Knowledge

Madryga

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is very simple. To start with, the entire key is XORed with a random constant of the same length as the key, then rotated to the left by 3 bits. It is rotated again after each iteration of rotation and XOR. The rightmost byte of it is used in each iteration to XOR with the rightmost byte of the data
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has reviewed the algorithm without making a formal analysis. He noticed that "the parity of all the bits of the plaintext and the ciphertext is a constant, depending only on the key. So, if you have one plaintext and its corresponding ciphertext, you can predict the parity of the ciphertext for any
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a key byte with the rightmost byte, and rotates the other two as one block. The rotation varies with the output of the XOR. Then, the algorithm moves to the right by one byte. So if it were working on bytes 2, 3 and 4, after it finished rotating and XORing them, it would repeat the process on bytes
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published in 1984 by W. E. Madryga. It was designed to be easy and efficient for implementation in software. Serious weaknesses have since been found in the algorithm, but it was one of the first encryption algorithms to make use of data-dependent rotations, later used in other ciphers, such as
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Madryga is specified with eight rounds, but this can be increased to provide more security if need be. In each round, the algorithm passes over the entire plaintext
178:). A ciphertext-only attack is devastating for a modern block cipher; as such, it is probably more prudent to use another algorithm for encrypting sensitive data. 166:
and Kushilevitz (1998) published an improved differential attack requiring only 16 chosen-plaintext pairs, and then demonstrated that it could be converted to a
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In his proposal, Madryga set forth twelve design objectives that are generally considered to be good goals in the design of a block cipher.
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The decryption algorithm is simply the reverse of the encryption algorithm. Due to the nature of the XOR operation, it is reversible.
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is the length of the plaintext in bytes. The algorithm looks at three bytes at a time, so Madryga is a 24-bit block cipher. It
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At a glance, Madryga seems less secure than, for example, DES. All of Madryga's operations are linear. DES's
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seek to exploit. While Madryga's rotations are data-dependent to a small degree, they are still linear.
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using 2 ciphertexts, under reasonable assumptions about the redundancy of the plaintext (for example,
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The length of the key and the text should be adjustable to meet varying security requirements.
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Madryga met the objective of being efficient in software: the only operations it uses are
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In 1995, Ken Shirriff found a differential attack on Madryga that requires 5,000
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had already fulfilled nine of them. The three that DES did not fulfill were:
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The algorithm should be efficiently implementable in software on large
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are its only non-linear component, and flaws in them are what both
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Perhaps Madryga's fatal flaw is that it does not exhibit the
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Any possible key should produce a strong cipher. (Meaning no
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W. E. Madryga, "A High Performance Encryption Algorithm",
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From Differential Cryptanalysis to Ciphertext-Only Attacks
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Cryptographically secure pseudorandom number generator
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Here, 73:, and in discrete 1661: 1660: 1657: 1656: 1540:Key-based routing 1530:Trapdoor function 1396:Digital signature 1267: 1266: 1263: 1262: 1250:Mode of operation 927:Lai–Massey scheme 160:chosen plaintexts 88:XOR and rotations 55:, which DES has.) 1681: 1647: 1646: 1475:Insecure channel 1327:Classical cipher 1296: 1289: 1282: 1273: 1272: 1121:Power-monitoring 962:Avalanche effect 670:Khufu and Khafre 323:security summary 312: 305: 298: 289: 288: 285: 284: 281: 280: 260: 258: 252: 247: 245: 237: 229: 223: 222: 220: 197: 176:English language 142:avalanche effect 1689: 1688: 1684: 1683: 1682: 1680: 1679: 1678: 1664: 1663: 1662: 1653: 1635: 1564: 1305: 1300: 1259: 1233: 1202:Standardization 1197: 1126:Electromagnetic 1078:Integral/Square 1035:Piling-up lemma 1019:Biclique attack 1008:EFF DES cracker 992: 986: 917:Feistel network 905: 530:CIPHERUNICORN-E 525:CIPHERUNICORN-A 457: 451: 384: 378: 332: 326: 316: 269: 267:Further reading 264: 263: 250: 248: 239: 238: 230: 226: 218:10.1.1.128.3697 198: 189: 184: 123: 84: 17: 12: 11: 5: 1687: 1677: 1676: 1659: 1658: 1655: 1654: 1652: 1651: 1640: 1637: 1636: 1634: 1633: 1628: 1626:Random numbers 1623: 1618: 1613: 1608: 1603: 1598: 1593: 1588: 1583: 1578: 1572: 1570: 1566: 1565: 1563: 1562: 1557: 1552: 1550:Garlic routing 1547: 1542: 1537: 1532: 1527: 1522: 1517: 1512: 1507: 1502: 1497: 1492: 1487: 1482: 1477: 1472: 1470:Secure channel 1467: 1461: 1460: 1459: 1448: 1443: 1438: 1433: 1428: 1426:Key stretching 1423: 1418: 1413: 1408: 1403: 1398: 1393: 1392: 1391: 1386: 1381: 1371: 1369:Cryptovirology 1366: 1361: 1356: 1354:Cryptocurrency 1351: 1346: 1341: 1340: 1339: 1329: 1324: 1319: 1313: 1311: 1307: 1306: 1299: 1298: 1291: 1284: 1276: 1269: 1268: 1265: 1264: 1261: 1260: 1258: 1257: 1252: 1247: 1241: 1239: 1235: 1234: 1232: 1231: 1226: 1221: 1216: 1211: 1205: 1203: 1199: 1198: 1196: 1195: 1190: 1185: 1180: 1175: 1170: 1165: 1160: 1155: 1150: 1145: 1140: 1139: 1138: 1133: 1128: 1123: 1118: 1108: 1103: 1098: 1093: 1085: 1080: 1075: 1068:Distinguishing 1065: 1060: 1059: 1058: 1053: 1048: 1038: 1028: 1027: 1026: 1021: 1011: 1000: 998: 988: 987: 985: 984: 974: 969: 964: 959: 954: 949: 944: 939: 934: 932:Product cipher 929: 924: 919: 913: 911: 907: 906: 904: 903: 898: 893: 888: 883: 878: 873: 868: 863: 858: 853: 848: 843: 838: 833: 828: 823: 818: 813: 808: 803: 798: 793: 788: 783: 778: 773: 768: 763: 758: 753: 748: 743: 738: 733: 728: 723: 718: 713: 708: 703: 698: 687: 682: 677: 672: 667: 662: 657: 652: 647: 642: 637: 632: 627: 622: 617: 612: 607: 602: 597: 592: 587: 582: 577: 572: 567: 562: 560:Cryptomeria/C2 557: 552: 547: 542: 537: 532: 527: 522: 517: 512: 507: 502: 497: 492: 487: 482: 477: 472: 467: 461: 459: 453: 452: 450: 449: 444: 439: 434: 429: 424: 419: 414: 409: 404: 399: 394: 388: 386: 380: 379: 377: 376: 371: 366: 361: 347: 342: 336: 334: 328: 327: 315: 314: 307: 300: 292: 278: 277: 268: 265: 262: 261: 251:|journal= 224: 186: 185: 183: 180: 122: 119: 83: 80: 79: 78: 71:microcomputers 59: 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324: 320: 319:Block ciphers 313: 308: 306: 301: 299: 294: 293: 290: 286: 282: 275: 271: 270: 256: 243: 235: 228: 219: 214: 210: 206: 202: 201:Alex Biryukov 196: 194: 192: 187: 179: 177: 173: 169: 165: 161: 156: 154: 149: 145: 143: 138: 136: 132: 128: 121:Cryptanalysis 118: 115: 112: 107: 104: 100: 97:times, where 96: 91: 89: 82:The algorithm 76: 72: 68: 67:minicomputers 64: 60: 57: 54: 50: 49: 48: 46: 41: 39: 35: 30: 26: 22: 1581:Block cipher 1421:Key schedule 1411:Key exchange 1401:Kleptography 1359:Cryptosystem 1303:Cryptography 1153:Partitioning 1111:Side-channel 1089: 1056:Higher-order 1041:Differential 922:Key schedule 720: 273: 242:cite journal 227: 204: 157: 146: 139: 124: 116: 111:key schedule 108: 106:3, 4 and 5. 98: 94: 92: 85: 42: 29:block cipher 24: 21:cryptography 18: 16:Block cipher 1569:Mathematics 1560:Mix network 1238:Utilization 1224:NSA Suite B 1209:AES process 1158:Rubber-hose 1096:Related-key 1004:Brute-force 383:Less common 1520:Ciphertext 1490:Decryption 1485:Encryption 1446:Ransomware 1188:Chi-square 1106:Rotational 1046:Impossible 967:Block size 861:Spectr-H64 685:Ladder-DES 680:Kuznyechik 625:Hierocrypt 495:BassOmatic 458:algorithms 385:algorithms 358:Triple DES 333:algorithms 182:References 63:mainframes 1510:Plaintext 1163:Black-bag 1083:Boomerang 1072:Known-key 1051:Truncated 876:Threefish 871:SXAL/MBAL 761:MultiSwap 716:MacGuffin 675:KN-Cipher 615:Grand Cru 570:CS-Cipher 550:COCONUT98 213:CiteSeerX 174:-encoded 148:Eli Biham 53:weak keys 1668:Category 1649:Category 1555:Kademlia 1515:Codetext 1458:(CSPRNG) 1436:Machines 1214:CRYPTREC 1178:Weak key 1131:Acoustic 972:Key size 816:Red Pike 635:IDEA NXT 515:Chiasmus 510:CAST-256 490:BaseKing 475:Akelarre 470:Adiantum 437:Skipjack 402:CAST-128 397:Camellia 345:Blowfish 164:Biryukov 1310:General 1255:Padding 1173:Rebound 881:Treyfer 831:SAVILLE 791:PRESENT 781:NOEKEON 726:MAGENTA 721:Madryga 701:Lucifer 565:CRYPTON 374:Twofish 364:Serpent 127:S-boxes 114:block. 25:Madryga 1431:Keygen 1219:NESSIE 1168:Davies 1116:Timing 1031:Linear 991:Attack 910:Design 901:Zodiac 866:Square 841:SHACAL 836:SC2000 796:Prince 776:Nimbus 771:NewDES 756:MULTI2 746:MISTY1 689:LOKI ( 665:KHAZAD 660:KeeLoq 655:KASUMI 650:Kalyna 535:CLEFIA 520:CIKS-1 480:Anubis 331:Common 215:  209:CRYPTO 153:parity 69:, and 1466:(PRN) 1101:Slide 957:Round 942:P-box 937:S-box 896:XXTEA 856:Speck 851:Simon 846:SHARK 826:SAFER 811:REDOC 736:Mercy 695:89/91 645:Iraqi 610:G-DES 600:FEA-M 580:DES-X 545:Cobra 500:BATON 485:Ascon 465:3-Way 456:Other 172:ASCII 75:logic 27:is a 1229:CNSA 1088:Mod 1014:MITM 786:NUSH 741:MESH 731:MARS 605:FROG 595:FEAL 575:DEAL 555:Crab 540:CMEA 447:XTEA 432:SEED 412:IDEA 407:GOST 392:ARIA 255:help 133:and 109:The 103:XORs 36:and 1183:Tau 1143:XSL 947:SPN 891:xmx 886:UES 821:S-1 806:RC2 751:MMB 630:ICE 585:DFC 442:TEA 427:RC6 422:RC5 417:LEA 369:SM4 350:DES 340:AES 45:DES 38:RC6 34:RC5 19:In 1670:: 711:M8 706:M6 693:, 691:97 590:E2 356:, 246:: 244:}} 240:{{ 207:. 190:^ 162:. 65:, 40:. 23:, 1295:e 1288:t 1281:v 1090:n 1074:) 1070:( 1037:) 1033:( 1010:) 1006:( 997:) 993:( 983:) 979:( 801:Q 697:) 360:) 352:( 325:) 321:( 311:e 304:t 297:v 257:) 253:( 236:. 221:. 99:n 95:n

Index

cryptography
block cipher
RC5
RC6
DES
weak keys
mainframes
minicomputers
microcomputers
logic
XOR and rotations
XORs
key schedule
S-boxes
differential cryptanalysis
linear cryptanalysis
avalanche effect
Eli Biham
parity
chosen plaintexts
Biryukov
ciphertext-only attack
ASCII
English language



Alex Biryukov
CRYPTO
CiteSeerX

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