Introducing the SLSA framework

Introducing the SLSA framework

Preserving the integrity of the code has always been a concern. However, events such as the SolarWinds hack have encouraged organizations such as the Cybersecurity and Infrastructure Security Agency (CISA) to release guidelines to minimize the risk of attacks against the software supply chain.

In parallel, the open-source community and the technology industry are also joining forces in this regard. Proof of this is the SLSA framework, a set of incremental security guidelines that aim to help defend against hacks in the software supply chain.

Codenotary is not just fully aware of the SLSA framework but provides crucial functions for our customers to comply with all SLSA levels.

What is SLSA?

According to its development team, SLSA (Supply chain Levels for Software Artifacts) is a “security framework from source to service, giving anyone working with software a common language for increasing levels of software security and supply chain integrity“. However, SLSA promises to be much more.

The SLSA framework, proposed by Google and inspired by its Borg Binary Authorization framework, has been developed in collaboration with the Open Source Security Foundation (OpenSSF) to formalize the criteria related to software supply chain integrity. This standardization of criteria, if you like, aims to protect each stage of the software development lifecycle.

SLSA and supply chain integrity

While the idea behind SLSA sounds promising, you may be wondering how I can use this framework to increase the security of the software supply chain?

The first thing to understand about the SLSA framework is that it is not a certification (at least not yet) but rather a series of security guidelines. These guidelines consist of 4 levels that are directed to the different phases of the software supply chain.

  • SLSA 1. The most basic level consists of automating the build process and generating a metadata file (known as provenance) with crucial information such as the build process, top-level source, and dependencies. While this metadata is not sufficient to ensure the safety of artifacts, it does at least provide risk managers with a high-level view of the potential risks they face.
  • SLSA 2. This level requires that the source code be hosted in a service that supports version control and generates an authenticated provenance. In addition, it is essential for this level that there is an immutable reference that points to each change in the repository. With these two simple steps, the authenticated provenance makes it very difficult for an attacker to modify the software, to the point that the build service can be considered safe.
  • SLSA 3. You can think of this level as an extension of SLSA 2. This is because the source and build platforms must meet stricter security standards that guarantee a more reliable and detailed source audit. Some of the values that should be included in each revision history include author of the change, uploader, reviewer (s), and timestamp. This care to the integrity of the build process makes it easier to prevent sophisticated attacks such as cross-build contamination for example. 
  • SLSA 4. Currently, this is the maximum level of protection of the SLSA framework. In addition to meeting all the requirements of the previous levels, SLSA 4 consists of a two-person review of all changes as well as reproducibility of the build process. Other requirements include an immutable history of changes and unlimited retention of code changes.

Since the SLSA framework is a work in progress, the requirements for each level may vary to include additional best practices. An updated list of requirements is available in the project documentation.

Implementing these levels of protection does not have to be a daunting task.

Codenotary offers you a platform with an innovative immutable ledger technology that guarantees a trusted supply chain thanks to its tamperproof provenance SBOM. For more information, please contact us.

Codenotary Cloud


Trusted CI/CD, SBOM and artifact protection with cryptographic proof. One CLI to manage all.
Our highly scalable service already processes tens of millions of transactions every single month.


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Use Case - Tamper-resistant Clinical Trials


Blockchain PoCs were unsuccessful due to complexity and lack of developers.

Still the goal of data immutability as well as client verification is a crucial. Furthermore, the system needs to be easy to use and operate (allowing backup, maintenance windows aso.).


immudb is running in different datacenters across the globe. All clinical trial information is stored in immudb either as transactions or the pdf documents as a whole.

Having that single source of truth with versioned, timestamped, and cryptographically verifiable records, enables a whole new way of transparency and trust.

Use Case - Finance


Store the source data, the decision and the rule base for financial support from governments timestamped, verifiable.

A very important functionality is the ability to compare the historic decision (based on the past rulebase) with the rulebase at a different date. Fully cryptographic verifiable Time Travel queries are required to be able to achieve that comparison.


While the source data, rulebase and the documented decision are stored in verifiable Blobs in immudb, the transaction is stored using the relational layer of immudb.

That allows the use of immudb’s time travel capabilities to retrieve verified historic data and recalculate with the most recent rulebase.

Use Case - eCommerce and NFT marketplace


No matter if it’s an eCommerce platform or NFT marketplace, the goals are similar:

  • High amount of transactions (potentially millions a second)
  • Ability to read and write multiple records within one transaction
  • prevent overwrite or updates on transactions
  • comply with regulations (PCI, GDPR, …)


immudb is typically scaled out using Hyperscaler (i. e. AWS, Google Cloud, Microsoft Azure) distributed across the Globe. Auditors are also distributed to track the verification proof over time. Additionally, the shop or marketplace applications store immudb cryptographic state information. That high level of integrity and tamper-evidence while maintaining a very high transaction speed is key for companies to chose immudb.

Use Case - IoT Sensor Data


IoT sensor data received by devices collecting environment data needs to be stored locally in a cryptographically verifiable manner until the data is transferred to a central datacenter. The data integrity needs to be verifiable at any given point in time and while in transit.


immudb runs embedded on the IoT device itself and is consistently audited by external probes. The data transfer to audit is minimal and works even with minimum bandwidth and unreliable connections.

Whenever the IoT devices are connected to a high bandwidth, the data transfer happens to a data center (large immudb deployment) and the source and destination date integrity is fully verified.

Use Case - DevOps Evidence


CI/CD and application build logs need to be stored auditable and tamper-evident.
A very high Performance is required as the system should not slow down any build process.
Scalability is key as billions of artifacts are expected within the next years.
Next to a possibility of integrity validation, data needs to be retrievable by pipeline job id or digital asset checksum.


As part of the CI/CD audit functionality, data is stored within immudb using the Key/Value functionality. Key is either the CI/CD job id (i. e. Jenkins or GitLab) or the checksum of the resulting build or container image.

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