CryptoGraphy

These are the lab assignments performed during the course of cryptography

Lab 1

• WAP in python to implement client and server communication.

• WAP in python to implement Euclidean algorithm to find the GCD.

• WAP in python to implement extended Euclidean algorithm to find the GCD along with s and t values.

• WAP in python to find out the additive and multiplicative inverse pairs of set Zn.

• WAP in python to find out the additive and multiplicative inverse of an integer b using extended Euclidean algorithmof set Zn.

Lab 2

• WAP to find the solutions of equations: a.14x=12mod 18 b.3x+4=6 mod 132.

• WAP to implement Additive cipher(key=20), Multiplicative cipher(key=15)and affine cipher(key=15,20). To encrypt the message “this is an exercise”.

• WAP to perform brute force attack on the cipher text“dvvkzecfssprkkve”.

• WAP to perform brute force attack on the cipher text “YMJHFJXFWHNUMJWNXTSJTKYMJJFWQNJXYPSTBSFSIXNRUQJXYHNUMJWX”

• WAP to use brute force attack to decipher the message :Assume Affine cipher is used and “ab” is encrypted by “GL”.

• WAP to perform statistical attack on the ciphertext:

ymnxhtzwxjfnrxytuwtanijdtzbnymijyfnqjipstbqjiljtknrutwyfsyyjhmstqtlnjxfsifuuqnhfyntsymfyfwjzxjinsymjnsyjwsjyizjytymjgwtfisfyzwjtkymnxknjqiymjhtzwxjhtajwxtsqdxjqjhyjiytunhxkthzxxnslknwxytsxtrjfiafshjiytunhxnsnsyjwsjyyjhmstqtlnjxjlbnwjqjxxqfsxrtgnqjnsyjwsjyrzqynhfxyfsiymjsfxjqjhyntstkhzwwjsyfsisjcyljsjwfyntsfuuqnhfyntsxfsixjwanhjxjluunuyaatnudtzbnqqqjfwsmtbymjnsyjwsjybtwpxfsimtbxjwanhjxfsifuuqnhfyntsxfwjuwtanijiytzxjwxtkymjnsyjwsjyymnxpstbqjiljbnqqmjqudtz

• WAP to perform statistical and pattern attack over the ciphertext:

ziolegxkltqodlzgofzkgrxetngxzgzithkofeohstlqfrzteifojxtlgyltexkofuegdhxztklqfregdhxztkftzvgkalvoziygexlgfofztkftzltexkoznzitegxkltoltyytezoctsnlhsozofzgzvghqkzlyoklzofzkgrxeofuzitzitgkngyeknhzgukqhinofesxrofuigvdqfnesqlloeqsqfrhghxsqkqsugkozidlvgkaturtlklqrouozqsloufqzxktlqfrltegfrhkgcorofurtzqoslgyktqsofztkftzltexkoznhkgzgegslqsugkozidlqfrziktqzltuohltecokxltlyoktvqsslitfetngxvossstqkfwgzizitgktzoeqsqlhtezlgyegdhxztkqfrftzvgkaltexkoznqlvtssqligvziqzzitgknolqhhsotrofzitofztkftzziolafgvstrutvossitshngxofrtloufofuqfrrtctsghofultexktqhhsoeqzogflqfrftzvgkahkgzgegslqlvtssqlwxosrofultexktftzvgkal

Lab 3

• Generate the cipher text of the plain text “we are discovered, save yourself” using playfair cipher.

• Generate the cipher text of the plain text “PL AY FA IR ME SS AG E” using playfair cipher and the secret key is “COMMONLOUNGE”.

• WAP to encrypt the message “She is listening” using the 6-character keyword “PASCAL” with Vigenere cipher.

• WAP to perform cryptanalysis over ciphertext “fupcmtgzkyukbqfjhuktzkkixtta” using hill cipher.

Lab 4

• Alice needs to send the message “Enemy attacks tonight” to Bob.They agreed to use keyed transposition cipher with key value:31452. Implement double transpositioncipher over it and generate the ciphertext.

• Create a key stream with linear feedback shift register with 4 cells in whichb4= b1 exor b0 Show the value of output for 20 transitions(if the seed is 0001).

• Write a code to encrypt a message A Midsummer Night's Dream, which is a comedy written by Shakespeare.You have to use key: SWINDONand keyed transpositioncipher row-column.

• Findthe result of multiplying P1=000100110and P2=10011110 with irreducible polynomial100011010(nine bits).

Lab 5

• Implement DES Algorithm by using the helping PDF.

• Implement AES Algorithm by using the helping PDF.

• Implement a client and a server on different computers. Perform the communication between these two entities by using RSA cryptosystem. (Client.ipynb and Server.ipynb)

• Implement a client and a server on different computers. Perform the authentication of senderbetween these two entities by using RSA digital signature cryptosystem. (UDPClient.ipynb and UPDServer.ipynb)

Lab 6

• Write a program to implement Chinese Remainder Theorem.