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Forward secrecy implemented into crypto.

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This commit is contained in:
irungentoo 2013-07-06 10:57:49 -04:00
parent 928fc1e65a
commit 7458473dca
4 changed files with 88 additions and 44 deletions
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92
core/net_crypto.c
View File

@ -18,9 +18,12 @@ uint8_t self_secret_key[crypto_box_SECRETKEYBYTES];
typedef struct
{
uint8_t public_key[crypto_box_PUBLICKEYBYTES];
uint8_t public_key[crypto_box_PUBLICKEYBYTES];//the real public key of the peer.
uint8_t recv_nonce[crypto_box_NONCEBYTES];//nonce of recieved packets
uint8_t sent_nonce[crypto_box_NONCEBYTES];//nonce of sent packets.
uint8_t sessionpublic_key[crypto_box_PUBLICKEYBYTES];//our public key for this session.
uint8_t sessionsecret_key[crypto_box_SECRETKEYBYTES];//our private key for this session.
uint8_t peersessionpublic_key[crypto_box_PUBLICKEYBYTES];//The public key of the peer.
uint8_t status;//0 if no connection, 1 we have sent a handshake, 2 if connexion is not confirmed yet
//(we have recieved a hanshake but no empty data packet), 3 if the connection is established.
//4 if the connection is timed out.
@ -43,10 +46,11 @@ int outbound_friendrequests[MAX_FRIEND_REQUESTS];
int incoming_connections[MAX_INCOMING];
//encrypts plain of length length to encrypted of length + 16 using the
//public key(32 bytes) of the reciever and a 24 byte nonce
//public key(32 bytes) of the reciever and the secret key of the sender and a 24 byte nonce
//return -1 if there was a problem.
//return length of encrypted data if everything was fine.
int encrypt_data(uint8_t * public_key, uint8_t * nonce, uint8_t * plain, uint32_t length, uint8_t * encrypted)
int encrypt_data(uint8_t * public_key, uint8_t * secret_key, uint8_t * nonce,
uint8_t * plain, uint32_t length, uint8_t * encrypted)
{
if(length - crypto_box_BOXZEROBYTES + crypto_box_ZEROBYTES > MAX_DATA_SIZE || length == 0)
{
@ -59,7 +63,7 @@ int encrypt_data(uint8_t * public_key, uint8_t * nonce, uint8_t * plain, uint32_
memcpy(temp_plain + crypto_box_ZEROBYTES, plain, length);//pad the message with 32 0 bytes.
crypto_box(temp_encrypted, temp_plain, length + crypto_box_ZEROBYTES, nonce, public_key, self_secret_key);
crypto_box(temp_encrypted, temp_plain, length + crypto_box_ZEROBYTES, nonce, public_key, secret_key);
//if encryption is successful the first crypto_box_BOXZEROBYTES of the message will be zero
if(memcmp(temp_encrypted, zeroes, crypto_box_BOXZEROBYTES) != 0)
@ -72,10 +76,11 @@ int encrypt_data(uint8_t * public_key, uint8_t * nonce, uint8_t * plain, uint32_
}
//decrypts encrypted of length length to plain of length length - 16 using the
//public key(32 bytes) of the sender and a 24 byte nonce
//public key(32 bytes) of the sender, the secret key of the reciever and a 24 byte nonce
//return -1 if there was a problem(decryption failed)
//return length of plain data if everything was fine.
int decrypt_data(uint8_t * public_key, uint8_t * nonce, uint8_t * encrypted, uint32_t length, uint8_t * plain)
int decrypt_data(uint8_t * public_key, uint8_t * secret_key, uint8_t * nonce,
uint8_t * encrypted, uint32_t length, uint8_t * plain)
{
if(length > MAX_DATA_SIZE || length <= crypto_box_BOXZEROBYTES)
{
@ -88,7 +93,7 @@ int decrypt_data(uint8_t * public_key, uint8_t * nonce, uint8_t * encrypted, uin
memcpy(temp_encrypted + crypto_box_BOXZEROBYTES, encrypted, length);//pad the message with 16 0 bytes.
if(crypto_box_open(temp_plain, temp_encrypted, length + crypto_box_BOXZEROBYTES,
nonce, public_key, self_secret_key) == -1)
nonce, public_key, secret_key) == -1)
{
return -1;
}
@ -146,7 +151,8 @@ int read_cryptpacket(int crypt_connection_id, uint8_t * data)
{
return -1;
}
int len = decrypt_data(crypto_connections[crypt_connection_id].public_key,
int len = decrypt_data(crypto_connections[crypt_connection_id].peersessionpublic_key,
crypto_connections[crypt_connection_id].sessionsecret_key,
crypto_connections[crypt_connection_id].recv_nonce, temp_data + 1, length - 1, data);
if(len != -1)
{
@ -170,7 +176,8 @@ int write_cryptpacket(int crypt_connection_id, uint8_t * data, uint32_t length)
return 0;
}
uint8_t temp_data[MAX_DATA_SIZE];
int len = encrypt_data(crypto_connections[crypt_connection_id].public_key,
int len = encrypt_data(crypto_connections[crypt_connection_id].peersessionpublic_key,
crypto_connections[crypt_connection_id].sessionsecret_key,
crypto_connections[crypt_connection_id].sent_nonce, data, length, temp_data + 1);
if(len == -1)
{
@ -210,7 +217,8 @@ int send_friendrequest(uint8_t * public_key, IP_Port ip_port, uint8_t * data, ui
uint8_t temp_data[MAX_DATA_SIZE];
uint8_t nonce[crypto_box_NONCEBYTES];
random_nonce(nonce);
int len = encrypt_data(public_key, nonce, data, length, 1 + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES + temp_data);
int len = encrypt_data(public_key, self_secret_key, nonce, data, length,
1 + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES + temp_data);
if(len == -1)
{
return -1;
@ -266,14 +274,20 @@ int check_friendrequest(int friend_request)
return 0;
}
//Send a crypto handshake packet containing an encrypted secret nonce to peer with connection_id and public_key
//Send a crypto handshake packet containing an encrypted secret nonce and session public key
//to peer with connection_id and public_key
//the packet is encrypted with a random nonce which is sent in plain text with the packet
int send_cryptohandshake(int connection_id, uint8_t * public_key, uint8_t * secret_nonce)
int send_cryptohandshake(int connection_id, uint8_t * public_key, uint8_t * secret_nonce, uint8_t * session_key)
{
uint8_t temp_data[MAX_DATA_SIZE];
uint8_t temp[crypto_box_NONCEBYTES + crypto_box_PUBLICKEYBYTES];
uint8_t nonce[crypto_box_NONCEBYTES];
random_nonce(nonce);
int len = encrypt_data(public_key, nonce, secret_nonce, crypto_box_NONCEBYTES,
memcpy(temp, secret_nonce, crypto_box_NONCEBYTES);
memcpy(temp + crypto_box_NONCEBYTES, session_key, crypto_box_PUBLICKEYBYTES);
int len = encrypt_data(public_key, self_secret_key, nonce, temp, crypto_box_NONCEBYTES + crypto_box_PUBLICKEYBYTES,
1 + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES + temp_data);
if(len == -1)
{
@ -285,13 +299,15 @@ int send_cryptohandshake(int connection_id, uint8_t * public_key, uint8_t * secr
return write_packet(connection_id, temp_data, len + 1 + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES);
}
//Extract secret nonce and public_key from a packet(data) with length length
//Extract secret nonce, session public key and public_key from a packet(data) with length length
//return 1 if successful
//return 0 if failure
int handle_cryptohandshake(uint8_t * public_key, uint8_t * secret_nonce, uint8_t * data, uint16_t length)
int handle_cryptohandshake(uint8_t * public_key, uint8_t * secret_nonce,
uint8_t * session_key, uint8_t * data, uint16_t length)
{
int pad = (- crypto_box_BOXZEROBYTES + crypto_box_ZEROBYTES);
if(length != 1 + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES + crypto_box_NONCEBYTES + pad)
if(length != 1 + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES
+ crypto_box_NONCEBYTES + crypto_box_PUBLICKEYBYTES + pad)
{
return 0;
}
@ -299,13 +315,21 @@ int handle_cryptohandshake(uint8_t * public_key, uint8_t * secret_nonce, uint8_t
{
return 0;
}
uint8_t temp[crypto_box_NONCEBYTES + crypto_box_PUBLICKEYBYTES];
memcpy(public_key, data + 1, crypto_box_PUBLICKEYBYTES);
int len = decrypt_data(public_key, data + 1 + crypto_box_PUBLICKEYBYTES,
data + 1 + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES, crypto_box_NONCEBYTES + pad, secret_nonce);
if(len != crypto_box_NONCEBYTES)
int len = decrypt_data(public_key, self_secret_key, data + 1 + crypto_box_PUBLICKEYBYTES,
data + 1 + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES,
crypto_box_NONCEBYTES + crypto_box_PUBLICKEYBYTES + pad, temp);
if(len != crypto_box_NONCEBYTES + crypto_box_PUBLICKEYBYTES)
{
return 0;
}
memcpy(secret_nonce, temp, crypto_box_NONCEBYTES);
memcpy(session_key, temp + crypto_box_NONCEBYTES, crypto_box_PUBLICKEYBYTES);
return 1;
}
@ -330,7 +354,7 @@ int handle_friendrequest(uint8_t * public_key, uint8_t * data)
memcpy(public_key, temp_data + 1, crypto_box_PUBLICKEYBYTES);
uint8_t nonce[crypto_box_NONCEBYTES];
memcpy(nonce, temp_data + 1 + crypto_box_PUBLICKEYBYTES, crypto_box_NONCEBYTES);
int len1 = decrypt_data(public_key, nonce, temp_data + 1 + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES,
int len1 = decrypt_data(public_key, self_secret_key, nonce, temp_data + 1 + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES,
len - (crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES + 1), data);
if(len1 != -1)
{
@ -371,7 +395,10 @@ int crypto_connect(uint8_t * public_key, IP_Port ip_port)
crypto_connections[i].status = 1;
random_nonce(crypto_connections[i].recv_nonce);
memcpy(crypto_connections[i].public_key, public_key, crypto_box_PUBLICKEYBYTES);
if(send_cryptohandshake(id, public_key, crypto_connections[i].recv_nonce) == 1)
crypto_box_keypair(crypto_connections[i].sessionpublic_key, crypto_connections[i].sessionsecret_key);
if(send_cryptohandshake(id, public_key, crypto_connections[i].recv_nonce,
crypto_connections[i].sessionpublic_key) == 1)
{
increment_nonce(crypto_connections[i].recv_nonce);
return i;
@ -385,10 +412,11 @@ int crypto_connect(uint8_t * public_key, IP_Port ip_port)
//handle an incoming connection
//return -1 if no crypto inbound connection
//return incomming connection id (Lossless_UDP one) if there is an incomming crypto connection
//Put the public key of the peer in public_key and the secret_nonce from the handshake into secret_nonce
//Put the public key of the peer in public_key, the secret_nonce from the handshake into secret_nonce
//and the session public key for the connection in session_key
//to accept it see: accept_crypto_inbound(...)
//to refuse it just call kill_connection(...) on the connection id
int crypto_inbound(uint8_t * public_key, uint8_t * secret_nonce)
int crypto_inbound(uint8_t * public_key, uint8_t * secret_nonce, uint8_t * session_key)
{
uint32_t i;
for(i = 0; i < MAX_INCOMING; i++)
@ -399,7 +427,7 @@ int crypto_inbound(uint8_t * public_key, uint8_t * secret_nonce)
{
uint8_t temp_data[MAX_DATA_SIZE];
uint16_t len = read_packet(incoming_connections[i], temp_data);
if(handle_cryptohandshake(public_key, secret_nonce, temp_data, len))
if(handle_cryptohandshake(public_key, secret_nonce, session_key, temp_data, len))
{
int connection_id = incoming_connections[i];
incoming_connections[i] = -1;//remove this connection from the incoming connection list.
@ -433,7 +461,7 @@ int crypto_kill(int crypt_connection_id)
//accept an incoming connection using the parameters provided by crypto_inbound
//return -1 if not successful
//returns the crypt_connection_id if successful
int accept_crypto_inbound(int connection_id, uint8_t * public_key, uint8_t * secret_nonce)
int accept_crypto_inbound(int connection_id, uint8_t * public_key, uint8_t * secret_nonce, uint8_t * session_key)
{
uint32_t i;
if(connection_id == -1)
@ -448,9 +476,14 @@ int accept_crypto_inbound(int connection_id, uint8_t * public_key, uint8_t * sec
crypto_connections[i].status = 2;
random_nonce(crypto_connections[i].recv_nonce);
memcpy(crypto_connections[i].sent_nonce, secret_nonce, crypto_box_NONCEBYTES);
memcpy(crypto_connections[i].peersessionpublic_key, session_key, crypto_box_PUBLICKEYBYTES);
increment_nonce(crypto_connections[i].sent_nonce);
memcpy(crypto_connections[i].public_key, public_key, crypto_box_PUBLICKEYBYTES);
if(send_cryptohandshake(connection_id, public_key, crypto_connections[i].recv_nonce) == 1)
crypto_box_keypair(crypto_connections[i].sessionpublic_key, crypto_connections[i].sessionsecret_key);
if(send_cryptohandshake(connection_id, public_key, crypto_connections[i].recv_nonce,
crypto_connections[i].sessionpublic_key) == 1)
{
increment_nonce(crypto_connections[i].recv_nonce);
uint32_t zero = 0;
@ -535,12 +568,14 @@ void recieve_crypto()
uint8_t temp_data[MAX_DATA_SIZE];
uint8_t secret_nonce[crypto_box_NONCEBYTES];
uint8_t public_key[crypto_box_PUBLICKEYBYTES];
uint8_t session_key[crypto_box_PUBLICKEYBYTES];
uint16_t len = read_packet(crypto_connections[i].number, temp_data);
if(handle_cryptohandshake(public_key, secret_nonce, temp_data, len))
if(handle_cryptohandshake(public_key, secret_nonce, session_key, temp_data, len))
{
if(memcmp(public_key, crypto_connections[i].public_key, crypto_box_PUBLICKEYBYTES) == 0)
{
memcpy(crypto_connections[i].sent_nonce, secret_nonce, crypto_box_NONCEBYTES);
memcpy(crypto_connections[i].peersessionpublic_key, session_key, crypto_box_PUBLICKEYBYTES);
increment_nonce(crypto_connections[i].sent_nonce);
uint32_t zero = 0;
crypto_connections[i].status = 3;//connection status needs to be 3 for write_cryptpacket() to work
@ -564,7 +599,8 @@ void recieve_crypto()
uint8_t temp_data[MAX_DATA_SIZE];
uint8_t data[MAX_DATA_SIZE];
int length = read_packet(crypto_connections[i].number, temp_data);
int len = decrypt_data(crypto_connections[i].public_key,
int len = decrypt_data(crypto_connections[i].peersessionpublic_key,
crypto_connections[i].sessionsecret_key,
crypto_connections[i].recv_nonce, temp_data + 1, length - 1, data);
uint32_t zero = 0;
if(len == sizeof(uint32_t) && memcmp(((uint8_t *)&zero), data, sizeof(uint32_t)) == 0)

17
core/net_crypto.h
View File

@ -19,17 +19,19 @@ extern uint8_t self_public_key[crypto_box_PUBLICKEYBYTES];
//encrypts plain of length length to encrypted of length + 16 using the
//public key(32 bytes) of the reciever and a 24 byte nonce
//public key(32 bytes) of the reciever and the secret key of the sender and a 24 byte nonce
//return -1 if there was a problem.
//return length of encrypted data if everything was fine.
int encrypt_data(uint8_t * public_key, uint8_t * nonce, uint8_t * plain, uint32_t length, uint8_t * encrypted);
int encrypt_data(uint8_t * public_key, uint8_t * secret_key, uint8_t * nonce,
uint8_t * plain, uint32_t length, uint8_t * encrypted);
//decrypts encrypted of length length to plain of length length - 16 using the
//public key(32 bytes) of the sender and a 24 byte nonce
//public key(32 bytes) of the sender, the secret key of the reciever and a 24 byte nonce
//return -1 if there was a problem(decryption failed)
//return length of plain data if everything was fine.
int decrypt_data(uint8_t * public_key, uint8_t * nonce, uint8_t * encrypted, uint32_t length, uint8_t * plain);
int decrypt_data(uint8_t * public_key, uint8_t * secret_key, uint8_t * nonce,
uint8_t * encrypted, uint32_t length, uint8_t * plain);
//return 0 if there is no received data in the buffer
@ -76,16 +78,17 @@ int crypto_kill(int crypt_connection_id);
//handle an incoming connection
//return -1 if no crypto inbound connection
//return incomming connection id (Lossless_UDP one) if there is an incomming crypto connection
//Put the public key of the peer in public_key and the secret_nonce from the handshake into secret_nonce
//Put the public key of the peer in public_key, the secret_nonce from the handshake into secret_nonce
//and the session public key for the connection in session_key
//to accept it see: accept_crypto_inbound(...)
//to refuse it just call kill_connection(...) on the connection id
int crypto_inbound(uint8_t * public_key, uint8_t * secret_nonce);
int crypto_inbound(uint8_t * public_key, uint8_t * secret_nonce, uint8_t * session_key);
//accept an incoming connection using the parameters provided by crypto_inbound
//return -1 if not successful
//returns the crypt_connection_id if successful
int accept_crypto_inbound(int connection_id, uint8_t * public_key, uint8_t * secret_nonce);
int accept_crypto_inbound(int connection_id, uint8_t * public_key, uint8_t * secret_nonce, uint8_t * session_key);
//return 0 if no connection, 1 we have sent a handshake, 2 if connexion is not confirmed yet
//(we have recieved a hanshake but no empty data packet), 3 if the connection is established.

10
docs/Crypto.txt
View File

@ -40,14 +40,18 @@ only crypto_box() is used for encryption and only crypto_box_open() for decrypti
Connecting to an already added friend:
Alice and Bob are friends.
As soon as they connect they each send themselves the following packet (the crypto handshake) (encrypted part encrypted with the public nonce in the packet
As soon as they connect they each generate a new keypair which will only be used for the current connection (The session keys).
They then send themselves the following packet (the crypto handshake) (encrypted part encrypted with the public nonce in the packet
the public key of the receiver and private key of the sender)
[char with a value of 02][Senders Public key (client_id) (32 bytes)][Random nonce (24 bytes)][Encrypted message containing a random 24 bytes base nonce]
[char with a value of 02][Senders Public key (client_id) (32 bytes)][Random nonce (24 bytes)][Encrypted message containing a random 24 bytes base nonce and the session public key of the peer]
If the packet is decrypted successfully:
Each start using the secret nonce provided by the other to encrypt data packets (adding to it + 1 for each packet.)
Each start using the secret nonce, the public key provided by the other and their own session private key to encrypt data packets (adding to it + 1 for each packet.)
Each node sends themselves an empty data packet (data packet with 4 encrypted zero bytes)
Data packet:
[char with a value of 03][Encrypted data]
Each data packet received it is decrypted using the secret nonce sent to the other(with +1 added for the first packet +2 for the second, etc...)
along with the private session key of the reciever.
Every data packet sent is encrypted using the secret nonce we received (with +1 added for the first packet +2 for the second, etc...)
the session public key of the reciever and the session private key of the sender.
The encrypted connection is only deemed successful when a data packet is received and decrypted successfully.

5
testing/DHT_cryptosendfiletest.c
View File

@ -167,8 +167,9 @@ int main(int argc, char *argv[])
{
uint8_t secret_nonce[crypto_box_NONCEBYTES];
uint8_t public_key[crypto_box_PUBLICKEYBYTES];
inconnection = crypto_inbound(public_key, secret_nonce);
inconnection = accept_crypto_inbound(inconnection, acceptedfriend_public_key, secret_nonce);
uint8_t session_key[crypto_box_PUBLICKEYBYTES];
inconnection = crypto_inbound(public_key, secret_nonce, session_key);
inconnection = accept_crypto_inbound(inconnection, acceptedfriend_public_key, secret_nonce, session_key);
//inconnection = incoming_connection();
if(inconnection != -1)
{