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utun2/src/dm/dm_crypto.c

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/*
* dm_crypto.c — криптография прямого чата (DM)
*/
#include "dm_crypto.h"
#include "../../lib/debug_config.h"
#define OPENSSL_API_COMPAT 0x10100000L
#include <openssl/evp.h>
#include <openssl/sha.h>
#include <string.h>
#include <stdio.h>
#define DM_ID "dm_crypto"
/* Медиа использует тот же ключ target, но отдельное пространство nonce. */
void dm_build_media_nonce(uint64_t author, const uint8_t media_id[16], uint64_t part, uint8_t nonce[DM_NONCE_SIZE]) {
SHA256_CTX ctx;
uint8_t hash[32];
SHA256_Init(&ctx);
SHA256_Update(&ctx, "utun_dm_media", 13);
SHA256_Update(&ctx, &author, sizeof(author));
SHA256_Update(&ctx, media_id, 16);
SHA256_Update(&ctx, &part, sizeof(part));
SHA256_Final(hash, &ctx);
memcpy(nonce, hash, DM_NONCE_SIZE);
}
uint64_t dm_derive_conv_id(uint64_t a, uint64_t b) {
uint64_t lo = a < b ? a : b;
uint64_t hi = a < b ? b : a;
SHA256_CTX ctx;
uint8_t hash[32];
SHA256_Init(&ctx);
SHA256_Update(&ctx, "utun_dm_v1", 9);
SHA256_Update(&ctx, &lo, 8);
SHA256_Update(&ctx, &hi, 8);
SHA256_Final(hash, &ctx);
uint64_t id;
memcpy(&id, hash, 8);
id &= 0x7FFFFFFFFFFFFFFFULL;
if (id == 0) id = 1;
return id;
}
int dm_derive_content_key(const uint8_t my_priv[32], const uint8_t peer_pub[32],
uint8_t out[DM_CONTENT_KEY_SIZE]) {
if (!my_priv || !peer_pub || !out) return -1;
EVP_PKEY* my_pkey = EVP_PKEY_new_raw_private_key(EVP_PKEY_X25519, NULL, my_priv, 32);
if (!my_pkey) { DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: EVP_PKEY_new_raw_private_key failed", DM_ID); return -1; }
EVP_PKEY* peer_pkey = EVP_PKEY_new_raw_public_key(EVP_PKEY_X25519, NULL, peer_pub, 32);
if (!peer_pkey) { EVP_PKEY_free(my_pkey); DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: EVP_PKEY_new_raw_public_key failed", DM_ID); return -1; }
EVP_PKEY_CTX* dctx = EVP_PKEY_CTX_new(my_pkey, NULL);
uint8_t shared[32];
size_t shared_len = sizeof(shared);
int rc = -1;
if (!dctx) goto out;
if (EVP_PKEY_derive_init(dctx) <= 0) goto out;
if (EVP_PKEY_derive_set_peer(dctx, peer_pkey) <= 0) goto out;
if (EVP_PKEY_derive(dctx, shared, &shared_len) <= 0 || shared_len != sizeof(shared)) goto out;
SHA256_CTX sctx;
SHA256_Init(&sctx);
SHA256_Update(&sctx, shared, sizeof(shared));
SHA256_Update(&sctx, "utun_dm_content", 15);
SHA256_Final(out, &sctx);
rc = 0;
out:
if (dctx) EVP_PKEY_CTX_free(dctx);
EVP_PKEY_free(my_pkey);
EVP_PKEY_free(peer_pkey);
if (rc != 0) DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: X25519 derive failed", DM_ID);
return rc;
}
void dm_build_nonce(uint64_t conv_id, uint64_t author, uint64_t seq, uint8_t nonce[DM_NONCE_SIZE]) {
SHA256_CTX ctx;
uint8_t hash[32];
SHA256_Init(&ctx);
SHA256_Update(&ctx, &conv_id, 8);
SHA256_Update(&ctx, &author, 8);
SHA256_Update(&ctx, &seq, 8);
SHA256_Final(hash, &ctx);
memcpy(nonce, hash, DM_NONCE_SIZE);
}
static int dm_ccm_crypt(const uint8_t key[DM_CONTENT_KEY_SIZE], const uint8_t nonce[DM_NONCE_SIZE],
const uint8_t* in, size_t in_len, uint8_t* out, size_t* out_len,
int encrypt, const uint8_t* tag_in) {
if (!key || !nonce || (!in && in_len) || !out || !out_len ||
(encrypt ? in_len > DM_CCM_PLAIN_MAX : in_len < DM_TAG_SIZE || in_len - DM_TAG_SIZE > DM_CCM_PLAIN_MAX)) {
DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: invalid CCM arguments encrypt=%d bytes=%zu", DM_ID, encrypt, in_len);
return -1;
}
*out_len = 0;
static const uint8_t empty = 0;
if (!in) in = &empty;
EVP_CIPHER_CTX* ectx = EVP_CIPHER_CTX_new();
if (!ectx) { DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: CCM context allocation failed", DM_ID); return -1; }
const EVP_CIPHER* cipher = EVP_aes_256_ccm();
int rc = -1;
if (encrypt) {
if (EVP_EncryptInit_ex(ectx, cipher, NULL, NULL, NULL) != 1
|| EVP_CIPHER_CTX_ctrl(ectx, EVP_CTRL_AEAD_SET_IVLEN, DM_NONCE_SIZE, NULL) != 1
|| EVP_CIPHER_CTX_ctrl(ectx, EVP_CTRL_AEAD_SET_TAG, DM_TAG_SIZE, NULL) != 1
|| EVP_EncryptInit_ex(ectx, NULL, NULL, key, nonce) != 1) goto done;
int outl;
if (EVP_EncryptUpdate(ectx, NULL, &outl, NULL, (int)in_len) != 1) goto done;
if (EVP_EncryptUpdate(ectx, out, &outl, in, (int)in_len) != 1 || outl != (int)in_len) goto done;
int tmpl;
if (EVP_EncryptFinal_ex(ectx, out + outl, &tmpl) != 1) goto done;
if (EVP_CIPHER_CTX_ctrl(ectx, EVP_CTRL_AEAD_GET_TAG, DM_TAG_SIZE, out + in_len) != 1) goto done;
*out_len = in_len + DM_TAG_SIZE;
} else {
if (in_len < DM_TAG_SIZE) goto done;
size_t body = in_len - DM_TAG_SIZE;
if (EVP_DecryptInit_ex(ectx, cipher, NULL, NULL, NULL) != 1
|| EVP_CIPHER_CTX_ctrl(ectx, EVP_CTRL_AEAD_SET_IVLEN, DM_NONCE_SIZE, NULL) != 1
|| EVP_CIPHER_CTX_ctrl(ectx, EVP_CTRL_AEAD_SET_TAG, DM_TAG_SIZE, (void*)(tag_in ? tag_in : in + body)) != 1
|| EVP_DecryptInit_ex(ectx, NULL, NULL, key, nonce) != 1) goto done;
int outl;
if (EVP_DecryptUpdate(ectx, NULL, &outl, NULL, (int)body) != 1) goto done;
if (EVP_DecryptUpdate(ectx, out, &outl, in, (int)body) != 1 || outl != (int)body) goto done;
*out_len = body;
}
rc = 0;
done:
EVP_CIPHER_CTX_free(ectx);
if (rc) DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: CCM %s failed bytes=%zu", DM_ID, encrypt ? "encrypt" : "decrypt", in_len);
return rc;
}
int dm_encrypt(const uint8_t key[DM_CONTENT_KEY_SIZE], const uint8_t nonce[DM_NONCE_SIZE],
const uint8_t* plain, size_t plain_len, uint8_t* out, size_t* out_len) {
return dm_ccm_crypt(key, nonce, plain, plain_len, out, out_len, 1, NULL);
}
int dm_decrypt(const uint8_t key[DM_CONTENT_KEY_SIZE], const uint8_t nonce[DM_NONCE_SIZE],
const uint8_t* ct, size_t ct_len, uint8_t* out, size_t* out_len) {
return dm_ccm_crypt(key, nonce, ct, ct_len, out, out_len, 0, NULL);
}
/* Каждая порция имеет собственный nonce, ciphertext неизменен для всех сетевых повторов. */
int dm_media_encrypt_stream(const uint8_t key[DM_CONTENT_KEY_SIZE], uint64_t author, const uint8_t media_id[16],
FILE* src, FILE* dst, uint64_t* plain_size, uint8_t ciphertext_hash[32]) {
if (!key || !author || !media_id || !src || !dst || src == dst || !plain_size || !ciphertext_hash) {
DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: invalid media encryption arguments", DM_ID);
return -1;
}
*plain_size = 0;
memset(ciphertext_hash, 0, 32);
uint8_t plain[DM_MEDIA_PLAIN_SIZE], cipher[DM_MEDIA_PLAIN_SIZE + DM_TAG_SIZE], nonce[DM_NONCE_SIZE];
uint64_t part = 0, total = 0;
SHA256_CTX hash;
SHA256_Init(&hash);
for (;;) {
size_t n = fread(plain, 1, sizeof(plain), src);
if (ferror(src)) {
DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: media source read failed part=%llu", DM_ID, (unsigned long long)part);
return -1;
}
if (!n && part) break;
size_t clen = 0;
dm_build_media_nonce(author, media_id, part, nonce);
if (dm_encrypt(key, nonce, plain, n, cipher, &clen) != 0) return -1;
if (fwrite(cipher, 1, clen, dst) != clen) {
DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: media ciphertext write failed part=%llu", DM_ID, (unsigned long long)part);
return -1;
}
SHA256_Update(&hash, cipher, clen);
total += n;
part++;
if (n < sizeof(plain)) break;
}
if (fflush(dst) != 0) {
DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: media ciphertext flush failed", DM_ID);
return -1;
}
SHA256_Final(ciphertext_hash, &hash);
*plain_size = total;
DEBUG_DEBUG(DEBUG_CATEGORY_DM, "%s: media encrypted author=%llu plain=%llu records=%llu", DM_ID,
(unsigned long long)author, (unsigned long long)total, (unsigned long long)part);
return 0;
}
/* Размер и хеш берутся из подписанного manifest; никакого size-only принятия файла. */
int dm_media_decrypt_stream(const uint8_t key[DM_CONTENT_KEY_SIZE], uint64_t author, const uint8_t media_id[16],
uint64_t plain_size, const uint8_t ciphertext_hash[32], FILE* src, FILE* dst) {
if (!key || !author || !media_id || !ciphertext_hash || !src || !dst || src == dst) {
DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: invalid media decryption arguments", DM_ID);
return -1;
}
uint8_t plain[DM_MEDIA_PLAIN_SIZE], cipher[DM_MEDIA_PLAIN_SIZE + DM_TAG_SIZE], nonce[DM_NONCE_SIZE];
uint64_t remaining = plain_size, part = 0;
SHA256_CTX hash;
SHA256_Init(&hash);
do {
size_t n = remaining > DM_MEDIA_PLAIN_SIZE ? DM_MEDIA_PLAIN_SIZE : (size_t)remaining;
size_t clen = n + DM_TAG_SIZE, plen = 0;
if (fread(cipher, 1, clen, src) != clen) {
DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: media ciphertext short/read failure part=%llu expected=%zu", DM_ID,
(unsigned long long)part, clen);
return -1;
}
SHA256_Update(&hash, cipher, clen);
dm_build_media_nonce(author, media_id, part, nonce);
if (dm_decrypt(key, nonce, cipher, clen, plain, &plen) != 0) return -1;
if (plen != n || fwrite(plain, 1, plen, dst) != plen) {
DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: media plaintext write/length failure part=%llu", DM_ID, (unsigned long long)part);
return -1;
}
remaining -= n;
part++;
} while (remaining);
uint8_t actual_hash[32];
SHA256_Final(actual_hash, &hash);
if (fgetc(src) != EOF || ferror(src) || memcmp(actual_hash, ciphertext_hash, 32)) {
DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: media ciphertext size/hash mismatch plain=%llu", DM_ID, (unsigned long long)plain_size);
return -1;
}
if (fflush(dst) != 0) {
DEBUG_ERROR(DEBUG_CATEGORY_DM, "%s: media plaintext flush failed", DM_ID);
return -1;
}
DEBUG_DEBUG(DEBUG_CATEGORY_DM, "%s: media verified author=%llu plain=%llu records=%llu", DM_ID,
(unsigned long long)author, (unsigned long long)plain_size, (unsigned long long)part);
return 0;
}