Hashing implementation is not good for which of the following operations on external data?

__________ is a security enhancement to the MIME Internet e-mail format standard based on technology from RSA Data Security.

Fill in the blank(s) with the appropriate word(s).

Fill in the code to complete the following function for checking whether a string is a palindrome.

``` bool isPalindrome(const char * const s) { if (strlen(s) <= 1) // Base case return true; else if _____________________________ // Base case return false; else return isPalindrome(substring(s, 1, strlen(s) - 2)); } ``` bool isPalindrome(const char * const s) { if (strlen(s) <= 1) // Base case return true; else if _____________________________ // Base case return false; else return isPalindrome(substring(s, 1, strlen(s) - 2)); } A. (s[0] <> s[strlen(s) - 1]) B. (s[0] = s[strlen(s) - 1]) C. (s[0] == s[strlen(s) - 1]) D. (s[0] != s[strlen(s) - 1])