cryptography
common sense there are five solution to solve unser problems symmetric cryptography public-key cryptography hash Message Authentication Code Digital Signature threat speciality solution eavesdrop Confidentiality 1 & 2 falsity Integrity 3 & 4 & 5 disguise Authenticity 4 & 5 denial Nonrepudiation 5 shoule use public crypto algorithm, instead of private crypto algorithm cryptography in history caesar cipher just brute-force attack #include <cctype> #include <iostream> using namespace std; void func(string s) { for (int i = 0; i < 26; ++i) { string temp(s); for (auto &c : temp) { c = tolower(c); c = ((c + i) - 97) % 26 + 97; } cout << temp << endl; } } int main() { string s; cin >> s; func(s); } simple substitution cipher Letter_frequency ...