Java AES-256用IGE解密 [英] Java AES-256 decrypt with IGE

问题描述

我试图用IGE解密AES-256。但是我不知道如何使用256位密钥。

在代码键 - byte [] em> length == 32; IV 。长度 == 32; BlockSize == 16

 密码密码= Cipher.getInstance（AES / ECB / NoPadding） ; 
 cipher.init（Cipher.DECRYPT_MODE，new SecretKeySpec（key，AES））; 
 
 Xprev = java.util.Arrays.copyOfRange（IV，0，BlockSize）; 
 Yprev = java.util.Arrays.copyOfRange（IV，BlockSize，IV.length）; 
 
 Decripted = new byte [0]; （int i = 0; i< Message.length; i + = BlockSize）{
 Y = java.util.Arrays.copyOfRange（Message，i，i + BlockSize）
 
 ; 
 X = XOR（cipher.doFinal（XOR（Y，Xprev）），Yprev）; 
 Xprev = X; 
 Yprev = Y; 
 
 Decripted = sumBytes（Decripted，X）; 
} 
  

解决方案

你几乎在那里您应该使用 Xprev 与 YPrev 在功能和 X 与 Y 。警告：只针对单个测试向量进行测试。

  public static final byte [] ige（final byte [] key，final byte [] IV，
 final byte [] Message）throws异常{
 
 final Cipher cipher = Cipher.getInstance（AES / ECB / NoPadding）; 
 cipher.init（Cipher.DECRYPT_MODE，new SecretKeySpec（key，AES））; 
 
 final int blocksize = cipher.getBlockSize（）; 
 
 byte [] xPrev = Arrays.copyOfRange（IV，0，blocksize）; 
 byte [] yPrev = Arrays.copyOfRange（IV，blocksize，IV.length）; 
 
 byte [] decryptpted = new byte [0]; 
 
 byte [] y，x; （int i = 0; i< Message.length; i + = blocksize）{
 x = java.util.Arrays.copyOfRange（Message，i，i + blocksize）; 
 
 y = xor（cipher.doFinal（xor（x，yPrev）），xPrev）; 
 xPrev = x; 
 yPrev = y; 
 
 decrypted = sumBytes（decryptiled，y）; 
} 
 
返回解密; 
} 
  

I'm trying to decrypt AES-256 with IGE. But i don't know how use 256 bit key.

in code key - byte[] with length == 32; IV.length == 32; BlockSize == 16

Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding");
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "AES"));

Xprev = java.util.Arrays.copyOfRange(IV, 0, BlockSize);
Yprev = java.util.Arrays.copyOfRange(IV, BlockSize, IV.length);

Decripted = new byte[0];

for (int i = 0; i < Message.length; i += BlockSize) { 
    Y = java.util.Arrays.copyOfRange(Message, i, i+BlockSize); 
    X = XOR(cipher.doFinal(XOR(Y,Xprev)), Yprev);
    Xprev = X;
    Yprev = Y;

    Decripted = sumBytes(Decripted, X);
}

解决方案

You are almost there. You should swap Xprev with YPrev in the function and X with Y. Warning: only tested against a single test vector.

public static final byte[] ige(final byte[] key, final byte[] IV,
        final byte[] Message) throws Exception {

    final Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding");
    cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "AES"));

    final int blocksize = cipher.getBlockSize();

    byte[] xPrev = Arrays.copyOfRange(IV, 0, blocksize);
    byte[] yPrev = Arrays.copyOfRange(IV, blocksize, IV.length);

    byte[] decrypted = new byte[0];

    byte[] y, x;
    for (int i = 0; i < Message.length; i += blocksize) {
        x = java.util.Arrays.copyOfRange(Message, i, i + blocksize);
        y = xor(cipher.doFinal(xor(x, yPrev)), xPrev);
        xPrev = x;
        yPrev = y;

        decrypted = sumBytes(decrypted, y);
    }

    return decrypted;
}

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