Initial commit of microsign FunctionApp

microsign/function_app.py

@@ -0,0 +1,51 @@
+import logging
+import azure.functions as func
+from azure.identity import DefaultAzureCredential
+from azure.keyvault.keys import KeyClient
+from azure.keyvault.keys.crypto import CryptographyClient, SignatureAlgorithm
+import json
+import base64
+
+app = func.FunctionApp()
+
+key_vault_url = "https://ghaf-devenv-ca.vault.azure.net/"
+credential = DefaultAzureCredential()
+key_client = KeyClient(vault_url=key_vault_url, credential=credential)
+
+@app.function_name(name="VerifySignatureFunction") 
+@app.route(route="verify-signature", methods=["POST"], auth_level=func.AuthLevel.ANONYMOUS) 
+def verify_signature(req: func.HttpRequest) -> func.HttpResponse:
+    logging.info('Received an HTTP request to verify signature.')
+
+    try:
+        req_body = req.get_json()
+        certificate_name = req_body['certificateName']
+        signature = req_body['Signature']
+        hash_value = req_body['Hash']
+        logging.info("SIGNATURE: "+signature)
+        logging.info("HASH: "+hash_value)
+
+        key = key_client.get_key(certificate_name)
+        crypto_client = CryptographyClient(key, credential)
+
+        sig = base64.b64decode(signature)
+        digest = base64.b64decode(hash_value)
+#        logging.info("decoded SIG: "+str(sig))
+#        logging.info("decoded HASH: "+str(digest))
+        result = crypto_client.verify(SignatureAlgorithm.es256, digest, sig)
+        logging.info("Verification result: "+ str(result.is_valid))
+
+
+        return func.HttpResponse(
+            body=json.dumps({'is_valid': result.is_valid, 'message': 'Signature verification result'}),
+            mimetype="application/json",
+            status_code=200
+        )
+
+    except Exception as e:
+        logging.error(f"An error occurred: {e}")
+        return func.HttpResponse(
+            body=json.dumps({'error': str(e), 'message': 'An error occurred during signature verification'}),
+            mimetype="application/json",
+            status_code=500
+        )