1. Implement both encryption AND decryption of the Vigenere cipher with 26 English letters and 1 space character "_" in its tableau as shown in class. You may use any major programming languages.
You will get extra 5 points if you add a cgi interface to this cipher.
2. The following cipher-text was encrypted using the Vigenere cipher with 26 English letters and 1 space character "_" in its tableau as shown in class:
tyxvahlvowsrahsoervceispsqlj_hxgyqfjtqgi_j___bafebacoewvowsohvs_nvet_dgo_tghidzvbklvodsjuhsjwdsmerwdnvkn_jgvrvv_ilxvhzevnelvodsohvsyhrfyeqga_yan_dgo_rloatcdnxsxujsmaj__rqgi_j___wtytqlcajsreq_wvvshauxvokjvpekdtzgi_kfwsitdlrugeqlceqxidqtidqtdmqga_ihtidzvidswlbsdtisailxvvrjdeja_sqan_afjwbxzgvsjfqlceqxiecqvadwvtyan_afjwbxzgvsyadsjnbqvbvszehaqeusdnqlceqydrilvidkoadv__wjjmqlceqvjnlxmtvwvsfqvhvfyeqao_zkveik_njawlqlcajsohvsyodn_rjxz_iht_sxvthxwtvwvwzlc_j___klhoilvlzu_rrddto
This cipher-text is also downloadable from this file .
The plaintext consists of several meaningful English sentences.
a). Try to decrypt this message. Write down your decryption procedure.
b). In general, how do you break the simple vigenere cipher?
3. Implement the 3-rotor machine with the wirings as shown in Fig. Your implementation should be able to easily change a) the order of the 3 rotors b) the initial rotational positions of the rotors.
New : now you can check your rotor implementation here .
What to sumbit : submit any paper version of your homework in class on Sep. 20, and also send me a URL which contains all your files related to this homework, such as readme files, source codes, executables.
The Vigenere Tableau
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z -
A A B C D E F G H I J K L M N O P Q R S T U V W X Y Z -
B B C D E F G H I J K L M N O P Q R S T U V W X Y Z - A
C C D E F G H I J K L M N O P Q R S T U V W X Y Z - A B
D D E F G H I J K L M N O P Q R S T U V W X Y Z - A B C
E E F G H I J K L M N O P Q R S T U V W X Y Z - A B C D
F F G H I J K L M N O P Q R S T U V W X Y Z - A B C D E
G G H I J K L M N O P Q R S T U V W X Y Z - A B C D E F
H H I J K L M N O P Q R S T U V W X Y Z - A B C D E F G
I I J K L M N O P Q R S T U V W X Y Z - A B C D E F G H
J J K L M N O P Q R S T U V W X Y Z - A B C D E F G H I
K K L M N O P Q R S T U V W X Y Z - A B C D E F G H I J
L L M N O P Q R S T U V W X Y Z - A B C D E F G H I J K
M M N O P Q R S T U V W X Y Z - A B C D E F G H I J K L
N N O P Q R S T U V W X Y Z - A B C D E F G H I J K L M
O O P Q R S T U V W X Y Z - A B C D E F G H I J K L M N
P P Q R S T U V W X Y Z - A B C D E F G H I J K L M N O
Q Q R S T U V W X Y Z - A B C D E F G H I J K L M N O P
R R S T U V W X Y Z - A B C D E F G H I J K L M N O P Q
S S T U V W X Y Z - A B C D E F G H I J K L M N O P Q R
T T U V W X Y Z - A B C D E F G H I J K L M N O P Q R S
U U V W X Y Z - A B C D E F G H I J K L M N O P Q R S T
v V W X Y Z - A B C D E F G H I J K L M N O P Q R S T U
W W X Y Z - A B C D E F G H I J K L M N O P Q R S T U V
X X Y Z - A B C D E F G H I J K L M N O P Q R S T U V W
Y Y Z - A B C D E F G H I J K L M N O P Q R S T U V W X
Z Z - A B C D E F G H I J K L M N O P Q R S T U V W X Y
- - A B C D E F G H I J K L M N O P Q R S T U V W X Y Z