CRYPTOGRAPHY PROBLEMS
---------------------

1.  Decode:  KYRFGQDSL

2.  Decode:

LEDFKPKLEX DP VODQQHJ DJ QEDP MOZJC AKKB, QEH TJDUHOPH, VEDRE PQZJCP
RKJQDJTZFFX KLHJ QK KTO MZYH. ATQ QEH AKKB RZJJKQ AH TJCHOPQKKC TJFHPP
KJH IDOPQ FHZOJP QK RKGLOHEHJC QEH FZJMTZMH ZJC OHZC QEH FHQQHOP DJ
VEDRE DQ DP RKGLKPHC. DQ DP VODQQHJ DJ QEH FZJMTZMH KI GZQEHGZQDRP,
ZJC DQP REZOZRQHOP ZOH QODZJMFHP, RDORFHP, ZJC KQEHO MHKGHQODR IDMTOHP
VDQEKTQ VEDRE DQ DP ETGZJFX DGLKPPDAFH QK TJCHOPQZJC Z PDJMFH VKOC KI
DQ.

   --- MZFDFHK
   
3.  Decode:

HFSGLQUIE PUB UVTTG MKRRH HEQ

Vigenere, keyword CRYPTOGRAPHY.
From Davis, p. 8

4.  Decode:

23, 52, 85, 91, 15, 06, 53, 61, 30, 72, 23

"Numerical Vigenere"  --- pseudorandom sequence
based on a seed (the "keyword").  See section 6
of Davis.  Use the character encoding on page 9.

5.  Decode:

14756

RSA with N = 16781, e = 5.  The result 
is a nice four-digit number.
See Davis, section 9.

REFERENCES:

   Tom Davis' article at  http://mathcircle.berkeley.edu/BMC3/crypto.pdf