# Bouncy Castle Crypto Package

## 1.0 Introduction

The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. The package is organised so that it contains a light-weight API suitable for use in any environment (including the newly released J2ME) with the additional infrastructure to conform the algorithms to the JCE framework.

This software is distributed under a license based on the MIT X Consortium license. To view the license, see here

If you have the full package you will have six jar files, bcprov*.jar which contains the BC provider, jce-*.jar which contains the JCE provider, clean room API, and bcmail*.jar which contains the mail API.

Note: if you are using JDK 1.0, you will just find a class hierarchy in the classes directory.

To view examples, look at the test programs in the packages:

- org.bouncycastle.crypto.test
- org.bouncycastle.jce.provider.test

To verify the packages, run the following Java programs with the appropriate classpath:

- java org.bouncycastle.crypto.test.RegressionTest
- java org.bouncycastle.jce.provider.test.RegressionTest

## 2.0 Patents

Some of the algorithms in the Bouncy Castle APIs are patented in some places. It is upon the user of the library to be aware of what the legal situation is in their own situation, however we have been asked to specifically mention the patent below at the request of the patent holder.

The IDEA encryption algorithm is patented in the USA, Japan, and Europe including at least Austria, France, Germany, Italy, Netherlands, Spain, Sweden, Switzerland and the United Kingdom. Non-commercial use is free, however any commercial products that make use of IDEA are liable for royalties. Please see www.mediacrypt.com for further details.

## 3.0 Specifications

- clean room implementation of the JCE API
- light-weight cryptographic API consisting of support for
  - BlockCipher
  - BufferedBlockCipher
  - AsymmetricBlockCipher
  - BufferedAsymmetricBlockCipher
  - StreamCipher
  - BufferedStreamCipher
  - KeyAgreement
  - IESCipher
  - Digest
  - Mac
  - PBE
- JCE compatible framework for a Bouncy Castle provider

## 4.0 Light-weight API

This API has been specifically developed for those circumstances where the rich API and integration requirements of the JCE are not required.

However as a result, the light-weight API requires more effort and understanding on the part of a developer to initialise and utilise the algorithms.

### 4.1 Example

To utilise the light-weight API in a program, the fundamentals are as follows;

    	/*
    	 * This will use a supplied key, and encrypt the data
    	 * This is the equivalent of DES/CBC/PKCS5Padding
    	 */
    	BlockCipher engine = new DESEngine();
    	BufferedBlockCipher cipher = new PaddedBlockCipher(new CBCCipher(engine));

    	byte[] key = keyString.getBytes();
    	byte[] input = inputString.getBytes();

    	cipher.init(true, new KeyParameter(key));

    	byte[] cipherText = new byte[cipher.getOutputSize(input.length)];

    	int outputLen = cipher.processBytes(input, 0, input.length, cipherText, 0);
    	try
    	{
    		cipher.doFinal(cipherText, outputLen);
    	}
    	catch (CryptoException ce)
    	{
    		System.err.println(ce);
    		System.exit(1);
    	}

### 4.2 Algorithms

The light-weight API has built in support for the following:

#### Symmetric (Block)

The base interface is BlockCipher and has the following implementations which match the modes the block cipher can be operated in.

Name | Constructor | Notes
--- | --- | ---
BufferedBlockCipher | BlockCipher |
CBCBlockCipher | BlockCipher |
CFBBlockCipher | BlockCipher, block size (in bits) |
OFBBlockCipher | BlockCipher, block size (in bits) |
PGPCFBBlockCipher | BlockCipher |

BufferedBlockCipher has a further sub-classes

Name | Constructor | Notes
--- | --- | ---
PaddedBufferedBlockCipher | BlockCipher | a buffered block cipher that can use padding - default PKCS5/7 padding
CTSBlockCipher | BlockCipher | Cipher Text Stealing

The following paddings can be used with the PaddedBufferedBlockCipher.

Name | Description
--- | ---
PKCS7Padding | PKCS7/PKCS5 padding
ISO10126d2Padding | ISO 10126-2 padding
X932Padding | X9.23 padding

The following cipher engines are implemented that can be used with the above modes.

Name | KeySizes (in bits) | Block Size | Notes
--- | --- | --- | ---
AESEngine | 0 .. 256 | 128 bit |
AESWrapEngine | 0 .. 256 | 128 bit | Implements FIPS AES key wrapping
BlowfishEngine | 0 .. 448 | 64 bit |
CAST5Engine | 0 .. 128 | 64 bit |
CAST6Engine | 0 .. 256 | 128 bit |
DESEngine | 64 | 64 bit |
DESedeEngine | 128, 192 | 64 bit |
DESedeWrapEngine | 128, 192 | 64 bit | Implements Draft IETF DESede key wrapping
IDEAEngine | 128 | 64 bit |
RC2Engine | 0 .. 1024 | 64 bit |
RC532Engine | 0 .. 128 | 64 bit | Uses a 32 bit word
RC564Engine | 0 .. 128 | 128 bit | Uses a 64 bit word
RC6Engine | 0 .. 256 | 128 bit |
RijndaelEngine | 0 .. 256 | 128 bit, 160 bit, 192 bit, 224 bit, 256 bit |
SkipjackEngine | 0 .. 128 | 64 bit |
TwofishEngine | 128, 192, 256 | 128 bit |
SerpentEngine | 128, 192, 256 | 128 bit |

#### Symmetric (Stream)

The base interface is StreamCipher and has the following implementations which match the modes the stream cipher can be operated in.

Name | Constructor | Notes
--- | --- | ---
BlockStreamCipher | BlockCipher |

The following cipher engines are implemented that can be used with the above modes.

Name | KeySizes (in bits) | Notes
--- | --- | ---
RC4Engine | 40 .. 2048 |

#### Block Asymmetric

The base interface is AsymmetricBlockCipher and has the following implementations which match the modes the cipher can be operated in.

Name | Constructor | Notes
--- | --- | ---
BufferedAsymmetricBlockCipher | AsymmetricBlockCipher |
OAEPEncoding | AsymmetricBlockCipher |
PKCS1Encoding | AsymmetricBlockCipher |
ISO9796d1Encoding | AsymmetricBlockCipher | ISO9796-1

The following cipher engines are implemented that can be used with the above modes.

Name | KeySizes (in bits) | Notes
--- | --- | ---
RSAEngine | any multiple of 8 large enough for the encoding. |

#### Digest

The base interface is Digest and has the following implementations

Name | Output (in bits) | Notes
--- | --- | ---
MD2Digest | 128 |
MD4Digest | 128 |
MD5Digest | 128 |
RipeMD128Digest | 160 | basic RipeMD
RipeMD160Digest | 160 | enhanced version of RipeMD
SHA1Digest | 160 |
SHA256Digest | 256 | Draft version from FIPS 180-2
SHA384Digest | 384 | Draft version from FIPS 180-2
SHA512Digest | 512 | Draft version from FIPS 180-2
TigerDigest | 192 | The Tiger Digest.

#### MAC

The base interface is Mac and has the following implementations

Name | Output (in bits) | Notes
--- | --- | ---
CBCBlockCipherMac | blocksize/2 unless specified |
CFBBlockCipherMac | blocksize/2, in CFB 8 mode, unless specified |
HMac | digest length |

#### PBE

The base class is PBEParametersGenerator and has the following sub-classes

Name | Constructor | Notes
--- | --- | ---
PKCS5S1ParametersGenerator | Digest |
PKCS5S2ParametersGenerator |  | Uses SHA1/Hmac as defined
PKCS12ParametersGenerator | Digest |

#### Key Agreement

Two versions of Diffie-Hellman key agreement are supported, the basic version, and one for use with long term public keys. Two versions of key agreement using Elliptic Curve cryptography are also supported, standard Diffie-Hellman key agreement and standard key agreement with co-factors.

The agreement APIs are in the org.bouncycastle.crypto.agreement package. Classes for generating Diffie-Hellman parameters can be found in the org.bouncycastle.crypto.params and org.bouncycastle.crypto.generators packages.

#### IESCipher

The IES cipher is based on the one described in IEEE P1363a (draft 10), for use with either traditional Diffie-Hellman or Elliptic Curve Diffie-Hellman.

Note: At the moment this is still a draft, don't use it for anything that may be subject to long term storage, the key values produced may well change as the draft is finalised.

#### Signers

DSA, ECDSA and RSA-PSS are supported by the org.bouncycastle.crypto.signers package. Note: as these are light weight classes, if you need to use SHA1 (as defined in the standard) you'll also need to make use of the SHA1 digest class in conjunction with these. Classes for generating DSA and ECDSA parameters can be found in the org.bouncycastle.crypto.params and org.bouncycastle.crypto.generators packages.

### 4.3 ASN.1 package

The light-weight API has direct interfaces into a package capable of reading and writing DER-encoded ASN.1 objects and for the generation of X.509 V3 certificate objects and PKCS12 files. BER InputStream and OutputStream classes are provided as well.

## 5.0 Bouncy Castle Provider

The Bouncy Castle provider is a JCE compliant provider that is a wrapper built on top of the light-weight API.

The advantage for writing application code that uses the provider interface to cryptographic algorithms is that the actual provider used can be selected at run time. This is extremely valuable for applications that may wish to make use of a provider that has underlying hardware for cryptographic computation, or where an application may have been developed in an environment with cryptographic export controls.

### 5.1 Example

To utilise the JCE provider in a program, the fundamentals are as follows;

    	/*
    	 * This will generate a random key, and encrypt the data
    	 */
    	Key		key;
    	KeyGenerator	keyGen;
    	Cipher		encrypt;

    	Security.addProvider(new BouncyCastleProvider());

    	try
    	{
    		// "BC" is the name of the BouncyCastle provider
    		keyGen = KeyGenerator.getInstance("DES", "BC");
    		keyGen.init(new SecureRandom());

    		key = keyGen.generateKey();

    		encrypt = Cipher.getInstance("DES/CBC/PKCS5Padding", "BC");
    	}
    	catch (Exception e)
    	{
    		System.err.println(e);
    		System.exit(1);
    	}

    	encrypt.init(Cipher.ENCRYPT_MODE, key);

    	bOut = new ByteArrayOutputStream();
    	cOut = new CipherOutputStream(bOut, encrypt);

    	cOut.write("plaintext".getBytes());
    	cOut.close();

    	// bOut now contains the cipher text

The provider can also be configured as part of your environment via static registration by adding an entry to the java.security properties file (found in $JAVA_HOME/jre/lib/security/java.security, where $JAVA_HOME is the location of your JDK/JRE distribution). You'll find detailed instructions in the file but basically it comes down to adding a line:

        security.provider.<n>=org.bouncycastle.jce.provider.BouncyCastleProvider

Where <n> is the preference you want the provider at (1 being the most prefered).

Where you put the jar is up to mostly up to you, although with jdk1.3 and jdk1.4 the best (and in some cases only) place to have it is in $JAVA_HOME/jre/lib/ext.

### 5.2 Algorithms

#### Symmetric (Block)

Modes:

- ECB
- CBC
- OFB(n)
- CFB(n)
- PGPCFB

Where (n) is a multiple of 8 that gives the blocksize in bits, eg, OFB8. Note that OFB and CFB mode can be used with plain text that is not an exact multiple of the block size if NoPadding has been specified.

Padding Schemes:

- No padding
- PKCS5/7
- ISO10126/ISO10126-2
- X9.23/X923
- CTS

When placed together this gives a specification for an algorithm as;

- DES/CBC/WithCTS
- DES/CBC/X9.23Padding
- DES/OFB8/NoPadding
- IDEA/CBC/ISO10126Padding
- SKIPJACK/ECB/PKCS7Padding

Note: default key sizes are in bold.

Name | KeySizes (in bits) | Block Size | Notes
--- | --- | --- | ---
AES | 0 .. 256 (192) | 128 bit |
AESWrap | 0 .. 256 (192) | 128 bit | A FIPS AES key wrapper
Blowfish | 0 .. 448 (448) | 64 bit |
CAST5 | 0 .. 128(128) | 64 bit |
CAST6 | 0 .. 256(256) | 128 bit |
DES | 64 | 64 bit |
DESede | 128, 192 | 64 bit |
DESedeWrap | 128, 192 | 128 bit | A Draft IETF DESede key wrapper
IDEA | 128 (128) | 64 bit |
RC2 | 0 .. 1024 (128) | 64 bit |
RC5 | 0 .. 128 (128) | 64 bit | Uses a 32 bit word
RC5-64 | 0 .. 256 (256) | 128 bit | Uses a 64 bit word
RC6 | 0 .. 256 (128) | 128 bit |
Rijndael | 0 .. 256 (192) | 128 bit |
Skipjack | 0 .. 128 (128) | 64 bit |
Twofish | 128, 192, 256 (256) | 128 bit |
Serpent | 128, 192, 256 (256) | 128 bit |

#### Symmetric (Stream)

Note: default key sizes are in bold.

Name | KeySizes (in bits) | Notes
--- | --- | ---
RC4 | 40 .. 2048 bits (128) |

#### Block Asymmetric

Encoding:

- OAEP - Optimal Asymmetric Encryption Padding
- PCKS1 - PKCS v1.5 Padding
- ISO9796-1 - ISO9796-1 edition 1 Padding

Note: except as indicated in PKCS 1v2 we recommend you use OAEP, as mandated in X9.44.

When placed together with RSA this gives a specification for an algorithm as;

- RSA/NONE/NoPadding
- RSA/NONE/PKCS1Padding
- RSA/NONE/OAEPPadding
- RSA/NONE/ISO9796-1Padding

Name | KeySizes (in bits) | Notes
--- | --- | ---
RSA | any multiple of 8 bits large enough for the encryption(2048) |

#### Key Agreement

Diffie-Hellman key agreement is supported using the "DH", "ECDH", and "ECDHC" (ECDH with cofactors) key agreement instances.

Note: with basic "DH" only the basic algorithm fits in with the JCE API, if you're using long-term public keys you may want to look at the light-weight API.

#### ECIES

An implementation of ECIES (stream mode) as described in IEEE P 1363a.

Note: At the moment this is still a draft, don't use it for anything that may be subject to long term storage, the key values produced may well change as the draft is finalised.

#### Digest

Name | Output (in bits) | Notes
--- | --- | ---
MD2 | 128 |
MD4 | 128 |
MD5 | 128 |
RipeMD128 | 128 | basic RipeMD
RipeMD160 | 160 | enhanced version of RipeMD
SHA1 | 160 |
SHA-256 | 256 | Draft version from FIPS 180-2
SHA-384 | 384 | Draft version from FIPS 180-2
SHA-512 | 512 | Draft version from FIPS 180-2
Tiger | 192 |

#### MAC

Name | Output (in bits) | Notes
--- | --- | ---
Any MAC based on a block cipher, CBC (the default) and CFB modes. | half the cipher's block size (usually 32 bits) |
MD2-HMac | 128 |
MD4-HMac | 128 |
MD5-HMac | 128 |
RipeMD128-HMac | 128 |
RipeMD160-HMac | 160 |
SHA1-HMac | 160 |
Tiger-HMac | 192 |

Examples:

- DESMac
- DESMac/CFB8
- DESedeMac
- DESedeMac/CFB8
- SKIPJACKMac
- SKIPJACKMac/CFB8
- IDEAMac
- IDEAMac/CFB8
- RC2Mac
- RC2Mac/CFB8
- RC5Mac
- RC5Mac/CFB8

#### Signature Algorithms

Schemes:

- MD2withRSA
- MD5withRSA
- SHA1withRSA
- RIPEMD160withRSA
- SHA1withDSA
- SHA1withECDSA

#### PBE

Schemes:

- PKCS5S1, any Digest, any symmetric Cipher, ASCII
- PKCS5S2, SHA1/HMac, any symmetric Cipher, ASCII
- PKCS12, any Digest, any symmetric Cipher, Unicode

Defined in Bouncy Castle JCE Provider

Name | Key Generation Scheme | Key Length (in bits)
--- | --- | ---
PBEWithMD5AndDES | PKCS5 Scheme 1 | 64
PBEWithMD5AndRC2 | PKCS5 Scheme 1 | 128
PBEWithSHA1AndDES | PKCS5 Scheme 1 | 64
PBEWithSHA1AndRC2 | PKCS5 Scheme 1 | 128
PBEWithSHAAnd2-KeyTripleDES-CBC | PKCS12 | 128
PBEWithSHAAnd3-KeyTripleDES-CBC | PKCS12 | 192
PBEWithSHAAnd128BitRC2-CBC | PKCS12 | 128
PBEWithSHAAnd40BitRC2-CBC | PKCS12 | 40
PBEWithSHAAnd128BitRC4 | PKCS12 | 128
PBEWithSHAAnd40BitRC4 | PKCS12 | 40
PBEWithSHAAndTwofish-CBC | PKCS12 | 256
PBEWithSHAAndIDEA-CBC | PKCS12 | 128

### 5.3 Certificates

The Bouncy Castle provider will read X.509 certficates (v2 or v3) as per the examples in the java.security.cert.CertificateFactory class. They can be provided either in the normal PEM encoded format, or as DER binaries.

The CertificiateFactory will also read X.509 CRLs (v2) from either PEM or DER encodings.

In addition to the classes in the org.bouncycastle.ans1.x509 package for certificate generation a more JCE "friendly" class is provided in the package org.bouncycastle.jce. The JCE "friendly" class supports RSA, DSA, and EC-DSA.

### 5.4 Keystore

The Bouncy Castle package has three implementation of a keystore.

The first "BKS" is a keystore that will work with the keytool in the same fashion as the Sun "JKS" keystore. The keystore is resistent to tampering but not inspection.

The second, Keystore.BouncyCastle, or Keystore.UBER will only work with the keytool if the password is provided on the command line, as the entire keystore is encrypted with a PBE based on SHA1 and Twofish. PBEWithSHAAndTwofish-CBC. This makes the entire keystore resistant to tampering and inspection, and forces verification. The Sun JDK provided keytool will attempt to load a keystore even if no password is given, this is impossible for this version. (One might wonder about going to all this trouble and then having the password on the command line! New keytool anyone?).

In the first case, the keys are encrypted with 3-Key-TripleDES.

The third is a PKCS12 compatabile keystore. PKCS12 provides a slightly different situation from the regular key store, the keystore password is currently the only password used for storing keys. Otherwise it supports all the functionality required for it to be used with the keytool. In some situations other libraries always expect to be dealing with Sun certificates, if this is the case use PKCS12-DEF, and the certificates produced by the key store will be made using the default provider.

There is an example program that produces PKCS12 files suitable for loading into browsers. It is in the package org.bouncycastle.jce.examples.

### 5.5 Additional support classes for Elliptic Curve.

Currently there are no classes for supporting EC keys and parameters in the JCE or JCA. Classes for supporting these can be found in the following packages:

- org.bouncycastle.jce.spec
- org.bouncycastle.jce.interfaces
- org.bouncycastle.jce

### 6.0 BouncyCastle S/MIME

To be able to fully compile and utilise the BouncyCastle S/MIME package (including the test classes) you need the jar files for the following APIs.

- Junit - http://www.junit.org
- JavaMail - http://java.sun.com/products/javamail/index.html
- The Java Activation Framework - http://java.sun.com/products/javabeans/glasgow/jaf.html

### 6.1 Setting up BouncyCastle S/MIME in JavaMail

The BouncyCastle S/MIME handlers may be set in JavaMail two ways.

- STATICALLY
  Add the following entries to the mailcap file:

          application/pkcs7-signature;; x-java-content-handler=org.bouncycastle.mail.smime.handlers.pkcs7_signature
          application/pkcs7-mime;; x-java-content-handler=org.bouncycastle.mail.smime.handlers.pkcs7_mime
          application/x-pkcs7-signature;; x-java-content-handler=org.bouncycastle.mail.smime.handlers.x_pkcs7_signature
          application/x-pkcs7-mime;; x-java-content-handler=org.bouncycastle.mail.smime.handlers.x_pkcs7_mime
          multipart/signed;; x-java-content-handler=org.bouncycastle.mail.smime.handlers.multipart_signed

- DYNAMICALLY
  The following code will add the BouncyCastle S/MIME handlers dynamically:

          import javax.activation.MailcapCommandMap;
          import javax.activation.CommandMap;

          public static void setDefaultMailcap()
          {
              MailcapCommandMap _mailcap =
                  (MailcapCommandMap)CommandMap.getDefaultCommandMap();

              _mailcap.addMailcap("application/pkcs7-signature;; x-java-content-handler=org.bouncycastle.mail.smime.handlers.pkcs7_signature");
              _mailcap.addMailcap("application/pkcs7-mime;; x-java-content-handler=org.bouncycastle.mail.smime.handlers.pkcs7_mime");
              _mailcap.addMailcap("application/x-pkcs7-signature;; x-java-content-handler=org.bouncycastle.mail.smime.handlers.x_pkcs7_signature");
              _mailcap.addMailcap("application/x-pkcs7-mime;; x-java-content-handler=org.bouncycastle.mail.smime.handlers.x_pkcs7_mime");
              _mailcap.addMailcap("multipart/signed;; x-java-content-handler=org.bouncycastle.mail.smime.handlers.multipart_signed");

              CommandMap.setDefaultCommandMap(_mailcap);
          }