def pk_verify(hashed, signature, public_key):
    """
    Verify `hashed` based on `signature` and `public_key`.

    hashed: string
        A hash for the data that is signed.

    signature: tuple
        Value returned by :func:`pk_sign`.

    public_key: :class:`Crypto.PublicKey.RSA`
        Public portion of key pair.
    """
    return public_key.verify(hashed, signature)