mirror of
https://github.com/zerotier/ZeroTierOne.git
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228 lines
7.3 KiB
C++
228 lines
7.3 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: 2026-01-01
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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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/*
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* This file defines the elliptic curve crypto used for ZeroTier V1. The normal
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* public version uses C25519 and Ed25519, while the FIPS version uses NIST.
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* FIPS builds are completely incompatible with regular ZeroTier, but that's
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* fine since FIPS users typically want a fully isolated private network. If you
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* are not such a user you probably don't want this.
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*/
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#ifndef ZT_ECC_HPP
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#define ZT_ECC_HPP
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#include "Utils.hpp"
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#ifdef ZT_FIPS
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/* FIPS140/NIST ECC cryptography */
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/* Note that to be FIPS we also need to link against a FIPS-certified library. */
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#include <openssl/bn.h>
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#include <openssl/ec.h>
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#include <openssl/err.h>
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#include <openssl/evp.h>
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#include <openssl/pem.h>
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#define ZT_ECC_EPHEMERAL_PUBLIC_KEY_LEN 97 /* Single ECC P-384 key */
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#define ZT_ECC_PUBLIC_KEY_SET_LEN (97 * 2) /* Two ECC P-384 keys */
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#define ZT_ECC_PRIVATE_KEY_SET_LEN (48 * 2) /* Two ECC P-384 secret keys */
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#define ZT_ECC_SIGNATURE_LEN 96 /* NIST P-384 ECDSA signature */
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class ECC {
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public:
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struct Public {
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uint8_t data[ZT_ECC_PUBLIC_KEY_SET_LEN];
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};
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struct Private {
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uint8_t data[ZT_ECC_PRIVATE_KEY_SET_LEN];
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};
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struct Signature {
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uint8_t data[ZT_ECC_SIGNATURE_LEN];
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};
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struct Pair {
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Public pub;
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Private priv;
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};
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};
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#else // Curve25519 / Ed25519
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namespace ZeroTier {
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#define ZT_ECC_EPHEMERAL_PUBLIC_KEY_LEN 32 /* Single C25519 ECDH key */
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#define ZT_ECC_PUBLIC_KEY_SET_LEN 64 /* C25519 and Ed25519 keys */
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#define ZT_ECC_PRIVATE_KEY_SET_LEN 64 /* C25519 and Ed25519 secret keys */
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#define ZT_ECC_SIGNATURE_LEN 96 /* Ed25519 signature plus (not necessary) hash */
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class ECC {
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public:
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struct Public {
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uint8_t data[ZT_ECC_PUBLIC_KEY_SET_LEN];
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};
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struct Private {
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uint8_t data[ZT_ECC_PRIVATE_KEY_SET_LEN];
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};
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struct Signature {
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uint8_t data[ZT_ECC_SIGNATURE_LEN];
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};
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struct Pair {
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Public pub;
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Private priv;
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};
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/**
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* Generate an elliptic curve key pair
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*/
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static inline Pair generate()
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{
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Pair kp;
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Utils::getSecureRandom(kp.priv.data, ZT_ECC_PRIVATE_KEY_SET_LEN);
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_calcPubDH(kp);
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_calcPubED(kp);
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return kp;
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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> static inline Pair generateSatisfying(F cond)
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{
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Pair kp;
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void* const priv = (void*)kp.priv.data;
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Utils::getSecureRandom(priv, ZT_ECC_PRIVATE_KEY_SET_LEN);
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_calcPubED(kp); // 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(kp); // keep regenerating bytes 0-31 until satisfied
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} while (! cond(kp));
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return kp;
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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 keybuf Buffer to fill
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* @param keylen Number of key bytes to generate
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*/
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static void agree(const Private& mine, const Public& their, void* keybuf, unsigned int keylen);
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static inline void agree(const Pair& mine, const Public& their, void* keybuf, unsigned int keylen)
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{
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agree(mine.priv, their, keybuf, keylen);
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}
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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 Private& myPrivate, const Public& myPublic, const void* msg, unsigned int len, void* signature);
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static inline void sign(const Pair& mine, const void* msg, unsigned int len, void* signature)
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{
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sign(mine.priv, mine.pub, msg, len, signature);
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}
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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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* @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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* @return Signature
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*/
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static inline Signature sign(const Private& myPrivate, const Public& myPublic, const void* msg, unsigned int len)
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{
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Signature sig;
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sign(myPrivate, myPublic, msg, len, sig.data);
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return sig;
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}
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static inline Signature sign(const Pair& mine, const void* msg, unsigned int len)
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{
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Signature sig;
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sign(mine.priv, mine.pub, msg, len, sig.data);
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return sig;
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}
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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 96-byte signature
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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 Public& their, const void* msg, unsigned int len, const 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 96-byte signature
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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 inline bool verify(const Public& their, const void* msg, unsigned int len, const Signature& signature)
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{
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return verify(their, msg, len, signature.data);
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}
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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(Pair& kp);
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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(Pair& kp);
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};
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} // namespace ZeroTier
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#endif
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#endif
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