FeiShuEventDataDecrypter.java
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package com.pipihelper.project.feishu.utils;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;
/**
* @Description: TODO
* @author: charles
* @date: 2022年03月31日 10:03
*/
public class FeiShuEventDataDecrypter {
private byte[] keyBs;
public FeiShuEventDataDecrypter(String key) {
MessageDigest digest = null;
try {
digest = MessageDigest.getInstance("SHA-256");
} catch (NoSuchAlgorithmException e) {
// won't happen
}
keyBs = digest.digest(key.getBytes(StandardCharsets.UTF_8));
}
public String decrypt(String base64) throws Exception {
byte[] decode = Base64.getDecoder().decode(base64);
Cipher cipher = Cipher.getInstance("AES/CBC/NOPADDING");
byte[] iv = new byte[16];
System.arraycopy(decode, 0, iv, 0, 16);
byte[] data = new byte[decode.length - 16];
System.arraycopy(decode, 16, data, 0, data.length);
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(keyBs, "AES"), new IvParameterSpec(iv));
byte[] r = cipher.doFinal(data);
if (r.length > 0) {
int p = r.length - 1;
for (; p >= 0 && r[p] <= 16; p--) {
}
if (p != r.length - 1) {
byte[] rr = new byte[p + 1];
System.arraycopy(r, 0, rr, 0, p + 1);
r = rr;
}
}
return new String(r, StandardCharsets.UTF_8);
}
public static void main(String[] args) throws Exception {
FeiShuEventDataDecrypter d = new FeiShuEventDataDecrypter("kudryavka");
System.out.println(d.decrypt("5QyoWWZ3QI5xbQ6Q/niQRVUS+nxnOLk+EEoWJbwPoi1+tQvl92BzKwfS8vFc/ubRHJ4VmOROpjA8TZieBLBWBmh5IcphCVIh5ciPSgjMY5wKRA26G+LN2VvldyO8hUwm7z9XGCNpM7Cbdi/qWmQEC9AmFxdVlSaR0H8m15TVVLVKOHZt9yFCa8s4hy7Q2kG/")); //hello world
}
}