PLEASE SOLVE FROM 4 TO 10

1. (1 point) Decrypt the following messages encrypted using the Caesar 4. (1 point ) cipher: Decrypt the message BFAASDPXWYBP which was en- f(p)=(p+3)mod26 crypted using the affine cipher: Alphabet: 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) HDW GLP VXP (b) FUDCB KDWV f(p)=(5p+9)mod26 Answer(s) submitted: Alphabet: A=0,B=1,,Z=25 Message: (incorrect) Answer(s) submitted: 2. (1 point) Encrypt the message " HALT " by translating the letters into numbers (via A=0,B=1,C=2,D=3,E=4,F=5,G=6,H=7,I= 5. (1 point) In this problem we explore the relationship be8 , tween password length and cryptographic security. J=9,K=10,L=11,M=12,N=13,O=14,P=15,Q= Suppose a password consists of 9 ASCII characters. You can S=18,T=19,U=20,V=21,W=22,X=23,Y=24,Z=25 ter in the password is printable. and then applying the encryption function given, and then trans- What is the size of the keyspace that consists of passwords lating the numbers back into letters. of this form? (a) f(p)=(p+2)mod26 What is the equivalent key length in bits? (b) f(p)=(p+11)mod26 Assuming that you could check one password every 1012 (c) f(p)=(p+3)mod26 seconds, what is the worst case running time for cracking this Answer(s) submitted: password by brute force search (in days)? Now assume that the user used only 29 characters from the keyboard. What is the key length in bits in this case? How many days, in the worst case, would it take to break this weaker password? You can't round to the nearest day here - be as exact as possible. 3. (1 point) Encrypt the message " MATH " by translating Supposing you used only 29 characters, how long is the the letters into numbers shortest password that achieves 182 bits of security? and then applying the encryption function given, and then transAnswer(s) submitted: lating the numbers back into letters