How can i encode a string in base64 using meteor - amazon-s3

Question

I am trying to use a form to upload files to a s3 bucket using Meteor. I am following this amazon article. At "Sign Your S3 POST Form", near the end, I need to encode a string to base64 but I've been unable to find a way to do this. Can anyone tell me how to do this? Notice that the string first needs to be encoded and then signed. This is how it's done in python:
import base64
import hmac, hashlib
policy = base64.b64encode(policy_document)
signature = base64.b64encode(hmac.new(AWS_SECRET_ACCESS_KEY, policy, hashlib.sha1).digest())

Answer 1

You can do this without the NodeJS crypto module, creating a package looked a bit like breaking a fly on the wheel to me so I figured out this:
if (Meteor.isServer) {
Meteor.methods({
'base64Encode':function(unencoded) {
return new Buffer(unencoded || '').toString('base64');
},
'base64Decode':function(encoded) {
return new Buffer(encoded || '', 'base64').toString('utf8');
},
'base64UrlEncode':function(unencoded) {
var encoded = Meteor.call('base64Encode',unencoded);
return encoded.replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '');
},
'base64UrlDecode':function(encoded) {
encoded = encoded.replace(/-/g, '+').replace(/_/g, '/');
while (encoded.length % 4)
encoded += '=';
return Meteor.call('base64Decode',encoded);
}
console.log(Meteor.call('base64Encode','abc'));
});
This is based on the base64.js by John Hurliman found at https://gist.github.com/jhurliman/1250118 Note that this will work like a charm on the server but for porting it to the client you have call the methods with a callback function that stores the result as a session variable.

Answer 2

You need NodeJS crypto module to perform these tasks.
First create a "packages" directory at the root of your meteor project, then create a "my-package" directory.
Inside it, you need two files : a "package.js" and "my-package.js".
package.js should look like :
Package.describe({
summary:"MyPackage doing amazing stuff with AWS."
});
Package.on_use(function(api){
// add your package file to the server app
api.add_files("my-package.js","server");
// what we export outside of the package
// (this is important : packages have their own scope !)
api.export("MyPackage","server");
});
my-package.js should look like :
var crypto=Npm.require("crypto");
MyPackage={
myFunction:function(arguments){
// here you can use crypto functions !
}
};
The function you will probably need is crypto.createHmac.
Here is an example code of how I encode a JSON security policy in base64 then use it to generate a security signature in my own app :
encodePolicy:function(jsonPolicy){
// stringify the policy, store it in a NodeJS Buffer object
var buffer=new Buffer(JSON.stringify(jsonPolicy));
// convert it to base64
var policy=buffer.toString("base64");
// replace "/" and "+" so that it is URL-safe.
return policy.replace(/\//g,"_").replace(/\+/g,"-");
},
encodeSignature:function(policy){
var hmac=crypto.createHmac("sha256",APP_SECRET);
hmac.update(policy);
return hmac.digest("hex");
}
This will allow you to call MyPackage.myFunction in the server-side of your Meteor app.
Last but not last, don't forget to "meteor add my-package" in order to use it !

Answer 3

You can use meteor-crypto-base64 package.
CryptoJS.enc.Base64.stringify(CryptoJS.enc.Utf8.parse('Hello, World!'));
//"SGVsbG8sIFdvcmxkIQ=="