Security assignment

Use the openssl library ([login to view URL]) to write the following two functions for encryption and decryption in a file fscrypt.cc. You should use block cipher method blowfish for encryption. Blowfish uses 64-bit blocks and typically 128-bit keys. // put the following lines in fscrypt.h #include "openssl/blowfish.h" // encrypt plaintext of length bufsize. Use keystr as the key. const int BLOCKSIZE = 8; // Block size for blowfish void *fs_encrypt(void *plaintext, int bufsize, char *keystr, int *resultlen); // decrypt ciphertext of length bufsize. Use keystr as the key. void *fs_decrypt(void *ciphertext, int bufsize, char *keystr, int *resultlen); Both functions allocate the result buffer of at least the required size (using new()) and return a pointer to it. Both functions also return the number of valid bytes in the result buffer in resultlen. The application code is responsible for deleting the buffer. Use CBC mode of encryption. For padding, pad with length of the pad in all the padded characters. Assume that the initialization vector contains NULL characters (all 0's). Description of blowfish functions can be found at [login to view URL] Use the following functions to faciliate your work: BF_set_key: use all characters of the keystr, excluding NULL terminator. Valid keystr is assumed to be a string. BF_cbc_encrypt and BF_ecb_encrypt ================================================ #include <assert.h> #include <stdio.h> #include <string.h> #include "fscrypt.h" int main() { char s[] = "hello world"; char *outbuf, *recvbuf; char pass[] = "top secret"; int len = 0; int recvlen = 0; outbuf = (char *) fs_encrypt((void *) s, strlen(s)+1, pass, &len); printf("%s %d\n", "length after encryption = ", len); int i = 0; printf("ciphertext = "); for (i = 0; i < len; i++) printf("%02x", outbuf[i]); printf("\n"); recvbuf = (char *) fs_decrypt((void *) outbuf, len, pass, &recvlen); assert(memcmp(s, recvbuf, recvlen) == 0); assert(recvlen == (strlen(s) + 1)); printf("plaintext = %s\n", recvbuf); } ================================================