base-golang/pkg/aes/padding.go
2024-07-23 10:23:43 +08:00

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package aes
import (
"bytes"
)
/**
* 填充有六种NoPadding, PKCS#5, PKCS#7, ISO 10126, ANSI X9.23和ZerosPadding
* 对于AES来说PKCS5Padding和PKCS7Padding是完全一样的不同在于PKCS5限定了块大小为8bytes而PKCS7没有限定
* 因此对于AES来说两者完全相同但是对于Rijndael就不一样了
* AES是Rijndael在块大小为8bytes时的特例对于使用其他信息块大小的Rijndael算法只能使用PKCS7
* 在AES加密当中严格来说是不能使用pkcs5的因为AES的块大小是16bytes而pkcs5只能用于8bytes通常我们在AES加密中所说的pkcs5指的就是pkcs7
*/
func pkcsPadding(cipherText []byte, blockSize int) []byte {
p := blockSize - len(cipherText)%blockSize
padText := bytes.Repeat([]byte{byte(p)}, p)
return append(cipherText, padText...)
}
func pkcsUnPadding(decrypted []byte) []byte {
length := len(decrypted)
u := int(decrypted[length-1])
return decrypted[:(length - u)]
}