diff --git a/package-lock.json b/package-lock.json
index 5895c34..ef90f3b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -16,7 +16,6 @@
         "email-addresses": "^3.1.0",
         "express": "^4.17.1",
         "http-errors": "^1.8.0",
-        "iab_verifier": "^0.1.2",
         "lodash": "^4.17.21",
         "mariadb": "^2.5.2",
         "nodemailer": "^6.7.2",
@@ -1217,12 +1216,6 @@
         "node": ">= 8"
       }
     },
-    "node_modules/crypto": {
-      "version": "1.0.1",
-      "resolved": "https://registry.npmjs.org/crypto/-/crypto-1.0.1.tgz",
-      "integrity": "sha512-VxBKmeNcqQdiUQUW2Tzq0t377b54N2bMtXO/qiLa+6eRRmmC4qT3D4OnTGoT/U6O9aklQ/jTwbOtRMTTY8G0Ig==",
-      "deprecated": "This package is no longer supported. It's now a built-in Node module. If you've depended on crypto, you should switch to the one that's built-in."
-    },
     "node_modules/cuint": {
       "version": "0.2.2",
       "resolved": "https://registry.npmjs.org/cuint/-/cuint-0.2.2.tgz",
@@ -2150,17 +2143,6 @@
         "node": ">= 0.6"
       }
     },
-    "node_modules/iab_verifier": {
-      "version": "0.1.2",
-      "resolved": "https://registry.npmjs.org/iab_verifier/-/iab_verifier-0.1.2.tgz",
-      "integrity": "sha1-2t5VDuOJu96FaLL0ynHV0RFQCV4=",
-      "dependencies": {
-        "crypto": "*"
-      },
-      "engines": {
-        "node": ">= 0.10.0"
-      }
-    },
     "node_modules/iconv-lite": {
       "version": "0.4.24",
       "resolved": "https://registry.npmjs.org/iconv-lite/-/iconv-lite-0.4.24.tgz",
@@ -6344,11 +6326,6 @@
         "which": "^2.0.1"
       }
     },
-    "crypto": {
-      "version": "1.0.1",
-      "resolved": "https://registry.npmjs.org/crypto/-/crypto-1.0.1.tgz",
-      "integrity": "sha512-VxBKmeNcqQdiUQUW2Tzq0t377b54N2bMtXO/qiLa+6eRRmmC4qT3D4OnTGoT/U6O9aklQ/jTwbOtRMTTY8G0Ig=="
-    },
     "cuint": {
       "version": "0.2.2",
       "resolved": "https://registry.npmjs.org/cuint/-/cuint-0.2.2.tgz",
@@ -7079,14 +7056,6 @@
         "toidentifier": "1.0.1"
       }
     },
-    "iab_verifier": {
-      "version": "0.1.2",
-      "resolved": "https://registry.npmjs.org/iab_verifier/-/iab_verifier-0.1.2.tgz",
-      "integrity": "sha1-2t5VDuOJu96FaLL0ynHV0RFQCV4=",
-      "requires": {
-        "crypto": "*"
-      }
-    },
     "iconv-lite": {
       "version": "0.4.24",
       "resolved": "https://registry.npmjs.org/iconv-lite/-/iconv-lite-0.4.24.tgz",
diff --git a/package.json b/package.json
index 854f7dd..d68d154 100644
--- a/package.json
+++ b/package.json
@@ -55,7 +55,6 @@
     "email-addresses": "^3.1.0",
     "express": "^4.17.1",
     "http-errors": "^1.8.0",
-    "iab_verifier": "^0.1.2",
     "lodash": "^4.17.21",
     "mariadb": "^2.5.2",
     "nodemailer": "^6.7.2",
diff --git a/src/function/purchase/iab_verifierr.ts b/src/function/purchase/iab_verifierr.ts
new file mode 100644
index 0000000..0e0f012
--- /dev/null
+++ b/src/function/purchase/iab_verifierr.ts
@@ -0,0 +1,48 @@
+/*
+ * The MIT License
+ *
+ * Copyright (c) Paul Crawford
+ * Copyright (c) 2020 Jonas Lochmann
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+import { createPublicKey, createVerify, KeyObject } from 'crypto'
+
+const ALGORITHM = 'RSA-SHA1'
+
+export class IABVerifier {
+  private readonly publicKey: KeyObject
+
+  constructor(publicKeyString: string) {
+    this.publicKey = createPublicKey({
+      key: Buffer.from(publicKeyString, 'base64'),
+      format: 'der',
+      type: 'spki'
+    })
+  }
+
+  verifyReceipt(signedData: string, signature: string) {
+      const verifier = createVerify(ALGORITHM)
+
+      verifier.update(signedData)
+
+      return verifier.verify(this.publicKey, signature, 'base64')
+  }
+}
diff --git a/src/function/purchase/verification.ts b/src/function/purchase/verification.ts
index 03ec6c7..5ba62a2 100644
--- a/src/function/purchase/verification.ts
+++ b/src/function/purchase/verification.ts
@@ -15,21 +15,18 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-const IABVerifier: new (publicKey: string) => {
-  verifyReceipt: (data: string, signature: string) => boolean
-  // eslint-disable-next-line @typescript-eslint/no-var-requires
-} = require('iab_verifier')
+import { IABVerifier } from './iab_verifierr'
 
 export const googlePlayPublicKey = process.env.GOOGLE_PLAY_PUBLIC_KEY || ''
 
-const verifier = new IABVerifier(googlePlayPublicKey)
+const verifier = googlePlayPublicKey !== '' ? new IABVerifier(googlePlayPublicKey) : null
 
-export const areGooglePlayPaymentsPossible = !!googlePlayPublicKey
+export const areGooglePlayPaymentsPossible = !!verifier
 export const isGooglePlayPurchaseSignatureValid = ({ receipt, signature }: {
   receipt: string
   signature: string
 }) => {
-  if (googlePlayPublicKey) {
+  if (verifier) {
     return verifier.verifyReceipt(receipt, signature)
   } else {
     return false