Javascript simple library

I need you to develop a simple javascript library, which will help me easily use [login to view URL] interface (supported by modern web browsers). For simple description, read [login to view URL] The library will provide functions to do the following tasks: 1) create public+private keypair for ECDSA algorithm 2) export private and public keys in base58 encoding 3) use a base58-encoded private key to sign a message* 4) use a base58-encoded public key to verify a message* 5) use a base58-encoded public key to encrypt a message* 6) use a base58-encoded private key to decrypt a message* *messages supported must include following types: string, binary blob I expect the javascript source code to be 100 lines of code max.