What Is a Digital Signature, and Why Does It Matter for Government Credentials?
Just as physical IDs use visible security features to support trust, digital credentials use cryptographic digital signatures to make that trust verifiable.
When agencies build digital identity systems, discussions often focus on technology choices: credential formats, wallets, interoperability standards, and security controls. But one of the most important questions comes earlier: is the system trying to establish who someone is, confirm that they are the rightful user of an account or credential, or both?
That distinction matters because identity proofing and authentication solve different problems, require different controls, and should be specified separately in legislation, policy, and procurement requirements.
Two Different Moments, Two Different Questions
Identity proofing and authentication address different points in a resident's relationship with a government system.
Identity proofing happens once, at enrollment. It is the process of establishing that a person is who they claim to be - verifying identity documents, checking biometric matches against authoritative records, or confirming information against trusted data sources. The goal is to create a reliable link between a real-world identity and a digital account or credential. When a resident visits a DMV to enroll in a digital ID program and the DMV checks their physical license, scans their face, and confirms their identity against records, that is identity proofing.
Authentication happens repeatedly, at every subsequent interaction. It is the process of confirming that the person accessing a system or presenting a credential today is the same person who enrolled. When that same resident opens their digital wallet to present a credential at an airport or a pharmacy, the system confirms they are the rightful holder, that is authentication.
The core distinction: proofing establishes identity once. Authentication confirms it on an ongoing basis. Understanding how verifiable digital credentials work helps illustrate why both layers matter, a credential is only as trustworthy as the proofing process that produced it and the authentication mechanism that protects its use.
Why This Difference Matters
A system can have strong identity proofing and lighter authentication, or lighter proofing and strong authentication. They are independent design decisions, and each shapes different aspects of program integrity.
When proofing is strong and authentication is lighter, an agency can be confident about who enrolled, but the ongoing credential presentation may rely on controls that are less rigorous. When proofing is lighter and authentication is strong, the ongoing access controls are robust, but they rest on an enrollment foundation that may not have been as carefully verified.
This is why effective government digital identity systems treat the two as separate design requirements, each with its own standards and evaluation criteria. The right balance depends on the risk profile of the program.
The NIST Framework That Structures This Distinction
NIST SP 800-63 gives agencies a shared vocabulary for specifying both properties independently. Identity Assurance Level (IAL) governs proofing strength, and authenticator Assurance Level (AAL) governs authentication strength, ranging from single-factor to hardware-based cryptographic authentication.
The right combination depends on the risk profile of the program. The framework is designed to let agencies make that call deliberately, rather than applying a single standard across every use case.
What This Means When Writing Requirements
The practical implication for agencies building digital services is that IAL and AAL are worth specifying separately in both legislation and procurement documents, since they reflect different technical and operational requirements.
Legislation that references "strong identity verification" without specifying whether it means IAL2 proofing, AAL2 authentication, or both leaves room for inconsistent interpretation across the agencies and programs it covers. Referencing NIST SP 800-63 IAL and AAL levels directly gives implementing agencies a specific, testable, and widely understood target.
Building on the Right Foundation
A digital identity system works best when both layers are thoughtfully designed, when the enrollment process genuinely establishes who someone is, and when the authentication process reliably confirms they remain in control of their credentials. Getting that combination right is less about picking the highest assurance levels and more about matching the design to what the program actually requires.
The residents those programs serve are best protected by systems where both questions have been asked, and answered, with care.
If your agency is working through these questions, designing enrollment flows, or assessing the assurance levels appropriate for a specific program, SpruceID can help. Get in touch to start the conversation.
Building digital services that scale take the right foundation.
About SpruceID: SpruceID builds digital trust infrastructure for government. We help states and cities modernize identity, security, and service delivery — from digital wallets and SSO to fraud prevention and workflow optimization. Our standards-based technology and public-sector expertise ensure every project advances a more secure, interoperable, and citizen-centric digital future.
