Math for Liberal Studies – Fall 2007 Dr. Hamblin Chapter 17: Substitution Ciphers Answer the following questions based on the discussions from class. 1. Use the Caesar cipher (shift 3) to encode the message “ET TU BRUTUS.” 2. Use the Caesar cipher (shift 3) to decode the message “BRX MXVW VWDEEHG PH.” 3. Use the ROT13 cipher to encode the message “HASTA LA VISTA BABY.” 4. Encode the message “AFFINE CIPHER” using an affine cipher where you multiply by 5 and add 2. 5. The quotation below has been encrypted using a substitution cipher. Use frequency analysis and your knowledge of English to decrypt the message. UGSXQXAI XI QEZ WZYQSZ PVQ GJ WZQQXYW FGQZI JVGL QEZ UGGV PYH APLUPXWY JDYHI JVGL QEZ VXAE OM UVGLXIXYW QG UVGQZAQ ZPAE JVGL QEZ GQEZV. Hints: GJ and QG are both words, so there are very few possibilities for what these words can be. Also, Q appears very frequently. Math for Liberal Studies – Fall 2007 Dr. Hamblin 6. Encode the message “DRINK YOUR OVALTINE” using a Vignère cipher with key word “RALPH.” 7. The message “LFNRQ ZLQER REXWQ STHTM BSNHG AA” was encoded using a Vignère cipher with the keyword “GONE.” Decode the message. 8. Encode the message “HERE’S LOOKING AT YOU, KID” using an Autokey cipher with keyword “RICK.” 9. The message “IOWGG VBQWA OIAEW RJFLT D” was encoded using an Autokey cipher with keyword “BACON.” Decode the message. Solutions 1. HW WX EUXWXV 2. YOU JUST STABBED ME 3. UNFGN YN IVFGN ONOL 4. CBBQPW MQZLWJ 5. Politics is the gentle art of getting votes from the poor and campaign funds from the rich by promising to protect each from the other. 6. VKWEI QHII MNTZKGFX 7. Frankly, my dear, I don’t give a damn. 8. YMTO’Z PFSCTBU KB LUU, DGR 9. Houston, we have a problem .