Encryptor and Decryptor

Hi All,

I want to ask about encryptor and decryptor (XML Encryption
Syntax and Processing, Section 4.1 and 4.2). 

1. What programming languange do I choose for developing
encryptor  and decryptor ?

2. What best algorithms do I choose for developing encryptor
and decryptor on Table of Algorithm in Section 5 ?

Thanks.