CSE 190 -- Lecture 4,5 -- Apr 6,8


Substitution Ciphers: Rot-N, general mono-alphabetic substitution.
Block Ciphers: DES. (Substitution w/ large blocks, or an alphabet of 2blocksize.)
RSA overview.

Assignment 2. Decrypt the following messages:
  • VH OJCQNA QJM J BVJUU NBCJCN RW WXCCRWPQJVBQRAN; R FJB CQN CQRAM XO
    OREN BXWB. QN BNWC VN CX NVJWDNU LXUUNPN RW LJVKARMPN JC OXDACNNW
    HNJAB XUM, FQNAN R ANBRMNM CQANN HNJAB, JWM JYYURNM VHBNUO LUXBN CX VH
    BCDMRNB: KDC CQN LQJAPN XO VJRWCJRWRWP VN (JUCQXDPQ R QJM J ENAH
    BLJWCH JUUXFJWLN) KNRWP CXX PANJC OXA J WJAAXF OXACDWN, R FJB KXDWM
    JYYANWCRLN CX VA. SJVNB KJCNB, JW NVRWNWC BDAPNXW RW UXWMXW, FRCQ FQXV
    R LXWCRWDNM OXDA HNJAB; JWM VH OJCQNA WXF JWM CQNW BNWMRWP VN BVJUU
    BDVB XO VXWNH, R UJRM CQNV XDC RW UNJAWRWP WJERPJCRXW, JWM XCQNA YJACB
    XO CQN VJCQNVJCRLB, DBNODU CX CQXBN FQX RWCNWM CX CAJENU, JB R JUFJHB
    KNURNENM RC FXDUM KN BXVN CRVN XA XCQNA VH OXACDWN CX MX.  FQNW R UNOC
    VA. KJCNB, R FNWC MXFW CX VH OJCQNA; FQNAN, KH CQN JBBRBCJWLN XO QRV
    JWM VH DWLUN SXQW, JWM BXVN XCQNA ANUJCRXWB, R PXC OXACH YXDWMB, JWM J
    YAXVRBN XO CQRACH YXDWMB J HNJA CX VJRWCJRW VN JC UNHMNW: CQNAN R
    BCDMRNM YQHBRL CFX HNJAB JWM BNENW VXWCQB, TWXFRWP RC FXDUM KN DBNODU
    RW UXWP EXHJPNB.
    
  • SYGKJNDGSZCUIMPLDIFUGNIDXKCGCSYYWDXIDWXW
    NFGJGGKKIFWYLKCGYSDGWDXBGKKCGFWYYUGKFGGD
    MBIDRGWZWSDFGLGGOKCGFWYYUGKFGGDMBWBFGZIK
    IGWRCKCGUIMYXGPBKCWKCWAGQWYYGDKIGWRCWDXB
    IJGWPGYIWAGBWDXBIJGBIDGWPYNUWYYBFGCWAGKI
    MBGWBOGYYKIJWLGKCGJUWYWDRGBKWNFCGPGNIMWP
    GMDKSYIMPUWRLBWPGKMPDGXFGFGWPIMPQSDZGPBP
    IMZCFSKCCWDXYSDZKCGJICVMBKWDIKCGPLSDXIQI
    MKXIIPZWJGIDGIDWBSXGSKRIJGBKIYSKKYGJIPGK
    CGPGFCGPGSKSBFGXIDIKDGGXKCGFWYYCGSBWYYOS
    DGWDXSWJWOOYGIPRCWPXJNWOOYGKPGGBFSYYDGAG
    PZGKWRPIBBWDXGWKKCGRIDGBMDXGPCSBOSDGBSKG
    YYCSJCGIDYNBWNBZIIXQGDRGBJWLGZIIXDGSZCUI
    MPB
    
  • You may wish to write short programs to calculate various statistics to aid you in decrypting these messages (esp the 2nd).
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