User management (incomplete)

user.go

package main

import (
  "crypto/rand"
  "crypto/sha1"
  "code.google.com/p/go.crypto/pbkdf2"
  "bytes"
  "labix.org/v2/mgo"
  "labix.org/v2/mgo/bson"
)

type User struct {
    Username string
    PasswordHash []byte
    Salt []byte
    Role string
}

func generateSalt() []byte {
    buf := make([]byte, 32)
    rand.Read(buf)
    return buf
}

func generateHash(password string, salt []byte) []byte {
    buf := bytes.NewBufferString(password)
    return pbkdf2.Key(buf.Bytes(), salt, 4096, 32, sha1.New)
}

func AddUser(db *mgo.Database, username string, password string) {
    salt := generateSalt()
    user := User{Username: username,
                 Salt: salt,
                 Role: "admin",
                 PasswordHash: generateHash(password, salt)}
    db.C("user").Insert(user)
}

func Auth(db *mgo.Database, username string, password string) bool {
    i := db.C("user").Find(bson.M{"username": username}).Iter()
    var user User
    if i.Next(&user) {
        hash := generateHash(password, user.Salt)
        return bytes.Equal(hash, user.PasswordHash)
    }
    return false
}