CallanHP

A Better Mechanism for Periodic Functions Invocation?

Functions in Oracle Cloud Infrastructure are great. As a serverless execution environment with pre-built logging, metrics, etc. it allows developers to simply focus on their code and not worry about all of the supporting infrastructure, while still providing a lot of flexibility through the use of container primitives. As great as Functions are, they are reactive, they can only be invoked and can’t natively be configured to be executed in a spontaneous or scheduled manner. Often this won’t matter, as Functions will be invoked directly or indirectly by users, or in response to events, but sometimes you simply need a bit of code to run periodically.

Using OCI Bastions with PuTTY

Recently, Oracle rolled out the OCI Bastions service, which is designed to simplify the process of accessing instances which do not have a public IP address. They are really easy to use, with simple commands to allow access to these internal hosts… if you are using a Unix shell. Unfortunately I suffer from being quite wedded to various tools, and as a Windows user, I tend to use PuTTY to access hosts via SSH, so this blog post will detail both the OCI Bastion service in a little more detail, as well as how I continued to resist changing my old habits, and set up connections using the OCI Bastion service using a number of components of the PuTTY suite of tools.

Simple, Secure Log Retention using OCI Services

Between the Oracle Cloud Infrastructure (OCI) Audit Service recording administrative operations and Oracle Identity Cloud Service (IDCS) tracking access and user management events, Oracle Cloud provides pretty comprehensive tracking of security events. Recently however, I have been in conversations with a number of organisations who have been seeking longer term retention of audit events for several different reasons, including governance, compliance and forensic requirements. The OCI Audit service supports requesting bulk export of audit events to Object Storage, which allows you manage the retention and archiving of those events yourself, so I started wondering if I could do the same for the IDCS access events. A bit of testing and some simple coding later, and I had events being pulled directly from the IDCS Audit Events API periodically and sent to Object Storage for retention.

In this blog post, I will provide this code as a sample, and discuss some of the techniques and technologies that are available in Oracle Cloud Infrastructure to enable simple, but highly secure and cost-effective, automation of cross-service tasks such as this.

Secure Inter-Service Communication in OCI

Oracle Cloud Infrastructure provides a ton of useful services for automating and orchestrating behaviours in your cloud environment, and while they are often pretty handy on their own, leveraging them together gives almost complete flexibility on what you can achieve. Want to trigger a backup using a command in slack, then have a message get sent back when it completes? Sure! Want to periodically poll a log API and archive the results? Easy. Oracle Cloud Infrastructure provides a number of inbuilt capabilities, as well as the ability to jump into arbitrary code to build elaborate automation flows, and this blog post will focus upon the security constructs around this, looking at how services can be authorised to invoke one another, as well as how they authenticate themselves, while avoiding storing sensitive data in insecure ways. This post is intended as an overview of the concepts, and will be referenced in more concrete ways in future.

Consumer Data Right (CDR) – User-specific Identifiers for ID Permanence

Version 1.0.0 of the Consumer Data Right standard was released in September, and it introduces a common set of Banking APIs in line with Australian government legislation. The principles behind the standards design are very solid, though the some of the specific requirements are pretty wild and they result in a bit of rethinking of some of the classical API conventions. The most prominent example of this is the approach the CDR standards take towards ‘object identifiers’, in the ID Permanence section, and I considered the requirements for this interesting enough to spend some time thinking about and documenting.

In this context, an ‘object identifier’ refers to the way in which you refer to an individual instance of an object from your API, such as the ‘accountId’ in the following URI:

GET /banking/accounts/{accountId}

In this blog post we will look at what the CDR requires for these types of identifiers, and provide some sample code which implements the obfuscation requirements specified in the standard.

Invoking Oracle PaaS service APIs protected by OAuth

Oracle PaaS services are typically protected by Identity Cloud Service (IDCS), which provides unified access management for the Oracle Cloud. This protection extends to their exposed APIs, which usually require you to present a valid access token as part of your invocation. Unfortunately, the documentation for a number of the services tends to assume that the reader has an in-depth knowledge of OAuth concepts, and IDCS operations.

Typically my blog posts are around specific proof of concept things I have been working on, or go in-depth into more advanced IDCS concepts, but I have realised (mostly because people kept asking me…) that many developers using these services don’t have a strong practical understanding of OAuth, and struggle to interpret the documentation around the authentication requirements for the services. This blog post is designed to provide a step by step explanation of what is required from an IDCS perspective, as well as an explanation of the techniques to obtain a an access token to use the service APIs.

A non-exhaustive list of PaaS services for which these instructions are applicable:

Oracle Integration Cloud
Oracle Blockchain Platform
Oracle API Platform Cloud Service
Oracle Mobile Hub
Oracle Digital Assistant

Calling OCI APIs from Postman

Oracle’s Cloud Infrastructure has been designed in an API-first manner, which is awesome for all sorts of infrastructure automation tasks. It also implements an interesting API security model, in which all requests must be signed using a private key, associated with a public key which has already been configured in OCI (here, the developers are showing their infrastructure roots, as this echoes how SSH Auth is normally handled). The documentation of this model provides sample code in a number of languages, which is perfect if you are writing automation scripts, but is a little inflexible for ad-hoc testing. Typically I much prefer to use a rich graphical REST client, such a Postman, so that I can easily tweak my parameters and try out different types of calls before I write any code. Unfortunately while Postman is well equipped for Basic and Token based Auth, HTTP-Signature is not natively implemented, and rather than abandon Postman for a new tool, I set out to implement it using Postman’s powerful scripting capabilities. In this blog post I provide the result of this, which is a downloadable collection which provides all of the required scripts, and discuss the approach used.

Hashed Timelock Agreements in Hyperledger Fabric

Hashed Timelock Agreements, or Contracts, have emerged as an important concept in the cryptocurrency space in order to perform transactions across ledgers – and I feel could be a valid mechanism to handle the issue of performing verifiable cross-channel transactions in Hyperledger in some use cases. The basic concept of a Hashed Timelock Agreement (HTLA) is that it allows for a conditional transaction (which I have deemed a ‘proposal’) with a cryptographic challenge which ensures it can only be completed by a pre-defined party. This can be chained through multiple intermediaries, which can enable two organisations who do not share a channel to interact, and for transactions to be confirmed across channels.

Using Public/Private Key Authentication for Oracle IDCS

In a recent blog post, I added a throwaway reference to the use of signed assertions as a better mechanism for interacting with the Oracle Identity Cloud Service REST APIs than the use of Client id/secret, though qualified it with ‘if you want to handle the additional complexity in your consuming client’. Reflecting upon this, I thought that perhaps it was worth trying to explain this ‘additional complexity’, since the use of signed assertions have a number of benefits; primarily that it does not require an exchange of sensitive information, as the private keys used to sign the assertion never need to leave the machine on which they are generated. In this blog post, I will delve deeper into what is required to leverage this authentication mechanism, for both clients and users.

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Custom User Activation and Password Reset Flows in Oracle IDCS

Oracle’s Identity Cloud Service is typically associated with its role in acting as the primary identity store for Oracle’s Cloud services – acting as the gatekeeper for administrators and developers, and providing single-sign-on across Oracle services for end users. However, thanks to its API-first design, it is also very capable of acting as a headless OAuth server and user store, providing authenticated access to custom applications and APIs. When these custom applications are customer facing, you will want fine-grained control over your user experience, without them interacting with IDCS directly. In this post we will explore implementing custom user activation and password reset flows; which provides the opportunity to implement pixel perfect UIs, modify the flows for different classes of users, or just do whatever your custom application requires.

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