diff --git a/moto/awslambda/models.py b/moto/awslambda/models.py
index 2fb39617..5879b9d9 100644
--- a/moto/awslambda/models.py
+++ b/moto/awslambda/models.py
@@ -52,8 +52,8 @@ class LambdaFunction(object):
                         "InvalidParameterValueException",
                         "Error occurred while GetObject. S3 Error Code: NoSuchKey. S3 Error Message: The specified key does not exist.")
                 else:
-                    self.code_size = 123
-                    self.code_sha_256 = 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'
+                    self.code_size = key.size
+                    self.code_sha_256 = hashlib.sha256(key.value).hexdigest()
         self.function_arn = 'arn:aws:lambda:123456789012:function:{0}'.format(self.function_name)
 
     @property
diff --git a/tests/test_awslambda/test_lambda.py b/tests/test_awslambda/test_lambda.py
index 9fe54486..ea4eea31 100644
--- a/tests/test_awslambda/test_lambda.py
+++ b/tests/test_awslambda/test_lambda.py
@@ -63,7 +63,9 @@ def test_create_based_on_s3_with_missing_bucket():
 def test_create_function_from_aws_bucket():
     s3_conn = boto3.client('s3', 'us-west-2')
     s3_conn.create_bucket(Bucket='test-bucket')
-    s3_conn.put_object(Bucket='test-bucket', Key='test.zip', Body=get_test_zip_file())
+
+    zip_content = get_test_zip_file()
+    s3_conn.put_object(Bucket='test-bucket', Key='test.zip', Body=zip_content)
     conn = boto3.client('lambda', 'us-west-2')
 
     result = conn.create_function(
@@ -90,12 +92,12 @@ def test_create_function_from_aws_bucket():
         'Runtime': 'python2.7',
         'Role': 'test-iam-role',
         'Handler': 'lambda_function.handler',
-        'CodeSize': 123,
+        "CodeSha256": hashlib.sha256(zip_content).hexdigest(),
+        "CodeSize": len(zip_content),
         'Description': 'test lambda function',
         'Timeout': 3,
         'MemorySize': 128,
         'LastModified': '2015-01-01 00:00:00',
-        'CodeSha256': 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa',
         'Version': '$LATEST',
         'VpcConfig': {
             "SecurityGroupIds": ["sg-123abc"],
@@ -154,7 +156,9 @@ def test_create_function_from_zipfile():
 def test_get_function():
     s3_conn = boto3.client('s3', 'us-west-2')
     s3_conn.create_bucket(Bucket='test-bucket')
-    s3_conn.put_object(Bucket='test-bucket', Key='test.zip', Body=get_test_zip_file())
+
+    zip_content = get_test_zip_file()
+    s3_conn.put_object(Bucket='test-bucket', Key='test.zip', Body=zip_content)
     conn = boto3.client('lambda', 'us-west-2')
 
     conn.create_function(
@@ -180,8 +184,8 @@ def test_get_function():
             "RepositoryType": "S3"
         },
         "Configuration": {
-            "CodeSha256": 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa',
-            "CodeSize": 123,
+            "CodeSha256": hashlib.sha256(zip_content).hexdigest(),
+            "CodeSize": len(zip_content),
             "Description": "test lambda function",
             "FunctionArn": "arn:aws:lambda:123456789012:function:testFunction",
             "FunctionName": "testFunction",
@@ -207,7 +211,9 @@ def test_get_function():
 def test_delete_function():
     s3_conn = boto3.client('s3', 'us-west-2')
     s3_conn.create_bucket(Bucket='test-bucket')
-    s3_conn.put_object(Bucket='test-bucket', Key='test.zip', Body=get_test_zip_file())
+
+    zip_content = get_test_zip_file()
+    s3_conn.put_object(Bucket='test-bucket', Key='test.zip', Body=zip_content)
     conn = boto3.client('lambda', 'us-west-2')
 
     conn.create_function(
@@ -241,7 +247,9 @@ def test_list_create_list_get_delete_list():
     """
     s3_conn = boto3.client('s3', 'us-west-2')
     s3_conn.create_bucket(Bucket='test-bucket')
-    s3_conn.put_object(Bucket='test-bucket', Key='test.zip', Body=get_test_zip_file())
+
+    zip_content = get_test_zip_file()
+    s3_conn.put_object(Bucket='test-bucket', Key='test.zip', Body=zip_content)
     conn = boto3.client('lambda', 'us-west-2')
 
     conn.list_functions()['Functions'].should.have.length_of(0)
@@ -266,8 +274,8 @@ def test_list_create_list_get_delete_list():
             "RepositoryType": "S3"
         },
         "Configuration": {
-            "CodeSha256": 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa',
-            "CodeSize": 123,
+            "CodeSha256": hashlib.sha256(zip_content).hexdigest(),
+            "CodeSize": len(zip_content),
             "Description": "test lambda function",
             "FunctionArn": "arn:aws:lambda:123456789012:function:testFunction",
             "FunctionName": "testFunction",