3DES

I read about 3DES encryption but I don't understand exactly what the specific meaning of key size is. For example I found that 3DES supports 64, 128, 192, and 256 bits key size.

The key length for 3DES is 168 bits since three separate 56-bit keys are used. However, there is a meet-in-the-middle attack on 3DES that reduces its effective key strength to 112 bits.

It supports variable key sizes which range from 128 bits to 192 bits. It basically involves the usage of a symmetric key encryption system, which states that the same key is used for both encryption and decryption.

Key Length: 3DES provides up to 168 bits of key length, compared to DES's 56 bits. Security: The triple application of DES makes brute-force attacks far less feasible.

由于计算机运算能力的增强，原版DES由於 密钥长度 過低容易被 暴力破解；3DES即是设计用来提供一种相对简单的方法，即通过增加DES的密钥长度来避免类似的攻击，而不是设计一种全新的块密码算法。

我司的加密芯片或者加密狗中3DES密钥长度一般设置为16字节，这是因为将KEY3设置与KEY1相等的原因，但实际运算的时候，和国际通用的3DES加密算法流程一致，所以并不会影响用户的使用。