Symmetric or private key cryptography uses fixed size m-bit key and m-bit messag
ID: 3576395 • Letter: S
Question
Symmetric or private key cryptography uses fixed size m-bit key and m-bit message block to be encrypted to produce m-bit cipher text. If the message to be encrypted is n-bits long and n >> m, the message needs to be broken into multiple blocks of m-bits.
a) Explain the working of a Cipher Chain Mode stream cipher of doing such encryption.
b) Show the detailed working of Cipher Chain Mode stream cipher having a block size n = 4 bits. Show the detailed working of this cipher for that encrypts and decrypts a 16-bit message organized as four blocks b0, b1, b2, b3 = “0001 0010 0011 0100”. The 4-bit block encryption (and decryption) is done by EX-ORing each 4-bit message block with the 4-bit key K = “1010”. The stream cipher is initialized to C-1 = 1101. Compute the value of 4-bit cipher blocks C0, C1, C2, C3 and using these cipher blocks, compute the value of decrypted 4-bit message blocks M0, M1, M2, M3.
Explanation / Answer
#include <stdio.h>
#include <string.h>
void encrypt(char password[],int key)
unsigned int i;
for(i=0;i<strlen(password);++i)
}
void decrypt(char password[],int key)
unsigned int i;
for(i=0;i<strlen(password);++i)
}
int main()
#include <stdio.h>
#include <string.h>
void encrypt(char password[],int key)
unsigned int i;
for(i=0;i<strlen(password);++i)
}
void decrypt(char password[],int key)
unsigned int i;
for(i=0;i<strlen(password);++i)
}
int main()
#include <stdio.h>
#include <string.h>
void encrypt(char password[],int key)
unsigned int i;
for(i=0;i<strlen(password);++i)
}
void decrypt(char password[],int key)
unsigned int i;
for(i=0;i<strlen(password);++i)
}
int main()
#include <stdio.h>
#include <string.h>
void encrypt(char password[],int key)
unsigned int i;
for(i=0;i<strlen(password);++i)
}
void decrypt(char password[],int key)
unsigned int i;
for(i=0;i<strlen(password);++i)
}
int main()
#include <stdio.h>
#include <string.h>
void encrypt(char password[],int key)
unsigned int i;
for(i=0;i<strlen(password);++i)
}
void decrypt(char password[],int key)
unsigned int i;
for(i=0;i<strlen(password);++i)
}
int main()
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