20.2 Logjam
Logjam (see [1]) represents the practical implementation of the attack template shown in Figure 20.1 with respect to the DHE key-establishment protocol. Here, the server is tricked into selecting a weak export-grade DHE cipher suite such as this:
As discussed earlier, the client therefore receives weak key parameters and uses them to generate a shared secret that can be computed by Mallory, despite having negotiated a stronger cipher suite. The underlying weakness, the lack of early authentication of the cipher suite selected by the server, is resolved in TLS 1.3.
