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Discrete logarithm

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Discrete logarithms are quickly computable in a few special cases. However, no efficient method is known for computing them in general. In cryptography, the computational complexity of the discrete logarithm problem, along with its application, was first proposed in the
328: 2428: 536: 53 = 1.724276
 means that 10 = 53. While integer exponents can be defined in any group using products and inverses, arbitrary real exponents, such as this 1.724276
, require other concepts such as the 504: 1190: 1086: 3007: 1545:
The authors of the Logjam attack estimate that the much more difficult precomputation needed to solve the discrete log problem for a 1024-bit prime would be within the budget of a large national
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these three steps for a specific group, one need only carry out the last step, which is much less computationally expensive than the first three, to obtain a specific logarithm in that group.
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The discrete logarithm problem is considered to be computationally intractable. That is, no efficient classical algorithm is known for computing discrete logarithms in general.
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Other base-10 logarithms in the real numbers are not instances of the discrete logarithm problem, because they involve non-integer exponents. For example, the equation log
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attack used this vulnerability to compromise a variety of internet services that allowed the use of groups whose order was a 512-bit prime number, so called
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traffic uses one of a handful of groups that are of order 1024 bits or less, e.g. cyclic groups with order of the Oakley primes specified in RFC 2409. The
2642: 1461:, for example). This asymmetry is analogous to the one between integer factorization and integer multiplication. Both asymmetries (and other possibly 2297: 1933: 1782:; Springall, Drew; Thomé, Emmanuel; Valenta, Luke; VanderSloot, Benjamin; Wustrow, Eric; Zanella-Béguelin, Santiago; Zimmermann, Paul (October 2015). 1318: 644: 3086: 2821: 2815: 721:
The discrete logarithm is just the inverse operation. For example, consider the equation 3 ≡ 13 (mod 17). From the example above, one solution is
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satisfying 3 ≡ 1 (mod 17), these are the only solutions. Equivalently, the set of all possible solutions can be expressed by the constraint that
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There exist groups for which computing discrete logarithms is apparently difficult. In some cases (e.g. large prime order subgroups of groups
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of the size of the group, and thus exponential in half the number of digits in the size of the group. However, none of them runs in
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in the number of digits in the size of the group. Therefore, it is an exponential-time algorithm, practical only for small groups
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While there is no publicly known algorithm for solving the discrete logarithm problem in general, the first three steps of the
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is used, allowing an efficient computation of the discrete logarithm with Pohlig–Hellman if the order of the group (being
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is an integer then 3 ≡ 3 × (3) ≡ 13 × 1 ≡ 13 (mod 17). Hence the equation has infinitely many solutions of the form 4 + 16
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Shor, Peter (1997). "Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer".
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At the same time, the inverse problem of discrete exponentiation is not difficult (it can be computed efficiently using
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Efficient classical algorithms also exist in certain special cases. For example, in the group of the integers modulo
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While computing discrete logarithms and integer factorization are distinct problems, they share some properties:
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Adrian, David; Bhargavan, Karthikeyan; Durumeric, Zakir; Gaudry, Pierrick; Green, Matthew; Halderman, J. Alex;
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Lam; Shparlinski; Wang; Xing (2001). Lam, Kwok-Yan; Shparlinski, Igor; Wang, Huaxiong; Xing, Chaoping (eds.).
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multiple times during the computation. Regardless of the specific algorithm used, this operation is called
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that the discrete logarithm problem (DLP) over carefully chosen groups has no efficient solution.
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Can the discrete logarithm be computed in polynomial time on a classical computer?
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More sophisticated algorithms exist, usually inspired by similar algorithms for
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both problems seem to be difficult (no efficient algorithms are known for non-
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The familiar base change formula for ordinary logarithms remains valid: If
2478: 529: 0.001 = −3. These are instances of the discrete logarithm problem. 2959: 2893: 2764: 2759: 2754: 2635: 1801: 1734:"On the complexity of the discrete logarithm and Diffie–Hellman problems" 1693: 1531: 871: 587: 692:
th power as an integer and then finding the remainder after division by
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for both problems efficient algorithms on quantum computers are known,
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the difficulty of both problems has been used to construct various
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of one of the numbers in this group may be computed by finding its
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One of the simplest settings for discrete logarithms is the group
1784:"Imperfect Forward Secrecy: How Diffie-Hellman Fails in Practice" 2989: 2482: 1922: 1630:. Progress in Computer Science and Applied Logic (1 ed.). 1472:
in discrete logarithm cryptography (DLC) are the cyclic groups
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algorithms from one problem are often adapted to the other, and
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can be shown to be about as hard as the worst case using
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that NSA is able to break much of current cryptography.
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is also unique, and the discrete logarithm amounts to a
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The problem of inverting exponentiation in finite groups
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indicate that algorithm is for numbers of special forms
1185:{\displaystyle \log _{c}a=\log _{c}b\cdot \log _{b}a.} 1081:{\displaystyle \log _{b}\colon H\to \mathbf {Z} _{n},} 1595:
Menezes, A. J.; van Oorschot, P. C.; Vanstone, S. A.
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A similar example holds for any non-zero real number
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} of the non-zero real numbers. For any element 1184: 1080: 992:{\displaystyle \log _{b}\colon H\to \mathbf {Z} .} 991: 835: 498: 322: 1732:Blake, Ian F.; Garefalakis, Theo (2004-04-01). 1100:denotes the additive group of integers modulo 3001: 2494: 1934: 1773: 1771: 1769: 1251:is found. This algorithm is sometimes called 8: 1837:Elementary Number Theory and Its Application 1627:Cryptography and Computational Number Theory 1217:(more unsolved problems in computer science) 1597:"Chapter 8.4 ElGamal public-key encryption" 3008: 2994: 2986: 2520: 2501: 2487: 2479: 1941: 1927: 1919: 1890:Prime Numbers: A computational perspective 558:for this group. The discrete logarithm log 309: 1800:Harkins, D.; Carrel, D. (November 1998). 1749: 1692: 1167: 1148: 1129: 1123: 1069: 1064: 1048: 1042: 981: 966: 960: 836:{\displaystyle f\colon \mathbf {Z} \to G} 822: 814: 791:Powers obey the usual algebraic identity 440: 310: 305: 275: 265: 259: 1587: 1353:, and equality means congruence modulo 757:is the identity element 1 of the group 1319:Pollard's rho algorithm for logarithms 654:. This is the group of multiplication 3241:Unsolved problems in computer science 1392:Comparison with integer factorization 1225:A general algorithm for computing log 7: 2822:Naccache–Stern knapsack cryptosystem 1839:(6 ed.). Pearson. p. 368. 1619: 1617: 1208:Unsolved problem in computer science 1515:algorithm only depend on the group 586:. The powers form a multiplicative 3236:Computational hardness assumptions 3017:Computational hardness assumptions 1519:, not on the specific elements of 554:under multiplication, and 10 is a 14: 3076: 2852: 2150:Special number field sieve (SNFS) 2144:General number field sieve (GNFS) 1898:Cryptography: Theory and Practice 1802:"The Internet Key Exchange (IKE)" 513:in this list, one can compute log 112:, the more commonly used term is 3056:Decisional composite residuosity 1896:Stinson, Douglas Robert (2006). 1604:Handbook of Applied Cryptography 1523:whose finite log is desired. By 1372:, a cyclic group modulo a prime 1326:(aka Pollard's lambda algorithm) 1065: 982: 823: 775:other than 1, and every integer 2853:Discrete logarithm cryptography 547:terms, the powers of 10 form a 1468:Popular choices for the group 1400:both are special cases of the 1060: 978: 827: 1: 578:Powers of a fixed real number 203:, base their security on the 3092:Computational Diffie–Hellman 2868:Non-commutative cryptography 2108:Lenstra elliptic curve (ECM) 1359:extended Euclidean algorithm 1324:Pollard's kangaroo algorithm 1243:to larger and larger powers 779:is a discrete logarithm for 761:, the discrete logarithm log 665:. Its elements are non-zero 3180:Exponential time hypothesis 2965:Identity-based cryptography 2858:Elliptic-curve cryptography 1506:Elliptic curve cryptography 1491:Digital Signature Algorithm 1487:Diffie–Hellman key exchange 235:. For any positive integer 3257: 2415:Exponentiation by squaring 2098:Continued fraction (CFRAC) 1900:(3 ed.). London, UK: 1835:Rosen, Kenneth H. (2011). 1493:) and cyclic subgroups of 1459:exponentiation by squaring 1345:under addition, the power 1202:Discrete logarithm records 1199: 753:In the special case where 353:th power is the identity: 223:by multiplication and its 3190:Planted clique conjecture 3159:Ring learning with errors 3087:Decisional Diffie–Hellman 2970:Post-quantum cryptography 2919:Post-Quantum Cryptography 2462: 1751:10.1016/j.jco.2004.01.002 1703:10.1137/s0097539795293172 1681:SIAM Journal on Computing 1640:10.1007/978-3-0348-8295-8 1262:in the size of the group 729:—it also follows that if 525: 10000 = 4, and log 375:that solves the equation 219:be any group. Denote its 1551:National Security Agency 1452:random self-reducibility 1314:Pohlig–Hellman algorithm 1304:Index calculus algorithm 1111:is another generator of 704:. For example, consider 3185:Unique games conjecture 3134:Shortest vector problem 3108:External Diffie–Hellman 2863:Hash-based cryptography 2510:Public-key cryptography 2328:Greatest common divisor 1530:It turns out that much 1448:average-case complexity 1402:hidden subgroup problem 727:Fermat's little theorem 243:denotes the product of 197:public-key cryptography 73:can be defined for all 3164:Short integer solution 3144:Closest vector problem 2439:Modular exponentiation 1330:There is an efficient 1186: 1082: 1002:On the other hand, if 993: 837: 803:. In other words, the 749:Powers of the identity 702:modular exponentiation 500: 393:, in this context) of 367:also be an element of 337:denote the product of 324: 189:Diffie–Hellman problem 133:) (read "the index of 62:. Analogously, in any 3051:Quadratic residuosity 3031:Integer factorization 2525:Integer factorization 2166:Shanks's square forms 2090:Integer factorization 2065:Sieve of Eratosthenes 1806:Network Working Group 1738:Journal of Complexity 1567:A. W. Faber Model 366 1406:finite abelian groups 1357:in the integers. The 1279:integer factorization 1187: 1083: 1027:is unique only up to 994: 838: 625:, one can compute log 501: 325: 3154:Learning with errors 2444:Montgomery reduction 2318:Function field sieve 2293:Baby-step giant-step 2139:Quadratic sieve (QS) 1892:, 2nd ed., Springer. 1856:"Discrete Logarithm" 1555:leaked NSA documents 1384:, i.e. has no large 1380:−1) is sufficiently 1299:Function field sieve 1294:Baby-step giant-step 1253:trial multiplication 1122: 1041: 959: 813: 538:exponential function 439: 258: 191:. Several important 2828:Three-pass protocol 2454:Trachtenberg system 2420:Integer square root 2361:Modular square root 2080:Wheel factorization 2032:Quadratic Frobenius 2012:Lucas–Lehmer–Riesel 1854:Weisstein, Eric W. 1547:intelligence agency 920:does not exist for 566:is defined for any 205:hardness assumption 3211:Modular arithmetic 3077:Discrete logarithm 3061:Higher residuosity 2598:Discrete logarithm 2346:Extended Euclidean 2285:Discrete logarithm 2214:Schönhage–Strassen 2070:Sieve of Pritchard 1634:. pp. 54–56. 1513:number field sieve 1483:ElGamal encryption 1349:becomes a product 1309:Number field sieve 1247:until the desired 1182: 1078: 1029:congruence modulo 989: 862:from the integers 860:group homomorphism 833: 667:congruence classes 639:Modular arithmetic 521:. For example, log 496: 387:discrete logarithm 320: 316: 303: 231:be any element of 82:discrete logarithm 3198: 3197: 3173:Non-cryptographic 2983: 2982: 2935:Digital signature 2878:Trapdoor function 2841: 2840: 2558:Goldwasser–Micali 2476: 2475: 2075:Sieve of Sundaram 1911:978-1-58488-508-5 1657:978-3-7643-6510-3 1549:such as the U.S. 1463:one-way functions 1413:quantum computers 1332:quantum algorithm 1235:in finite groups 951:group isomorphism 771:is undefined for 313: 276: 274: 239:, the expression 183:) = 1. 3248: 3113:Sub-group hiding 3024:Number theoretic 3010: 3003: 2996: 2987: 2824: 2725: 2720: 2680:signature scheme 2583:Okamoto–Uchiyama 2521: 2503: 2496: 2489: 2480: 2425:Integer relation 2398:Other algorithms 2303:Pollard kangaroo 2194:Ancient Egyptian 2052:Prime-generating 2037:Solovay–Strassen 1950:Number-theoretic 1943: 1936: 1929: 1920: 1915: 1882:Richard Crandall 1870: 1868: 1867: 1850: 1826: 1825: 1814:10.17487/RFC2409 1797: 1791: 1790: 1788: 1775: 1764: 1763: 1753: 1729: 1723: 1722: 1696: 1694:quant-ph/9508027 1687:(5): 1484–1509. 1676: 1670: 1669: 1632:BirkhĂ€user Basel 1621: 1612: 1611: 1601: 1592: 1209: 1191: 1189: 1188: 1183: 1172: 1171: 1153: 1152: 1134: 1133: 1087: 1085: 1084: 1079: 1074: 1073: 1068: 1053: 1052: 998: 996: 995: 990: 985: 971: 970: 924:that are not in 842: 840: 839: 834: 826: 505: 503: 502: 497: 405: = log 384: 359: 329: 327: 326: 321: 315: 314: 311: 304: 299: 270: 269: 225:identity element 107: 61: 3256: 3255: 3251: 3250: 3249: 3247: 3246: 3245: 3201: 3200: 3199: 3194: 3168: 3122: 3118:Decision linear 3096: 3070:Group theoretic 3065: 3019: 3014: 2984: 2979: 2923: 2887:Standardization 2882: 2837: 2820: 2769: 2717:Lattice/SVP/CVP 2711: 2592: 2538:Blum–Goldwasser 2512: 2507: 2477: 2472: 2458: 2393: 2355: 2322: 2279: 2223: 2180: 2084: 2046: 2019:Proth's theorem 1961:Primality tests 1955: 1947: 1912: 1895: 1878: 1876:Further reading 1873: 1865: 1863: 1853: 1847: 1834: 1830: 1829: 1799: 1798: 1794: 1786: 1780:Heninger, Nadia 1777: 1776: 1767: 1731: 1730: 1726: 1678: 1677: 1673: 1658: 1623: 1622: 1615: 1599: 1594: 1593: 1589: 1584: 1576:Irish logarithm 1563: 1495:elliptic curves 1480: 1445: 1435: 1394: 1287:polynomial time 1230: 1220: 1219: 1214: 1211: 1207: 1204: 1198: 1163: 1144: 1125: 1120: 1119: 1099: 1063: 1044: 1039: 1038: 1022: 962: 957: 956: 944: 915: 901: 866:under addition 811: 810: 789: 766: 751: 717: 710: 652: 641: 630: 580: 561: 545:group-theoretic 535: 528: 524: 516: 509:For any number 437: 436: 426: 421: 410: 376: 354: 333:Similarly, let 277: 261: 256: 255: 221:group operation 213: 125: 116:: we can write 99: 89: 53: 43: 17: 12: 11: 5: 3254: 3252: 3244: 3243: 3238: 3233: 3228: 3223: 3218: 3213: 3203: 3202: 3196: 3195: 3193: 3192: 3187: 3182: 3176: 3174: 3170: 3169: 3167: 3166: 3161: 3156: 3151: 3141: 3130: 3128: 3124: 3123: 3121: 3120: 3115: 3110: 3104: 3102: 3098: 3097: 3095: 3094: 3089: 3084: 3082:Diffie-Hellman 3079: 3073: 3071: 3067: 3066: 3064: 3063: 3058: 3053: 3048: 3043: 3038: 3033: 3027: 3025: 3021: 3020: 3015: 3013: 3012: 3005: 2998: 2990: 2981: 2980: 2978: 2977: 2972: 2967: 2962: 2957: 2952: 2947: 2942: 2937: 2931: 2929: 2925: 2924: 2922: 2921: 2916: 2911: 2906: 2901: 2896: 2890: 2888: 2884: 2883: 2881: 2880: 2875: 2870: 2865: 2860: 2855: 2849: 2847: 2843: 2842: 2839: 2838: 2836: 2835: 2830: 2825: 2818: 2816:Merkle–Hellman 2813: 2808: 2803: 2798: 2793: 2788: 2783: 2777: 2775: 2771: 2770: 2768: 2767: 2762: 2757: 2752: 2747: 2742: 2737: 2731: 2729: 2713: 2712: 2710: 2709: 2704: 2699: 2694: 2689: 2684: 2683: 2682: 2672: 2667: 2662: 2661: 2660: 2655: 2645: 2640: 2639: 2638: 2633: 2623: 2618: 2613: 2608: 2602: 2600: 2594: 2593: 2591: 2590: 2585: 2580: 2575: 2570: 2565: 2563:Naccache–Stern 2560: 2555: 2550: 2545: 2540: 2535: 2529: 2527: 2518: 2514: 2513: 2508: 2506: 2505: 2498: 2491: 2483: 2474: 2473: 2471: 2470: 2463: 2460: 2459: 2457: 2456: 2451: 2446: 2441: 2436: 2422: 2417: 2412: 2407: 2401: 2399: 2395: 2394: 2392: 2391: 2386: 2381: 2379:Tonelli–Shanks 2376: 2371: 2365: 2363: 2357: 2356: 2354: 2353: 2348: 2343: 2338: 2332: 2330: 2324: 2323: 2321: 2320: 2315: 2313:Index calculus 2310: 2308:Pohlig–Hellman 2305: 2300: 2295: 2289: 2287: 2281: 2280: 2278: 2277: 2272: 2267: 2262: 2260:Newton-Raphson 2257: 2252: 2247: 2242: 2236: 2234: 2225: 2224: 2222: 2221: 2216: 2211: 2206: 2201: 2196: 2190: 2188: 2186:Multiplication 2182: 2181: 2179: 2178: 2173: 2171:Trial division 2168: 2163: 2158: 2156:Rational sieve 2153: 2146: 2141: 2136: 2128: 2120: 2115: 2110: 2105: 2100: 2094: 2092: 2086: 2085: 2083: 2082: 2077: 2072: 2067: 2062: 2060:Sieve of Atkin 2056: 2054: 2048: 2047: 2045: 2044: 2039: 2034: 2029: 2022: 2015: 2008: 2001: 1996: 1991: 1986: 1984:Elliptic curve 1981: 1976: 1971: 1965: 1963: 1957: 1956: 1948: 1946: 1945: 1938: 1931: 1923: 1917: 1916: 1910: 1893: 1886:Carl Pomerance 1877: 1874: 1872: 1871: 1851: 1846:978-0321500311 1845: 1831: 1828: 1827: 1792: 1765: 1744:(2): 148–170. 1724: 1671: 1656: 1613: 1586: 1585: 1583: 1580: 1579: 1578: 1569: 1562: 1559: 1476: 1441: 1434: 1431: 1430: 1429: 1422: 1419: 1416: 1409: 1393: 1390: 1370:Diffie–Hellman 1328: 1327: 1321: 1316: 1311: 1306: 1301: 1296: 1255:. It requires 1226: 1215: 1212: 1206: 1197: 1194: 1193: 1192: 1181: 1178: 1175: 1170: 1166: 1162: 1159: 1156: 1151: 1147: 1143: 1140: 1137: 1132: 1128: 1095: 1089: 1088: 1077: 1072: 1067: 1062: 1059: 1056: 1051: 1047: 1018: 1000: 999: 988: 984: 980: 977: 974: 969: 965: 940: 911: 897: 844: 843: 832: 829: 825: 821: 818: 788: 785: 762: 750: 747: 745:≡ 4 (mod 16). 715: 708: 648: 640: 637: 626: 579: 576: 559: 533: 526: 522: 514: 507: 506: 495: 492: 489: 486: 483: 480: 477: 474: 471: 468: 465: 462: 459: 456: 453: 450: 447: 444: 425: 422: 420: 417: 406: 331: 330: 319: 308: 302: 298: 295: 292: 289: 286: 283: 280: 273: 268: 264: 212: 209: 165:primitive root 121: 94:is an integer 85: 39: 15: 13: 10: 9: 6: 4: 3: 2: 3253: 3242: 3239: 3237: 3234: 3232: 3231:Finite fields 3229: 3227: 3224: 3222: 3219: 3217: 3214: 3212: 3209: 3208: 3206: 3191: 3188: 3186: 3183: 3181: 3178: 3177: 3175: 3171: 3165: 3162: 3160: 3157: 3155: 3152: 3149: 3145: 3142: 3139: 3135: 3132: 3131: 3129: 3125: 3119: 3116: 3114: 3111: 3109: 3106: 3105: 3103: 3099: 3093: 3090: 3088: 3085: 3083: 3080: 3078: 3075: 3074: 3072: 3068: 3062: 3059: 3057: 3054: 3052: 3049: 3047: 3044: 3042: 3039: 3037: 3034: 3032: 3029: 3028: 3026: 3022: 3018: 3011: 3006: 3004: 2999: 2997: 2992: 2991: 2988: 2976: 2973: 2971: 2968: 2966: 2963: 2961: 2958: 2956: 2953: 2951: 2948: 2946: 2943: 2941: 2938: 2936: 2933: 2932: 2930: 2926: 2920: 2917: 2915: 2912: 2910: 2907: 2905: 2902: 2900: 2897: 2895: 2892: 2891: 2889: 2885: 2879: 2876: 2874: 2871: 2869: 2866: 2864: 2861: 2859: 2856: 2854: 2851: 2850: 2848: 2844: 2834: 2831: 2829: 2826: 2823: 2819: 2817: 2814: 2812: 2809: 2807: 2804: 2802: 2799: 2797: 2794: 2792: 2789: 2787: 2784: 2782: 2779: 2778: 2776: 2772: 2766: 2763: 2761: 2758: 2756: 2753: 2751: 2748: 2746: 2743: 2741: 2738: 2736: 2733: 2732: 2730: 2728: 2723: 2718: 2714: 2708: 2705: 2703: 2700: 2698: 2695: 2693: 2690: 2688: 2685: 2681: 2678: 2677: 2676: 2673: 2671: 2668: 2666: 2663: 2659: 2656: 2654: 2651: 2650: 2649: 2646: 2644: 2641: 2637: 2634: 2632: 2629: 2628: 2627: 2624: 2622: 2619: 2617: 2614: 2612: 2609: 2607: 2604: 2603: 2601: 2599: 2595: 2589: 2588:Schmidt–Samoa 2586: 2584: 2581: 2579: 2576: 2574: 2571: 2569: 2566: 2564: 2561: 2559: 2556: 2554: 2551: 2549: 2548:DamgĂ„rd–Jurik 2546: 2544: 2543:Cayley–Purser 2541: 2539: 2536: 2534: 2531: 2530: 2528: 2526: 2522: 2519: 2515: 2511: 2504: 2499: 2497: 2492: 2490: 2485: 2484: 2481: 2468: 2465: 2464: 2461: 2455: 2452: 2450: 2447: 2445: 2442: 2440: 2437: 2434: 2430: 2426: 2423: 2421: 2418: 2416: 2413: 2411: 2408: 2406: 2403: 2402: 2400: 2396: 2390: 2387: 2385: 2382: 2380: 2377: 2375: 2374:Pocklington's 2372: 2370: 2367: 2366: 2364: 2362: 2358: 2352: 2349: 2347: 2344: 2342: 2339: 2337: 2334: 2333: 2331: 2329: 2325: 2319: 2316: 2314: 2311: 2309: 2306: 2304: 2301: 2299: 2296: 2294: 2291: 2290: 2288: 2286: 2282: 2276: 2273: 2271: 2268: 2266: 2263: 2261: 2258: 2256: 2253: 2251: 2248: 2246: 2243: 2241: 2238: 2237: 2235: 2233: 2230: 2226: 2220: 2217: 2215: 2212: 2210: 2207: 2205: 2202: 2200: 2197: 2195: 2192: 2191: 2189: 2187: 2183: 2177: 2174: 2172: 2169: 2167: 2164: 2162: 2159: 2157: 2154: 2152: 2151: 2147: 2145: 2142: 2140: 2137: 2135: 2133: 2129: 2127: 2125: 2121: 2119: 2118:Pollard's rho 2116: 2114: 2111: 2109: 2106: 2104: 2101: 2099: 2096: 2095: 2093: 2091: 2087: 2081: 2078: 2076: 2073: 2071: 2068: 2066: 2063: 2061: 2058: 2057: 2055: 2053: 2049: 2043: 2040: 2038: 2035: 2033: 2030: 2028: 2027: 2023: 2021: 2020: 2016: 2014: 2013: 2009: 2007: 2006: 2002: 2000: 1997: 1995: 1992: 1990: 1987: 1985: 1982: 1980: 1977: 1975: 1972: 1970: 1967: 1966: 1964: 1962: 1958: 1954: 1951: 1944: 1939: 1937: 1932: 1930: 1925: 1924: 1921: 1913: 1907: 1903: 1899: 1894: 1891: 1888:. Chapter 5, 1887: 1883: 1880: 1879: 1875: 1862:. Wolfram Web 1861: 1857: 1852: 1848: 1842: 1838: 1833: 1832: 1823: 1819: 1815: 1811: 1807: 1803: 1796: 1793: 1785: 1781: 1774: 1772: 1770: 1766: 1761: 1757: 1752: 1747: 1743: 1739: 1735: 1728: 1725: 1720: 1716: 1712: 1708: 1704: 1700: 1695: 1690: 1686: 1682: 1675: 1672: 1667: 1663: 1659: 1653: 1649: 1645: 1641: 1637: 1633: 1629: 1628: 1620: 1618: 1614: 1609: 1605: 1598: 1591: 1588: 1581: 1577: 1573: 1572:Percy Ludgate 1570: 1568: 1565: 1564: 1560: 1558: 1556: 1552: 1548: 1543: 1541: 1537: 1533: 1528: 1526: 1522: 1518: 1514: 1509: 1507: 1504: 1500: 1499:finite fields 1496: 1492: 1488: 1484: 1479: 1475: 1471: 1466: 1464: 1460: 1455: 1453: 1449: 1444: 1440: 1432: 1427: 1426:cryptographic 1423: 1420: 1417: 1414: 1410: 1407: 1403: 1399: 1398: 1397: 1391: 1389: 1387: 1386:prime factors 1383: 1379: 1375: 1371: 1366: 1364: 1360: 1356: 1352: 1348: 1344: 1339: 1337: 1333: 1325: 1322: 1320: 1317: 1315: 1312: 1310: 1307: 1305: 1302: 1300: 1297: 1295: 1292: 1291: 1290: 1288: 1284: 1280: 1275: 1273: 1269: 1265: 1261: 1258: 1254: 1250: 1246: 1242: 1238: 1234: 1229: 1223: 1218: 1203: 1195: 1179: 1176: 1173: 1168: 1164: 1160: 1157: 1154: 1149: 1145: 1141: 1138: 1135: 1130: 1126: 1118: 1117: 1116: 1114: 1110: 1105: 1103: 1098: 1094: 1075: 1070: 1057: 1054: 1049: 1045: 1037: 1036: 1035: 1033: 1032: 1026: 1021: 1016: 1013: 1009: 1005: 986: 975: 972: 967: 963: 955: 954: 953: 952: 948: 943: 938: 934: 929: 927: 923: 919: 914: 909: 905: 900: 895: 891: 887: 883: 880: 876: 873: 869: 865: 861: 857: 853: 849: 830: 819: 816: 809: 808: 807: 806: 802: 798: 794: 786: 784: 782: 778: 774: 770: 765: 760: 756: 748: 746: 744: 740: 736: 732: 728: 724: 719: 714: 707: 703: 699: 695: 691: 687: 683: 678: 676: 672: 668: 664: 661: 657: 653: 651: 647: 638: 636: 634: 629: 624: 620: 616: 612: 608: 604: 600: 596: 592: 589: 585: 577: 575: 573: 569: 565: 557: 553: 550: 546: 541: 539: 530: 520: 512: 493: 490: 487: 484: 481: 478: 475: 472: 469: 466: 463: 460: 457: 454: 451: 448: 445: 442: 435: 434: 433: 431: 423: 418: 416: 414: 409: 404: 401:. One writes 400: 396: 392: 388: 383: 379: 374: 371:. An integer 370: 366: 361: 357: 352: 348: 344: 340: 336: 317: 306: 300: 296: 293: 290: 287: 284: 281: 278: 271: 266: 262: 254: 253: 252: 250: 246: 242: 238: 234: 230: 226: 222: 218: 210: 208: 206: 202: 198: 194: 190: 184: 182: 178: 174: 170: 166: 162: 158: 154: 150: 146: 143: 140: 136: 132: 128: 124: 119: 115: 111: 110:number theory 106: 102: 97: 93: 88: 83: 79: 76: 72: 68: 65: 60: 56: 51: 47: 42: 37: 33: 29: 26: 22: 3221:Cryptography 3216:Group theory 2975:OpenPGP card 2955:Web of trust 2611:Cramer–Shoup 2597: 2466: 2284: 2148: 2131: 2123: 2042:Miller–Rabin 2024: 2017: 2010: 2005:Lucas–Lehmer 2003: 1897: 1889: 1864:. Retrieved 1859: 1836: 1805: 1795: 1741: 1737: 1727: 1684: 1680: 1674: 1626: 1603: 1590: 1544: 1540:export grade 1529: 1525:precomputing 1520: 1516: 1510: 1502: 1477: 1473: 1469: 1467: 1456: 1442: 1438: 1436: 1433:Cryptography 1395: 1377: 1373: 1367: 1362: 1354: 1350: 1346: 1342: 1340: 1329: 1276: 1271: 1263: 1257:running time 1252: 1248: 1244: 1240: 1239:is to raise 1236: 1232: 1227: 1224: 1221: 1112: 1108: 1106: 1101: 1096: 1092: 1090: 1030: 1024: 1019: 1014: 1003: 1001: 946: 941: 932: 930: 925: 921: 917: 912: 903: 898: 893: 889: 885: 878: 874: 863: 855: 851: 847: 845: 800: 796: 792: 790: 780: 776: 772: 768: 763: 758: 754: 752: 742: 738: 734: 730: 722: 720: 712: 705: 697: 693: 689: 681: 679: 674: 670: 662: 649: 645: 642: 632: 627: 622: 618: 614: 610: 606: 602: 598: 594: 590: 583: 581: 571: 567: 563: 551: 549:cyclic group 542: 531: 518: 510: 508: 430:powers of 10 427: 424:Powers of 10 412: 407: 402: 398: 397:to the base 394: 390: 386: 385:is termed a 381: 377: 372: 368: 364: 362: 355: 350: 346: 342: 341:with itself 338: 334: 332: 248: 247:with itself 244: 240: 236: 232: 228: 216: 214: 185: 180: 176: 168: 160: 156: 152: 148: 144: 138: 137:to the base 134: 130: 126: 122: 117: 113: 104: 100: 95: 91: 86: 81: 77: 70: 66: 58: 54: 49: 48:is a number 45: 40: 31: 27: 25:real numbers 23:, for given 18: 3041:RSA problem 2945:Fingerprint 2909:NSA Suite B 2873:RSA problem 2750:NTRUEncrypt 2298:Pollard rho 2255:Goldschmidt 1989:Pocklington 1979:Baillie–PSW 1283:square root 1268:exponential 846:defined by 389:(or simply 345:times. For 21:mathematics 3226:Logarithms 3205:Categories 3046:Strong RSA 3036:Phi-hiding 2899:IEEE P1363 2517:Algorithms 2410:Cornacchia 2405:Chakravala 1953:algorithms 1866:2019-01-01 1582:References 1489:, and the 1336:Peter Shor 1200:See also: 1196:Algorithms 1017:, then log 939:, then log 908:Conversely 888:. For all 787:Properties 227:by 1. Let 211:Definition 199:, such as 193:algorithms 155:(mod  129:(mod  98:such that 80:, and the 52:such that 2384:Berlekamp 2341:Euclidean 2229:Euclidean 2209:Toom–Cook 2204:Karatsuba 1902:CRC Press 1860:MathWorld 1822:2070-1721 1760:0885-064X 1666:2297-0576 1648:2297-0584 1608:CRC Press 1365:quickly. 1266:and thus 1174:⁡ 1161:⋅ 1155:⁡ 1136:⁡ 1061:→ 1055:: 979:→ 973:: 882:generated 828:→ 820:: 556:generator 491:… 443:… 391:logarithm 349:= 0, the 301:⏟ 294:⋅ 291:… 288:⋅ 282:⋅ 69:, powers 36:logarithm 3127:Lattices 3101:Pairings 2960:Key size 2894:CRYPTREC 2811:McEliece 2765:RLWE-SIG 2760:RLWE-KEX 2755:NTRUSign 2568:Paillier 2351:Lehmer's 2245:Chunking 2232:division 2161:Fermat's 1561:See also 1532:internet 1428:systems. 937:infinite 906:exists. 872:subgroup 805:function 588:subgroup 419:Examples 75:integers 2806:Lamport 2786:CEILIDH 2745:NewHope 2692:Schnorr 2675:ElGamal 2653:Ed25519 2533:Benaloh 2467:Italics 2389:Kunerth 2369:Cipolla 2250:Fourier 2219:FĂŒrer's 2113:Euler's 2103:Dixon's 2026:PĂ©pin's 1719:2337707 1711:1471990 1334:due to 1231:  1115:, then 1023:  945:  916:  902:  799:  767:  669:modulo 631:  562:  517:  411:  312:factors 251:times: 201:ElGamal 147:") for 90:  44:  2928:Topics 2904:NESSIE 2846:Theory 2774:Others 2631:X25519 2449:Schoof 2336:Binary 2240:Binary 2176:Shor's 1994:Fermat 1908:  1843:  1820:  1758:  1717:  1709:  1664:  1654:  1646:  1536:Logjam 1481:(e.g. 1382:smooth 1361:finds 1260:linear 1091:where 1008:finite 656:modulo 593:= {
, 142:modulo 34:, the 2740:Kyber 2735:BLISS 2697:SPEKE 2665:ECMQV 2658:Ed448 2648:EdDSA 2643:ECDSA 2573:Rabin 2270:Short 1999:Lucas 1787:(PDF) 1715:S2CID 1689:arXiv 1644:eISSN 1600:(PDF) 1497:over 1368:With 1012:order 910:, log 896:, log 858:is a 783:= 1. 686:power 660:prime 605:, 1, 449:0.001 163:is a 159:) if 120:= ind 114:index 108:. In 64:group 2940:OAEP 2914:CNSA 2791:EPOC 2636:X448 2626:ECDH 2265:Long 2199:Long 1906:ISBN 1841:ISBN 1818:ISSN 1756:ISSN 1662:ISSN 1652:ISBN 1574:and 1404:for 870:the 868:onto 854:) = 680:The 658:the 485:1000 455:0.01 432:are 428:The 363:Let 215:Let 171:and 30:and 3148:gap 3138:gap 2950:PKI 2833:XTR 2801:IES 2796:HFE 2727:SIS 2722:LWE 2707:STS 2702:SRP 2687:MQV 2670:EKE 2621:DSA 2606:BLS 2578:RSA 2553:GMR 2429:LLL 2275:SRT 2134:+ 1 2126:− 1 1974:APR 1969:AKS 1810:doi 1746:doi 1699:doi 1636:doi 1508:). 1503:see 1165:log 1146:log 1127:log 1046:log 1010:of 1006:is 964:log 935:is 931:If 892:in 884:by 877:of 684:th 621:of 570:in 543:In 479:100 461:0.1 358:= 1 195:in 173:gcd 167:of 84:log 38:log 19:In 3207:: 2781:AE 2616:DH 2433:KZ 2431:; 1904:. 1884:; 1858:. 1816:. 1808:. 1804:. 1768:^ 1754:. 1742:20 1736:. 1713:. 1707:MR 1705:. 1697:. 1685:26 1683:. 1660:. 1650:. 1642:. 1616:^ 1606:. 1602:. 1542:. 1485:, 1454:. 1415:), 1388:. 1351:bk 1338:. 1274:. 1104:. 928:. 795:= 718:. 716:17 709:17 677:. 635:. 613:, 609:, 601:, 597:, 574:. 560:10 540:. 534:10 527:10 523:10 515:10 473:10 415:. 380:= 360:. 151:≡ 103:= 57:= 3150:) 3146:( 3140:) 3136:( 3009:e 3002:t 2995:v 2724:/ 2719:/ 2502:e 2495:t 2488:v 2435:) 2427:( 2132:p 2124:p 1942:e 1935:t 1928:v 1914:. 1869:. 1849:. 1824:. 1812:: 1789:. 1762:. 1748:: 1721:. 1701:: 1691:: 1668:. 1638:: 1610:. 1521:G 1517:G 1501:( 1478:p 1474:Z 1470:G 1443:p 1439:Z 1408:, 1378:p 1374:p 1363:k 1355:p 1347:b 1343:p 1272:G 1264:G 1249:a 1245:k 1241:b 1237:G 1233:a 1228:b 1210:: 1180:. 1177:a 1169:b 1158:b 1150:c 1142:= 1139:a 1131:c 1113:H 1109:c 1102:n 1097:n 1093:Z 1076:, 1071:n 1066:Z 1058:H 1050:b 1031:n 1025:a 1020:b 1015:n 1004:H 987:. 983:Z 976:H 968:b 947:a 942:b 933:H 926:H 922:a 918:a 913:b 904:a 899:b 894:H 890:a 886:b 879:G 875:H 864:Z 856:b 852:k 850:( 848:f 831:G 824:Z 817:f 801:b 797:b 793:b 781:a 777:k 773:a 769:a 764:b 759:G 755:b 743:k 739:m 735:n 731:n 723:k 713:Z 706:Z 698:p 694:p 690:k 682:k 675:p 671:p 663:p 650:p 646:Z 633:a 628:b 623:G 619:a 615:b 611:b 607:b 603:b 599:b 595:b 591:G 584:b 572:G 568:a 564:a 552:G 519:a 511:a 494:. 488:, 482:, 476:, 470:, 467:1 464:, 458:, 452:, 446:, 413:a 408:b 403:k 399:b 395:a 382:a 378:b 373:k 369:G 365:a 356:b 351:k 347:k 343:k 339:b 335:b 318:. 307:k 297:b 285:b 279:b 272:= 267:k 263:b 249:k 245:b 241:b 237:k 233:G 229:b 217:G 181:m 179:, 177:a 175:( 169:m 161:r 157:m 153:a 149:r 145:m 139:r 135:a 131:m 127:a 123:r 118:x 105:a 101:b 96:k 92:a 87:b 78:k 71:b 67:G 59:a 55:b 50:x 46:a 41:b 32:b 28:a

Index

mathematics
real numbers
logarithm
group
integers
number theory
modulo
primitive root
gcd
Diffie–Hellman problem
algorithms
public-key cryptography
ElGamal
hardness assumption
group operation
identity element
powers of 10
exponential function
group-theoretic
cyclic group
generator
subgroup
Zp
modulo
prime
congruence classes
power
modular exponentiation
Fermat's little theorem
function

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