/*
 * Copyright (c)2013-2021 ZeroTier, Inc.
 *
 * Use of this software is governed by the Business Source License included
 * in the LICENSE.TXT file in the project's root directory.
 *
 * Change Date: 2026-01-01
 *
 * On the date above, in accordance with the Business Source License, use
 * of this software will be governed by version 2.0 of the Apache License.
 */
/****/

#include "Constants.hpp"
#include "Identity.hpp"
#include "SHA512.hpp"
#include "Salsa20.hpp"
#include "Utils.hpp"
#include "Endpoint.hpp"
#include "MIMC52.hpp"

#include <memory>
#include <utility>

namespace ZeroTier {

namespace {

// This is the memory-intensive hash function used to compute v0 identities from v0 public keys.
#define ZT_V0_IDENTITY_GEN_MEMORY 2097152

void identityV0ProofOfWorkFrankenhash(const void *const restrict publicKey, unsigned int publicKeyBytes, void *const restrict digest, void *const restrict genmem) noexcept
{
	// Digest publicKey[] to obtain initial digest
	SHA512(digest, publicKey, publicKeyBytes);

	// Initialize genmem[] using Salsa20 in a CBC-like configuration since
	// ordinary Salsa20 is randomly seek-able. This is good for a cipher
	// but is not what we want for sequential memory-hardness.
	Utils::zero< ZT_V0_IDENTITY_GEN_MEMORY >(genmem);
	Salsa20 s20(digest, (char *)digest + 32);
	s20.crypt20((char *)genmem, (char *)genmem, 64);
	for (unsigned long i = 64; i < ZT_V0_IDENTITY_GEN_MEMORY; i += 64) {
		unsigned long k = i - 64;
		*((uint64_t *)((char *)genmem + i)) = *((uint64_t *)((char *)genmem + k));
		*((uint64_t *)((char *)genmem + i + 8)) = *((uint64_t *)((char *)genmem + k + 8));
		*((uint64_t *)((char *)genmem + i + 16)) = *((uint64_t *)((char *)genmem + k + 16));
		*((uint64_t *)((char *)genmem + i + 24)) = *((uint64_t *)((char *)genmem + k + 24));
		*((uint64_t *)((char *)genmem + i + 32)) = *((uint64_t *)((char *)genmem + k + 32));
		*((uint64_t *)((char *)genmem + i + 40)) = *((uint64_t *)((char *)genmem + k + 40));
		*((uint64_t *)((char *)genmem + i + 48)) = *((uint64_t *)((char *)genmem + k + 48));
		*((uint64_t *)((char *)genmem + i + 56)) = *((uint64_t *)((char *)genmem + k + 56));
		s20.crypt20((char *)genmem + i, (char *)genmem + i, 64);
	}

	// Render final digest using genmem as a lookup table
	for (unsigned long i = 0; i < (ZT_V0_IDENTITY_GEN_MEMORY / sizeof(uint64_t));) {
		unsigned long idx1 = (unsigned long)(Utils::ntoh(((uint64_t *)genmem)[i++]) % (64 / sizeof(uint64_t))); // NOLINT(hicpp-use-auto,modernize-use-auto)
		unsigned long idx2 = (unsigned long)(Utils::ntoh(((uint64_t *)genmem)[i++]) % (ZT_V0_IDENTITY_GEN_MEMORY / sizeof(uint64_t))); // NOLINT(hicpp-use-auto,modernize-use-auto)
		uint64_t tmp = ((uint64_t *)genmem)[idx2];
		((uint64_t *)genmem)[idx2] = ((uint64_t *)digest)[idx1];
		((uint64_t *)digest)[idx1] = tmp;
		s20.crypt20(digest, digest, 64);
	}
}

struct identityV0ProofOfWorkCriteria
{
	ZT_INLINE identityV0ProofOfWorkCriteria(unsigned char *restrict sb, char *restrict gm) noexcept: digest(sb), genmem(gm)
	{}

	ZT_INLINE bool operator()(const uint8_t pub[ZT_C25519_COMBINED_PUBLIC_KEY_SIZE]) const noexcept
	{
		identityV0ProofOfWorkFrankenhash(pub, ZT_C25519_COMBINED_PUBLIC_KEY_SIZE, digest, genmem);
		return (digest[0] < 17);
	}

	unsigned char *digest;
	char *genmem;
};

void v1ChallengeFromPub(const uint8_t pub[ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE], uint64_t challenge[4])
{
	// This builds a 256-bit challenge by XORing the two public keys together. This doesn't need to be
	// a hash, just different for different public keys. Public keys are basically kind of hashes of
	// private keys, so that's good enough. This is only used to seed a PRNG in MIMC52 for a proof of
	// sequential work. It's not used for authentication beyond checking PoW.
	Utils::copy< 32 >(challenge, pub + 7);
	challenge[0] ^= Utils::loadMachineEndian< uint64_t >(pub + 40);
	challenge[1] ^= Utils::loadMachineEndian< uint64_t >(pub + 48);
	challenge[2] ^= Utils::loadMachineEndian< uint64_t >(pub + 56);
	challenge[3] ^= Utils::loadMachineEndian< uint64_t >(pub + 64);
	challenge[0] ^= Utils::loadMachineEndian< uint64_t >(pub + 72);
	challenge[1] ^= Utils::loadMachineEndian< uint64_t >(pub + 80);
	challenge[2] ^= Utils::loadMachineEndian< uint64_t >(pub + 88);
	challenge[3] ^= Utils::loadMachineEndian< uint64_t >(pub + 96);
	challenge[0] ^= Utils::loadMachineEndian< uint64_t >(pub + 104);
	challenge[1] ^= Utils::loadMachineEndian< uint64_t >(pub + 112);
}

} // anonymous namespace

const Identity Identity::NIL;

bool Identity::generate(const Type t)
{
	m_type = t;
	m_hasPrivate = true;

	switch (t) {

		case C25519: {
			// Generate C25519/Ed25519 key pair whose hash satisfies a "hashcash" criterion and generate the
			// address from the last 40 bits of this hash. This is different from the fingerprint hash for V0.
			uint8_t digest[64];
			char *const genmem = new char[ZT_V0_IDENTITY_GEN_MEMORY];
			Address address;
			do {
				C25519::generateSatisfying(identityV0ProofOfWorkCriteria(digest, genmem), m_pub, m_priv);
				address.setTo(digest + 59);
			} while (address.isReserved());
			delete[] genmem;
			m_fp.address = address; // address comes from PoW hash for type 0 identities
			m_computeHash();
		}
			break;

		case P384:
			for (;;) {
				C25519::generateCombined(m_pub + 7, m_priv);
				ECC384GenerateKey(m_pub + 7 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE, m_priv + ZT_C25519_COMBINED_PRIVATE_KEY_SIZE);

				uint64_t challenge[4];
				v1ChallengeFromPub(m_pub, challenge);
				const uint64_t proof = MIMC52::delay(reinterpret_cast<const uint8_t *>(challenge), ZT_IDENTITY_TYPE1_MIMC52_ROUNDS);
				m_pub[0] = (uint8_t)(proof >> 48U);
				m_pub[1] = (uint8_t)(proof >> 40U);
				m_pub[2] = (uint8_t)(proof >> 32U);
				m_pub[3] = (uint8_t)(proof >> 24U);
				m_pub[4] = (uint8_t)(proof >> 16U);
				m_pub[5] = (uint8_t)(proof >> 8U);
				m_pub[6] = (uint8_t)proof;

				m_computeHash();
				const Address addr(m_fp.hash);
				if (!addr.isReserved()) {
					m_fp.address = addr;
					break;
				}
			}
			break;

		default:
			return false;
	}

	return true;
}

bool Identity::locallyValidate() const noexcept
{
	try {
		if ((m_fp) && ((!Address(m_fp.address).isReserved()))) {
			switch (m_type) {

				case C25519: {
					uint8_t digest[64];
					char *const genmem = (char *)malloc(ZT_V0_IDENTITY_GEN_MEMORY);
					if (!genmem)
						return false;
					identityV0ProofOfWorkFrankenhash(m_pub, ZT_C25519_COMBINED_PUBLIC_KEY_SIZE, digest, genmem);
					free(genmem);
					return ((Address(digest + 59) == m_fp.address) && (digest[0] < 17));
				}

				case P384:
					if (Address(m_fp.hash) == m_fp.address) {
						uint64_t challenge[4];
						v1ChallengeFromPub(m_pub, challenge);
						return MIMC52::verify(reinterpret_cast<const uint8_t *>(challenge), ZT_IDENTITY_TYPE1_MIMC52_ROUNDS, ((uint64_t)m_pub[0] << 48U) | ((uint64_t)m_pub[1] << 40U) | ((uint64_t)m_pub[2] << 32U) | ((uint64_t)m_pub[3] << 24U) | ((uint64_t)m_pub[4] << 16U) | ((uint64_t)m_pub[5] << 8U) | (uint64_t)m_pub[6]);
					}
					return false;

			}
		}
	} catch (...) {}
	return false;
}

void Identity::hashWithPrivate(uint8_t h[ZT_FINGERPRINT_HASH_SIZE]) const
{
	if (m_hasPrivate) {
		switch (m_type) {

			case C25519:
				SHA384(h, m_pub, ZT_C25519_COMBINED_PUBLIC_KEY_SIZE, m_priv, ZT_C25519_COMBINED_PRIVATE_KEY_SIZE);
				return;

			case P384:
				SHA384(h, m_pub, sizeof(m_pub), m_priv, sizeof(m_priv));
				return;

		}
	}
	Utils::zero< ZT_FINGERPRINT_HASH_SIZE >(h);
}

unsigned int Identity::sign(const void *data, unsigned int len, void *sig, unsigned int siglen) const
{
	if (m_hasPrivate) {
		switch (m_type) {

			case C25519:
				if (siglen >= ZT_C25519_SIGNATURE_LEN) {
					C25519::sign(m_priv, m_pub, data, len, sig);
					return ZT_C25519_SIGNATURE_LEN;
				}
				break;

			case P384:
				if (siglen >= ZT_ECC384_SIGNATURE_SIZE) {
					static_assert(ZT_ECC384_SIGNATURE_HASH_SIZE == ZT_SHA384_DIGEST_SIZE, "weird!");
					uint8_t h[ZT_ECC384_SIGNATURE_HASH_SIZE];
					SHA384(h, data, len, m_pub, ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE);
					ECC384ECDSASign(m_priv + ZT_C25519_COMBINED_PRIVATE_KEY_SIZE, h, (uint8_t *)sig);
					return ZT_ECC384_SIGNATURE_SIZE;
				}
				break;

		}
	}
	return 0;
}

bool Identity::verify(const void *data, unsigned int len, const void *sig, unsigned int siglen) const
{
	switch (m_type) {

		case C25519:
			return C25519::verify(m_pub, data, len, sig, siglen);

		case P384:
			if (siglen == ZT_ECC384_SIGNATURE_SIZE) {
				uint8_t h[ZT_ECC384_SIGNATURE_HASH_SIZE];
				SHA384(h, data, len, m_pub, ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE);
				return ECC384ECDSAVerify(m_pub + 7 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE, h, (const uint8_t *)sig);
			}
			break;

	}
	return false;
}

bool Identity::agree(const Identity &id, uint8_t key[ZT_SYMMETRIC_KEY_SIZE]) const
{
	uint8_t rawkey[128], h[64];
	if (likely(m_hasPrivate)) {
		if ((m_type == C25519) || (id.m_type == C25519)) {
			// If we are a C25519 key we can agree with another C25519 key or with only the
			// C25519 portion of a type 1 P-384 key.
			C25519::agree(m_priv, id.m_pub, rawkey);
			SHA512(h, rawkey, ZT_C25519_ECDH_SHARED_SECRET_SIZE);
			Utils::copy< ZT_SYMMETRIC_KEY_SIZE >(key, h);
			return true;
		} else if ((m_type == P384) && (id.m_type == P384)) {
			// For another P384 identity we execute DH agreement with BOTH keys and then
			// hash the results together. For those (cough FIPS cough) who only consider
			// P384 to be kosher, the C25519 secret can be considered a "salt"
			// or something. For those who don't trust P384 this means the privacy of
			// your traffic is also protected by C25519.
			C25519::agree(m_priv, id.m_pub, rawkey);
			ECC384ECDH(id.m_pub + 7 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE, m_priv + ZT_C25519_COMBINED_PRIVATE_KEY_SIZE, rawkey + ZT_C25519_ECDH_SHARED_SECRET_SIZE);
			SHA384(key, rawkey, ZT_C25519_ECDH_SHARED_SECRET_SIZE + ZT_ECC384_SHARED_SECRET_SIZE);
			return true;
		}
	}
	return false;
}

char *Identity::toString(bool includePrivate, char buf[ZT_IDENTITY_STRING_BUFFER_LENGTH]) const
{
	char *p = buf;
	Address(m_fp.address).toString(p);
	p += 10;
	*(p++) = ':';

	switch (m_type) {
		case C25519: {
			*(p++) = '0';
			*(p++) = ':';
			Utils::hex(m_pub, ZT_C25519_COMBINED_PUBLIC_KEY_SIZE, p);
			p += ZT_C25519_COMBINED_PUBLIC_KEY_SIZE * 2;
			if ((m_hasPrivate) && (includePrivate)) {
				*(p++) = ':';
				Utils::hex(m_priv, ZT_C25519_COMBINED_PRIVATE_KEY_SIZE, p);
				p += ZT_C25519_COMBINED_PRIVATE_KEY_SIZE * 2;
			}
			*p = (char)0;
			return buf;
		}
		case P384: {
			*(p++) = '1';
			*(p++) = ':';
			int el = Utils::b32e(m_pub, sizeof(m_pub), p, (int)(ZT_IDENTITY_STRING_BUFFER_LENGTH - (uintptr_t)(p - buf)));
			if (el <= 0) return nullptr;
			p += el;
			if ((m_hasPrivate) && (includePrivate)) {
				*(p++) = ':';
				el = Utils::b32e(m_priv, sizeof(m_priv), p, (int)(ZT_IDENTITY_STRING_BUFFER_LENGTH - (uintptr_t)(p - buf)));
				if (el <= 0) return nullptr;
				p += el;
			}
			*p = (char)0;
			return buf;
		}
		default:
			buf[0] = 0;
	}

	return nullptr;
}

bool Identity::fromString(const char *str)
{
	char tmp[ZT_IDENTITY_STRING_BUFFER_LENGTH];
	memoryZero(this);
	if ((!str) || (!Utils::scopy(tmp, sizeof(tmp), str)))
		return false;

	int fno = 0;
	char *saveptr = nullptr;
	for (char *f = Utils::stok(tmp, ":", &saveptr); ((f) && (fno < 4)); f = Utils::stok(nullptr, ":", &saveptr)) {
		switch (fno++) {

			case 0:
				m_fp.address = Utils::hexStrToU64(f) & ZT_ADDRESS_MASK;
				if (Address(m_fp.address).isReserved())
					return false;
				break;

			case 1:
				if ((f[0] == '0') && (!f[1])) {
					m_type = C25519;
				} else if ((f[0] == '1') && (!f[1])) {
					m_type = P384;
				} else {
					return false;
				}
				break;

			case 2:
				switch (m_type) {

					case C25519:
						if (Utils::unhex(f, strlen(f), m_pub, ZT_C25519_COMBINED_PUBLIC_KEY_SIZE) != ZT_C25519_COMBINED_PUBLIC_KEY_SIZE)
							return false;
						break;

					case P384:
						if (Utils::b32d(f, m_pub, sizeof(m_pub)) != sizeof(m_pub))
							return false;
						break;

				}
				break;

			case 3:
				if (strlen(f) > 1) {
					switch (m_type) {

						case C25519:
							if (Utils::unhex(f, strlen(f), m_priv, ZT_C25519_COMBINED_PRIVATE_KEY_SIZE) != ZT_C25519_COMBINED_PRIVATE_KEY_SIZE) {
								return false;
							} else {
								m_hasPrivate = true;
							}
							break;

						case P384:
							if (Utils::b32d(f, m_priv, sizeof(m_priv)) != sizeof(m_priv)) {
								return false;
							} else {
								m_hasPrivate = true;
							}
							break;

					}
					break;
				}

		}
	}

	if (fno < 3)
		return false;

	m_computeHash();
	return !((m_type == P384) && (Address(m_fp.hash) != m_fp.address));
}

int Identity::marshal(uint8_t data[ZT_IDENTITY_MARSHAL_SIZE_MAX], const bool includePrivate) const noexcept
{
	Address(m_fp.address).copyTo(data);
	switch (m_type) {

		case C25519:
			data[ZT_ADDRESS_LENGTH] = (uint8_t)C25519;
			Utils::copy< ZT_C25519_COMBINED_PUBLIC_KEY_SIZE >(data + ZT_ADDRESS_LENGTH + 1, m_pub);
			if ((includePrivate) && (m_hasPrivate)) {
				data[ZT_ADDRESS_LENGTH + 1 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE] = ZT_C25519_COMBINED_PRIVATE_KEY_SIZE;
				Utils::copy< ZT_C25519_COMBINED_PRIVATE_KEY_SIZE >(data + ZT_ADDRESS_LENGTH + 1 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE + 1, m_priv);
				return ZT_ADDRESS_LENGTH + 1 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE + 1 + ZT_C25519_COMBINED_PRIVATE_KEY_SIZE;
			}
			data[ZT_ADDRESS_LENGTH + 1 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE] = 0;
			return ZT_ADDRESS_LENGTH + 1 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE + 1;

		case P384:
			data[ZT_ADDRESS_LENGTH] = (uint8_t)P384;
			Utils::copy< ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE >(data + ZT_ADDRESS_LENGTH + 1, m_pub);
			if ((includePrivate) && (m_hasPrivate)) {
				data[ZT_ADDRESS_LENGTH + 1 + ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE] = ZT_IDENTITY_P384_COMPOUND_PRIVATE_KEY_SIZE;
				Utils::copy< ZT_IDENTITY_P384_COMPOUND_PRIVATE_KEY_SIZE >(data + ZT_ADDRESS_LENGTH + 1 + ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE + 1, m_priv);
				return ZT_ADDRESS_LENGTH + 1 + ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE + 1 + ZT_IDENTITY_P384_COMPOUND_PRIVATE_KEY_SIZE;
			}
			data[ZT_ADDRESS_LENGTH + 1 + ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE] = 0;
			return ZT_ADDRESS_LENGTH + 1 + ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE + 1;

	}
	return -1;
}

int Identity::unmarshal(const uint8_t *data, const int len) noexcept
{
	memoryZero(this);

	if (len < (1 + ZT_ADDRESS_LENGTH))
		return -1;
	m_fp.address = Address(data);

	unsigned int privlen;
	switch ((m_type = (Type)data[ZT_ADDRESS_LENGTH])) {

		case C25519:
			if (len < (ZT_ADDRESS_LENGTH + 1 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE + 1))
				return -1;

			Utils::copy< ZT_C25519_COMBINED_PUBLIC_KEY_SIZE >(m_pub, data + ZT_ADDRESS_LENGTH + 1);
			m_computeHash();

			privlen = data[ZT_ADDRESS_LENGTH + 1 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE];
			if (privlen == ZT_C25519_COMBINED_PRIVATE_KEY_SIZE) {
				if (len < (ZT_ADDRESS_LENGTH + 1 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE + 1 + ZT_C25519_COMBINED_PRIVATE_KEY_SIZE))
					return -1;
				m_hasPrivate = true;
				Utils::copy< ZT_C25519_COMBINED_PRIVATE_KEY_SIZE >(m_priv, data + ZT_ADDRESS_LENGTH + 1 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE + 1);
				return ZT_ADDRESS_LENGTH + 1 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE + 1 + ZT_C25519_COMBINED_PRIVATE_KEY_SIZE;
			} else if (privlen == 0) {
				m_hasPrivate = false;
				return ZT_ADDRESS_LENGTH + 1 + ZT_C25519_COMBINED_PUBLIC_KEY_SIZE + 1;
			}
			break;

		case P384:
			if (len < (ZT_ADDRESS_LENGTH + 1 + ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE + 1))
				return -1;

			Utils::copy< ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE >(m_pub, data + ZT_ADDRESS_LENGTH + 1);
			m_computeHash(); // this sets the address for P384
			if (Address(m_fp.hash) != m_fp.address) // this sanity check is possible with V1 identities
				return -1;

			privlen = data[ZT_ADDRESS_LENGTH + 1 + ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE];
			if (privlen == 0) {
				m_hasPrivate = false;
				return ZT_ADDRESS_LENGTH + 1 + ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE + 1;
			} else if (privlen == ZT_IDENTITY_P384_COMPOUND_PRIVATE_KEY_SIZE) {
				if (len < (ZT_ADDRESS_LENGTH + 1 + ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE + 1 + ZT_IDENTITY_P384_COMPOUND_PRIVATE_KEY_SIZE))
					return -1;
				m_hasPrivate = true;
				Utils::copy< ZT_IDENTITY_P384_COMPOUND_PRIVATE_KEY_SIZE >(&m_priv, data + ZT_ADDRESS_LENGTH + 1 + ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE + 1);
				return ZT_ADDRESS_LENGTH + 1 + ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE + 1 + ZT_IDENTITY_P384_COMPOUND_PRIVATE_KEY_SIZE;
			}
			break;

	}

	return -1;
}

void Identity::m_computeHash()
{
	switch (m_type) {
		default:
			m_fp.zero();
			break;

		case C25519:
			SHA384(m_fp.hash, m_pub, ZT_C25519_COMBINED_PUBLIC_KEY_SIZE);
			break;

		case P384:
			SHA384(m_fp.hash, m_pub, ZT_IDENTITY_P384_COMPOUND_PUBLIC_KEY_SIZE);
			break;
	}
}

} // namespace ZeroTier