AES/CBC/PKCS5Padding 与 AES/CBC/PKCS7Padding 与 256 密钥大小性能 java [英] AES/CBC/PKCS5Padding vs AES/CBC/PKCS7Padding with 256 key size performance java

问题描述

我目前使用 AES/CBC/PKCS5Padding 用 256 字节 密钥大小加密 Java 文件，但在搜索时我在 stackexchange PKCS#5-PKCS#7 Padding 并提到,

<块引用>

PKCS#5 填充是 8 字节块大小的 PKCS#7 填充的子集

所以我想知道

1. 对于上述配置，AES/CBC/PKCS7Padding的性能会比AES/CBC/PKCS5Padding更好吗?
2. 我们如何配置 Java 中提到的块大小<块引用>

   PKCS#7 填充适用于从 1 到 255 字节的任何块大小.

我的示例代码是，

SecureRandom rnd = new SecureRandom();IvParameterSpec iv = 新的 IvParameterSpec(rnd.generateSeed(16));KeyGenerator generator = KeyGenerator.getInstance("AES");生成器初始化(256)；SecretKey k = generator.generateKey();Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");c.init(Cipher.ENCRYPT_MODE, k, iv);

解决方案

块大小是所用密码算法的属性.对于 AES，它总是 16 字节.

严格来说，PKCS5Padding 不能与 AES 一起使用，因为它仅定义为 8 字节的块大小.我假设 AES/CBC/PKCS5Padding 在内部被解释为 AES/CBC/PKCS7Padding.

这些填充方案的唯一区别是 PKCS7Padding 将块大小作为参数，而对于 PKCS5Padding，它固定为 8 个字节.当块大小为 8 字节时，它们的作用完全相同.

I am currently using AES/CBC/PKCS5Padding for encrypting files in Java with 256 bytes key size, but while searching I found on stackexchange PKCS#5-PKCS#7 Padding and it is mentioned,

PKCS#5 padding is a subset of PKCS#7 padding for 8 byte block sizes

So I want to know

1. Will the performance of AES/CBC/PKCS7Padding will be better then AES/CBC/PKCS5Padding for the above configuration?
2. How can we configure the block size in Java as it is mentioned

   PKCS#7 padding would work for any block size from 1 to 255 bytes.

My sample code is,

SecureRandom rnd = new SecureRandom();
IvParameterSpec iv = new IvParameterSpec(rnd.generateSeed(16));

KeyGenerator generator = KeyGenerator.getInstance("AES");
generator.init(256);
SecretKey k = generator.generateKey();

Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");
c.init(Cipher.ENCRYPT_MODE, k, iv);

解决方案

The block size is a property of the used cipher algorithm. For AES it is always 16 bytes.

So strictly speaking, PKCS5Padding cannot be used with AES since it is defined only for a block size of 8 bytes. I assume, AES/CBC/PKCS5Padding is interpreted as AES/CBC/PKCS7Padding internally.

The only difference between these padding schemes is that PKCS7Padding has the block size as a parameter, while for PKCS5Padding it is fixed at 8 bytes. When the Block size is 8 bytes they do exactly the same.

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