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Space–time tradeoff

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A space–time trade off can be applied to the problem of data storage. If data is stored uncompressed, it takes more space but access takes less time than if the data were stored compressed (since compressing the data reduces the amount of space it takes, but it takes time to run the
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every time the page is requested would be trading time for space; more time used, but less space. Rendering the image when the page is changed and storing the rendered images would be trading space for time; more space used, but less time. This technique is more generally known as
200:: an implementation can include the entire table, which reduces computing time, but increases the amount of memory needed, or it can compute table entries as needed, increasing computing time, but reducing memory requirements. 229:). Depending on the particular instance of the problem, either way is practical. There are also rare instances where it is possible to directly work with compressed data, such as in the case of compressed 270:. This technique makes the code longer for each iteration of a loop, but saves the computation time required for jumping back to the beginning of the loop at the end of each iteration. 168:. Using stored knowledge or encoding stimuli reactions as "instincts" in the DNA avoids the need for "calculation" in time-critical situations. More specific to computers, 380: 344: 410: 439: 302:
to crack passwords in minutes instead of weeks. Decreasing the size of the rainbow table increases the time required to iterate over the hash space.
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data structures. Indexes improve the speed of lookup operations at the cost of additional space. Without indexes, time-consuming
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in cryptography, where the adversary is trying to do better than the exponential time required for a
40: 522: 475: 242: 484: – Something a computer needs needed to solve a problem, such as processing steps or memory 517: 481: 463: 349: 316: 385: 487: 447:, where the time complexity of a problem can be reduced significantly by using more memory. 282: 415: 8: 444: 153: 535: 310: 295: 286: 255: 35: 561: 556: 527: 226: 114: 103: 95: 539: 472: – Rules out assigning to arbitrary functions their computational complexity 246: 213: 130: 122: 267: 209: 176: 164:
Biological usage of time–memory tradeoffs can be seen in the earlier stages of
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which uses the space–time tradeoff with the additional parameter of data.
298:. Rainbow tables use partially precomputed values in the hash space of a 169: 233:, where it is faster to work with compression than without compression. 557:
Philippe Oechslin: Making a Faster Cryptanalytic Time-Memory Trade-Off.
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Larger code size can be traded for higher program speed when applying
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Hellman, Martin (July 1980). "A Cryptanalytic Time-Memory Tradeoff".
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The utility of a given space–time tradeoff is affected by related
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have been implemented since the very earliest operating systems.
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Algorithms that also make use of space–time tradeoffs include:
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Database Management Systems offer the capability to create
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operations are sometimes required to locate desired data.
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refers to the time consumed in performing a given task (
418: 388: 352: 319: 478: – Amount of resources to perform an algorithm 219: 203: 433: 404: 374: 338: 261: 191: 236: 109:increased space usage with decreased time. Here, 568: 179:first proposed using a time–memory tradeoff for 507: 196:A common situation is an algorithm involving a 16:Algorithm trading more space for lower time 521: 152:speed, storage space), and is subject to 68:Learn how and when to remove this message 80: 510:IEEE Transactions on Information Theory 309:uses a space–time tradeoff to find the 569: 117:consumed in performing a given task ( 186: 92:the algorithmic space-time continuum 18: 13: 14: 588: 562:Once Upon a Time-Memory Tradeoff. 550: 273: 466: – Property of an algorithm 451:Time/memory/data tradeoff attack 220:Compressed vs. uncompressed data 204:Database indexes vs. table scans 23: 262:Smaller code vs. loop unrolling 192:Lookup tables vs. recalculation 501: 428: 422: 369: 356: 237:Re-rendering vs. stored images 1: 494: 45:casual tone, lack of detail. 7: 457: 441:space) of the naive attack. 382:space) versus the expected 300:cryptographic hash function 43:. The specific problem is: 10: 593: 285:algorithm for calculating 159: 307:meet-in-the-middle attack 532:10.1109/tit.1980.1056220 476:Computational complexity 375:{\displaystyle O(2^{n})} 339:{\displaystyle 2^{n+1}} 227:decompression algorithm 482:Computational resource 470:Blum's speedup theorem 464:Algorithmic efficiency 435: 412:encryptions (but only 406: 405:{\displaystyle 2^{2n}} 376: 340: 249:and rendering it as a 577:Software optimization 436: 407: 377: 341: 88:time–memory trade-off 434:{\displaystyle O(1)} 416: 386: 350: 317: 283:Baby-step giant-step 84:space–time trade-off 50:improve this article 39:to meet Knowledge's 445:Dynamic programming 287:discrete logarithms 154:diminishing returns 98:is a case where an 431: 402: 372: 336: 296:brute-force attack 488:Savitch's theorem 346:encryptions (and 311:cryptographic key 241:Storing only the 187:Types of tradeoff 78: 77: 70: 41:quality standards 32:This article may 584: 544: 543: 525: 505: 440: 438: 437: 432: 411: 409: 408: 403: 401: 400: 381: 379: 378: 373: 368: 367: 345: 343: 342: 337: 335: 334: 96:computer science 86:, also known as 82: 73: 66: 62: 59: 53: 27: 26: 19: 592: 591: 587: 586: 585: 583: 582: 581: 567: 566: 553: 548: 547: 523:10.1.1.120.2463 506: 502: 497: 460: 417: 414: 413: 393: 389: 387: 384: 383: 363: 359: 351: 348: 347: 324: 320: 318: 315: 314: 276: 264: 239: 222: 214:Full table scan 206: 194: 189: 166:animal behavior 162: 74: 63: 57: 54: 47: 28: 24: 17: 12: 11: 5: 590: 580: 579: 565: 564: 559: 552: 551:External links 549: 546: 545: 516:(4): 401–406. 499: 498: 496: 493: 492: 491: 485: 479: 473: 467: 459: 456: 455: 454: 448: 442: 430: 427: 424: 421: 399: 396: 392: 371: 366: 362: 358: 355: 333: 330: 327: 323: 303: 292:Rainbow tables 289: 275: 274:Other examples 272: 268:loop unrolling 263: 260: 238: 235: 231:bitmap indices 221: 218: 210:Database index 205: 202: 193: 190: 188: 185: 177:Martin Hellman 170:look-up tables 161: 158: 146:variable costs 113:refers to the 76: 75: 31: 29: 22: 15: 9: 6: 4: 3: 2: 589: 578: 575: 574: 572: 563: 560: 558: 555: 554: 541: 537: 533: 529: 524: 519: 515: 511: 504: 500: 489: 486: 483: 480: 477: 474: 471: 468: 465: 462: 461: 452: 449: 446: 443: 425: 419: 397: 394: 390: 364: 360: 353: 331: 328: 325: 321: 312: 308: 304: 301: 297: 293: 290: 288: 284: 281: 280: 279: 271: 269: 259: 257: 252: 248: 244: 234: 232: 228: 217: 215: 211: 201: 199: 184: 182: 181:cryptanalysis 178: 173: 171: 167: 157: 155: 151: 147: 143: 138: 136: 135:response time 132: 128: 125:, etc.), and 124: 120: 116: 112: 108: 105: 101: 97: 93: 89: 85: 72: 69: 61: 51: 46: 42: 38: 37: 30: 21: 20: 513: 509: 503: 277: 265: 251:bitmap image 247:vector image 245:source of a 240: 223: 207: 198:lookup table 195: 174: 163: 139: 126: 115:data storage 110: 91: 87: 83: 79: 64: 55: 48:Please help 44: 33: 148:(of, e.g., 131:computation 52:if you can. 495:References 58:March 2014 518:CiteSeerX 100:algorithm 571:Category 458:See also 313:in only 175:In 1980 133:time or 34:require 256:caching 160:History 104:program 36:cleanup 540:552536 538:  520:  107:trades 536:S2CID 142:fixed 111:space 305:The 144:and 127:time 528:doi 243:SVG 150:CPU 137:). 123:HDD 119:RAM 102:or 94:in 90:or 573:: 534:. 526:. 514:26 512:. 258:. 183:. 156:. 121:, 542:. 530:: 429:) 426:1 423:( 420:O 398:n 395:2 391:2 370:) 365:n 361:2 357:( 354:O 332:1 329:+ 326:n 322:2 81:A 71:) 65:( 60:) 56:(

Index

cleanup
quality standards
improve this article
Learn how and when to remove this message
computer science
algorithm
program
trades
data storage
RAM
HDD
computation
response time
fixed
variable costs
CPU
diminishing returns
animal behavior
look-up tables
Martin Hellman
cryptanalysis
lookup table
Database index
Full table scan
decompression algorithm
bitmap indices
SVG
vector image
bitmap image
caching

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