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add(aes): meme aes pcbc string encryption for class presentation
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@ItzSomebody
ItzSomebody committed Dec 5, 2022
1 parent edd80f9 commit 7d3e871
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293 changes: 293 additions & 0 deletions ...radon.template/src/main/java/xyz/itzsomebody/radon/templates/string/AESPCBCDecryptor.java
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package xyz.itzsomebody.radon.templates.string;

import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.Base64;

public class AESPCBCDecryptor {
public static int[][] sbox;
public static int[][] invSbox;
public static int[] rcon; // round constants
public static int[] expandedKey; // expanded key
public static int[][] mcTables; // lookup tables for MixColumns

static {
// SBox
// See https://crypto.stackexchange.com/questions/85670/need-help-understanding-math-behind-rijndael-s-box
// for an explanation of how 3 generates GF[2^8]
sbox = new int[0x10][0x10];
int p = 1;
int q = 1;

do {
p = gfMult(3, p);
q = gfMult(0xF6, q);

int trans = q; // Affine transformation
trans ^= ((q << 1) | (q >>> (8 - 1))) & 0xFF;
trans ^= ((q << 2) | (q >>> (8 - 2))) & 0xFF;
trans ^= ((q << 3) | (q >>> (8 - 3))) & 0xFF;
trans ^= ((q << 4) | (q >>> (8 - 4))) & 0xFF;
sbox[p / 16][p % 16] = (trans ^ 0x63) & 0xFF;
} while (p != 1);

sbox[0][0] = 0x63; // 0 is never invertible so set manually

// InvSBox
invSbox = new int[sbox.length][sbox.length];
for (int row = 0; row < sbox.length; row++) {
for (int col = 0; col < sbox[0].length; col++) {
int b = sbox[row][col];
invSbox[b >> 4][b & 0xF] = (row << 4) | col;
}
}

// Round constants
rcon = new int[10];
for (int i = 0; i < rcon.length; i++) {
if (i == 0) {
rcon[i] = 1;
} else if (rcon[i - 1] < 0x80) {
rcon[i] = 2 * rcon[i - 1];
} else if (rcon[i - 1] >= 0x80) {
rcon[i] = (2 * rcon[i - 1]) ^ 0x11B;
}
}
for (int i = 0; i < rcon.length; i++) {
rcon[i] <<= 24;
}

// Multiplication tables for MixColumns
mcTables = new int[0xF][];
mcTables[0xE] = new int[0x100];
mcTables[0xB] = new int[0x100];
mcTables[0xD] = new int[0x100];
mcTables[0x9] = new int[0x100];

for (int mult = 0; mult < mcTables.length; mult++) {
if (mcTables[mult] != null) {
int[] table = mcTables[mult];

for (int n = 0; n < table.length; n++) {
table[n] = gfMult(mult, n);
}
}
}
}

public static int subWord(int word) {
int b0 = (word >> (8 * 3)) & 0xFF;
int b1 = (word >> (8 * 2)) & 0xFF;
int b2 = (word >> 8) & 0xFF;
int b3 = word & 0xFF;

return (sbox[b0 >> 4][b0 & 0xF] << 8 * 3)
| (sbox[b1 >> 4][b1 & 0xF] << 8 * 2)
| (sbox[b2 >> 4][b2 & 0xF] << 8)
| (sbox[b3 >> 4][b3 & 0xF]);
}

public static void keySchedule(int[] key) {
// AES-128
int R = 11;
expandedKey = new int[4 * R];

for (int i = 0; i < expandedKey.length; i++) {
if (i < key.length) {
expandedKey[i] = key[i];
} else if (i % key.length == 0) {
int b = (expandedKey[i - 1] << 8) | (expandedKey[i - 1] >>> (32 - 8));
expandedKey[i] = expandedKey[i - key.length];
expandedKey[i] ^= subWord(b);
expandedKey[i] ^= rcon[i / key.length - 1];
} else {
expandedKey[i] = expandedKey[i - key.length] ^ expandedKey[i - 1];
}
}
}

public static void addRoundKey(int[][] state, int round) {
for (int row = 0; row < state.length; row++) {
for (int col = 0; col < state[0].length; col++) {
int rkey = expandedKey[round * state[0].length + col];
int xbyte = (rkey >> (8 * (state.length - 1) - 8 * row)) & 0xFF;
state[row][col] ^= xbyte;
}
}
}

public static void invShiftRows(int[][] state) {
for (int offset = 0; offset < state.length; offset++) {
int[] row = state[offset];
int[] shifted = new int[row.length];
for (int i = 0; i < row.length; i++) {
shifted[(i + offset) % 4] = row[i];
}
state[offset] = shifted;
}
}

public static void invSubBytes(int[][] state) {
for (int row = 0; row < state.length; row++) {
for (int col = 0; col < state[row].length; col++) {
int s = state[row][col];
int upper = s >> 4;
int lower = s & 0xF;
state[row][col] = invSbox[upper][lower];
}
}
}

// Multiply in GF[2^8]
public static int gfMult(int mult, int b) {
int result = 0;
for (int i = 0; i < 8; i++) {
if ((mult & 0x1) != 0) {
result ^= b;
}
mult >>= 1;
int mod = 0;
if ((b & 0x80) != 0) {
mod = 0x11B;
}
b = (b << 1) ^ mod;
}
return result;
}

public static void invMixColumns(int[][] state) {
for (int col = 0; col < state[0].length; col++) {
int s1 = mcTables[0xE][state[0][col]] ^ mcTables[0xB][state[1][col]] ^ mcTables[0xD][state[2][col]] ^ mcTables[0x9][state[3][col]];
int s2 = mcTables[0x9][state[0][col]] ^ mcTables[0xE][state[1][col]] ^ mcTables[0xB][state[2][col]] ^ mcTables[0xD][state[3][col]];
int s3 = mcTables[0xD][state[0][col]] ^ mcTables[0x9][state[1][col]] ^ mcTables[0xE][state[2][col]] ^ mcTables[0xB][state[3][col]];
int s4 = mcTables[0xB][state[0][col]] ^ mcTables[0xD][state[1][col]] ^ mcTables[0x9][state[2][col]] ^ mcTables[0xE][state[3][col]];

state[0][col] = s1;
state[1][col] = s2;
state[2][col] = s3;
state[3][col] = s4;
}
}

public static void invCipher(int[][] state) {
int round = 10;

addRoundKey(state, round);

for (round = 9; round > 0; round--) {
invShiftRows(state);
invSubBytes(state);
addRoundKey(state, round);
invMixColumns(state);
}

invSubBytes(state);
invShiftRows(state);
addRoundKey(state, round);
}

public static String decrypt(String input, long[] ivInts) {
// Compute key based on callstack (yes we're doing this meme again)
var callstack = Thread.currentThread().getStackTrace();
int[] key = new int[]{
callstack[1].getClassName().hashCode(),
callstack[1].getMethodName().hashCode(),
callstack[2].getClassName().hashCode(),
callstack[2].getMethodName().hashCode()
};
keySchedule(key);

// Convert IV to correct format
int[] ivBytes = new int[0x10];
for (int i = 0; i < ivInts.length; i++) {
for (int j = 0; j < 8; j++) {
ivBytes[i * 8 + j] = (int) ((ivInts[i] >>> (56 - j * 8)) & 0xFF);
}
}
int[][] iv = create_state(ivBytes);

// Input -> state for InvCipher
int[] cipherText = design(Base64.getDecoder().decode(input));
int[][][] states = new int[cipherText.length / 16][][];
for (int i = 0; i < states.length; i++) {
int[] subarray = Arrays.copyOfRange(cipherText, i * 16, (i + 1) * 16);
states[i] = create_state(subarray);
}

// PCBC decryption alg
int[][] previousBlock1 = copyBlock(states[0]);
invCipher(states[0]);
for (int row = 0; row < states[0].length; row++) {
for (int col = 0; col < states[0][0].length; col++) {
states[0][row][col] ^= iv[row][col];
previousBlock1[row][col] ^= states[0][row][col];
}
}

for (int i = 1; i < states.length; i++) {
int[][] previousBlock2 = copyBlock(states[i]);
invCipher(states[i]);
int[][] state = states[i];
for (int row = 0; row < state.length; row++) {
for (int col = 0; col < state[0].length; col++) {
state[row][col] ^= previousBlock1[row][col];
previousBlock2[row][col] ^= state[row][col];
}
}
previousBlock1 = previousBlock2;
}

// Reconstruct bytes
byte[] processed = new byte[cipherText.length];
for (int i = 0; i < states.length; i++) {
int[] vector = new int[0x10];
for (int col = 0; col < states[0].length; col++) {
for (int row = 0; row < states[0][0].length; row++) {
vector[col * 4 + row] = states[i][row][col];
}
}
System.arraycopy(resign(vector), 0, processed, i * 16, vector.length);
}

// Remove padding
int nPadBytes = processed[processed.length - 1];
byte[] message = new byte[processed.length - nPadBytes];
System.arraycopy(processed, 0, message, 0, message.length);

return new String(message, StandardCharsets.UTF_8);
}

public static int[][] copyBlock(int[][] block) {
int[][] copy = new int[block.length][block[0].length];
for (int row = 0; row < block.length; row++) {
for (int col = 0; col < block[0].length; col++) {
copy[row][col] = block[row][col];
}
}
return copy;
}

public static int[] design(byte[] arr) {
int[] designed = new int[arr.length];
for (int i = 0; i < arr.length; i++) {
designed[i] = arr[i] & 0xFF;
}
return designed;
}

public static byte[] resign(int[] arr) {
byte[] signed = new byte[arr.length];
for (int i = 0; i < arr.length; i++) {
signed[i] = (byte) arr[i];
}
return signed;
}

public static int[][] create_state(int[] bytes) {
int[][] state = new int[4][4];
for (int i = 0; i < bytes.length; i++) {
state[i % 4][i / 4] = bytes[i];
}
return state;
}
}
2 changes: 2 additions & 0 deletions xyz.itzsomebody.radon/src/main/java/xyz/itzsomebody/radon/transformers/Transformers.java
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Expand Up @@ -19,6 +19,7 @@
package xyz.itzsomebody.radon.transformers;

import xyz.itzsomebody.radon.transformers.misc.*;
import xyz.itzsomebody.radon.transformers.strings.AESPCBCStringEncryption;
import xyz.itzsomebody.radon.transformers.strings.StaticFieldStrPool;
import xyz.itzsomebody.radon.transformers.strings.Str2Base64Encoding;

Expand All @@ -39,6 +40,7 @@ public enum Transformers {
// String encryption/encoding
STRING_TO_BASE64_ENCODING(Str2Base64Encoding.class),
POOL_STRINGS_TO_STATIC_FIELD(StaticFieldStrPool.class),
AES_PCBC_STRING_ENCRYPTION(AESPCBCStringEncryption.class),

;//TODO

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