return NT_STATUS_OK;
}
+
+NTSTATUS
+samba_gnutls_aead_aes_256_cbc_hmac_sha512_decrypt(TALLOC_CTX *mem_ctx,
+ const DATA_BLOB *ciphertext,
+ const DATA_BLOB *cdk,
+ const DATA_BLOB *key_salt,
+ const DATA_BLOB *mac_salt,
+ const DATA_BLOB *iv,
+ const uint8_t auth_tag[64],
+ DATA_BLOB *pplaintext)
+{
+ gnutls_hmac_hd_t hmac_hnd = NULL;
+ gnutls_mac_algorithm_t hash_algo = GNUTLS_MAC_SHA512;
+ size_t hmac_size = gnutls_hmac_get_len(hash_algo);
+ uint8_t dec_key_data[32];
+ uint8_t mac_key_data[64];
+ gnutls_datum_t mac_key = {
+ .data = mac_key_data,
+ .size = sizeof(mac_key_data),
+ };
+ gnutls_cipher_hd_t cipher_hnd = NULL;
+ gnutls_cipher_algorithm_t cipher_algo = GNUTLS_CIPHER_AES_256_CBC;
+ gnutls_datum_t dec_key = {
+ .data = dec_key_data,
+ .size = sizeof(dec_key_data),
+ };
+ gnutls_datum_t iv_datum = {
+ .data = iv->data,
+ .size = iv->length,
+ };
+ uint8_t version_byte = SAMR_AES_VERSION_BYTE;
+ uint8_t version_byte_len = SAMR_AES_VERSION_BYTE_LEN;
+ uint8_t auth_data[hmac_size];
+ uint8_t padding;
+ size_t i;
+ NTSTATUS status;
+ int cmp;
+ int rc;
+
+ if (cdk->length == 0 || ciphertext->length == 0 ||
+ key_salt->length == 0 || mac_salt->length == 0 || iv->length == 0 ||
+ pplaintext == NULL) {
+ return NT_STATUS_INVALID_PARAMETER;
+ }
+
+ /* Calculate mac key */
+ status = calculate_mac_key(cdk, mac_salt, mac_key_data);
+ if (!NT_STATUS_IS_OK(status)) {
+ return status;
+ }
+
+ rc = gnutls_hmac_init(&hmac_hnd, hash_algo, mac_key.data, mac_key.size);
+ BURN_DATA(mac_key_data);
+ if (rc < 0) {
+ return gnutls_error_to_ntstatus(rc,
+ NT_STATUS_DECRYPTION_FAILED);
+ }
+
+ rc = gnutls_hmac(hmac_hnd, &version_byte, sizeof(uint8_t));
+ if (rc < 0) {
+ gnutls_hmac_deinit(hmac_hnd, NULL);
+ return gnutls_error_to_ntstatus(rc,
+ NT_STATUS_DECRYPTION_FAILED);
+ }
+
+ rc = gnutls_hmac(hmac_hnd, iv->data, iv->length);
+ if (rc < 0) {
+ gnutls_hmac_deinit(hmac_hnd, NULL);
+ return gnutls_error_to_ntstatus(rc,
+ NT_STATUS_DECRYPTION_FAILED);
+ }
+
+ rc = gnutls_hmac(hmac_hnd, ciphertext->data, ciphertext->length);
+ if (rc < 0) {
+ gnutls_hmac_deinit(hmac_hnd, NULL);
+ return gnutls_error_to_ntstatus(rc,
+ NT_STATUS_DECRYPTION_FAILED);
+ }
+
+ rc = gnutls_hmac(hmac_hnd, &version_byte_len, sizeof(uint8_t));
+ if (rc < 0) {
+ gnutls_hmac_deinit(hmac_hnd, NULL);
+ return gnutls_error_to_ntstatus(rc,
+ NT_STATUS_DECRYPTION_FAILED);
+ }
+ gnutls_hmac_deinit(hmac_hnd, auth_data);
+
+ cmp = memcmp(auth_data, auth_tag, sizeof(auth_data));
+ if (cmp != 0) {
+ return NT_STATUS_DECRYPTION_FAILED;
+ }
+
+ *pplaintext = data_blob_talloc_zero(mem_ctx, ciphertext->length);
+ if (pplaintext->data == NULL) {
+ return NT_STATUS_NO_MEMORY;
+ }
+
+ /* Calculate decryption key */
+ status = calculate_enc_key(cdk, key_salt, dec_key_data);
+ if (!NT_STATUS_IS_OK(status)) {
+ return status;
+ }
+
+ rc = gnutls_cipher_init(&cipher_hnd, cipher_algo, &dec_key, &iv_datum);
+ BURN_DATA(dec_key_data);
+ if (rc < 0) {
+ data_blob_free(pplaintext);
+ return gnutls_error_to_ntstatus(rc,
+ NT_STATUS_DECRYPTION_FAILED);
+ }
+
+ rc = gnutls_cipher_decrypt2(cipher_hnd,
+ ciphertext->data,
+ ciphertext->length,
+ pplaintext->data,
+ pplaintext->length);
+ gnutls_cipher_deinit(cipher_hnd);
+ if (rc < 0) {
+ data_blob_clear_free(pplaintext);
+ return gnutls_error_to_ntstatus(rc,
+ NT_STATUS_DECRYPTION_FAILED);
+ }
+
+ /*
+ * PKCS#7 padding
+ *
+ * TODO: Use gnutls_cipher_decrypt3()
+ */
+
+ /*
+ * The plaintext is always padded.
+ *
+ * We already checked for ciphertext->length == 0 above and the
+ * pplaintext->length is equal to ciphertext->length here. We need to
+ * remove the padding from the plaintext size.
+ */
+ padding = pplaintext->data[pplaintext->length - 1];
+ if (padding == 0 || padding > 16) {
+ data_blob_clear_free(pplaintext);
+ return NT_STATUS_DECRYPTION_FAILED;
+ }
+
+ for (i = pplaintext->length - padding; i < pplaintext->length; i++) {
+ if (pplaintext->data[i] != padding) {
+ data_blob_clear_free(pplaintext);
+ return NT_STATUS_DECRYPTION_FAILED;
+ }
+ }
+
+ pplaintext->length -= padding;
+
+ return NT_STATUS_OK;
+}
DATA_BLOB *pciphertext,
uint8_t pauth_tag[64]);
+/**
+ * @brief Decypt cipher text using AEAD_AES_256_CBC_HMAC_SHA512 and the session
+ * key.
+ *
+ * This decrypts the cipher text using AEAD_AES_256_CBC_HMAC_SHA512 with the
+ * given content decryption key key. The plaintext will be zeroed as soon as the
+ * data blob is freed.
+ *
+ * @param mem_ctx The memory context to allocate the plaintext on.
+ *
+ * @param ciphertext The cipher text to decrypt.
+ *
+ * @param cdk The content decryption key.
+ *
+ * @param key_salt The salt used to calculate the encryption key.
+ *
+ * @param key_salt The salt used to calculate the mac key.
+
+ * @param iv The initialization vector used for the encryption.
+ *
+ * @param auth_tag[64] The authentication blob to be verified.
+ *
+ * @param pplaintext A pointer to a DATA_BLOB to store the plaintext.
+ *
+ * @return NT_STATUS_OK on success, an nt status error code otherwise.
+ */
+NTSTATUS
+samba_gnutls_aead_aes_256_cbc_hmac_sha512_decrypt(TALLOC_CTX *mem_ctx,
+ const DATA_BLOB *ciphertext,
+ const DATA_BLOB *cdk,
+ const DATA_BLOB *key_salt,
+ const DATA_BLOB *mac_salt,
+ const DATA_BLOB *iv,
+ const uint8_t auth_tag[64],
+ DATA_BLOB *pplaintext);
+
/**
* @brief Check if weak crypto is allowed.
*