from django.shortcuts import resolve_url
from django.core.signing import Signer
from django.core.exceptions import SuspiciousOperation

signer = Signer()

def signed_url(name, **kwargs):
    """
    >>> signed_url('foo/bar')
    """
    url = resolve_url(name, **kwargs)
    sig = signer.sign(url)
    return sig.replace(":", "?auth=")

def check_signed_url(url, auth):
    sig = signer.sign(url)
    if sig[len(url)+1:] != auth:
        sig = "_HIDDEN_"
        raise SuspiciousOperation("Bad auth code")
    
if __name__ == '__main__':
    import doctest
    print(doctest.testmod())