The following sequences have errors. Are they detectable? If you know that each has exactly two bits in error, are the errors correctable, and what ASCII characters might they each represent?
Your job is to (1) decompress this compressed message (which
is a brief description of an out-take from the munchkinland
scenes in The Wizard of Oz) and (2) report the
ratio of the size of the compressed data to the size
of the uncompressed data.
116, 111, 109, 32, 256, 111, 116, 101, 100,
259, 111, 265, 256, 32, 97, 110, 264, 261,
268, 260, 262, 264, 274, 261, 266, 260
Once you've turned your message into a sequence of integers between 1 and 42, you can encrypt the message one integer at a time using your recipient's public RSA key. At the other end, your recipient decrypts the integers using her private RSA key, translates the resulting integers into pairs of letters, and guesses at where you intended the spaces and punctuation to go. The end.
Suppose you have published your oh-so-secure public key (E,N) = (23,55) and someone has sent you the message "30 7 36 18". What's the message?
The technique described above for encrypting messages has a major weakness in addition to the pathetic smallness of your public key. What's the extra weakness, and how could a malefactor exploit it?
By the way, this is what "Digital Webster" says:
male·fac·tor \'mal-e-,fak-ter\ n
[ME, fr. L, fr. malefactus, pp. of malefacere to do evil,
fr. male + facere to do Ð more at DO] (15c)
1: one who commits an offense against the law; esp: FELON
2: one who does ill toward another
malefactor n
syn CRIMINAL, felon, lawbreaker, offender
rel blackguard, knave, miscreant, rascal, rogue, scoundrel;
evildoer, sinner, wrongdoer