X-Git-Url: http://cvs.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/b957bcd382bf718f766c0774839752eb99f668af..9f3839139568c064633102c3da240be65d8c6205:/client/cmdhflist.c

diff --git a/client/cmdhflist.c b/client/cmdhflist.c
index 5ff3192b..5538b6fb 100644
--- a/client/cmdhflist.c
+++ b/client/cmdhflist.c
@@ -16,11 +16,13 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include "util.h"
-#include "data.h"
 #include "ui.h"
 #include "iso14443crc.h"
 #include "parity.h"
 #include "protocols.h"
+#include "crapto1/crapto1.h"
+#include "mifarehost.h"
+#include "mifaredefault.h"
 
 
 enum MifareAuthSeq {
@@ -28,9 +30,9 @@ enum MifareAuthSeq {
 	masNt,
 	masNrAr,
 	masAt,
+	masAuthComplete,
 	masFirstData,
 	masData,
-	masDataNested,
 	masError,
 };
 static enum MifareAuthSeq MifareAuthState;
@@ -39,7 +41,9 @@ static TAuthData AuthData;
 void ClearAuthData() {
 	AuthData.uid = 0;
 	AuthData.nt = 0;
-	AuthData.first_auth = false;
+	AuthData.first_auth = true;
+	AuthData.ks2 = 0;
+	AuthData.ks3 = 0;
 }
 
 /**
@@ -71,9 +75,6 @@ uint8_t mifare_CRC_check(bool isResponse, uint8_t* data, uint8_t len)
 {
 	switch(MifareAuthState) {
 		case masNone:
-		case masFirstData:
-		case masData:
-		case masDataNested:
 		case masError:
 			return iso14443A_CRC_check(isResponse, data, len);
 		default:
@@ -81,13 +82,122 @@ uint8_t mifare_CRC_check(bool isResponse, uint8_t* data, uint8_t len)
 	}
 }
 
+void annotateIclass(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize)
+{
+	switch(cmd[0])
+	{
+	case ICLASS_CMD_ACTALL:      snprintf(exp,size,"ACTALL"); break;
+	case ICLASS_CMD_READ_OR_IDENTIFY:{
+		if(cmdsize > 1){
+			snprintf(exp,size,"READ(%d)",cmd[1]);
+		}else{
+			snprintf(exp,size,"IDENTIFY");
+		}
+		break;
+	}
+	case ICLASS_CMD_SELECT:      snprintf(exp,size,"SELECT"); break;
+	case ICLASS_CMD_PAGESEL:     snprintf(exp,size,"PAGESEL(%d)", cmd[1]); break;
+	case ICLASS_CMD_READCHECK_KC:snprintf(exp,size,"READCHECK[Kc](%d)", cmd[1]); break;
+	case ICLASS_CMD_READCHECK_KD:snprintf(exp,size,"READCHECK[Kd](%d)", cmd[1]); break;
+	case ICLASS_CMD_CHECK:       snprintf(exp,size,"CHECK"); break;
+	case ICLASS_CMD_DETECT:      snprintf(exp,size,"DETECT"); break;
+	case ICLASS_CMD_HALT:        snprintf(exp,size,"HALT"); break;
+	case ICLASS_CMD_UPDATE:      snprintf(exp,size,"UPDATE(%d)",cmd[1]); break;
+	case ICLASS_CMD_ACT:         snprintf(exp,size,"ACT"); break;
+	case ICLASS_CMD_READ4:       snprintf(exp,size,"READ4(%d)",cmd[1]); break;
+	default:                     snprintf(exp,size,"?"); break;
+	}
+	return;
+}
+
+void annotateIso15693(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize)
+{
+
+	if(cmd[0] == 0x26)
+	{
+		switch(cmd[1]){
+		case ISO15693_INVENTORY           :snprintf(exp, size, "INVENTORY");break;
+		case ISO15693_STAYQUIET           :snprintf(exp, size, "STAY_QUIET");break;
+		default:                     snprintf(exp,size,"?"); break;
+
+		}
+	}else if(cmd[0] == 0x02)
+	{
+		switch(cmd[1])
+		{
+		case ISO15693_READBLOCK            :snprintf(exp, size, "READBLOCK");break;
+		case ISO15693_WRITEBLOCK           :snprintf(exp, size, "WRITEBLOCK");break;
+		case ISO15693_LOCKBLOCK            :snprintf(exp, size, "LOCKBLOCK");break;
+		case ISO15693_READ_MULTI_BLOCK     :snprintf(exp, size, "READ_MULTI_BLOCK");break;
+		case ISO15693_SELECT               :snprintf(exp, size, "SELECT");break;
+		case ISO15693_RESET_TO_READY       :snprintf(exp, size, "RESET_TO_READY");break;
+		case ISO15693_WRITE_AFI            :snprintf(exp, size, "WRITE_AFI");break;
+		case ISO15693_LOCK_AFI             :snprintf(exp, size, "LOCK_AFI");break;
+		case ISO15693_WRITE_DSFID          :snprintf(exp, size, "WRITE_DSFID");break;
+		case ISO15693_LOCK_DSFID           :snprintf(exp, size, "LOCK_DSFID");break;
+		case ISO15693_GET_SYSTEM_INFO      :snprintf(exp, size, "GET_SYSTEM_INFO");break;
+		case ISO15693_READ_MULTI_SECSTATUS :snprintf(exp, size, "READ_MULTI_SECSTATUS");break;
+		default:                            snprintf(exp,size,"?"); break;
+		}
+	}
+}
+
+
+void annotateTopaz(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize)
+{
+	switch(cmd[0]) {
+		case TOPAZ_REQA						:snprintf(exp, size, "REQA");break;
+		case TOPAZ_WUPA						:snprintf(exp, size, "WUPA");break;
+		case TOPAZ_RID						:snprintf(exp, size, "RID");break;
+		case TOPAZ_RALL						:snprintf(exp, size, "RALL");break;
+		case TOPAZ_READ						:snprintf(exp, size, "READ");break;
+		case TOPAZ_WRITE_E					:snprintf(exp, size, "WRITE-E");break;
+		case TOPAZ_WRITE_NE					:snprintf(exp, size, "WRITE-NE");break;
+		case TOPAZ_RSEG						:snprintf(exp, size, "RSEG");break;
+		case TOPAZ_READ8					:snprintf(exp, size, "READ8");break;
+		case TOPAZ_WRITE_E8					:snprintf(exp, size, "WRITE-E8");break;
+		case TOPAZ_WRITE_NE8				:snprintf(exp, size, "WRITE-NE8");break;
+		default:                            snprintf(exp,size,"?"); break;
+	}
+}
+
+
+/**
+06 00 = INITIATE
+0E xx = SELECT ID (xx = Chip-ID)
+0B = Get UID
+08 yy = Read Block (yy = block number)
+09 yy dd dd dd dd = Write Block (yy = block number; dd dd dd dd = data to be written)
+0C = Reset to Inventory
+0F = Completion
+0A 11 22 33 44 55 66 = Authenticate (11 22 33 44 55 66 = data to authenticate)
+**/
+
+void annotateIso14443b(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize)
+{
+	switch(cmd[0]){
+	case ISO14443B_REQB   : snprintf(exp,size,"REQB");break;
+	case ISO14443B_ATTRIB : snprintf(exp,size,"ATTRIB");break;
+	case ISO14443B_HALT   : snprintf(exp,size,"HALT");break;
+	case ISO14443B_INITIATE     : snprintf(exp,size,"INITIATE");break;
+	case ISO14443B_SELECT       : snprintf(exp,size,"SELECT(%d)",cmd[1]);break;
+	case ISO14443B_GET_UID      : snprintf(exp,size,"GET UID");break;
+	case ISO14443B_READ_BLK     : snprintf(exp,size,"READ_BLK(%d)", cmd[1]);break;
+	case ISO14443B_WRITE_BLK    : snprintf(exp,size,"WRITE_BLK(%d)",cmd[1]);break;
+	case ISO14443B_RESET        : snprintf(exp,size,"RESET");break;
+	case ISO14443B_COMPLETION   : snprintf(exp,size,"COMPLETION");break;
+	case ISO14443B_AUTHENTICATE : snprintf(exp,size,"AUTHENTICATE");break;
+	default                     : snprintf(exp,size ,"?");break;
+	}
+
+}
+
 void annotateIso14443a(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize)
 {
 	switch(cmd[0])
 	{
 	case ISO14443A_CMD_WUPA:        
 		snprintf(exp,size,"WUPA"); 
-		MifareAuthState = masNone;
 		break;
 	case ISO14443A_CMD_ANTICOLL_OR_SELECT:{
 		// 93 20 = Anticollision (usage: 9320 - answer: 4bytes UID+1byte UID-bytes-xor)
@@ -113,7 +223,6 @@ void annotateIso14443a(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize)
 	}
 	case ISO14443A_CMD_REQA:		
 		snprintf(exp,size,"REQA"); 
-		MifareAuthState = masNone;
 		break;
 	case ISO14443A_CMD_READBLOCK:	snprintf(exp,size,"READBLOCK(%d)",cmd[1]); break;
 	case ISO14443A_CMD_WRITEBLOCK:	snprintf(exp,size,"WRITEBLOCK(%d)",cmd[1]); break;
@@ -187,13 +296,24 @@ void annotateIso14443a(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize)
 }
 
 void annotateMifare(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize, uint8_t* parity, uint8_t paritysize, bool isResponse) {
+	if (!isResponse && cmdsize == 1) {
+		switch(cmd[0]) {
+			case ISO14443A_CMD_WUPA:        
+			case ISO14443A_CMD_REQA:		
+				MifareAuthState = masNone;
+				break;
+			default:
+				break;
+		}
+	}
+	
 	// get UID
 	if (MifareAuthState == masNone) {
-		if (cmdsize == 7 && cmd[0] == ISO14443A_CMD_ANTICOLL_OR_SELECT && cmd[1] == 0x70) {
+		if (cmdsize == 9 && cmd[0] == ISO14443A_CMD_ANTICOLL_OR_SELECT && cmd[1] == 0x70) {
 			ClearAuthData();
 			AuthData.uid = bytes_to_num(&cmd[2], 4);
 		}
-		if (cmdsize == 7 && cmd[0] == ISO14443A_CMD_ANTICOLL_OR_SELECT_2 && cmd[1] == 0x70) {
+		if (cmdsize == 9 && cmd[0] == ISO14443A_CMD_ANTICOLL_OR_SELECT_2 && cmd[1] == 0x70) {
 			ClearAuthData();
 			AuthData.uid = bytes_to_num(&cmd[2], 4);
 		}
@@ -204,11 +324,12 @@ void annotateMifare(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize, uint8
 			if (cmdsize == 4 && isResponse) {
 				snprintf(exp,size,"AUTH: nt %s", (AuthData.first_auth) ? "" : "(enc)");
 				MifareAuthState = masNrAr;
-				if (AuthData.first_auth)
-					AuthData.nt = bytes_to_num(cmd, cmdsize);
-				else
-					AuthData.nt_enc = bytes_to_num(cmd, cmdsize);
+				if (AuthData.first_auth) {
+					AuthData.nt = bytes_to_num(cmd, 4);
+				} else {
+					AuthData.nt_enc = bytes_to_num(cmd, 4);
 					AuthData.nt_enc_par = parity[0];
+				}
 				return;
 			} else {
 				MifareAuthState = masError;
@@ -218,8 +339,8 @@ void annotateMifare(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize, uint8
 			if (cmdsize == 8 && !isResponse) {
 				snprintf(exp,size,"AUTH: nr ar (enc)");
 				MifareAuthState = masAt;
-				AuthData.nr_enc = bytes_to_num(cmd, cmdsize);
-				AuthData.ar_enc = bytes_to_num(&cmd[3], cmdsize);
+				AuthData.nr_enc = bytes_to_num(cmd, 4);
+				AuthData.ar_enc = bytes_to_num(&cmd[4], 4);
 				AuthData.ar_enc_par = parity[0] << 4;
 				return;
 			} else {
@@ -229,8 +350,8 @@ void annotateMifare(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize, uint8
 		case masAt:
 			if (cmdsize == 4 && isResponse) {
 				snprintf(exp,size,"AUTH: at (enc)");
-				MifareAuthState = masFirstData;
-				AuthData.at_enc = bytes_to_num(cmd, cmdsize);
+				MifareAuthState = masAuthComplete;
+				AuthData.at_enc = bytes_to_num(cmd, 4);
 				AuthData.at_enc_par = parity[0];
 				return;
 			} else {
@@ -241,7 +362,245 @@ void annotateMifare(char *exp, size_t size, uint8_t* cmd, uint8_t cmdsize, uint8
 			break;
 	}
 	
-	if (!isResponse)
+	if (!isResponse && ((MifareAuthState == masNone) || (MifareAuthState == masError)))
 		annotateIso14443a(exp, size, cmd, cmdsize);
 	
 }
+
+bool DecodeMifareData(uint8_t *cmd, uint8_t cmdsize, uint8_t *parity, bool isResponse, uint8_t *mfData, size_t *mfDataLen) {
+	static struct Crypto1State *traceCrypto1;	
+	static uint64_t mfLastKey;
+	
+	*mfDataLen = 0;
+	
+	if (MifareAuthState == masAuthComplete) {
+		if (traceCrypto1) {
+			crypto1_destroy(traceCrypto1);
+			traceCrypto1 = NULL;
+		}
+
+		MifareAuthState = masFirstData;
+		return false;
+	}
+	
+	if (cmdsize > 32)
+		return false;
+	
+	if (MifareAuthState == masFirstData) {
+		if (AuthData.first_auth) {
+			AuthData.ks2 = AuthData.ar_enc ^ prng_successor(AuthData.nt, 64);
+			AuthData.ks3 = AuthData.at_enc ^ prng_successor(AuthData.nt, 96);
+
+			mfLastKey = GetCrypto1ProbableKey(&AuthData);
+			PrintAndLog("            |          * | key | probable key:%012"PRIx64" Prng:%s   ks2:%08x ks3:%08x |     |", 
+				mfLastKey,
+				validate_prng_nonce(AuthData.nt) ? "WEAK": "HARD",
+				AuthData.ks2,
+				AuthData.ks3);
+			
+			AuthData.first_auth = false;
+
+			traceCrypto1 = lfsr_recovery64(AuthData.ks2, AuthData.ks3);
+		} else {
+			if (traceCrypto1) {
+				crypto1_destroy(traceCrypto1);
+				traceCrypto1 = NULL;
+			}
+
+			// check last used key
+			if (mfLastKey) {
+				if (NestedCheckKey(mfLastKey, &AuthData, cmd, cmdsize, parity)) {
+					PrintAndLog("            |          * | key | last used key:%012"PRIx64"            ks2:%08x ks3:%08x |     |", 
+						mfLastKey,
+						AuthData.ks2,
+						AuthData.ks3);
+
+				traceCrypto1 = lfsr_recovery64(AuthData.ks2, AuthData.ks3);
+				};
+			}
+			
+			// check default keys
+			if (!traceCrypto1) {
+				for (int defaultKeyCounter = 0; defaultKeyCounter < MifareDefaultKeysSize; defaultKeyCounter++){
+					if (NestedCheckKey(MifareDefaultKeys[defaultKeyCounter], &AuthData, cmd, cmdsize, parity)) {
+						PrintAndLog("            |          * | key | default key:%012"PRIx64"              ks2:%08x ks3:%08x |     |", 
+							MifareDefaultKeys[defaultKeyCounter],
+							AuthData.ks2,
+							AuthData.ks3);
+
+						mfLastKey = MifareDefaultKeys[defaultKeyCounter];
+						traceCrypto1 = lfsr_recovery64(AuthData.ks2, AuthData.ks3);
+						break;
+					};
+				}
+			}
+			
+			// nested
+			if (!traceCrypto1 && validate_prng_nonce(AuthData.nt)) {
+				uint32_t ntx = prng_successor(AuthData.nt, 90); 
+				for (int i = 0; i < 16383; i++) {
+					ntx = prng_successor(ntx, 1);
+					if (NTParityChk(&AuthData, ntx)){
+
+						uint32_t ks2 = AuthData.ar_enc ^ prng_successor(ntx, 64);
+						uint32_t ks3 = AuthData.at_enc ^ prng_successor(ntx, 96);
+						struct Crypto1State *pcs = lfsr_recovery64(ks2, ks3);
+						memcpy(mfData, cmd, cmdsize);
+						mf_crypto1_decrypt(pcs, mfData, cmdsize, 0);
+				
+						crypto1_destroy(pcs);
+						if (CheckCrypto1Parity(cmd, cmdsize, mfData, parity) && CheckCrc14443(CRC_14443_A, mfData, cmdsize)) {
+							AuthData.ks2 = ks2;
+							AuthData.ks3 = ks3;
+
+							AuthData.nt = ntx;
+							mfLastKey = GetCrypto1ProbableKey(&AuthData);
+							PrintAndLog("            |          * | key | nested probable key:%012"PRIx64"      ks2:%08x ks3:%08x |     |", 
+								mfLastKey,
+								AuthData.ks2,
+								AuthData.ks3);
+
+							traceCrypto1 = lfsr_recovery64(AuthData.ks2, AuthData.ks3);
+							break;
+						}
+					}						
+				}
+			}
+			
+			//hardnested
+			if (!traceCrypto1) {
+				printf("hardnested not implemented. uid:%x nt:%x ar_enc:%x at_enc:%x\n", AuthData.uid, AuthData.nt, AuthData.ar_enc, AuthData.at_enc);
+				MifareAuthState = masError;
+
+				/* TOO SLOW( needs to have more strong filter. with this filter - aprox 4 mln tests
+				uint32_t t = msclock();
+				uint32_t t1 = t;
+				int n = 0;
+				for (uint32_t i = 0; i < 0xFFFFFFFF; i++) {
+					if (NTParityChk(&AuthData, i)){
+
+						uint32_t ks2 = AuthData.ar_enc ^ prng_successor(i, 64);
+						uint32_t ks3 = AuthData.at_enc ^ prng_successor(i, 96);
+						struct Crypto1State *pcs = lfsr_recovery64(ks2, ks3);
+
+
+
+
+						n++;
+
+						if (!(n % 100000)) {
+							printf("delta=%d n=%d ks2=%x ks3=%x \n", msclock() - t1 , n, ks2, ks3);
+							t1 = msclock();
+						}
+
+					}
+				}
+				printf("delta=%d n=%d\n", msclock() - t, n);
+				*/
+			}
+		}
+		
+		
+		
+		MifareAuthState = masData;
+	}
+	
+	if (MifareAuthState == masData && traceCrypto1) {
+		memcpy(mfData, cmd, cmdsize);
+		mf_crypto1_decrypt(traceCrypto1, mfData, cmdsize, 0);
+		*mfDataLen = cmdsize;
+	}
+	
+	return *mfDataLen > 0;
+}
+
+bool NTParityChk(TAuthData *ad, uint32_t ntx) {
+	if (
+		(oddparity8(ntx >> 8 & 0xff) ^ (ntx & 0x01) ^ ((ad->nt_enc_par >> 5) & 0x01) ^ (ad->nt_enc & 0x01)) ||
+		(oddparity8(ntx >> 16 & 0xff) ^ (ntx >> 8 & 0x01) ^ ((ad->nt_enc_par >> 6) & 0x01) ^ (ad->nt_enc >> 8 & 0x01)) ||
+		(oddparity8(ntx >> 24 & 0xff) ^ (ntx >> 16 & 0x01) ^ ((ad->nt_enc_par >> 7) & 0x01) ^ (ad->nt_enc >> 16 & 0x01))
+		)
+		return false;
+	
+	uint32_t ar = prng_successor(ntx, 64);
+	if (
+		(oddparity8(ar >> 8 & 0xff) ^ (ar & 0x01) ^ ((ad->ar_enc_par >> 5) & 0x01) ^ (ad->ar_enc & 0x01)) ||
+		(oddparity8(ar >> 16 & 0xff) ^ (ar >> 8 & 0x01) ^ ((ad->ar_enc_par >> 6) & 0x01) ^ (ad->ar_enc >> 8 & 0x01)) ||
+		(oddparity8(ar >> 24 & 0xff) ^ (ar >> 16 & 0x01) ^ ((ad->ar_enc_par >> 7) & 0x01) ^ (ad->ar_enc >> 16 & 0x01))
+		)
+		return false;
+
+	uint32_t at = prng_successor(ntx, 96);
+	if (
+		(oddparity8(ar & 0xff) ^ (at >> 24 & 0x01) ^ ((ad->ar_enc_par >> 4) & 0x01) ^ (ad->at_enc >> 24 & 0x01)) ||
+		(oddparity8(at >> 8 & 0xff) ^ (at & 0x01) ^ ((ad->at_enc_par >> 5) & 0x01) ^ (ad->at_enc & 0x01)) ||
+		(oddparity8(at >> 16 & 0xff) ^ (at >> 8 & 0x01) ^ ((ad->at_enc_par >> 6) & 0x01) ^ (ad->at_enc >> 8 & 0x01)) ||
+		(oddparity8(at >> 24 & 0xff) ^ (at >> 16 & 0x01) ^ ((ad->at_enc_par >> 7) & 0x01) ^ (ad->at_enc >> 16 & 0x01))
+		)
+		return false;
+		
+	return true;
+}
+
+bool NestedCheckKey(uint64_t key, TAuthData *ad, uint8_t *cmd, uint8_t cmdsize, uint8_t *parity) {
+	uint8_t buf[32] = {0};
+	struct Crypto1State *pcs;
+	
+	AuthData.ks2 = 0;
+	AuthData.ks3 = 0;
+
+	pcs = crypto1_create(key);
+	uint32_t nt1 = crypto1_word(pcs, ad->nt_enc ^ ad->uid, 1) ^ ad->nt_enc;
+	uint32_t ar = prng_successor(nt1, 64);
+	uint32_t at = prng_successor(nt1, 96);
+
+	crypto1_word(pcs, ad->nr_enc, 1);
+//	uint32_t nr1 = crypto1_word(pcs, ad->nr_enc, 1) ^ ad->nr_enc;  // if needs deciphered nr
+	uint32_t ar1 = crypto1_word(pcs, 0, 0) ^ ad->ar_enc;
+	uint32_t at1 = crypto1_word(pcs, 0, 0) ^ ad->at_enc;
+
+	if (!(ar == ar1 && at == at1 && NTParityChk(ad, nt1))) {
+		crypto1_destroy(pcs);
+		return false;
+	}
+
+	memcpy(buf, cmd, cmdsize);
+	mf_crypto1_decrypt(pcs, buf, cmdsize, 0);
+	
+	crypto1_destroy(pcs);
+	
+	if (!CheckCrypto1Parity(cmd, cmdsize, buf, parity))
+		return false;
+
+	if(!CheckCrc14443(CRC_14443_A, buf, cmdsize)) 
+		return false;
+	
+	AuthData.nt = nt1;
+	AuthData.ks2 = AuthData.ar_enc ^ ar;
+	AuthData.ks3 = AuthData.at_enc ^ at;
+
+	return true;
+}
+
+bool CheckCrypto1Parity(uint8_t *cmd_enc, uint8_t cmdsize, uint8_t *cmd, uint8_t *parity_enc) {
+	for (int i = 0; i < cmdsize - 1; i++) {
+		if (oddparity8(cmd[i]) ^ (cmd[i + 1] & 0x01) ^ ((parity_enc[i / 8] >> (7 - i % 8)) & 0x01) ^ (cmd_enc[i + 1] & 0x01))
+			return false;
+	}
+	
+	return true;
+}
+
+uint64_t GetCrypto1ProbableKey(TAuthData *ad) {
+	struct Crypto1State *revstate = lfsr_recovery64(ad->ks2, ad->ks3);
+	lfsr_rollback_word(revstate, 0, 0);
+	lfsr_rollback_word(revstate, 0, 0);
+	lfsr_rollback_word(revstate, ad->nr_enc, 1);
+	lfsr_rollback_word(revstate, ad->uid ^ ad->nt, 0);
+
+	uint64_t lfsr = 0;
+	crypto1_get_lfsr(revstate, &lfsr);
+	crypto1_destroy(revstate);
+	
+	return lfsr;
+}