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-rw-r--r--gpxe/src/net/80211/wpa_tkip.c586
1 files changed, 586 insertions, 0 deletions
diff --git a/gpxe/src/net/80211/wpa_tkip.c b/gpxe/src/net/80211/wpa_tkip.c
new file mode 100644
index 00000000..0cb697fa
--- /dev/null
+++ b/gpxe/src/net/80211/wpa_tkip.c
@@ -0,0 +1,586 @@
+/*
+ * Copyright (c) 2009 Joshua Oreman <oremanj@rwcr.net>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <gpxe/net80211.h>
+#include <gpxe/crypto.h>
+#include <gpxe/hmac.h>
+#include <gpxe/sha1.h>
+#include <gpxe/md5.h>
+#include <gpxe/crc32.h>
+#include <gpxe/arc4.h>
+#include <gpxe/wpa.h>
+#include <byteswap.h>
+#include <errno.h>
+
+/** @file
+ *
+ * Backend for WPA using the TKIP encryption standard.
+ */
+
+/** Context for one direction of TKIP, either encryption or decryption */
+struct tkip_dir_ctx
+{
+ /** High 32 bits of last sequence counter value used */
+ u32 tsc_hi;
+
+ /** Low 32 bits of last sequence counter value used */
+ u16 tsc_lo;
+
+ /** MAC address used to derive TTAK */
+ u8 mac[ETH_ALEN];
+
+ /** If TRUE, TTAK is valid */
+ u16 ttak_ok;
+
+ /** TKIP-mixed transmit address and key, depends on tsc_hi and MAC */
+ u16 ttak[5];
+};
+
+/** Context for TKIP encryption and decryption */
+struct tkip_ctx
+{
+ /** Temporal key to use */
+ struct tkip_tk tk;
+
+ /** State for encryption */
+ struct tkip_dir_ctx enc;
+
+ /** State for decryption */
+ struct tkip_dir_ctx dec;
+};
+
+/** Header structure at the beginning of TKIP frame data */
+struct tkip_head
+{
+ u8 tsc1; /**< High byte of low 16 bits of TSC */
+ u8 seed1; /**< Second byte of WEP seed */
+ u8 tsc0; /**< Low byte of TSC */
+ u8 kid; /**< Key ID and ExtIV byte */
+ u32 tsc_hi; /**< High 32 bits of TSC, as an ExtIV */
+} __attribute__ (( packed ));
+
+
+/** TKIP header overhead (IV + KID + ExtIV) */
+#define TKIP_HEAD_LEN 8
+
+/** TKIP trailer overhead (MIC + ICV) [assumes unfragmented] */
+#define TKIP_FOOT_LEN 12
+
+/** TKIP MIC length */
+#define TKIP_MIC_LEN 8
+
+/** TKIP ICV length */
+#define TKIP_ICV_LEN 4
+
+
+/** TKIP S-box */
+static const u16 Sbox[256] = {
+ 0xC6A5, 0xF884, 0xEE99, 0xF68D, 0xFF0D, 0xD6BD, 0xDEB1, 0x9154,
+ 0x6050, 0x0203, 0xCEA9, 0x567D, 0xE719, 0xB562, 0x4DE6, 0xEC9A,
+ 0x8F45, 0x1F9D, 0x8940, 0xFA87, 0xEF15, 0xB2EB, 0x8EC9, 0xFB0B,
+ 0x41EC, 0xB367, 0x5FFD, 0x45EA, 0x23BF, 0x53F7, 0xE496, 0x9B5B,
+ 0x75C2, 0xE11C, 0x3DAE, 0x4C6A, 0x6C5A, 0x7E41, 0xF502, 0x834F,
+ 0x685C, 0x51F4, 0xD134, 0xF908, 0xE293, 0xAB73, 0x6253, 0x2A3F,
+ 0x080C, 0x9552, 0x4665, 0x9D5E, 0x3028, 0x37A1, 0x0A0F, 0x2FB5,
+ 0x0E09, 0x2436, 0x1B9B, 0xDF3D, 0xCD26, 0x4E69, 0x7FCD, 0xEA9F,
+ 0x121B, 0x1D9E, 0x5874, 0x342E, 0x362D, 0xDCB2, 0xB4EE, 0x5BFB,
+ 0xA4F6, 0x764D, 0xB761, 0x7DCE, 0x527B, 0xDD3E, 0x5E71, 0x1397,
+ 0xA6F5, 0xB968, 0x0000, 0xC12C, 0x4060, 0xE31F, 0x79C8, 0xB6ED,
+ 0xD4BE, 0x8D46, 0x67D9, 0x724B, 0x94DE, 0x98D4, 0xB0E8, 0x854A,
+ 0xBB6B, 0xC52A, 0x4FE5, 0xED16, 0x86C5, 0x9AD7, 0x6655, 0x1194,
+ 0x8ACF, 0xE910, 0x0406, 0xFE81, 0xA0F0, 0x7844, 0x25BA, 0x4BE3,
+ 0xA2F3, 0x5DFE, 0x80C0, 0x058A, 0x3FAD, 0x21BC, 0x7048, 0xF104,
+ 0x63DF, 0x77C1, 0xAF75, 0x4263, 0x2030, 0xE51A, 0xFD0E, 0xBF6D,
+ 0x814C, 0x1814, 0x2635, 0xC32F, 0xBEE1, 0x35A2, 0x88CC, 0x2E39,
+ 0x9357, 0x55F2, 0xFC82, 0x7A47, 0xC8AC, 0xBAE7, 0x322B, 0xE695,
+ 0xC0A0, 0x1998, 0x9ED1, 0xA37F, 0x4466, 0x547E, 0x3BAB, 0x0B83,
+ 0x8CCA, 0xC729, 0x6BD3, 0x283C, 0xA779, 0xBCE2, 0x161D, 0xAD76,
+ 0xDB3B, 0x6456, 0x744E, 0x141E, 0x92DB, 0x0C0A, 0x486C, 0xB8E4,
+ 0x9F5D, 0xBD6E, 0x43EF, 0xC4A6, 0x39A8, 0x31A4, 0xD337, 0xF28B,
+ 0xD532, 0x8B43, 0x6E59, 0xDAB7, 0x018C, 0xB164, 0x9CD2, 0x49E0,
+ 0xD8B4, 0xACFA, 0xF307, 0xCF25, 0xCAAF, 0xF48E, 0x47E9, 0x1018,
+ 0x6FD5, 0xF088, 0x4A6F, 0x5C72, 0x3824, 0x57F1, 0x73C7, 0x9751,
+ 0xCB23, 0xA17C, 0xE89C, 0x3E21, 0x96DD, 0x61DC, 0x0D86, 0x0F85,
+ 0xE090, 0x7C42, 0x71C4, 0xCCAA, 0x90D8, 0x0605, 0xF701, 0x1C12,
+ 0xC2A3, 0x6A5F, 0xAEF9, 0x69D0, 0x1791, 0x9958, 0x3A27, 0x27B9,
+ 0xD938, 0xEB13, 0x2BB3, 0x2233, 0xD2BB, 0xA970, 0x0789, 0x33A7,
+ 0x2DB6, 0x3C22, 0x1592, 0xC920, 0x8749, 0xAAFF, 0x5078, 0xA57A,
+ 0x038F, 0x59F8, 0x0980, 0x1A17, 0x65DA, 0xD731, 0x84C6, 0xD0B8,
+ 0x82C3, 0x29B0, 0x5A77, 0x1E11, 0x7BCB, 0xA8FC, 0x6DD6, 0x2C3A,
+};
+
+/**
+ * Perform S-box mapping on a 16-bit value
+ *
+ * @v v Value to perform S-box mapping on
+ * @ret Sv S-box mapped value
+ */
+static inline u16 S ( u16 v )
+{
+ return Sbox[v & 0xFF] ^ swap16 ( Sbox[v >> 8] );
+}
+
+/**
+ * Rotate 16-bit value right
+ *
+ * @v v Value to rotate
+ * @v bits Number of bits to rotate by
+ * @ret rotv Rotated value
+ */
+static inline u16 ror16 ( u16 v, int bits )
+{
+ return ( v >> bits ) | ( v << ( 16 - bits ) );
+}
+
+/**
+ * Rotate 32-bit value right
+ *
+ * @v v Value to rotate
+ * @v bits Number of bits to rotate by
+ * @ret rotv Rotated value
+ */
+static inline u32 ror32 ( u32 v, int bits )
+{
+ return ( v >> bits ) | ( v << ( 32 - bits ) );
+}
+
+/**
+ * Rotate 32-bit value left
+ *
+ * @v v Value to rotate
+ * @v bits Number of bits to rotate by
+ * @ret rotv Rotated value
+ */
+static inline u32 rol32 ( u32 v, int bits )
+{
+ return ( v << bits ) | ( v >> ( 32 - bits ) );
+}
+
+
+/**
+ * Initialise TKIP state and install key
+ *
+ * @v crypto TKIP cryptosystem structure
+ * @v key Pointer to tkip_tk to install
+ * @v keylen Length of key (32 bytes)
+ * @v rsc Initial receive sequence counter
+ */
+static int tkip_init ( struct net80211_crypto *crypto, const void *key,
+ int keylen, const void *rsc )
+{
+ struct tkip_ctx *ctx = crypto->priv;
+ const u8 *rscb = rsc;
+
+ if ( keylen != sizeof ( ctx->tk ) )
+ return -EINVAL;
+
+ if ( rscb ) {
+ ctx->dec.tsc_lo = ( rscb[1] << 8 ) | rscb[0];
+ ctx->dec.tsc_hi = ( ( rscb[5] << 24 ) | ( rscb[4] << 16 ) |
+ ( rscb[3] << 8 ) | rscb[2] );
+ }
+
+ memcpy ( &ctx->tk, key, sizeof ( ctx->tk ) );
+
+ return 0;
+}
+
+/**
+ * Perform TKIP key mixing, phase 1
+ *
+ * @v dctx TKIP directional context
+ * @v tk TKIP temporal key
+ * @v mac MAC address of transmitter
+ *
+ * This recomputes the TTAK in @a dctx if necessary, and sets
+ * @c dctx->ttak_ok.
+ */
+static void tkip_mix_1 ( struct tkip_dir_ctx *dctx, struct tkip_tk *tk, u8 *mac )
+{
+ int i, j;
+
+ if ( dctx->ttak_ok && ! memcmp ( mac, dctx->mac, ETH_ALEN ) )
+ return;
+
+ memcpy ( dctx->mac, mac, ETH_ALEN );
+
+ dctx->ttak[0] = dctx->tsc_hi & 0xFFFF;
+ dctx->ttak[1] = dctx->tsc_hi >> 16;
+ dctx->ttak[2] = ( mac[1] << 8 ) | mac[0];
+ dctx->ttak[3] = ( mac[3] << 8 ) | mac[2];
+ dctx->ttak[4] = ( mac[5] << 8 ) | mac[4];
+
+ for ( i = 0; i < 8; i++ ) {
+ j = 2 * ( i & 1 );
+
+ dctx->ttak[0] += S ( dctx->ttak[4] ^ ( ( tk->key[1 + j] << 8 ) |
+ tk->key[0 + j] ) );
+ dctx->ttak[1] += S ( dctx->ttak[0] ^ ( ( tk->key[5 + j] << 8 ) |
+ tk->key[4 + j] ) );
+ dctx->ttak[2] += S ( dctx->ttak[1] ^ ( ( tk->key[9 + j] << 8 ) |
+ tk->key[8 + j] ) );
+ dctx->ttak[3] += S ( dctx->ttak[2] ^ ( ( tk->key[13+ j] << 8 ) |
+ tk->key[12+ j] ) );
+ dctx->ttak[4] += S ( dctx->ttak[3] ^ ( ( tk->key[1 + j] << 8 ) |
+ tk->key[0 + j] ) ) + i;
+ }
+
+ dctx->ttak_ok = 1;
+}
+
+/**
+ * Perform TKIP key mixing, phase 2
+ *
+ * @v dctx TKIP directional context
+ * @v tk TKIP temporal key
+ * @ret key ARC4 key, 16 bytes long
+ */
+static void tkip_mix_2 ( struct tkip_dir_ctx *dctx, struct tkip_tk *tk,
+ void *key )
+{
+ u8 *kb = key;
+ u16 ppk[6];
+ int i;
+
+ memcpy ( ppk, dctx->ttak, sizeof ( dctx->ttak ) );
+ ppk[5] = dctx->ttak[4] + dctx->tsc_lo;
+
+ ppk[0] += S ( ppk[5] ^ ( ( tk->key[1] << 8 ) | tk->key[0] ) );
+ ppk[1] += S ( ppk[0] ^ ( ( tk->key[3] << 8 ) | tk->key[2] ) );
+ ppk[2] += S ( ppk[1] ^ ( ( tk->key[5] << 8 ) | tk->key[4] ) );
+ ppk[3] += S ( ppk[2] ^ ( ( tk->key[7] << 8 ) | tk->key[6] ) );
+ ppk[4] += S ( ppk[3] ^ ( ( tk->key[9] << 8 ) | tk->key[8] ) );
+ ppk[5] += S ( ppk[4] ^ ( ( tk->key[11] << 8 ) | tk->key[10] ) );
+
+ ppk[0] += ror16 ( ppk[5] ^ ( ( tk->key[13] << 8 ) | tk->key[12] ), 1 );
+ ppk[1] += ror16 ( ppk[0] ^ ( ( tk->key[15] << 8 ) | tk->key[14] ), 1 );
+ ppk[2] += ror16 ( ppk[1], 1 );
+ ppk[3] += ror16 ( ppk[2], 1 );
+ ppk[4] += ror16 ( ppk[3], 1 );
+ ppk[5] += ror16 ( ppk[4], 1 );
+
+ kb[0] = dctx->tsc_lo >> 8;
+ kb[1] = ( ( dctx->tsc_lo >> 8 ) | 0x20 ) & 0x7F;
+ kb[2] = dctx->tsc_lo & 0xFF;
+ kb[3] = ( ( ppk[5] ^ ( ( tk->key[1] << 8 ) | tk->key[0] ) ) >> 1 )
+ & 0xFF;
+
+ for ( i = 0; i < 6; i++ ) {
+ kb[4 + 2*i] = ppk[i] & 0xFF;
+ kb[5 + 2*i] = ppk[i] >> 8;
+ }
+}
+
+/**
+ * Update Michael message integrity code based on next 32-bit word of data
+ *
+ * @v V Michael code state (two 32-bit words)
+ * @v word Next 32-bit word of data
+ */
+static void tkip_feed_michael ( u32 *V, u32 word )
+{
+ V[0] ^= word;
+ V[1] ^= rol32 ( V[0], 17 );
+ V[0] += V[1];
+ V[1] ^= ( ( V[0] & 0xFF00FF00 ) >> 8 ) | ( ( V[0] & 0x00FF00FF ) << 8 );
+ V[0] += V[1];
+ V[1] ^= rol32 ( V[0], 3 );
+ V[0] += V[1];
+ V[1] ^= ror32 ( V[0], 2 );
+ V[0] += V[1];
+}
+
+/**
+ * Calculate Michael message integrity code
+ *
+ * @v key MIC key to use (8 bytes)
+ * @v da Destination link-layer address
+ * @v sa Source link-layer address
+ * @v data Start of data to calculate over
+ * @v len Length of header + data
+ * @ret mic Calculated Michael MIC (8 bytes)
+ */
+static void tkip_michael ( const void *key, const void *da, const void *sa,
+ const void *data, size_t len, void *mic )
+{
+ u32 V[2]; /* V[0] = "l", V[1] = "r" in 802.11 */
+ union {
+ u8 byte[12];
+ u32 word[3];
+ } cap;
+ const u8 *ptr = data;
+ const u8 *end = ptr + len;
+ int i;
+
+ memcpy ( V, key, sizeof ( V ) );
+ V[0] = le32_to_cpu ( V[0] );
+ V[1] = le32_to_cpu ( V[1] );
+
+ /* Feed in header (we assume non-QoS, so Priority = 0) */
+ memcpy ( &cap.byte[0], da, ETH_ALEN );
+ memcpy ( &cap.byte[6], sa, ETH_ALEN );
+ tkip_feed_michael ( V, le32_to_cpu ( cap.word[0] ) );
+ tkip_feed_michael ( V, le32_to_cpu ( cap.word[1] ) );
+ tkip_feed_michael ( V, le32_to_cpu ( cap.word[2] ) );
+ tkip_feed_michael ( V, 0 );
+
+ /* Feed in data */
+ while ( ptr + 4 <= end ) {
+ tkip_feed_michael ( V, le32_to_cpu ( *( u32 * ) ptr ) );
+ ptr += 4;
+ }
+
+ /* Add unaligned part and padding */
+ for ( i = 0; ptr < end; i++ )
+ cap.byte[i] = *ptr++;
+ cap.byte[i++] = 0x5a;
+ for ( ; i < 8; i++ )
+ cap.byte[i] = 0;
+
+ /* Feed in padding */
+ tkip_feed_michael ( V, le32_to_cpu ( cap.word[0] ) );
+ tkip_feed_michael ( V, le32_to_cpu ( cap.word[1] ) );
+
+ /* Output MIC */
+ V[0] = cpu_to_le32 ( V[0] );
+ V[1] = cpu_to_le32 ( V[1] );
+ memcpy ( mic, V, sizeof ( V ) );
+}
+
+/**
+ * Encrypt a packet using TKIP
+ *
+ * @v crypto TKIP cryptosystem
+ * @v iob I/O buffer containing cleartext packet
+ * @ret eiob I/O buffer containing encrypted packet
+ */
+static struct io_buffer * tkip_encrypt ( struct net80211_crypto *crypto,
+ struct io_buffer *iob )
+{
+ struct tkip_ctx *ctx = crypto->priv;
+ struct ieee80211_frame *hdr = iob->data;
+ struct io_buffer *eiob;
+ struct arc4_ctx arc4;
+ u8 key[16];
+ struct tkip_head head;
+ u8 mic[8];
+ u32 icv;
+ const int hdrlen = IEEE80211_TYP_FRAME_HEADER_LEN;
+ int datalen = iob_len ( iob ) - hdrlen;
+
+ ctx->enc.tsc_lo++;
+ if ( ctx->enc.tsc_lo == 0 ) {
+ ctx->enc.tsc_hi++;
+ ctx->enc.ttak_ok = 0;
+ }
+
+ tkip_mix_1 ( &ctx->enc, &ctx->tk, hdr->addr2 );
+ tkip_mix_2 ( &ctx->enc, &ctx->tk, key );
+
+ eiob = alloc_iob ( iob_len ( iob ) + TKIP_HEAD_LEN + TKIP_FOOT_LEN );
+ if ( ! eiob )
+ return NULL;
+
+ /* Copy frame header */
+ memcpy ( iob_put ( eiob, hdrlen ), iob->data, hdrlen );
+ hdr = eiob->data;
+ hdr->fc |= IEEE80211_FC_PROTECTED;
+
+ /* Fill in IV and key ID byte, and extended IV */
+ memcpy ( &head, key, 3 );
+ head.kid = 0x20; /* have Extended IV, key ID 0 */
+ head.tsc_hi = cpu_to_le32 ( ctx->enc.tsc_hi );
+ memcpy ( iob_put ( eiob, sizeof ( head ) ), &head, sizeof ( head ) );
+
+ /* Copy and encrypt the data */
+ cipher_setkey ( &arc4_algorithm, &arc4, key, 16 );
+ cipher_encrypt ( &arc4_algorithm, &arc4, iob->data + hdrlen,
+ iob_put ( eiob, datalen ), datalen );
+
+ /* Add MIC */
+ hdr = iob->data;
+ tkip_michael ( &ctx->tk.mic.tx, hdr->addr3, hdr->addr2,
+ iob->data + hdrlen, datalen, mic );
+ cipher_encrypt ( &arc4_algorithm, &arc4, mic,
+ iob_put ( eiob, sizeof ( mic ) ), sizeof ( mic ) );
+
+ /* Add ICV */
+ icv = crc32_le ( ~0, iob->data + hdrlen, datalen );
+ icv = crc32_le ( icv, mic, sizeof ( mic ) );
+ icv = cpu_to_le32 ( ~icv );
+ cipher_encrypt ( &arc4_algorithm, &arc4, &icv,
+ iob_put ( eiob, TKIP_ICV_LEN ), TKIP_ICV_LEN );
+
+ DBGC2 ( ctx, "WPA-TKIP %p: encrypted packet %p -> %p\n", ctx,
+ iob, eiob );
+
+ return eiob;
+}
+
+/**
+ * Decrypt a packet using TKIP
+ *
+ * @v crypto TKIP cryptosystem
+ * @v eiob I/O buffer containing encrypted packet
+ * @ret iob I/O buffer containing cleartext packet
+ */
+static struct io_buffer * tkip_decrypt ( struct net80211_crypto *crypto,
+ struct io_buffer *eiob )
+{
+ struct tkip_ctx *ctx = crypto->priv;
+ struct ieee80211_frame *hdr;
+ struct io_buffer *iob;
+ const int hdrlen = IEEE80211_TYP_FRAME_HEADER_LEN;
+ int datalen = iob_len ( eiob ) - hdrlen - TKIP_HEAD_LEN - TKIP_FOOT_LEN;
+ struct tkip_head *head;
+ struct arc4_ctx arc4;
+ u16 rx_tsc_lo;
+ u8 key[16];
+ u8 mic[8];
+ u32 icv, crc;
+
+ iob = alloc_iob ( hdrlen + datalen + TKIP_FOOT_LEN );
+ if ( ! iob )
+ return NULL;
+
+ /* Copy frame header */
+ memcpy ( iob_put ( iob, hdrlen ), eiob->data, hdrlen );
+ hdr = iob->data;
+ hdr->fc &= ~IEEE80211_FC_PROTECTED;
+
+ /* Check and update TSC */
+ head = eiob->data + hdrlen;
+ rx_tsc_lo = ( head->tsc1 << 8 ) | head->tsc0;
+
+ if ( head->tsc_hi < ctx->dec.tsc_hi ||
+ ( head->tsc_hi == ctx->dec.tsc_hi &&
+ rx_tsc_lo <= ctx->dec.tsc_lo ) ) {
+ DBGC ( ctx, "WPA-TKIP %p: packet received out of order "
+ "(%08x:%04x <= %08x:%04x)\n", ctx, head->tsc_hi,
+ rx_tsc_lo, ctx->dec.tsc_hi, ctx->dec.tsc_lo );
+ free_iob ( iob );
+ return NULL;
+ }
+ ctx->dec.tsc_lo = rx_tsc_lo;
+ if ( ctx->dec.tsc_hi != head->tsc_hi ) {
+ ctx->dec.ttak_ok = 0;
+ ctx->dec.tsc_hi = head->tsc_hi;
+ }
+
+ /* Calculate key */
+ tkip_mix_1 ( &ctx->dec, &ctx->tk, hdr->addr2 );
+ tkip_mix_2 ( &ctx->dec, &ctx->tk, key );
+
+ /* Copy-decrypt data, MIC, ICV */
+ cipher_setkey ( &arc4_algorithm, &arc4, key, 16 );
+ cipher_decrypt ( &arc4_algorithm, &arc4,
+ eiob->data + hdrlen + TKIP_HEAD_LEN,
+ iob_put ( iob, datalen ), datalen + TKIP_FOOT_LEN );
+
+ /* Check ICV */
+ icv = le32_to_cpu ( *( u32 * ) ( iob->tail + TKIP_MIC_LEN ) );
+ crc = ~crc32_le ( ~0, iob->data + hdrlen, datalen + TKIP_MIC_LEN );
+ if ( crc != icv ) {
+ DBGC ( ctx, "WPA-TKIP %p CRC mismatch: expect %08x, get %08x\n",
+ ctx, icv, crc );
+ free_iob ( iob );
+ return NULL;
+ }
+
+ /* Check MIC */
+ tkip_michael ( &ctx->tk.mic.rx, hdr->addr1, hdr->addr3,
+ iob->data + hdrlen, datalen, mic );
+ if ( memcmp ( mic, iob->tail, TKIP_MIC_LEN ) != 0 ) {
+ DBGC ( ctx, "WPA-TKIP %p ALERT! MIC failure\n", ctx );
+ /* XXX we should do the countermeasures here */
+ free_iob ( iob );
+ return NULL;
+ }
+
+ DBGC2 ( ctx, "WPA-TKIP %p: decrypted packet %p -> %p\n", ctx,
+ eiob, iob );
+
+ return iob;
+}
+
+/** TKIP cryptosystem */
+struct net80211_crypto tkip_crypto __net80211_crypto = {
+ .algorithm = NET80211_CRYPT_TKIP,
+ .init = tkip_init,
+ .encrypt = tkip_encrypt,
+ .decrypt = tkip_decrypt,
+ .priv_len = sizeof ( struct tkip_ctx ),
+};
+
+
+
+
+/**
+ * Calculate HMAC-MD5 MIC for EAPOL-Key frame
+ *
+ * @v kck Key Confirmation Key, 16 bytes
+ * @v msg Message to calculate MIC over
+ * @v len Number of bytes to calculate MIC over
+ * @ret mic Calculated MIC, 16 bytes long
+ */
+static void tkip_kie_mic ( const void *kck, const void *msg, size_t len,
+ void *mic )
+{
+ struct md5_ctx md5;
+ u8 kckb[16];
+ size_t kck_len = 16;
+
+ memcpy ( kckb, kck, kck_len );
+
+ hmac_init ( &md5_algorithm, &md5, kckb, &kck_len );
+ hmac_update ( &md5_algorithm, &md5, msg, len );
+ hmac_final ( &md5_algorithm, &md5, kckb, &kck_len, mic );
+}
+
+/**
+ * Decrypt key data in EAPOL-Key frame
+ *
+ * @v kek Key Encryption Key, 16 bytes
+ * @v iv Initialisation vector, 16 bytes
+ * @v msg Message to decrypt
+ * @v len Length of message
+ * @ret msg Decrypted message in place of original
+ * @ret len Unchanged
+ * @ret rc Always 0 for success
+ */
+static int tkip_kie_decrypt ( const void *kek, const void *iv,
+ void *msg, u16 *len )
+{
+ u8 key[32];
+ memcpy ( key, iv, 16 );
+ memcpy ( key + 16, kek, 16 );
+
+ arc4_skip ( key, 32, 256, msg, msg, *len );
+
+ return 0;
+}
+
+
+/** TKIP-style key integrity and encryption handler */
+struct wpa_kie tkip_kie __wpa_kie = {
+ .version = EAPOL_KEY_VERSION_WPA,
+ .mic = tkip_kie_mic,
+ .decrypt = tkip_kie_decrypt,
+};