BigInteger is a BigProblem

Java Cryptography
http://java.sun.com/j2se/1.4.2/docs/guide/security/CryptoSpec.html#RSAPrivateKeySpec
http://stellify.net/rijndael/KeyTools.java


J2ME BigInteger Support
http://www-128.ibm.com/developerworks/library/j-midpds.html
http://www.javaworld.com/javaworld/jw-12-2002/jw-1220-wireless.html
http://www.bouncycastle.org/documentation.html
http://www-128.ibm.com/developerworks/library/j-j2me/
http://java.sun.com/products/cdc/
http://java.sun.com/products/foundation/