This commit is contained in:
Adam Ierymenko 2019-08-15 15:32:16 -07:00
parent 81f0175251
commit c483f75fb4
No known key found for this signature in database
GPG Key ID: 1657198823E52A61
3 changed files with 11 additions and 86 deletions

View File

@ -70,7 +70,7 @@ bool IncomingPacket::tryDecode(const RuntimeEnvironment *RR,void *tPtr)
RR->t->incomingPacketMessageAuthenticationFailure(tPtr,_path,packetId(),sourceAddress,hops(),"path not trusted");
return true;
}
} else if ((c == ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_NONE)&&(verb() == Packet::VERB_HELLO)) {
} else if ((c == ZT_PROTO_CIPHER_SUITE__POLY1305_NONE)&&(verb() == Packet::VERB_HELLO)) {
// Only HELLO is allowed in the clear, but will still have a MAC
return _doHELLO(RR,tPtr,false);
}

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@ -895,7 +895,7 @@ void Packet::armor(const void *key,bool encryptPayload)
uint8_t *const data = reinterpret_cast<uint8_t *>(unsafeData());
// Set flag now, since it affects key mangle function
setCipher(encryptPayload ? ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_SALSA2012 : ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_NONE);
setCipher(encryptPayload ? ZT_PROTO_CIPHER_SUITE__POLY1305_SALSA2012 : ZT_PROTO_CIPHER_SUITE__POLY1305_NONE);
_salsa20MangleKey((const unsigned char *)key,mangledKey);
@ -933,11 +933,11 @@ bool Packet::dearmor(const void *key)
unsigned char *const payload = data + ZT_PACKET_IDX_VERB;
const unsigned int cs = cipher();
if ((cs == ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_NONE)||(cs == ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_SALSA2012)) {
if ((cs == ZT_PROTO_CIPHER_SUITE__POLY1305_NONE)||(cs == ZT_PROTO_CIPHER_SUITE__POLY1305_SALSA2012)) {
_salsa20MangleKey((const unsigned char *)key,mangledKey);
if (ZT_HAS_FAST_CRYPTO()) {
uint64_t keyStream[(ZT_PROTO_MAX_PACKET_LENGTH + 64 + 8) / 8];
ZT_FAST_SINGLE_PASS_SALSA2012(keyStream,((cs == ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_SALSA2012) ? (payloadLen + 64) : 64),(data + ZT_PACKET_IDX_IV),mangledKey);
ZT_FAST_SINGLE_PASS_SALSA2012(keyStream,((cs == ZT_PROTO_CIPHER_SUITE__POLY1305_SALSA2012) ? (payloadLen + 64) : 64),(data + ZT_PACKET_IDX_IV),mangledKey);
uint64_t mac[2];
poly1305(mac,payload,payloadLen,keyStream);
#ifdef ZT_NO_TYPE_PUNNING
@ -947,7 +947,7 @@ bool Packet::dearmor(const void *key)
if ((*reinterpret_cast<const uint64_t *>(data + ZT_PACKET_IDX_MAC)) != mac[0]) // also secure, constant time
return false;
#endif
if (cs == ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_SALSA2012)
if (cs == ZT_PROTO_CIPHER_SUITE__POLY1305_SALSA2012)
Salsa20::memxor(data + ZT_PACKET_IDX_VERB,reinterpret_cast<const uint8_t *>(keyStream + 8),payloadLen);
} else {
Salsa20 s20(mangledKey,data + ZT_PACKET_IDX_IV);
@ -962,7 +962,7 @@ bool Packet::dearmor(const void *key)
if ((*reinterpret_cast<const uint64_t *>(data + ZT_PACKET_IDX_MAC)) != mac[0]) // also secure, constant time
return false;
#endif
if (cs == ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_SALSA2012)
if (cs == ZT_PROTO_CIPHER_SUITE__POLY1305_SALSA2012)
s20.crypt12(payload,payload,payloadLen);
}

View File

@ -94,26 +94,14 @@
#define ZT_PROTO_MAX_HOPS 7
/**
* Cipher suite: Curve25519/Poly1305/Salsa20/12/NOCRYPT
*
* This specifies Poly1305 MAC using a 32-bit key derived from the first
* 32 bytes of a Salsa20/12 keystream as in the Salsa20/12 cipher suite,
* but the payload is not encrypted. This is currently only used to send
* HELLO since that's the public key specification packet and must be
* sent in the clear. Key agreement is performed using Curve25519 elliptic
* curve Diffie-Hellman.
* Cipher suite: Poly1305/NONE
*/
#define ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_NONE 0
#define ZT_PROTO_CIPHER_SUITE__POLY1305_NONE 0
/**
* Cipher suite: Curve25519/Poly1305/Salsa20/12
*
* This specifies Poly1305 using the first 32 bytes of a Salsa20/12 key
* stream as its one-time-use key followed by payload encryption with
* the remaining Salsa20/12 key stream. Key agreement is performed using
* Curve25519 elliptic curve Diffie-Hellman.
* Cipher suite: Poly1305/Salsa2012
*/
#define ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_SALSA2012 1
#define ZT_PROTO_CIPHER_SUITE__POLY1305_SALSA2012 1
/**
* Cipher suite: NONE
@ -147,69 +135,6 @@
*/
#define ZT_PROTO_VERB_FLAG_COMPRESSED 0x80
/**
* Rounds used for Salsa20 encryption in ZT
*
* Discussion:
*
* DJB (Salsa20's designer) designed Salsa20 with a significant margin of 20
* rounds, but has said repeatedly that 12 is likely sufficient. So far (as of
* July 2015) there are no published attacks against 12 rounds, let alone 20.
*
* In cryptography, a "break" means something different from what it means in
* common discussion. If a cipher is 256 bits strong and someone finds a way
* to reduce key search to 254 bits, this constitutes a "break" in the academic
* literature. 254 bits is still far beyond what can be leveraged to accomplish
* a "break" as most people would understand it -- the actual decryption and
* reading of traffic.
*
* Nevertheless, "attacks only get better" as cryptographers like to say. As
* a result, they recommend not using anything that's shown any weakness even
* if that weakness is so far only meaningful to academics. It may be a sign
* of a deeper problem.
*
* So why choose a lower round count?
*
* Turns out the speed difference is nontrivial. On a Macbook Pro (Core i3) 20
* rounds of SSE-optimized Salsa20 achieves ~508mb/sec/core, while 12 rounds
* hits ~832mb/sec/core. ZeroTier is designed for multiple objectives:
* security, simplicity, and performance. In this case a deference was made
* for performance.
*
* Meta discussion:
*
* The cipher is not the thing you should be paranoid about.
*
* I'll qualify that. If the cipher is known to be weak, like RC4, or has a
* key size that is too small, like DES, then yes you should worry about
* the cipher.
*
* But if the cipher is strong and your adversary is anyone other than the
* intelligence apparatus of a major superpower, you are fine in that
* department.
*
* Go ahead. Search for the last ten vulnerabilities discovered in SSL. Not
* a single one involved the breaking of a cipher. Now broaden your search.
* Look for issues with SSH, IPSec, etc. The only cipher-related issues you
* will find might involve the use of RC4 or MD5, algorithms with known
* issues or small key/digest sizes. But even weak ciphers are difficult to
* exploit in the real world -- you usually need a lot of data and a lot of
* compute time. No, virtually EVERY security vulnerability you will find
* involves a problem with the IMPLEMENTATION not with the cipher.
*
* A flaw in ZeroTier's protocol or code is incredibly, unbelievably
* more likely than a flaw in Salsa20 or any other cipher or cryptographic
* primitive it uses. We're talking odds of dying in a car wreck vs. odds of
* being personally impacted on the head by a meteorite. Nobody without a
* billion dollar budget is going to break into your network by actually
* cracking Salsa20/12 (or even /8) in the field.
*
* So stop worrying about the cipher unless you are, say, the Kremlin and your
* adversary is the NSA and the GCHQ. In that case... well that's above my
* pay grade. I'll just say defense in depth.
*/
#define ZT_PROTO_SALSA20_ROUNDS 12
/**
* PUSH_DIRECT_PATHS flag: forget path
*/
@ -1174,7 +1099,7 @@ public:
unsigned char &b = (*this)[ZT_PACKET_IDX_FLAGS];
b = (b & 0xc7) | (unsigned char)((c << 3) & 0x38); // bits: FFCCCHHH
// Set DEPRECATED "encrypted" flag -- used by pre-1.0.3 peers
if (c == ZT_PROTO_CIPHER_SUITE__C25519_POLY1305_SALSA2012)
if (c == ZT_PROTO_CIPHER_SUITE__POLY1305_SALSA2012)
b |= ZT_PROTO_FLAG_ENCRYPTED;
else b &= (~ZT_PROTO_FLAG_ENCRYPTED);
}