Contents

Chapter 8

Number Theory Check Digit Calculator use with section: 8.4 Letter Frequency Analysis Calculator use with sections: 8.6, 8.7 Affine Cipher Calculator for use with section: 8.6 RSA and Hill Cipher Calculator for use with section: 8.7 Applet 10. Checksum Calculator This applet calculates check digits for ISBN and UPC codes, and verifies the codes' accuracy. Applet 11. Letter Frequency Calculator This applet prepares a table of frequencies of occurrence of the letters in (encrypted) text that the user enters. Applet 12. Affine Cipher Calculator This applet encrypts and decrypts based on an affine cipher with user-defined key. Applet 13. RSA and Hill Cipher Calculator This applet encrypts and decrypts using the Hill Cypher and using the RSA public key system.