| 释义 |
trap-door|ˈtræpˈdɔə(r)|
[f. trap n.1 + door.]
a. A door, either sliding or moving on hinges, and flush with the surface, in a floor, roof, or ceiling, or in the stage of a theatre.
c1374Chaucer Troylus iii. 710 (759) ‘Which weye be ye comen..?’ Quod she... ‘Here at þis secre trappe dore’, quod he. 1489–90Rec. St. Mary at Hill 155 For viij ffoote di. tymber for o trapp dorr. 1579–80North Plutarch (1595) 1092 Aristippus..locked himself..in a litle high chamber with a trappe dore, and set his bed vpon it, and so slept. 1599Sandys Europæ Spec. (1632) 97 They have their trap doores or pit-falls in darke melancholy chambers. 1704S. Sewall Diary 12 Sept., Mrs. Tuthill falls through a Trap Door into the cellar. 1774Pennant Tour Scot. in 1772 93 The trap-door in the floor, contrived for the lowering in of the captives. 1840Dickens Old C. Shop xxxv, Getting on the roof of the house through the trap-door.
b. transf. and fig.
1648Gage West Ind. 82 Never to go to those parts, which were but snares and trap-dores to let down to hell. 1694Motteux Rabelais iv. xxxiv. 136 It no more open'd its Guttural Trap-door. 1860P. P. Carpenter in Rep. Smithsonian Instit. 1859 206 note, The operculum is a horny or shelly appendage to the end of the foot... It may be called..the trap-door or toe-nail. 1869J. Martineau Ess. II. 94 The trap-door of some hidden paradox.
c. Mining. A door in a level for directing the ventilating current; a weather-door.
1851Greenwell Coal-trade Terms Northumb. & Durh. 54 Trapper, a little boy whose employment consists in opening and shutting a trap-door when required. 1883Gresley Coal Mining Gloss., Trap-door, a small door, kept locked, fixed in a stopping or bolt, for giving access to firemen and certain others to the return air-ways, dams, or other disused places in a mine. 1886J. Barrowman Sc. Mining Terms 68.
d. Computers. A method of surreptitiously gaining unauthorized access to data belonging to other users of a computer.
[1976D. B. Parker Crime by Computer xii. 112 The Trojan horse had been rolled into the fortified city and fully accepted. In the unsuspecting environment a trap⁓door in its belly opened, and out popped the soldiers.] 1977New Yorker 29 Aug. 61/1 The nature of a trapdoor is that, while it is known to and usable by a penetrator, it is unrecognized by and unknown to other users of the system—even to the audit-trail mechanism. 1981Courier-Mail (Brisbane) 27 July 5/5 ‘Trapdoors’ allow people sharing a computer to slip into the confidential data streams of other users. 1982S. F. X. Dean Such Pretty Toys xiv. 191 He just entered the girl's name into the computer..as some sort of routing key or trapdoor to cut off any trace.
e. Cryptography. A piece of secret information that makes it easy to solve an otherwise very difficult code. Freq. attrib.
1978Communications Assoc. Computing Machinery XXI. 128 They are called ‘trap-door’ functions since the inverse functions are in fact easy to compute once certain private ‘trap-door’ information is known. 1982Beker & Piper Cipher Syst. 376 The general name given to this type of function (i.e. for which there does not appear to be a polynomial time algorithm but for which there is one so long as the method of application is known) is a trapdoor function. In our situation it is intended that the genuine receiver should be the only person who knows how to ‘open’ the trapdoor. 1984IEEE Trans. Information Theory XXX. 595/1 It is this presence of trapdoors that makes some of the attacks on the additive knapsack cryptosystems feasible.
f. Comb. trap-door spider, one of a group of large spiders, which make a nest in the shape of a tube with a hinged lid which opens and shuts like a trap-door; hence trap-door nest, etc.
1826Kirby & Sp. Entomol. III. xxxiv. 492 The trapdoor or mason spider (Mygale cœmentaria). 1864–5Wood Homes without H. vi. (1868) 116 Of all the burrowing spiders..none is so admirable an excavator as the Trap-door Spider of Jamaica [Cteniza]. 1883Pall Mall G. 29 Dec. 5/1 The trap-door spider is almost the typical natural curiosity of the Riviera. 1897A. Page Afternoon Ride 58 The..spider, decoyed out of his well-built trap-door nest. |