Add create and sign phar file

- Add documentation for end users how to verify the
  phar file
- Add composer scripts to automate generating and
  signing the phar file

.gitignore

@@ -1,5 +1,7 @@
 build/
 vendor/
+createPhar
+createPhar.asc
 composer.lock
 docker-compose.yml
 phpunit.phar

README.md

@@ -41,6 +41,16 @@ If you specify a locale as a second argument the format string options
 (see below) for the given locale will be shown:
 
     $ ./ddate.phar --help de
+
+The releases are signed using the GPG-key with the ID 
+```A6FED5506250B129``` and the Fingerprint ```F1F7 A70A 51E2 D0FA 0903
+65B7 A6FE D550 6250 B129```
+
+You can verify the PHAR file using these commmands:
+
+    $ gpg --keyserver pgp.mit.edu --recv-key 0xA6FED5506250B129
+    $ gpg --fingerprint A6FED5506250B129
+    $ gpg --verify ddate.phar.asc ddate.phar
 
 ## Usage
 
@@ -145,4 +155,4 @@ Pope Rotund Deluxe
 
 Bureflux, 3179
 
-(last updated: Prickle-Prickle, 47th of The Aftermath, 3186)
+(last updated: Prickle-Prickle, 48th of The Aftermath, 3186)

composer.json

@@ -26,5 +26,34 @@
     },
     "suggest": {
         "ext-calendar": "Performance improvement for calculating Easter/Erister"
+    },
+    "scripts": {
+        "buildphar" : [
+            "rm -rf vendor",
+            "composer install --no-dev --prefer-dist",
+            "curl -o createPhar -L https://api.getlatestassets.com/github/MacFJA/PharBuilder/phar-builder.phar",
+            "curl -o createPhar.asc -L https://api.getlatestassets.com/github/MacFJA/PharBuilder/phar-builder.phar.asc",
+            "chmod 755 createPhar",
+            "mkdir -p ./build/phar/",
+            "php -d phar.readonly=0 ./createPhar package composer.json"
+        ],
+        "signphar": [
+            "gpg -u 0xA6FED5506250B129 --armor --detach-sig --output ./build/phar/ddate.phar.asc --sign ./build/phar/ddate.phar"
+        ]
+    },
+    "extra": {
+        "phar-builder": {
+            "compression": "GZip",
+            "name": "ddate.phar",
+            "output-dir": "./build/phar",
+            "entry-point": "./bin/ddate",
+            "include-dev": false,
+            "include": [
+                "bin",
+                "src",
+                "vendor"
+            ],
+            "skip-shebang": false
+        }
     }
 }