def _kd_value(k_val, s_val):
return _h_value(b"<STR_LIT::>".join((k_val, s_val)))<EOL>
KD function of the DIGEST-MD5 algorithm.

    :Parameters:
        - `k_val`: a byte string.
        - `s_val`: a byte string.
    :Types:
        - `k_val`: `bytes`
        - `s_val`: `bytes`

    :return: MD5 sum of the strings joined with ':'.
    :returntype: `bytes`