1 files changed, 111 insertions, 0 deletions
diff --git a/epan/crypt/dot11decrypt_gcmp.c b/epan/crypt/dot11decrypt_gcmp.c
new file mode 100644
index 0000000000..fb823b5f43
--- /dev/null
+++ b/epan/crypt/dot11decrypt_gcmp.c
@@ -0,0 +1,111 @@
+/* dot11decrypt_gcmp.c
+ *
+ * Wireshark - Network traffic analyzer
+ * By Gerald Combs <gerald@wireshark.org>
+ * Copyright 1998 Gerald Combs
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+/****************************************************************************/
+/* File includes								*/
+#include "config.h"
+
+#include "dot11decrypt_debug.h"
+#include "dot11decrypt_int.h"
+#include "dot11decrypt_system.h"
+#include "dot11decrypt_util.h"
+
+#include <glib.h>
+#include <wsutil/wsgcrypt.h>
+
+/****************************************************************************/
+/*	Internal definitions							*/
+
+/****************************************************************************/
+/* Internal macros								*/
+
+#define READ_6(b0, b1, b2, b3, b4, b5) \
+	((((guint64)((guint16)((b4 << 0) | (b5 << 8)))) << 32) | \
+	    ((guint32)((b0 << 0) | (b1 << 8) | (b2 << 16) | (b3 << 24))))
+
+/****************************************************************************/
+/* Internal function prototypes declarations					*/
+
+/****************************************************************************/
+/* Function definitions							*/
+
+/* From IEEE 802.11 2016 Chapter 12.5.5.3.4 Construct GCM nonce */
+static void
+gcmp_construct_nonce(
+	PDOT11DECRYPT_MAC_FRAME wh,
+	guint64 pn,
+	guint8 nonce[12])
+{
+	/* Nonce: A2 | PN */
+	DOT11DECRYPT_ADDR_COPY(nonce, wh->addr2);
+	nonce[6] = (guint8)(pn >> 40);
+	nonce[7] = (guint8)(pn >> 32);
+	nonce[8] = (guint8)(pn >> 24);
+	nonce[9] = (guint8)(pn >> 16);
+	nonce[10] = (guint8)(pn >> 8);
+	nonce[11] = (guint8)(pn >> 0);
+}
+
+int Dot11DecryptGcmpDecrypt(
+	guint8 *m,
+	int mac_header_len,
+	int len,
+	guint8 *TK1,
+	int tk_len)
+{
+	PDOT11DECRYPT_MAC_FRAME wh;
+	guint8 aad[30];
+	guint8 nonce[12];
+	guint8 mic[16];
+	ssize_t data_len;
+	size_t aad_len;
+	int z = mac_header_len;
+	gcry_cipher_hd_t handle;
+	guint64 pn;
+	guint8 *ivp = m + z;
+
+	wh = (PDOT11DECRYPT_MAC_FRAME )m;
+	data_len = len - (z + DOT11DECRYPT_GCMP_HEADER + sizeof(mic));
+	if (data_len < 1) {
+		return 0;
+	}
+
+	memcpy(mic, m + len - sizeof(mic), sizeof(mic));
+	pn = READ_6(ivp[0], ivp[1], ivp[4], ivp[5], ivp[6], ivp[7]);
+	gcmp_construct_nonce(wh, pn, nonce);
+	dot11decrypt_construct_aad(wh, aad, &aad_len);
+
+	if (gcry_cipher_open(&handle, GCRY_CIPHER_AES, GCRY_CIPHER_MODE_GCM, 0)) {
+		return 1;
+	}
+	if (gcry_cipher_setkey(handle, TK1, tk_len)) {
+		goto err_out;
+	}
+	if (gcry_cipher_setiv(handle, nonce, sizeof(nonce))) {
+		goto err_out;
+	}
+	if (gcry_cipher_authenticate(handle, aad, aad_len)) {
+		goto err_out;
+	}
+	if (gcry_cipher_decrypt(handle, m + z + DOT11DECRYPT_GCMP_HEADER, data_len, NULL, 0)) {
+		goto err_out;
+	}
+	if (gcry_cipher_checktag(handle, mic, sizeof(mic))) {
+		goto err_out;
+	}
+
+	/* TODO replay check	(IEEE 802.11i-2004, pg. 62)			*/
+	/* TODO PN must be incremental (IEEE 802.11i-2004, pg. 62)		*/
+
+	gcry_cipher_close(handle);
+	return 0;
+err_out:
+	gcry_cipher_close(handle);
+	return 1;
+}