PHP Convert Hex String to String

How to decode Hex String to String?

Ex: Decode Hex String to get JWT token when integrating Apple ID login

Solved

Hex string is a data type commonly used for transmission over the internet in the lower network layers. In some cases PHP will need to manipulate this data type directly. To handle them, PHP provides us with the "pack" function to manipulate Hex and binary string data.

Ex:

$stringHexData = "65794a68624763694f694a49557a49314e694973496e523563434936496b705856434a392e65794a7063334d694f694a6f64485277637a6f764c3246776347786c61575175595842776247557559323974496977695958566b496a6f69593239744c6e4e68625842735a533568634841694c434a6c654841694f6a45324d5459354f4455794e6a4973496d6c68644349364d5459784e4449314d444d334d69776963335669496a6f694d4441774e7a677a4c6d4e6b5a6a45354d47526b4d544130595452685a6a42694e6d49774e6a63784d3249344d4455304d6a52694c6a45304d5451694c434a6a58326868633267694f694a7852557035546d7473556d4a5a626c46565679316b646d6774536b7452496977695a573168615777694f694a7a59573177624756415a3231686157777559323974496977695a57316861577866646d567961575a705a5751694f694a30636e566c4969776959585630614639306157316c496a6f784e6a45324f5441774d7a63794c434a756232356a5a56397a6458427762334a305a5751694f6e527964575573496e4a6c5957786664584e6c636c397a6447463064584d694f6a4a392e764b6c394873303057587463426851796f47326742766a744375394d5878787471674e46777854772d5034";

$stringData = pack("H*",$stringHexData);

echo $stringData;

Result (JWT String): 

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwczovL2FwcGxlaWQuYXBwbGUuY29tIiwiYXVkIjoiY29tLnNhbXBsZS5hcHAiLCJleHAiOjE2MTY5ODUyNjIsImlhdCI6MTYxNDI1MDM3Miwic3ViIjoiMDAwNzgzLmNkZjE5MGRkMTA0YTRhZjBiNmIwNjcxM2I4MDU0MjRiLjE0MTQiLCJjX2hhc2giOiJxRUp5TmtsUmJZblFVVy1kdmgtSktRIiwiZW1haWwiOiJzYW1wbGVAZ21haWwuY29tIiwiZW1haWxfdmVyaWZpZWQiOiJ0cnVlIiwiYXV0aF90aW1lIjoxNjE2OTAwMzcyLCJub25jZV9zdXBwb3J0ZWQiOnRydWUsInJlYWxfdXNlcl9zdGF0dXMiOjJ9.vKl9Hs00WXtcBhQyoG2gBvjtCu9MXxxtqgNFwxTw-P4

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In addition, the "pack" function also supports other data types. 

possible values of format are:
a – string which is NUL-padded
A – string which is SPACE-padded
h – low nibble first Hex string
H – high nibble first Hex string
c – signed character
C – unsigned character
s – signed short (16 bit, machine byte order)
S – unsigned short ( 16 bit, machine byte order)
n – unsigned short ( 16 bit, big endian byte order)
v – unsigned short ( 16 bit, little endian byte order)
i – signed integer (machine dependent byte order and size)
I – unsigned integer (machine dependent byte order and size)
l – signed long ( 32 bit, machine byte order)
L – unsigned long ( 32 bit, machine byte order)
N – unsigned long ( 32 bit, big endian byte order)
V – unsigned long ( 32 bit, little endian byte order)
f – float (machine dependent representation and size)
d – double (machine dependent representation and size)
x – NUL byte
X – Back up one byte
Z – string which is NUL-padded
@ – NUL-fill to absolute position

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Android - Replace OnLifecycleEvent is deprecated with DefaultLifecycleObserver or LifecycleEventObserver

As of androidx.lifecycle version 2.4.0, OnLifecycleEvent is deprecated. Instead Use DefaultLifecycleObserver or LifecycleEventObserver is recommended to use instead. Many android applications that use OnLifecycleEvent such as when integrating Admob Open Ads will receive a warning.

For example, the following code will be warned by Android Studio OnLifecycleEvent is deprecated:

    /**
     * LifecycleObserver methods
     */
    @OnLifecycleEvent(ON_START)
    public void onStart() {
        showAdIfAvailable();
        Log.d(LOG_TAG, "onStart");
    }

To replace OnLifecycleEvent, follow these instructions:

First: In build.gradle, please include the LifecycleObserver libraries:

apply plugin: 'com.android.application'

dependencies {
   ...

   implementation "androidx.lifecycle:lifecycle-extensions:2.2.0"
   implementation "androidx.lifecycle:lifecycle-runtime:2.5.1"
   annotationProcessor "androidx.lifecycle:lifecycle-compiler:2.2.0"
}

Then choose one of the following two alternatives:

Method 1: replace OnLifecycleEvent with DefaultLifecycleObserver

...
import androidx.lifecycle.DefaultLifecycleObserver;

public class MyApplication extends Application implements DefaultLifecycleObserver {
    @Override
    public void onCreate() {
        super.onCreate();
	// Register DefaultLifecycleObserver 
	ProcessLifecycleOwner.get().getLifecycle().addObserver(this);
    }

    /*Replace for OnLifecycleEvent onStart Event */
    @Override
    public void onStart(@NonNull LifecycleOwner owner) {
	// Perform actions every time the app is reopened
    }
}

Method 2: replace OnLifecycleEvent with LifecycleEventObserver

public class MyApplication extends Application implements LifecycleObserver
{
  @Override
  public void onCreate() {
    super.onCreate();
    //...
    // Register LifecycleObserver
    ProcessLifecycleOwner.get().getLifecycle().addObserver(this);
    //...
  }

  /*Replace for OnLifecycleEvent onStart Event */
  @OnLifecycleEvent(Event.ON_START)
  protected void onMoveToForeground() {
    // Perform actions every time the app is reopened (moves to foreground)
    // appOpenAdManager.showAdIfAvailable(currentActivity);
  }
}

Done !

If you have any difficulties, or have any questions, please leave a comment below the article. We will deal with them together. Thanks

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