Answer:
See explaination
Explanation:
//CryptoManager.java
public class CryptoManager {
static int LOWER_BOUND=32;
static int UPPER_BOUND=95;
/*This method determines if a string is within the allowable bounds of ASCII
codes according to the LOWER_BOUND and UPPER_BOUND characters. The parameter
plainText is the string to be encrypted. The method returns true if all
characters are within the allowable bounds, false if any character is outside.*/
public static boolean stringInBounds (String plainText)
{
boolean flag=true;
//determines if a string is within the allowable bounds of ASCII
//codes according to the LOWER_BOUND and UPPER_BOUND characters.
for(int i=0;i<plainText.length();i++)
{
if(!((int)plainText.charAt(i)>=LOWER_BOUND && (int)plainText.charAt(i)<=UPPER_BOUND))
{ //false if any character is outside the bounds
flag=false;
break;
}
}
//returns true if all characters are within the allowable bounds
return flag;
}
/*This method encrypts a string according to the Caesar Cipher. The integer key
specifies an offset and each character in plainText is replaced by the character
the specified distance away from it. The parameter plainText is an uppercase
string to be encrypted. The parameter key is an integer that specifies the
offset of each character. The method returns the encrypted string.*/
public static String encryptCaesar(String plainText, int key)
{
//Wrap around the key, if it is greater than the UPPER_BOUND
key=Wrap_around(key);
//encrypted text
String res="";
//encryption
for(int i=0;i<plainText.length();i++)
{
res+=Character.toString((char) ((int)plainText.charAt(i)+key));
}
//return result
return res;
}
/* This method decrypts a string according to the Caesar Cipher. The integer
key specifies an offset and each character in encryptedText is replaced by
the character "offset" characters before it. This is the inverse of the
encryptCaesar method. The parameter encryptedText is the encrypted string
to be decrypted, and key is the integer used to encrypt the original text.
The method returns the original plain text string.*/
public static String decryptCaesar(String encryptedText, int key){
//Wrap around the key, if it is greater than the UPPER_BOUND
key=Wrap_around(key);
//decrypted text
String org="";
//encryption
for(int i=0;i<encryptedText.length();i++)
{
org+=Character.toString((char) ((int)encryptedText.charAt(i)-key));
}
//return result
return org;
}
public static int Wrap_around(int key)
{
while(key>UPPER_BOUND)
{
key-=(UPPER_BOUND-LOWER_BOUND);
}
return key;
}
/* This method encrypts a string according to the Bellaso Cipher. Each character
in plainText is offset according to the ASCII value of the corresponding
character in bellasoStr, which is repeated to correspond to the length of
plaintext. The method returns the encrypted string.*/
public static String encryptBellaso(String plainText, String bellasoStr)
{
//encrypted text
String res="";
//Adjust length of bellasoStr to plainText
while(bellasoStr.length()<plainText.length())
{
bellasoStr+=bellasoStr.substring(0,(plainText.length()-bellasoStr.length()));
}
//encryption
for(int i=0;i<plainText.length();i++)
{
char c=(char)Wrap_around((int)plainText.charAt(i)+(int)bellasoStr.charAt(i) );
res+=Character.toString(c);
}
//return result
return res;
}
/*
This method decrypts a string according to the Bellaso Cipher. Each character
in encryptedText is replaced by the character corresponding to the character in
bellasoStr, which is repeated to correspond to the length of plainText. This is
the inverse of the encryptBellaso method. The parameter encryptedText is the
encrypted string to be decrypted, and bellasoStr is the string used to encrypt
the original text. The method returns the original plain text string.*/
public static String decryptBellaso(String encryptedText, String bellasoStr)
{
//decrypted text
String res="";
//Adjust length of bellasoStr to plainText
while(bellasoStr.length()<encryptedText.length())
{
bellasoStr+=bellasoStr.substring(0,(encryptedText.length()-bellasoStr.length()));
}
//decryption
for(int i=0;i<encryptedText.length();i++)
{
char c=(char)Wrap_around((int)encryptedText.charAt(i)-(int)bellasoStr.charAt(i) );
res+=Character.toString(c);
}
//return result
return res;
}
}
