInstance();
  CryptoToken tokenA = manager.getTokenByName("TokenA");
  CryptoToken tokenB = manager.getTokenByName("TokenB");
  
  // Create an RSA KeyPairGenerator using TokenA
  manager.setThreadToken(tokenA);
  KeyPairGenerator rsaKpg = KeyPairGenerator.getInstance("RSA", "Mozilla-JSS");
  
  // Create a DSA KeyPairGenerator using TokenB
  manager.setThreadToken(tokenB);
  KeyPairGenerator dsaKpg  = KeyPairGenerator.getInstance("DSA", "Mozilla-JSS");
  
  // Generate an RSA KeyPair. This will happen on TokenA because TokenA
  // was the per-thread default token when rsaKpg was created.
  rsaKpg.initialize(1024);
  KeyPair rsaPair = rsaKpg.generateKeyPair();
  
  // Generate a DSA KeyPair. This will happen on TokenB because TokenB
  // was the per-thread default token when dsaKpg was created.
  dsaKpg.initialize(1024);
  KeyPair dsaPair = dsaKpg.generateKeyPair();
  

Supported Classes

• Cipher
• DSAPrivateKey
• DSAPublicKey
• KeyFactory
• KeyGenerator
• KeyPairGenerator
• Mac
• MessageDigest
• RSAPrivateKey
• RSAPublicKey
• SecretKeyFactory
• SecretKey
• SecureRandom
• Signature

  What's Not Supported

  • The following classes don't work very well:
    • KeyStore: There are many serious problems mapping the JCA keystore interface onto NSS's model of PKCS #11 modules. The current implementation is almost useless. Since these problems lie deep in the NSS design and implementation, there is no clear timeframe for fixing them. Meanwhile, the org.mozilla.jss.crypto.CryptoStore class can be used for some of this functionality.

  Cipher Supported Algorithms Notes AES DES DESede (DES3 ) RC2 RC4 RSA The following modes and padding schemes are supported: Algorithm Mode Padding DES ECB NoPadding CBC NoPadding PKCS5 Padding DESede DES3 ECB NoPadding CBC NoPadding PKCS5 Padding AES ECB NoPadding CBC NoPadding PKCS5 Padding RC4 None None RC2 CBC NoPadding PKCS5Padding The SecureRandom argument passed to initSign() and initVerify() is ignored, because NSS does not support specifying an external source of randomness.

  DSAPrivateKey getX() is not supported because NSS does not support extracting data from private keys.

  KeyFactory Supported Algorithms Notes DSA RSA The following transformations are supported for generatePublic() and generatePrivate(): From To RSAPublicKeySpec RSAPublicKey DSAPublicKeySpec DSAPublicKey X509EncodedKeySpec RSAPublicKey DSAPublicKey RSAPrivateCrtKeySpec RSAPrivateKey DSAPrivateKeySpec DSAPrivateKey PKCS8EncodedKeySpec RSAPrivateKey DSAPrivateKey getKeySpec() is not supported. This method exports key material in plaintext and is therefore insecure. Note that a public key's data can be accessed directly from the key. translateKey() simply gets the encoded form of the given key and then tries to import it by calling generatePublic() or generatePrivate(). Only X509EncodedKeySpec is supported for public keys, and only PKCS8EncodedKeySpec is supported for private keys.

  KeyGenerator Supported Algorithms Notes AES DES DESede (DES3 ) RC4 The SecureRandom argument passed to init() is ignored, because NSS does not support specifying an external source of randomness. None of the key generation algorithms accepts an AlgorithmParameterSpec.

  KeyPairGenerator Supported Algorithms Notes DSA RSA The SecureRandom argument passed to initialize() is ignored, because NSS does not support specifying an external source of randomness.

  Mac Supported Algorithms Notes HmacSHA1 (Hmac-SHA1 ) Any secret key type (AES, DES, etc.) can be used as the MAC key, but it must be a JSS key. That is, it must be an instanceof org.mozilla.jss.crypto.SecretKeyFacade. The params passed to init() are ignored.

  MessageDigest Supported Algorithms MD5 MD2 SHA-1 (SHA1, SHA )

  RSAPrivateKey Notes getModulus() is not supported because NSS does not support extracting data from private keys. getPrivateExponent() is not supported because NSS does not support extracting data from private keys.

  SecretKeyFactory Supported Algorithms Notes AES DES DESede (DES3 ) PBAHmacSHA1 PBEWithMD5AndDES PBEWithSHA1AndDES PBEWithSHA1AndDESede (PBEWithSHA1AndDES3 ) PBEWithSHA1And128RC4 RC4 generateSecret supports the following transformations: KeySpec Class Key Algorithm PBEKeySpec org.mozilla.jss.crypto.PBEKeyGenParams Using the appropriate PBE algorithm: DES DESede RC4 DESedeKeySpec DESede DESKeySpec DES SecretKeySpec AES DES DESede RC4 getKeySpec supports the following transformations: Key Algorithm KeySpec Class DESede DESedeKeySpec DES DESKeySpec DESede DES AES RC4 SecretKeySpec For increased security, some SecretKeys may not be extractable from their PKCS #11 token. In this case, the key should be wrapped (encrypted with another key), and then the encrypted key might be extractable from the token. This policy varies across PKCS #11 tokens. translateKey tries two approaches to copying keys. First, it tries to copy the key material directly using NSS calls to PKCS #11. If that fails, it calls getEncoded() on the source key, and then tries to create a new key on the target token from the encoded bits. Both of these operations will fail if the source key is not extractable. The class java.security.spec.PBEKeySpec in JDK versions earlier than 1.4 does not contain the salt and iteration fields, which are necessary for PBE key generation. These fields were added in JDK 1.4. If you are using a JDK (or JRE) version earlier than 1.4, you cannot use class java.security.spec.PBEKeySpec. Instead, you can use org.mozilla.jss.crypto.PBEKeyGenParams. If you are using JDK (or JRE) 1.4 or later, you can use java.security.spec.PBEKeySpec or org.mozilla.jss.crypto.PBEKeyGenParams.

  SecretKey Supported Algorithms Notes AES DES DESede (DES3 ) HmacSHA1 RC2 RC4 SecretKey is implemented by the class org.mozilla.jss.crypto.SecretKeyFacade, which acts as a wrapper around the JSS class SymmetricKey. Any SecretKeys handled by JSS will actually be SecretKeyFacades. This should usually be transparent.

  SecureRandom Supported Algorithms Notes pkcs11prng This invokes the NSS internal pseudorandom number generator.

  Signature Supported Algorithms Notes SHA1withDSA (DSA, DSS, SHA/DSA, SHA-1/DSA, SHA1/DSA, DSAWithSHA1, SHAwithDSA ) SHA-1/RSA (SHA1/RSA, SHA1withRSA ) MD5/RSA (MD5withRSA ) MD2/RSA The SecureRandom argument passed to initSign() and initVerify() is ignored, because NSS does not support specifying an external source of randomness.