Golang Base64 encoded SHA256 digest of the user’s password

Question

I am attempting to complete the Top Code Go Learning Challenges as a vehicle to learn go. I'm currently working on their Simple API Web Server problem. Part of that problem calls for you to encrypt a password string as such "‘{SHA256}’ + Base64 encoded SHA256 digest of the user’s password"

I've used the following code to do this, but the results don't match the test case provided.

import (
    "encoding/base64"
    "crypto/sha256"
)

func encrtyptPasswords(password string) string {
    h := sha256.New()
    return "{SHA256}" + 
       string(base64.StdEncoding.EncodeToString(h.Sum([]byte(password))))
}

For an input of abcd1234 it should encrypt to: {SHA256}6c7nGrky_ehjM40Ivk3p3-OeoEm9r7NCzmWexUULaa4=

But I get {SHA256}YWJjZDEyMzTjsMRCmPwcFJr79MiZb7kkJ65B5GSbk0yklZkbeFK4VQ== instead. I suspect I'm using the encryption libraries wrong, but I'm not sure what I should be using as this seems to be the standard library method of encryption to SHA256.

Answer 1

You're misusing the Sum method. The docs for the hash.Hash interface clearly say that

Sum appends the current hash to b and returns the resulting slice.

(Emphasis added.)

You need to either write the data to the hash and use h.Sum like this

h.Write([]byte(password))
b := h.Sum(nil)

or just use sha256.Sum256

h := sha256.Sum256([]byte(password))

Playground: http://play.golang.org/p/oFBePRQzhN.