Verify a challenging hmac signature against a string / shared-secret

    .. versionadded:: 2014.7.0

    Returns a boolean if the verification succeeded or failed.

    CLI Example:

    .. code-block:: bash

        salt '*' hashutil.hmac_signature 'get salted' 'shared secret' 'eBWf9bstXg+NiP5AOwppB5HMvZiYMPzEM9W5YMm/AmQ='

def hmac_signature(string, shared_secret, challenge_hmac):
    '''
    Verify a challenging hmac signature against a string / shared-secret

    .. versionadded:: 2014.7.0

    Returns a boolean if the verification succeeded or failed.

    CLI Example:

    .. code-block:: bash

        salt '*' hashutil.hmac_signature 'get salted' 'shared secret' 'eBWf9bstXg+NiP5AOwppB5HMvZiYMPzEM9W5YMm/AmQ='
    '''
    return salt.utils.hashutils.hmac_signature(string, shared_secret, challenge_hmac)