1 files changed, 86 insertions, 0 deletions
diff --git a/wsutil/dot11decrypt_wep.c b/wsutil/dot11decrypt_wep.c
new file mode 100644
index 0000000..3747375
--- /dev/null
+++ b/wsutil/dot11decrypt_wep.c
@@ -0,0 +1,86 @@
+/* dot11decrypt_wep.c
+ *
+ * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
+ * Copyright (c) 2006 CACE Technologies, Davis (California)
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include "config.h"
+
+/************************************************************************/
+/*	File includes							*/
+
+#include "crc32.h"
+
+/************************************************************************/
+/* Note: copied from net80211/ieee80211_airpdcap_tkip.c			*/
+#define S_SWAP(a,b) { uint8_t t = S[a]; S[a] = S[b]; S[b] = t; }
+
+/* Note: copied from FreeBSD source code, RELENG 6,			*/
+/*		sys/net80211/ieee80211_crypto_wep.c, 391		*/
+int Dot11DecryptWepDecrypt(
+	const unsigned char *seed,
+	const size_t seed_len,
+	unsigned char *cypher_text,
+	const size_t data_len)
+{
+	uint32_t i, j, k, crc;
+	uint8_t S[256];
+	uint8_t icv[4];
+	size_t buflen;
+
+	/* Generate key stream (RC4 Pseudo-Random Number Generator) */
+	for (i = 0; i < 256; i++)
+		S[i] = (uint8_t)i;
+	for (j = i = 0; i < 256; i++) {
+		j = (j + S[i] + seed[i % seed_len]) & 0xff;
+		S_SWAP(i, j);
+	}
+
+	/* Apply RC4 to data and compute CRC32 over decrypted data */
+	crc = ~(uint32_t)0;
+	buflen = data_len;
+
+	for (i = j = k = 0; k < buflen; k++) {
+		i = (i + 1) & 0xff;
+		j = (j + S[i]) & 0xff;
+		S_SWAP(i, j);
+		*cypher_text ^= S[(S[i] + S[j]) & 0xff];
+		crc = crc32_ccitt_table_lookup((crc ^ *cypher_text) & 0xff) ^ (crc >> 8);
+		cypher_text++;
+	}
+
+	crc = ~crc;
+
+	/* Encrypt little-endian CRC32 and verify that it matches with the received ICV */
+	icv[0] = (uint8_t)crc;
+	icv[1] = (uint8_t)(crc >> 8);
+	icv[2] = (uint8_t)(crc >> 16);
+	icv[3] = (uint8_t)(crc >> 24);
+	for (k = 0; k < 4; k++) {
+		i = (i + 1) & 0xff;
+		j = (j + S[i]) & 0xff;
+		S_SWAP(i, j);
+		if ((icv[k] ^ S[(S[i] + S[j]) & 0xff]) != *cypher_text++) {
+			/* ICV mismatch - drop frame */
+			return 1/*DOT11DECRYPT_RET_UNSUCCESS*/;
+		}
+	}
+
+	return 0/*DOT11DECRYPT_RET_SUCCESS*/;
+}
+
+/*
+ * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
+ *
+ * Local variables:
+ * c-basic-offset: 8
+ * tab-width: 8
+ * indent-tabs-mode: t
+ * End:
+ *
+ * vi: set shiftwidth=8 tabstop=8 noexpandtab:
+ * :indentSize=8:tabSize=8:noTabs=false:
+ */