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Steps (3), (4), completed.
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@AndreasG9
AndreasG9 committed Nov 12, 2020
1 parent 391fb20 commit cd7e34d
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Showing 2 changed files with 333 additions and 82 deletions.
166 changes: 158 additions & 8 deletions Lab5/client.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,10 @@

#define ID_C "CIS3319USERID"
#define ID_TGS "CIS3319TGSID"
#define ID_V "CIS3319SERVERID"

std::string decrypt(std::string key_string, std::string ciphertext);
std::string encrypt(std::string key_string, std::string plaintext);
long long int get_epoch_time_seconds();


Expand All @@ -48,20 +51,20 @@ long long int get_epoch_time_seconds();
exit(1);
}

std::string AD_C = "127.0.01:" + std::to_string(port_num);

// Get keys
std::string key_c, key_tgs, key_v;
std::string key_c_string, key_tgs_string, key_v_string;
std::ifstream read_keys("keys.txt");

if (read_keys.is_open()) {
getline(read_keys, key_c);
getline(read_keys, key_tgs);
getline(read_keys, key_v);
getline(read_keys, key_c_string);
getline(read_keys, key_tgs_string);
getline(read_keys, key_v_string);
}

read_keys.close();

std::cout << key_c << "\n" << key_tgs << "\n" << key_v << std::endl;

// ----------- Network Setup (Winsock) ----------------------------------------------

// similar to what we did with server.cpp ...
Expand Down Expand Up @@ -111,7 +114,7 @@ long long int get_epoch_time_seconds();

do {
// Prompt user if ready to send user info msg to AS
std::cout << "Send msg to AS (CIS3319USERIDCIS3319TGSID || time stamp) ? hit any key to confirm ...\n";
std::cout << "Send msg to AS (CIS3319USERIDCIS3319TGSID || time stamp)? hit any key to confirm ...\n";
} while (std::cin.get() != '\n');

// info msg to send to AS
Expand All @@ -133,14 +136,109 @@ long long int get_epoch_time_seconds();

std::cout << "\nWaiting to receive a message from AS ... \n" << std::endl;

while ((retval_receive = recv(connected_socket, message_receive, BUFFER_LENGTH, 0)) > 0) {

if (retval_receive > 0) {
// store received data in c++ string
ciphertext.clear();
ciphertext.append(message_receive, retval_receive);
}

// DECRYPT msg to get session key, ticket, plus other info
plaintext.clear();
plaintext = decrypt(key_c_string, ciphertext); // plaintext will contain K_C_TGS || ID_TGS || TS_2 || LIFETIME_2 || TICKET_TGS

// SPLIT plaintext string to get TICKET_tgs (K_C_TGS will always be an 8-byte string, epoch time in string is 10-bytes, LIFETIME_2 will be 2-bytes)
int start = 8 + strlen(ID_TGS) + 10 + 2;
std::string ticket_ciphertext = plaintext.substr(start); // will return encrypted TICKET_TGS

// SPLIT plaintext string to get K_C_TGS (session_key from AS)
std::string k_c_tgs;
k_c_tgs = plaintext.substr(0, 8);


// DECRYPT TICKET_TGS with K_TGS
std::string ticket_tgs = decrypt(key_tgs_string, ticket_ciphertext);


// Print received plaintext and ticket from AS
std::cout << "\n***************************************************************" << std::endl;
std::cout << "received plaintext is: " << plaintext << std::endl; // in this plaintext string ticket_tgs was still encrypted
std::cout << "received Ticket_tgs is: " << ticket_tgs << std::endl;
std::cout << "*****************************************************************\n" << std::endl;

// ============================ (3) ============================================
// Generate Authenticator_C = E(K_C_TGS, [ID_C, AD_C, TS_3])
std::string auth_c = ID_C;
auth_c += AD_C;
auth_c += get_epoch_time_seconds();
auth_c = encrypt(k_c_tgs, auth_c);


// SEND ID_V || TICKET_TGS || AUTH_C to Ticket-granting server (still AS)
plaintext.clear();
plaintext += ID_V;
plaintext += ticket_tgs;
plaintext += auth_c;

do {
// Prompt user if ready to send user info msg to TGS
std::cout << "Send msg to TGS (ID_V || TICKET_TGS || AUTH_C)? hit any key to confirm ...\n";
} while (std::cin.get() != '\n');

retval_send = send(connected_socket, plaintext.c_str(), plaintext.size(), 0);
if (retval_send == SOCKET_ERROR) {
std::cout << "Error, failed to send" << std::endl;
closesocket(connected_socket);
WSACleanup();
return 1;
}

}

// ============================ (5) ============================================
// receive E(K_C_TGS[K_C_V || ID_V || TS_4 || TICKET_V]) from TGS

while ((retval_receive = recv(connected_socket, message_receive, BUFFER_LENGTH, 0)) > 0) {

if (retval_receive > 0) {
// store received ciphertext in c++ string
ciphertext.clear();
ciphertext.append(message_receive, retval_receive);

// decrypt and split msg, to get encrypted ticket_v, decrypt to get plaintext of ticket_v
plaintext.clear();
plaintext = decrypt(k_c_tgs, ciphertext);

int start = 8 + strlen(ID_V) + 10; // 8 for TGS session key, length of ID_V, and 10 bytes for time string.
std::string ticket_v = plaintext.substr(start);
ticket_v = decrypt(key_v_string, ticket_v);

// Print received plaintext and ticket from TGS
std::cout << "\n***************************************************************" << std::endl;
std::cout << "received plaintext is: " << plaintext << std::endl;
std::cout << "received Ticket_tgs is: " << ticket_v << std::endl;
std::cout << "*****************************************************************\n" << std::endl;

break;
}
}

// SEND TICKET_V || AUTH_C to V (server2.cpp)




}
if (retval_receive < 0) break;
}

// CONNECT TO server2 (SERVICE)

// server disconnected, cleanup, quit client.
shutdown(connected_socket, SD_SEND);
closesocket(connected_socket);
WSACleanup();
std::cout << "Client closed" << std::endl;

return 0;
}
Expand All @@ -151,4 +249,56 @@ long long int get_epoch_time_seconds();
long long int time = std::chrono::duration_cast<std::chrono::seconds>(std::chrono::system_clock::now().time_since_epoch()).count();

return time;
}


std::string encrypt(std::string key_string, std::string plaintext) {

CryptoPP::SecByteBlock key((const unsigned char*)(key_string.data()), key_string.size());
std::string ciphertext;

try {
CryptoPP::ECB_Mode< CryptoPP::DES >::Encryption encrypt;
encrypt.SetKey(key, key.size());

// Encrypt, add padding if needed
CryptoPP::StringSource(plaintext, true,
new CryptoPP::StreamTransformationFilter(encrypt,
new CryptoPP::StringSink(ciphertext)
)
);
}
catch (const CryptoPP::Exception& err) {
std::cerr << "ERROR" << err.what() << std::endl;
exit(1);
}

return ciphertext;
}

std::string decrypt(std::string key_string, std::string ciphertext) {

CryptoPP::SecByteBlock key((const unsigned char*)(key_string.data()), key_string.size());
std::string plaintext;

try {

CryptoPP::ECB_Mode< CryptoPP::DES >::Decryption decrypt;
decrypt.SetKey(key, key.size());

// Decrypt, remove padding if needed
CryptoPP::StringSource s(ciphertext, true,
new CryptoPP::StreamTransformationFilter(decrypt,
new CryptoPP::StringSink(plaintext)
)
);
}

catch (const CryptoPP::Exception& err) {
std::cerr << "ERROR probably exceeded the buffer length\n" << err.what() << std::endl;
exit(1);
}


return plaintext;
}
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