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Gronsfeld.java
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Gronsfeld.java
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package cryptography.ciphers.gronsfeld;
import cryptography.Mode;
public class Gronsfeld {
private static int[] addedNumeric;
public static void main(String[] args) {
}
public static String gronsfeld(String input, String keyword, Mode mode) {
String output = "";
if (mode == Mode.ENCRYPT) {
input = formatInputString(input);
int[] numericInput = turnInputNumeric(input);
keyword = formatKeywordString(keyword);
String lengthenedKeyword = generateGronsfeldKeyword(keyword, input);
int[] numericKeyword = turnKeywordNumeric(lengthenedKeyword);
addedNumeric = addNumericStrings(mode, numericInput, numericKeyword);
output = turnAlpha(addedNumeric);
}
if (mode == Mode.DECRYPT) {
input = formatInputString(input);
int[] numericInput = turnInputNumeric(input);
keyword = formatKeywordString(keyword);
String lengthenedKeyword = generateGronsfeldKeyword(keyword, input);
int[] numericKeyword = turnKeywordNumeric(lengthenedKeyword);
addedNumeric = addNumericStrings(mode, numericInput, numericKeyword);
output = turnAlpha(addedNumeric);
}
return output;
}
private static String formatInputString(String originalString) {
return (originalString.replaceAll("[^A-Za-z]", "")).toUpperCase();
}
private static String formatKeywordString(String originalString) {
return (originalString.replaceAll("[^0-9]", ""));
}
private static String generateGronsfeldKeyword(String keyword, String input) {
StringBuilder returnKeyword = new StringBuilder();
while (returnKeyword.length() < input.length()) {
returnKeyword.append(keyword);
}
returnKeyword = new StringBuilder(returnKeyword.substring(0, input.length()));
return returnKeyword.toString();
}
private static int[] turnInputNumeric(String originalString) {
int[] returnNumeric = new int[originalString.length()];
for (int i = 0; i < originalString.length(); i++) {
returnNumeric[i] = originalString.charAt(i) - 65;
}
return returnNumeric;
}
private static int[] turnKeywordNumeric(String originalString) {
int[] returnNumeric = new int[originalString.length()];
for (int i = 0; i < originalString.length(); i++) {
returnNumeric[i] = ((int) originalString.charAt(i)) - 48;
}
return returnNumeric;
}
private static int[] addNumericStrings(Mode mode, int[] numericInput, int[] numericKeyword) {
int[] returnAddedNumeric = new int[numericInput.length];
for (int i = 0; i < numericInput.length; i++) {
if (mode == Mode.ENCRYPT) {
returnAddedNumeric[i] = (numericInput[i] + numericKeyword[i]) % 26;
} else {
returnAddedNumeric[i] = (numericInput[i] + (26 - numericKeyword[i])) % 26;
}
}
return returnAddedNumeric;
}
private static String turnAlpha(int[] addedNumeric) {
StringBuilder returnString = new StringBuilder();
for (int value : addedNumeric) {
returnString.append((char) (value + 65));
}
return returnString.toString();
}
}