java外部存储设备写入认证 给个完整的示例
时间: 2023-05-21 19:02:17 浏览: 100
java认证例子
以下是一个 Java 外部存储设备写入认证的示例代码:
```java
import java.io.*;
import java.security.*;
public class ExternalStorageAuthenticator {
private static final String AUTH_FILE = "/mnt/sdcard/auth.txt";
private static final String AUTH_ALGORITHM = "SHA-256";
private static final String AUTH_KEY = "my_secret_key";
public static boolean authenticate(String data) {
try {
MessageDigest md = MessageDigest.getInstance(AUTH_ALGORITHM);
md.update(AUTH_KEY.getBytes());
byte[] keyHash = md.digest();
md.reset();
md.update(data.getBytes());
byte[] dataHash = md.digest();
byte[] authHash = new byte[keyHash.length + dataHash.length];
System.arraycopy(keyHash, 0, authHash, 0, keyHash.length);
System.arraycopy(dataHash, 0, authHash, keyHash.length, dataHash.length);
byte[] storedHash = readAuthFile();
return MessageDigest.isEqual(authHash, storedHash);
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
private static byte[] readAuthFile() throws IOException {
File file = new File(AUTH_FILE);
if (!file.exists()) {
throw new FileNotFoundException("Auth file not found");
}
byte[] buffer = new byte[(int) file.length()];
FileInputStream fis = new FileInputStream(file);
fis.read(buffer);
fis.close();
return buffer;
}
}
```
这个示例代码演示了如何使用 SHA-256 算法对数据进行哈希,然后将哈希值与一个密钥的哈希值拼接起来,最后将拼接后的哈希值与存储在外部存储设备上的认证哈希值进行比较,以实现认证的功能。
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