Guessing or knowing the initial TCP sequence number (ISN) that a server will choose enables an attacker to establish a TCP connection. Please discuss if the following solutions are secure (to prevent hijacking etc.) and why. [x]32 denotes truncation of x to the 32 least significant bits. K is a (permanent) secret key stored locally and only known to the server. H represents a secure hash function (e.g., SHA256) and its algorithm is publicly known. Also note that || means concatenation and the current timestamp is represented as a UNIX timestamp. Server computes ISN as follows: ISN = [H(source IP address XOR destination IP address XOR current timestamp XOR K)]32