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close #4204
This commit is contained in:
acbin
2023-06-09 18:52:05 +08:00
committed by GitHub
parent ad03086f54
commit 00282efd8b
521 changed files with 5233 additions and 7309 deletions
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57
src/main/java/com/thealgorithms/ciphers/Blowfish.java
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@ -10,7 +10,7 @@ package com.thealgorithms.ciphers;
public class Blowfish {
//Initializing substitution boxes
// Initializing substitution boxes
String[][] S = {
{
"d1310ba6",
@ -1046,7 +1046,7 @@ public class Blowfish {
},
};
//Initializing subkeys with digits of pi
// Initializing subkeys with digits of pi
String[] P = {
"243f6a88",
"85a308d3",
@ -1068,7 +1068,7 @@ public class Blowfish {
"8979fb1b",
};
//Initializing modVal to 2^32
// Initializing modVal to 2^32
long modVal = 4294967296L;
/**
@ -1098,7 +1098,8 @@ public class Blowfish {
* This method returns hexadecimal representation of the binary number passed as parameter
*
* @param binary Number for which hexadecimal representation is required
* @return String object which is a hexadecimal representation of the binary number passed as parameter
* @return String object which is a hexadecimal representation of the binary number passed as
* parameter
*/
private String binToHex(String binary) {
long num = Long.parseUnsignedLong(binary, 2);
@ -1109,7 +1110,8 @@ public class Blowfish {
}
/**
* This method returns a string obtained by XOR-ing two strings of same length passed a method parameters
* This method returns a string obtained by XOR-ing two strings of same length passed a method
* parameters
*
* @param String a and b are string objects which will be XORed and are to be of same length
* @return String object obtained by XOR operation on String a and String b
@ -1118,17 +1120,19 @@ public class Blowfish {
a = hexToBin(a);
b = hexToBin(b);
String ans = "";
for (int i = 0; i < a.length(); i++) ans +=
(char) (((a.charAt(i) - '0') ^ (b.charAt(i) - '0')) + '0');
for (int i = 0; i < a.length(); i++)
ans += (char) (((a.charAt(i) - '0') ^ (b.charAt(i) - '0')) + '0');
ans = binToHex(ans);
return ans;
}
/**
* This method returns addition of two hexadecimal numbers passed as parameters and moded with 2^32
* This method returns addition of two hexadecimal numbers passed as parameters and moded with
* 2^32
*
* @param String a and b are hexadecimal numbers
* @return String object which is a is addition that is then moded with 2^32 of hex numbers passed as parameters
* @return String object which is a is addition that is then moded with 2^32 of hex numbers
* passed as parameters
*/
private String addBin(String a, String b) {
String ans = "";
@ -1140,20 +1144,17 @@ public class Blowfish {
return ans.substring(ans.length() - 8);
}
/*F-function splits the 32-bit input into four 8-bit quarters
and uses the quarters as input to the S-boxes.
The S-boxes accept 8-bit input and produce 32-bit output.
The outputs are added modulo 232 and XORed to produce the final 32-bit output
*/
/*F-function splits the 32-bit input into four 8-bit quarters
and uses the quarters as input to the S-boxes.
The S-boxes accept 8-bit input and produce 32-bit output.
The outputs are added modulo 232 and XORed to produce the final 32-bit output
*/
private String f(String plainText) {
String[] a = new String[4];
String ans = "";
for (int i = 0; i < 8; i += 2) {
//column number for S-box is a 8-bit value
long col = Long.parseUnsignedLong(
hexToBin(plainText.substring(i, i + 2)),
2
);
// column number for S-box is a 8-bit value
long col = Long.parseUnsignedLong(hexToBin(plainText.substring(i, i + 2)), 2);
a[i / 2] = S[i / 2][(int) col];
}
ans = addBin(a[0], a[1]);
@ -1162,30 +1163,30 @@ public class Blowfish {
return ans;
}
//generate subkeys
// generate subkeys
private void keyGenerate(String key) {
int j = 0;
for (int i = 0; i < P.length; i++) {
//XOR-ing 32-bit parts of the key with initial subkeys
// XOR-ing 32-bit parts of the key with initial subkeys
P[i] = xor(P[i], key.substring(j, j + 8));
j = (j + 8) % key.length();
}
}
//round function
// round function
private String round(int time, String plainText) {
String left, right;
left = plainText.substring(0, 8);
right = plainText.substring(8, 16);
left = xor(left, P[time]);
//output from F function
// output from F function
String fOut = f(left);
right = xor(fOut, right);
//swap left and right
// swap left and right
return right + left;
}
@ -1198,12 +1199,12 @@ public class Blowfish {
* @return String cipherText is the encrypted value
*/
String encrypt(String plainText, String key) {
//generating key
// generating key
keyGenerate(key);
for (int i = 0; i < 16; i++) plainText = round(i, plainText);
//postprocessing
// postprocessing
String right = plainText.substring(0, 8);
String left = plainText.substring(8, 16);
right = xor(right, P[16]);
@ -1220,12 +1221,12 @@ public class Blowfish {
* @return String plainText is the decrypted text
*/
String decrypt(String cipherText, String key) {
//generating key
// generating key
keyGenerate(key);
for (int i = 17; i > 1; i--) cipherText = round(i, cipherText);
//postprocessing
// postprocessing
String right = cipherText.substring(0, 8);
String left = cipherText.substring(8, 16);
right = xor(right, P[1]);