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#include "hybbx/crypto.h"
#include "crypto_backends.h"
#include "monocypher.h"
#include <string.h>
#define HYBBX_CRYPTO_MAX_BYTES (256u * 1024u)
static hybbx_result_t crypto_len_ok(size_t len)
{
if (len > HYBBX_CRYPTO_MAX_BYTES) {
return HYBBX_ERR_INVALID;
}
return HYBBX_OK;
}
hybbx_result_t hybbx_crypto_random(uint8_t *buf, size_t len)
{
if (buf == NULL || len == 0) {
return HYBBX_ERR_INVALID;
}
return hybbx_backend_random(buf, len);
}
const char *hybbx_crypto_alg_name(hybbx_crypto_alg_t alg)
{
switch (alg) {
case HYBBX_CRYPTO_AES_256_GCM:
return "aes-256-gcm";
case HYBBX_CRYPTO_XCHACHA20_POLY1305:
return "xchacha20-poly1305";
case HYBBX_CRYPTO_X25519_AEAD:
return "x25519-xchacha20-poly1305";
default:
return "unknown";
}
}
size_t hybbx_crypto_nonce_size(hybbx_crypto_alg_t alg)
{
switch (alg) {
case HYBBX_CRYPTO_AES_256_GCM:
return HYBBX_CRYPTO_AES_GCM_NONCE;
case HYBBX_CRYPTO_XCHACHA20_POLY1305:
return HYBBX_CRYPTO_XCHACHA_NONCE;
default:
return 0;
}
}
static hybbx_result_t derive_x25519_key(const uint8_t shared[32],
uint8_t key[32])
{
static const uint8_t label[] = "hybbx-x25519-aead-key-v1";
hybbx_backend_blake2b_keyed(key, 32, shared, 32, label, sizeof(label) - 1);
return HYBBX_OK;
}
hybbx_result_t hybbx_crypto_encrypt(hybbx_crypto_alg_t alg,
const uint8_t key[HYBBX_CRYPTO_KEY_SIZE],
const uint8_t *nonce, size_t nonce_len,
const uint8_t *aad, size_t aad_len,
const uint8_t *plaintext,
size_t plaintext_len,
uint8_t *ciphertext,
uint8_t tag[HYBBX_CRYPTO_TAG_SIZE])
{
hybbx_result_t rc;
if (key == NULL || nonce == NULL || tag == NULL ||
(plaintext_len > 0 && (plaintext == NULL || ciphertext == NULL))) {
return HYBBX_ERR_INVALID;
}
rc = crypto_len_ok(plaintext_len);
if (rc != HYBBX_OK) {
return rc;
}
if (alg == HYBBX_CRYPTO_AES_256_GCM) {
if (nonce_len != HYBBX_CRYPTO_AES_GCM_NONCE) {
return HYBBX_ERR_INVALID;
}
if (hybbx_backend_aes256gcm_encrypt(key, nonce, aad, aad_len, plaintext,
plaintext_len, ciphertext, tag) !=
0) {
return HYBBX_ERR_IO;
}
return HYBBX_OK;
}
if (alg == HYBBX_CRYPTO_XCHACHA20_POLY1305) {
uint8_t nonce24[HYBBX_CRYPTO_XCHACHA_NONCE];
if (nonce_len != HYBBX_CRYPTO_XCHACHA_NONCE) {
return HYBBX_ERR_INVALID;
}
memcpy(nonce24, nonce, sizeof(nonce24));
hybbx_backend_chacha_lock(ciphertext, tag, key, nonce24, aad, aad_len,
plaintext, plaintext_len);
crypto_wipe(nonce24, sizeof(nonce24));
return HYBBX_OK;
}
return HYBBX_ERR_INVALID;
}
hybbx_result_t hybbx_crypto_decrypt(hybbx_crypto_alg_t alg,
const uint8_t key[HYBBX_CRYPTO_KEY_SIZE],
const uint8_t *nonce, size_t nonce_len,
const uint8_t *aad, size_t aad_len,
const uint8_t *ciphertext,
size_t ciphertext_len,
uint8_t *plaintext,
const uint8_t tag[HYBBX_CRYPTO_TAG_SIZE])
{
hybbx_result_t rc;
int ok;
if (key == NULL || nonce == NULL || tag == NULL ||
(ciphertext_len > 0 && (ciphertext == NULL || plaintext == NULL))) {
return HYBBX_ERR_INVALID;
}
rc = crypto_len_ok(ciphertext_len);
if (rc != HYBBX_OK) {
return rc;
}
if (alg == HYBBX_CRYPTO_AES_256_GCM) {
if (nonce_len != HYBBX_CRYPTO_AES_GCM_NONCE) {
return HYBBX_ERR_INVALID;
}
ok = hybbx_backend_aes256gcm_decrypt(key, nonce, aad, aad_len,
ciphertext, ciphertext_len,
plaintext, tag);
return ok == 0 ? HYBBX_OK : HYBBX_ERR_DENIED;
}
if (alg == HYBBX_CRYPTO_XCHACHA20_POLY1305) {
uint8_t nonce24[HYBBX_CRYPTO_XCHACHA_NONCE];
if (nonce_len != HYBBX_CRYPTO_XCHACHA_NONCE) {
return HYBBX_ERR_INVALID;
}
memcpy(nonce24, nonce, sizeof(nonce24));
ok = hybbx_backend_chacha_unlock(plaintext, tag, key, nonce24, aad,
aad_len, ciphertext, ciphertext_len);
crypto_wipe(nonce24, sizeof(nonce24));
return ok == 0 ? HYBBX_OK : HYBBX_ERR_DENIED;
}
return HYBBX_ERR_INVALID;
}
hybbx_result_t hybbx_crypto_x25519_keypair(
uint8_t public_key[HYBBX_CRYPTO_X25519_PUBLIC_KEY],
uint8_t secret_key[HYBBX_CRYPTO_X25519_SECRET_KEY])
{
if (public_key == NULL || secret_key == NULL) {
return HYBBX_ERR_INVALID;
}
if (hybbx_crypto_random(secret_key, HYBBX_CRYPTO_X25519_SECRET_KEY) !=
HYBBX_OK) {
return HYBBX_ERR_IO;
}
secret_key[0] &= 248;
secret_key[31] &= 127;
secret_key[31] |= 64;
hybbx_backend_x25519_public_key(public_key, secret_key);
return HYBBX_OK;
}
hybbx_result_t hybbx_crypto_x25519_seal(
const uint8_t recipient_pk[HYBBX_CRYPTO_X25519_PUBLIC_KEY],
const uint8_t *aad, size_t aad_len,
const uint8_t *plaintext, size_t plaintext_len,
uint8_t *sealed, size_t *sealed_len, size_t sealed_cap)
{
uint8_t ep_sk[32];
uint8_t ep_pk[32];
uint8_t shared[32];
uint8_t key[32];
uint8_t nonce[HYBBX_CRYPTO_XCHACHA_NONCE];
uint8_t *cipher;
uint8_t *tag;
size_t need;
hybbx_result_t rc;
if (recipient_pk == NULL || sealed == NULL || sealed_len == NULL) {
return HYBBX_ERR_INVALID;
}
rc = crypto_len_ok(plaintext_len);
if (rc != HYBBX_OK) {
return rc;
}
need = HYBBX_CRYPTO_X25519_SEAL_OVERHEAD + plaintext_len;
if (sealed_cap < need) {
return HYBBX_ERR_INVALID;
}
if (hybbx_crypto_random(ep_sk, sizeof(ep_sk)) != HYBBX_OK) {
return HYBBX_ERR_IO;
}
ep_sk[0] &= 248;
ep_sk[31] &= 127;
ep_sk[31] |= 64;
hybbx_backend_x25519_public_key(ep_pk, ep_sk);
hybbx_backend_x25519_shared(shared, ep_sk, recipient_pk);
derive_x25519_key(shared, key);
if (hybbx_crypto_random(nonce, sizeof(nonce)) != HYBBX_OK) {
crypto_wipe(ep_sk, sizeof(ep_sk));
crypto_wipe(shared, sizeof(shared));
crypto_wipe(key, sizeof(key));
return HYBBX_ERR_IO;
}
memcpy(sealed, ep_pk, 32);
memcpy(sealed + 32, nonce, sizeof(nonce));
cipher = sealed + 32 + sizeof(nonce);
tag = sealed + 32 + sizeof(nonce) + plaintext_len;
rc = hybbx_crypto_encrypt(HYBBX_CRYPTO_XCHACHA20_POLY1305, key, nonce,
sizeof(nonce), aad, aad_len, plaintext,
plaintext_len, cipher, tag);
crypto_wipe(ep_sk, sizeof(ep_sk));
crypto_wipe(shared, sizeof(shared));
crypto_wipe(key, sizeof(key));
if (rc != HYBBX_OK) {
return rc;
}
*sealed_len = need;
return HYBBX_OK;
}
hybbx_result_t hybbx_crypto_x25519_open(
const uint8_t recipient_sk[HYBBX_CRYPTO_X25519_SECRET_KEY],
const uint8_t *aad, size_t aad_len,
const uint8_t *sealed, size_t sealed_len,
uint8_t *plaintext, size_t *plaintext_len, size_t plaintext_cap)
{
const uint8_t *ep_pk;
const uint8_t *nonce;
const uint8_t *cipher;
const uint8_t *tag;
size_t cipher_len;
uint8_t shared[32];
uint8_t key[32];
uint8_t tag_buf[HYBBX_CRYPTO_TAG_SIZE];
hybbx_result_t rc;
if (recipient_sk == NULL || sealed == NULL || plaintext == NULL ||
plaintext_len == NULL) {
return HYBBX_ERR_INVALID;
}
if (sealed_len < HYBBX_CRYPTO_X25519_SEAL_OVERHEAD) {
return HYBBX_ERR_INVALID;
}
cipher_len = sealed_len - HYBBX_CRYPTO_X25519_SEAL_OVERHEAD;
if (cipher_len > plaintext_cap) {
return HYBBX_ERR_INVALID;
}
ep_pk = sealed;
nonce = sealed + 32;
cipher = sealed + 32 + HYBBX_CRYPTO_XCHACHA_NONCE;
tag = cipher + cipher_len;
memcpy(tag_buf, tag, sizeof(tag_buf));
hybbx_backend_x25519_shared(shared, recipient_sk, ep_pk);
derive_x25519_key(shared, key);
rc = hybbx_crypto_decrypt(HYBBX_CRYPTO_XCHACHA20_POLY1305, key, nonce,
HYBBX_CRYPTO_XCHACHA_NONCE, aad, aad_len,
cipher, cipher_len, plaintext, tag_buf);
crypto_wipe(shared, sizeof(shared));
crypto_wipe(key, sizeof(key));
if (rc != HYBBX_OK) {
return rc;
}
*plaintext_len = cipher_len;
return HYBBX_OK;
}
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