I am using NodeJS to interact with Amazon Web Services (specifically s3). I am attempting to use Server side encryption with customer keys. Only AES256 is allowed as an encryption method. The API specifies that the keys be base64 encoded.
At the moment I am merely testing the AWS api, I am using throwaway test files, so security (and secure key generation) are not an issue at the moment.
My problem is as follows: Given that I am in posession of a 256bit hexadecimal string, how do I obtain a base64 encoded string of the integer that that represents?
My first instinct was to first parse the Hexadecimal string as an integer, and convert it to a string using toString(radix) specifying a radix of 64. However toString() accepts a maximum radix of 36. Is there another way of doing this?
And even if I do this, is that a base64 encoded string of 256bit encryption key? The API reference just says that it expects a key that is "appropriate for use with the algorithm specified". (I am using the putObject method).
To convert a hex string to a base64 string in node.js, you can very easily use a Buffer;
var key_in_hex = '11223344556677881122334455667788'
var buf = new Buffer(key_in_hex, 'hex')
var str = buf.toString('base64')
...which will set str to the base64 equivalent of the hex string passed in ('112233...')
You could also of course combine it to a one liner;
var key_in_hex = '11223344556677881122334455667788'
var str = new Buffer(key_in_hex, 'hex').toString('base64')