1537:
260:, and in lack of a central authority to do so, the correct succession of transactions is defined only by the dominating consensus. This leads to the possibility of one actor gaining majority control over the entities deciding said consensus, to force their own version of events, including alternative and double transactions. Due to information propagation delays, 51% attacks are temporarily possible for a localized subset of actors too.
25:
1561:
1549:
188:, but as transactions (requests to spend money) are broadcast, they will arrive at each server at slightly different times. If two transactions attempt to spend the same token, each server will consider the first transaction it sees to be valid, and the other invalid. Once the servers disagree, there is no way to determine true balances, as each server's observations are considered equally valid.
244:
other, and eventually a single chain will continue on, while the other(s) will not. Since the longest (more technically "heaviest") chain is considered to be the valid data set, miners are incentivized to only build blocks on the longest chain they know about in order for it to become part of that dataset (and for their reward to be valid).
243:
The double-spending problem persists, however, if two blocks (with conflicting transactions) are mined at the same approximate time. When servers inevitably disagree on the order of the two blocks, they each keep both blocks temporarily. As new blocks arrive, they must commit to one history or the
263:
The total computational power of a decentralized proof-of-work system is the sum of the computational power of the nodes, which can differ significantly due to the hardware used. Larger computational power increases the chance to win the mining reward for each new block mined, which creates an
278:
A given cryptocurrency's susceptibility to attack depends on the existing hashing power of the network since the attacker needs to overcome it. For the attack to be economically viable, the market cap of the currency must be sufficiently large to justify the cost to rent hashing power.
247:
Transactions in this system are therefore never technically "final" as a conflicting chain of blocks can always outgrow the current canonical chain. However, as blocks are built on top of a transaction, it becomes increasingly costly and thus unlikely for another chain to overtake it.
124:
is the unauthorized production and spending of money, either digital or conventional. It represents a monetary design problem: a good money is verifiably scarce, and where a unit of value can be spent more than once, the monetary property of scarcity is challenged. As with
133:
by creating a new amount of copied currency that did not previously exist. Like all increasingly abundant resources, this devalues the currency relative to other monetary units or goods and diminishes user trust as well as the
183:
In a decentralized system, the double-spending problem is significantly harder to solve. To avoid the need for a trusted third party, many servers must store identical up-to-date copies of a public transaction
290:
which raised significant controversies about the safety of the network. The pool voluntarily capped their hashing power at 39.99% and requested other pools to follow in order to restore trust in the network.
141:
Fundamental cryptographic techniques to prevent double-spending, while preserving anonymity in a transaction, are the introduction of an authority (and hence centralization) for
240:. The block commits to the entire history of bitcoin transactions as well as the new set of incoming transactions. The miner is rewarded some bitcoins for solving it.
468:
395:
510:
1497:
89:
1477:
61:
268:. Any pool that achieves 51% hashing power can effectively overturn network transactions, resulting in double spending.
1152:
68:
1293:
353:
Osipkov, I.; Vasserman, E. Y.; Hopper, N.; Kim, Y. (2007). "Combating Double-Spending Using
Cooperative P2P Systems".
1487:
553:
311:
108:
42:
1592:
1553:
893:
224:
used a proof-of-work consensus mechanism where transactions are batched into blocks and chained together using a
75:
232:). Any server can produce a block by solving a computationally difficult puzzle (specifically finding a partial
1607:
988:
503:
46:
1467:
898:
444:
57:
944:
603:
192:
1587:
548:
1056:
1381:
1018:
1612:
1541:
1507:
1482:
1462:
1137:
1127:
939:
496:
1597:
1565:
1512:
1432:
469:"Popular Bitcoin Mining Pool Promises To Restrict Its Compute Power To Prevent Feared '51%' Fiasco"
363:
195:
algorithm, a way to bring the servers back in sync. Two notable types of consensus mechanisms are
1602:
1190:
1066:
1051:
805:
666:
166:
35:
1447:
1180:
1023:
1008:
993:
919:
860:
819:
538:
358:
221:
135:
1502:
1457:
1117:
1087:
1028:
840:
814:
558:
543:
82:
1122:
1046:
1013:
998:
924:
8:
1303:
162:
1107:
1061:
612:
583:
563:
376:
333:
207:
1364:
845:
573:
568:
126:
1522:
1472:
1452:
1308:
1288:
1258:
983:
978:
959:
716:
380:
368:
1442:
1253:
142:
178:
1318:
1248:
1198:
1102:
879:
850:
622:
617:
588:
519:
237:
233:
214:
200:
146:
1581:
1371:
637:
627:
196:
774:
661:
272:
165:
that can verify whether a token has been spent. This normally represents a
372:
355:
27th
International Conference on Distributed Computing Systems (ICDCS '07)
1517:
1406:
1278:
1142:
265:
225:
1437:
1328:
1273:
1160:
1112:
1038:
740:
735:
533:
396:"Bitcoin Gold hit by 51% attacks, $ 72K in cryptocurrency double-spent"
257:
229:
1268:
1170:
1097:
1003:
855:
130:
338:
332:
Jaap-Henk
Hoepman (2008). "Distributed Double Spending Prevention".
24:
1263:
1243:
1223:
1213:
1208:
1132:
1092:
1071:
934:
914:
908:
888:
865:
835:
765:
755:
750:
710:
701:
686:
681:
676:
578:
488:
283:
1411:
1376:
1333:
1228:
1203:
1175:
949:
691:
656:
287:
217:
420:"Cost of a 51% Attack for Different Cryptocurrencies | Crypto51"
1386:
1313:
1233:
1218:
1165:
969:
903:
795:
745:
726:
185:
158:
157:
Prevention of double-spending is usually implemented using an
1416:
1354:
1338:
1298:
1283:
1238:
954:
779:
647:
445:"Why Proof-of-work isn't suitable for small cryptocurrencies"
419:
275:, was hit by such an attack in 2018 and then again in 2020.
671:
593:
1359:
1323:
929:
352:
210:
for the prevention of double-spending had been proposed.
314:. School of Computer Science, University of Birmingham
264:
incentive to accumulate clusters of mining nodes, or
191:
Most decentralized systems solve this problem with a
172:
49:. Unsourced material may be challenged and removed.
331:
152:
1579:
504:
169:from both availability and trust viewpoints.
1560:
511:
497:
220:implemented a solution in early 2009. Its
362:
337:
109:Learn how and when to remove this message
442:
393:
346:
325:
1580:
1347:
305:
303:
145:and, particularly in offline systems,
1478:Decentralized autonomous organization
492:
309:
256:Due to the nature of a decentralized
1548:
518:
47:adding citations to reliable sources
18:
16:Failure mode of digital cash schemes
300:
13:
14:
1624:
1488:Distributed ledger technology law
1559:
1547:
1536:
1535:
173:Decentralized digital currencies
129:, such double-spending leads to
23:
138:and retention of the currency.
34:needs additional citations for
461:
436:
412:
394:Canellis, David (2020-01-27).
387:
286:obtained 51% hashing power in
153:Centralized digital currencies
1:
443:Varshney, Neer (2018-05-24).
294:
251:
7:
549:Cryptographic hash function
10:
1629:
271:One of the Bitcoin forks,
179:Blockchain § Finality
176:
1531:
1508:Initial exchange offering
1483:Decentralized application
1463:Cryptocurrency in Nigeria
1425:
1399:
1189:
1151:
1080:
1037:
968:
878:
828:
804:
788:
764:
725:
700:
646:
636:
602:
526:
1513:List of cryptocurrencies
1400:Crypto service companies
1191:Cryptocurrency exchanges
449:Hard Fork | The Next Web
400:Hard Fork | The Next Web
167:single point of failure
1593:Financial cryptography
1448:Complementary currency
554:Decentralized exchange
539:Cryptocurrency tumbler
222:cryptographic protocol
1608:Distributed computing
1503:Initial coin offering
1458:Cryptocurrency bubble
989:Basic Attention Token
559:Decentralized finance
544:Cryptocurrency wallet
373:10.1109/ICDCS.2007.91
282:In 2014, mining pool
206:By 2007, a number of
1498:Environmental impact
1468:Cryptocurrency scams
43:improve this article
1153:Inactive currencies
208:distributed systems
163:trusted third party
1588:Digital currencies
613:Proof of authority
584:Non-fungible token
564:Distributed ledger
228:of hash pointers (
1575:
1574:
1395:
1394:
874:
873:
574:Lightning Network
127:counterfeit money
119:
118:
111:
93:
58:"Double-spending"
1620:
1613:Cryptocurrencies
1563:
1562:
1551:
1550:
1539:
1538:
1523:Virtual currency
1473:Digital currency
1453:Crypto-anarchism
1345:
1344:
1098:HBAR (Hashgraph)
1081:Other currencies
717:Ethereum Classic
644:
643:
520:Cryptocurrencies
513:
506:
499:
490:
489:
484:
483:
481:
480:
465:
459:
458:
456:
455:
440:
434:
433:
431:
430:
424:www.crypto51.app
416:
410:
409:
407:
406:
391:
385:
384:
366:
350:
344:
343:
341:
329:
323:
322:
320:
319:
307:
147:secret splitting
143:blind signatures
114:
107:
103:
100:
94:
92:
51:
27:
19:
1628:
1627:
1623:
1622:
1621:
1619:
1618:
1617:
1598:Payment systems
1578:
1577:
1576:
1571:
1527:
1493:Double-spending
1443:Blockchain game
1421:
1391:
1343:
1185:
1147:
1076:
1033:
964:
870:
824:
800:
784:
760:
721:
696:
632:
598:
522:
517:
487:
478:
476:
467:
466:
462:
453:
451:
441:
437:
428:
426:
418:
417:
413:
404:
402:
392:
388:
351:
347:
330:
326:
317:
315:
308:
301:
297:
254:
181:
175:
155:
122:Double-spending
115:
104:
98:
95:
52:
50:
40:
28:
17:
12:
11:
5:
1626:
1616:
1615:
1610:
1605:
1603:Internet fraud
1600:
1595:
1590:
1573:
1572:
1570:
1569:
1557:
1545:
1532:
1529:
1528:
1526:
1525:
1520:
1515:
1510:
1505:
1500:
1495:
1490:
1485:
1480:
1475:
1470:
1465:
1460:
1455:
1450:
1445:
1440:
1435:
1429:
1427:
1426:Related topics
1423:
1422:
1420:
1419:
1414:
1409:
1403:
1401:
1397:
1396:
1393:
1392:
1390:
1389:
1384:
1379:
1374:
1369:
1368:
1367:
1357:
1351:
1349:
1342:
1341:
1336:
1331:
1326:
1321:
1316:
1311:
1306:
1301:
1296:
1291:
1286:
1281:
1276:
1271:
1266:
1261:
1256:
1251:
1246:
1241:
1236:
1231:
1226:
1221:
1216:
1211:
1206:
1201:
1195:
1193:
1187:
1186:
1184:
1183:
1178:
1173:
1168:
1163:
1157:
1155:
1149:
1148:
1146:
1145:
1140:
1135:
1130:
1125:
1120:
1115:
1110:
1105:
1100:
1095:
1090:
1084:
1082:
1078:
1077:
1075:
1074:
1069:
1064:
1059:
1054:
1049:
1043:
1041:
1035:
1034:
1032:
1031:
1026:
1021:
1016:
1011:
1006:
1001:
996:
991:
986:
981:
975:
973:
966:
965:
963:
962:
957:
952:
947:
942:
937:
932:
927:
922:
917:
912:
906:
901:
896:
891:
885:
883:
880:Proof of stake
876:
875:
872:
871:
869:
868:
863:
858:
853:
851:Nervos Network
848:
843:
838:
832:
830:
826:
825:
823:
822:
817:
811:
809:
802:
801:
799:
798:
792:
790:
786:
785:
783:
782:
777:
771:
769:
762:
761:
759:
758:
753:
748:
743:
738:
732:
730:
723:
722:
720:
719:
714:
707:
705:
698:
697:
695:
694:
689:
684:
679:
674:
669:
664:
659:
653:
651:
641:
634:
633:
631:
630:
625:
623:Proof of stake
620:
618:Proof of space
615:
609:
607:
600:
599:
597:
596:
591:
589:Smart contract
586:
581:
576:
571:
566:
561:
556:
551:
546:
541:
536:
530:
528:
524:
523:
516:
515:
508:
501:
493:
486:
485:
475:. 16 July 2014
460:
435:
411:
386:
357:. p. 41.
345:
324:
312:"Digital Cash"
298:
296:
293:
253:
250:
234:hash collision
215:cryptocurrency
201:proof-of-stake
174:
171:
154:
151:
117:
116:
31:
29:
22:
15:
9:
6:
4:
3:
2:
1625:
1614:
1611:
1609:
1606:
1604:
1601:
1599:
1596:
1594:
1591:
1589:
1586:
1585:
1583:
1568:
1567:
1558:
1556:
1555:
1546:
1544:
1543:
1534:
1533:
1530:
1524:
1521:
1519:
1516:
1514:
1511:
1509:
1506:
1504:
1501:
1499:
1496:
1494:
1491:
1489:
1486:
1484:
1481:
1479:
1476:
1474:
1471:
1469:
1466:
1464:
1461:
1459:
1456:
1454:
1451:
1449:
1446:
1444:
1441:
1439:
1436:
1434:
1431:
1430:
1428:
1424:
1418:
1415:
1413:
1410:
1408:
1405:
1404:
1402:
1398:
1388:
1385:
1383:
1380:
1378:
1375:
1373:
1372:LocalBitcoins
1370:
1366:
1363:
1362:
1361:
1358:
1356:
1353:
1352:
1350:
1346:
1340:
1337:
1335:
1332:
1330:
1327:
1325:
1322:
1320:
1317:
1315:
1312:
1310:
1307:
1305:
1304:ItBit (Paxos)
1302:
1300:
1297:
1295:
1292:
1290:
1287:
1285:
1282:
1280:
1277:
1275:
1272:
1270:
1267:
1265:
1262:
1260:
1257:
1255:
1252:
1250:
1247:
1245:
1242:
1240:
1237:
1235:
1232:
1230:
1227:
1225:
1222:
1220:
1217:
1215:
1212:
1210:
1207:
1205:
1202:
1200:
1197:
1196:
1194:
1192:
1188:
1182:
1179:
1177:
1174:
1172:
1169:
1167:
1164:
1162:
1159:
1158:
1156:
1154:
1150:
1144:
1141:
1139:
1136:
1134:
1131:
1129:
1126:
1124:
1121:
1119:
1116:
1114:
1111:
1109:
1106:
1104:
1101:
1099:
1096:
1094:
1091:
1089:
1086:
1085:
1083:
1079:
1073:
1070:
1068:
1065:
1063:
1060:
1058:
1055:
1053:
1050:
1048:
1045:
1044:
1042:
1040:
1036:
1030:
1027:
1025:
1022:
1020:
1017:
1015:
1012:
1010:
1007:
1005:
1002:
1000:
997:
995:
992:
990:
987:
985:
982:
980:
977:
976:
974:
971:
967:
961:
958:
956:
953:
951:
948:
946:
943:
941:
938:
936:
933:
931:
928:
926:
923:
921:
918:
916:
913:
910:
907:
905:
902:
900:
897:
895:
892:
890:
887:
886:
884:
881:
877:
867:
864:
862:
859:
857:
854:
852:
849:
847:
844:
842:
839:
837:
834:
833:
831:
827:
821:
818:
816:
813:
812:
810:
807:
803:
797:
794:
793:
791:
789:RandomX-based
787:
781:
778:
776:
773:
772:
770:
767:
763:
757:
754:
752:
749:
747:
744:
742:
739:
737:
734:
733:
731:
728:
724:
718:
715:
712:
709:
708:
706:
703:
699:
693:
690:
688:
685:
683:
680:
678:
675:
673:
670:
668:
665:
663:
660:
658:
655:
654:
652:
649:
645:
642:
639:
638:Proof of work
635:
629:
628:Proof of work
626:
624:
621:
619:
616:
614:
611:
610:
608:
605:
601:
595:
592:
590:
587:
585:
582:
580:
577:
575:
572:
570:
567:
565:
562:
560:
557:
555:
552:
550:
547:
545:
542:
540:
537:
535:
532:
531:
529:
525:
521:
514:
509:
507:
502:
500:
495:
494:
491:
474:
470:
464:
450:
446:
439:
425:
421:
415:
401:
397:
390:
382:
378:
374:
370:
365:
364:10.1.1.120.52
360:
356:
349:
340:
335:
328:
313:
306:
304:
299:
292:
289:
285:
280:
276:
274:
269:
267:
261:
259:
249:
245:
241:
239:
235:
231:
227:
223:
219:
216:
211:
209:
204:
202:
198:
197:proof-of-work
194:
189:
187:
180:
170:
168:
164:
160:
150:
148:
144:
139:
137:
132:
128:
123:
113:
110:
102:
99:December 2022
91:
88:
84:
81:
77:
74:
70:
67:
63:
60: –
59:
55:
54:Find sources:
48:
44:
38:
37:
32:This article
30:
26:
21:
20:
1564:
1552:
1540:
1492:
1417:Initiative Q
775:Bitcoin Gold
667:Counterparty
662:Bitcoin Cash
477:. Retrieved
472:
463:
452:. Retrieved
448:
438:
427:. Retrieved
423:
414:
403:. Retrieved
399:
389:
354:
348:
327:
316:. Retrieved
281:
277:
273:Bitcoin Gold
270:
266:mining pools
262:
255:
246:
242:
212:
205:
190:
182:
156:
140:
121:
120:
105:
96:
86:
79:
72:
65:
53:
41:Please help
36:verification
33:
1518:Token money
1407:Hyperledger
1279:EDX Markets
1143:WhopperCoin
1039:Stablecoins
339:0802.0832v1
310:Mark Ryan.
226:linked list
136:circulation
1582:Categories
1438:BitLicense
1382:QuadrigaCX
1365:bankruptcy
1329:ShapeShift
1274:Crypto.com
1161:BitConnect
1113:MobileCoin
882:currencies
741:Bitconnect
736:Auroracoin
640:currencies
606:mechanisms
534:Blockchain
527:Technology
479:2020-02-29
473:TechCrunch
454:2018-05-25
429:2020-02-29
405:2020-02-29
318:2017-05-27
295:References
258:blockchain
252:51% attack
230:blockchain
177:See also:
69:newspapers
1269:Coincheck
1171:KodakCoin
1019:Shiba Inu
1004:KodakCoin
994:Chainlink
920:Injective
894:Avalanche
856:Primecoin
604:Consensus
359:CiteSeerX
236:) called
193:consensus
131:inflation
1542:Category
1264:Coinbase
1244:Bitstamp
1224:Bitpanda
1214:bitFlyer
1209:Bitfinex
1133:SafeMoon
1093:Filecoin
1072:USD Coin
940:Polkadot
935:Peercoin
915:Gridcoin
909:Ethereum
889:Algorand
866:Vertcoin
836:AmbaCoin
766:Equihash
756:Litecoin
751:Dogecoin
711:Ethereum
687:Peercoin
682:Namecoin
677:MazaCoin
579:MetaMask
284:GHash.io
161:central
1554:Commons
1433:Airdrop
1412:IQ.Wiki
1377:Mt. Gox
1348:Defunct
1334:Uniswap
1294:Genesis
1229:Bithumb
1204:Binance
1176:OneCoin
1138:Stellar
1024:The DAO
1014:Polygon
984:Aventus
899:Cardano
692:Titcoin
657:Bitcoin
648:SHA-256
381:8097408
288:Bitcoin
218:Bitcoin
83:scholar
1387:Thodex
1314:Kucoin
1309:Kraken
1289:Gemini
1259:Circle
1234:BitMEX
1219:Bitkub
1166:Coinye
1128:Ripple
1103:Helium
1067:Tether
972:tokens
970:ERC-20
945:Solana
904:EOS.IO
808:-based
796:Monero
768:-based
746:Coinye
729:-based
727:Scrypt
704:-based
702:Ethash
650:-based
379:
361:
238:mining
186:ledger
159:online
85:
78:
71:
64:
56:
1355:BTC-e
1339:Upbit
1299:Huobi
1284:eToro
1239:Bitso
1181:Petro
1062:Terra
1009:Minds
979:Augur
955:Tezos
950:Steem
911:(2.0)
861:Verge
829:Other
820:Petro
780:Zcash
713:(1.0)
377:S2CID
334:arXiv
90:JSTOR
76:books
1566:List
1319:Kuna
1249:BTCC
1199:Abra
1118:Nano
1108:Luna
1088:Chia
1052:Diem
1029:TRON
846:IOTA
841:Firo
815:Dash
672:LBRY
594:Web3
569:Fork
213:The
199:and
62:news
1360:FTX
1324:OKX
1254:BUX
1123:NEO
1057:Pax
1047:Dai
999:Kin
960:TON
930:Nxt
925:Kin
806:X11
369:doi
45:by
1584::
471:.
447:.
422:.
398:.
375:.
367:.
302:^
203:.
149:.
512:e
505:t
498:v
482:.
457:.
432:.
408:.
383:.
371::
342:.
336::
321:.
112:)
106:(
101:)
97:(
87:·
80:·
73:·
66:·
39:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
