/*
*
* Routine: Phase 2 -- generate RC4KEY, given TK, P1K, IV16
*
* Inputs:
* TK[] = Temporal key [128 bits]
* P1K[] = Phase 1 output key [ 80 bits]
* IV16 = low 16 bits of IV counter [ 16 bits]
* Output:
* RC4KEY[] = the key used to encrypt the packet [128 bits]
*
* Note:
* The value {TA,IV32,IV16} for Phase1/Phase2 must be unique
* across all packets using the same key TK value. Then, for a
* given value of TK[], this TKIP48 construction guarantees that
* the final RC4KEY value is unique across all packets.
*
* Suggested implementation optimization: if PPK[] is "overlaid"
* appropriately on RC4KEY[], there is no need for the final
* for loop below that copies the PPK[] result into RC4KEY[].
*
*/
void
BCMROMFN(tkhash_phase2)(uint8 *RC4KEY, const uint8 *TK, const uint16 *P1K, uint16 IV16)
{
uint16 i;
uint16 PPK[6]; /* temporary key for mixing */
/* Note: all adds in the PPK[] equations below are mod 2**16 */
for (i = 0; i < 5; i++) PPK[i]=P1K[i]; /* first, copy P1K to PPK */
PPK[5] = P1K[4] + IV16; /* next, add in IV16 */
/* Bijective non-linear mixing of the 96 bits of PPK[0..5] */
PPK[0] += _S_(PPK[5] ^ TK16(0)); /* Mix key in each "round" */
PPK[1] += _S_(PPK[0] ^ TK16(1));
PPK[2] += _S_(PPK[1] ^ TK16(2));
PPK[3] += _S_(PPK[2] ^ TK16(3));
PPK[4] += _S_(PPK[3] ^ TK16(4));
PPK[5] += _S_(PPK[4] ^ TK16(5)); /* Total # S-box lookups == 6 */
/* Final sweep: bijective, "linear". Rotates kill LSB correlations */
PPK[0] += RotR1(PPK[5] ^ TK16(6));
PPK[1] += RotR1(PPK[0] ^ TK16(7)); /* Use all of TK[] in Phase2 */
PPK[2] += RotR1(PPK[1]);
PPK[3] += RotR1(PPK[2]);
PPK[4] += RotR1(PPK[3]);
PPK[5] += RotR1(PPK[4]);
/* Note: At this point, for a given key TK[0..15], the 96-bit output */
/* value PPK[0..5] is guaranteed to be unique, as a function */
/* of the 96-bit "input" value {TA,IV32,IV16}. That is, P1K */
/* is now a keyed permutation of {TA,IV32,IV16}. */
/* Set RC4KEY[0..3], which includes "cleartext" portion of RC4 key */
RC4KEY[0] = Hi8(IV16); /* RC4KEY[0..2] is the WEP IV */
RC4KEY[1] =(Hi8(IV16) | 0x20) & 0x7F; /* Help avoid weak (FMS) keys */
RC4KEY[2] = Lo8(IV16);
RC4KEY[3] = Lo8((PPK[5] ^ TK16(0)) >> 1);
/* Copy 96 bits of PPK[0..5] to RC4KEY[4..15] (little-endian) */
for (i = 0; i < 6; i++) {
RC4KEY[4 + 2 * i] = Lo8(PPK[i]);
RC4KEY[5 + 2 * i] = Hi8(PPK[i]);
}
}
static void AirPDcapTkipMixingPhase2(
UINT8 *wep_seed,
const UINT8 *TK,
UINT16 *TTAK,
UINT16 TSC16)
{
INT i;
TTAK[5] = (UINT16)(TTAK[4] + TSC16);
/* Step 2 - 96-bit bijective mixing using S-box */
TTAK[0] = (UINT16)(TTAK[0] + _S_((UINT16)(TTAK[5] ^ Mk16_le(&TK[0]))));
TTAK[1] = (UINT16)(TTAK[1] + _S_((UINT16)(TTAK[0] ^ Mk16_le(&TK[2]))));
TTAK[2] = (UINT16)(TTAK[2] + _S_((UINT16)(TTAK[1] ^ Mk16_le(&TK[4]))));
TTAK[3] = (UINT16)(TTAK[3] + _S_((UINT16)(TTAK[2] ^ Mk16_le(&TK[6]))));
TTAK[4] = (UINT16)(TTAK[4] + _S_((UINT16)(TTAK[3] ^ Mk16_le(&TK[8]))));
TTAK[5] = (UINT16)(TTAK[5] + _S_((UINT16)(TTAK[4] ^ Mk16_le(&TK[10]))));
TTAK[0] = (UINT16)(TTAK[0] + RotR1((UINT16)(TTAK[5] ^ Mk16_le(&TK[12]))));
TTAK[1] = (UINT16)(TTAK[1] + RotR1((UINT16)(TTAK[0] ^ Mk16_le(&TK[14]))));
TTAK[2] = (UINT16)(TTAK[2] + RotR1(TTAK[1]));
TTAK[3] = (UINT16)(TTAK[3] + RotR1(TTAK[2]));
TTAK[4] = (UINT16)(TTAK[4] + RotR1(TTAK[3]));
TTAK[5] = (UINT16)(TTAK[5] + RotR1(TTAK[4]));
/* Step 3 - bring in last of TK bits, assign 24-bit WEP IV value
* wep_seed[0..2] is transmitted as WEP IV */
wep_seed[0] = Hi8(TSC16);
wep_seed[1] = (UINT8)((Hi8(TSC16) | 0x20) & 0x7F);
wep_seed[2] = Lo8(TSC16);
wep_seed[3] = Lo8((UINT16)((TTAK[5] ^ Mk16_le(&TK[0])) >> 1));
for (i = 0; i < 6; i++)
{
wep_seed[4 + ( 2 * i)] = Lo8( TTAK[i] );
wep_seed[5 + ( 2 * i)] = Hi8( TTAK[i] );
}
}
