mirror of
https://github.com/zerotier/ZeroTierOne.git
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125 lines
4.2 KiB
C++
125 lines
4.2 KiB
C++
/*
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* Copyright (c)2019 ZeroTier, Inc.
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file in the project's root directory.
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*
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* Change Date: 2023-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2.0 of the Apache License.
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*/
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/****/
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#ifndef ZT_C25519_HPP
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#define ZT_C25519_HPP
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#include "Utils.hpp"
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namespace ZeroTier {
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#define ZT_C25519_PUBLIC_KEY_LEN 64
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#define ZT_C25519_PRIVATE_KEY_LEN 64
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#define ZT_C25519_SIGNATURE_LEN 96
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#define ZT_C25519_SHARED_KEY_LEN 32
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/**
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* A combined Curve25519 ECDH and Ed25519 signature engine
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*/
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class C25519
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{
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public:
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/**
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* Generate a C25519 elliptic curve key pair
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*/
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static inline void generate(uint8_t pub[ZT_C25519_PUBLIC_KEY_LEN],uint8_t priv[ZT_C25519_PRIVATE_KEY_LEN])
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{
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Utils::getSecureRandom(priv,ZT_C25519_PRIVATE_KEY_LEN);
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_calcPubDH(pub,priv);
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_calcPubED(pub,priv);
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}
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/**
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* Generate a key pair satisfying a condition
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*
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* This begins with a random keypair from a random secret key and then
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* iteratively increments the random secret until cond(kp) returns true.
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* This is used to compute key pairs in which the public key, its hash
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* or some other aspect of it satisfies some condition, such as for a
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* hashcash criteria.
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*
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* @param cond Condition function or function object
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* @return Key pair where cond(kp) returns true
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* @tparam F Type of 'cond'
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*/
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template<typename F>
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static inline void generateSatisfying(F cond,uint8_t pub[ZT_C25519_PUBLIC_KEY_LEN],uint8_t priv[ZT_C25519_PRIVATE_KEY_LEN])
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{
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Utils::getSecureRandom(priv,ZT_C25519_PRIVATE_KEY_LEN);
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_calcPubED(pub,priv); // do Ed25519 key -- bytes 32-63 of pub and priv
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do {
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++(((uint64_t *)priv)[1]);
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--(((uint64_t *)priv)[2]);
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_calcPubDH(pub,priv); // keep regenerating bytes 0-31 until satisfied
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} while (!cond(pub));
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}
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/**
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* Perform C25519 ECC key agreement
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*
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* Actual key bytes are generated from one or more SHA-512 digests of
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* the raw result of key agreement.
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*
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* @param mine My private key
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* @param their Their public key
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* @param rawkey Buffer to receive raw (not hashed) agreed upon key
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*/
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static void agree(const uint8_t mine[ZT_C25519_PRIVATE_KEY_LEN],const uint8_t their[ZT_C25519_PUBLIC_KEY_LEN],uint8_t rawkey[32]);
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/**
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* Sign a message with a sender's key pair
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*
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* This takes the SHA-521 of msg[] and then signs the first 32 bytes of this
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* digest, returning it and the 64-byte ed25519 signature in signature[].
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* This results in a signature that verifies both the signer's authenticity
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* and the integrity of the message.
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*
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* This is based on the original ed25519 code from NaCl and the SUPERCOP
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* cipher benchmark suite, but with the modification that it always
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* produces a signature of fixed 96-byte length based on the hash of an
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* arbitrary-length message.
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*
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* @param myPrivate My private key
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* @param myPublic My public key
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* @param msg Message to sign
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* @param len Length of message in bytes
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* @param signature Buffer to fill with signature -- MUST be 96 bytes in length
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*/
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static void sign(const uint8_t myPrivate[ZT_C25519_PRIVATE_KEY_LEN],const uint8_t myPublic[ZT_C25519_PUBLIC_KEY_LEN],const void *msg,unsigned int len,void *signature);
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/**
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* Verify a message's signature
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*
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* @param their Public key to verify against
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* @param msg Message to verify signature integrity against
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* @param len Length of message in bytes
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* @param signature Signature bytes
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* @param siglen Length of signature in bytes
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* @return True if signature is valid and the message is authentic and unmodified
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*/
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static bool verify(const uint8_t their[ZT_C25519_PUBLIC_KEY_LEN],const void *msg,unsigned int len,const void *signature,const unsigned int siglen);
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private:
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// derive first 32 bytes of kp.pub from first 32 bytes of kp.priv
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// this is the ECDH key
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static void _calcPubDH(uint8_t pub[ZT_C25519_PUBLIC_KEY_LEN],const uint8_t priv[ZT_C25519_PRIVATE_KEY_LEN]);
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// derive 2nd 32 bytes of kp.pub from 2nd 32 bytes of kp.priv
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// this is the Ed25519 sign/verify key
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static void _calcPubED(uint8_t pub[ZT_C25519_PUBLIC_KEY_LEN],const uint8_t priv[ZT_C25519_PRIVATE_KEY_LEN]);
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};
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} // namespace ZeroTier
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#endif
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