FIPS 186-5
Digital Signature Standard (DSS)
Standard Introduction
FIPS 186-5 is the current U.S. federal Digital Signature Standard. Published and effective on 3 February 2023, it superseded FIPS 186-4 after a one-year transition and specifies approved RSA, ECDSA and EdDSA signature generation and verification requirements.
The standard is mandatory for covered federal departments, agencies and signature systems operated for them under contract; private-sector adoption is otherwise available voluntarily. NIST posted a planning note on 12 May 2025 identifying errata intended for a future update or revision, so implementers should check the official errata alongside the published standard.
Three Signature Families
Approves RSA, ECDSA and EdDSA signature generation and verification subject to the standard's algorithm, parameter, key and assurance requirements.
DSA Generation Removed
No longer approves the Digital Signature Algorithm for generating new signatures; DSA may only verify signatures generated before the implementation date.
Federal Baseline
Applies to U.S. federal departments and agencies protecting covered sensitive unclassified information and to signature systems operated for them under contract.
list_alt FIPS 186-5 Implementation Focus
- RSA, ECDSA and EdDSA signature algorithms
- Approved hash functions and associated parameters
- Private-key secrecy and purpose separation
- Public-key, domain-parameter and key-possession assurances
- Signature generation and verification procedures
- DSA verification-only legacy treatment
- Cryptographic module validation dependencies
- NIST errata and revision monitoring
Who Needs to Comply?
U.S. federal agencies and contractors that design, operate or supply covered public-key signature systems; cryptographic module vendors and testing laboratories; software, hardware, PKI, identity, code-signing, payment and document-signing teams that need FIPS-aligned digital signatures. Private-sector adoption is available but is not universally mandatory.
Key Requirements
Select an Approved Signature Scheme
Use RSA, ECDSA, deterministic ECDSA, EdDSA or HashEdDSA as permitted by FIPS 186-5 and its incorporated references. Do not use DSA to generate new signatures.
Use Approved Supporting Functions
Pair signature algorithms with approved hash, key-generation and other security functions, including the applicable constraints in FIPS 180, FIPS 202, SP 800-186 and referenced specifications.
Protect and Separate Private Keys
Keep signature private keys secret, restrict them to signature generation, prevent reuse for key establishment, and control generation, access, backup, recovery, rotation, revocation and destruction.
Establish Required Assurances
Obtain assurance of domain-parameter validity, public-key validity and possession of the corresponding private key where the selected scheme and use case require them.
Validate the Implementation Context
Confirm whether the system requires a validated cryptographic module under FIPS 140-3 and CMVP, then test algorithm behavior, failure handling, interoperability and evidence in the deployed environment.
Track Errata and Transition Decisions
Record the migration from FIPS 186-4, retain any permitted legacy DSA verification boundary, and review NIST's May 2025 errata notice before making new design or validation decisions.
Implementation Roadmap
Confirm applicability and system boundary
Identify federal information, contracts, authorizations and system components in scope. Separate the signature service, cryptographic module, key-management service, certificate infrastructure and relying applications, and record the authority for each requirement.
Inventory algorithms, keys and legacy signatures
Map every signature-generation and verification path, algorithm, parameter set, hash, key purpose, module validation status and external dependency. Locate DSA generation and any legacy DSA verification that must be isolated.
Design the approved target state
Select permitted RSA, ECDSA or EdDSA profiles and approved supporting functions. Define key generation, ownership, possession assurance, protection, purpose separation, rotation, revocation, archival and destruction controls.
Implement and validate
Use modules and validation pathways required by the authorization or procurement context. Test known-answer behavior, malformed signatures, parameter rejection, interoperability, key isolation, audit logging and operational failure handling.
Approve migration and monitor NIST changes
Document residual legacy verification, complete authorization and supplier evidence, retire prohibited generation paths, and assign an owner to review the May 2025 errata and any later FIPS 186-5 update or revision.
Compliance Checklist
checklist Scope and authority
checklist Algorithms and parameters
checklist Keys and assurances
checklist Validation and lifecycle
Which cryptographic reference answers which question?
Use FIPS 186-5 for approved signature algorithms, FIPS 140-3 and CMVP for module validation, and key-management or PKI rules for the surrounding lifecycle and trust model.
| Reference | Primary question | Typical evidence |
|---|---|---|
| FIPS 186-5 | Which digital-signature algorithms and procedures are approved? | Algorithm selection, parameters, signature and key assurances |
| FIPS 140-3 / CMVP | Has the cryptographic module been independently validated? | Certificate, module version, security policy and operational environment |
| NIST SP 800-57 | How should cryptographic keys be managed through their lifecycle? | Key-management policy, periods, roles, protection and recovery |
| PKI or certificate policy | How is a public key bound to an identity and trusted? | Certificate profile, issuance, revocation, validation and relying-party rules |
Common Misconceptions
FIPS 186-5 is optional for every organization because NIST standards are guidance.
The standard is mandatory for the covered federal systems stated in its applicability section. Use by private organizations is voluntary unless another authority or agreement requires it.
Any RSA, ECDSA or EdDSA implementation is automatically compliant.
Compliance depends on approved parameters and supporting functions, required assurances, key controls, incorporated references and the implementation and validation context.
A CMVP certificate proves the whole application is secure.
A certificate applies to a defined cryptographic module and version under specified conditions. System integration, key custody, identity, authorization, error handling and operational security remain separate responsibilities.
Penalties & Enforcement
FIPS 186-5 does not state a standalone monetary penalty. It is mandatory for the covered federal systems identified in the standard, and FISMA does not permit waivers from FIPS made mandatory by the Secretary of Commerce. Contract, authorization, procurement or operational consequences can arise when a system or module fails applicable federal requirements.
Frequently Asked Questions
What algorithms does FIPS 186-5 approve for digital signatures?
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FIPS 186-5 covers RSA, ECDSA and EdDSA families, including deterministic ECDSA and HashEdDSA under the stated conditions and incorporated references. The selected scheme still needs approved parameters, supporting functions and implementation controls.
Can DSA still be used under FIPS 186-5?
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DSA is not approved for generating new signatures. It may be used to verify signatures generated before the implementation date, so organizations need a documented legacy-verification boundary rather than a continuing DSA signing service.
Who is required to follow FIPS 186-5?
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The standard applies to covered U.S. federal departments and agencies and to relevant public-key signature systems operated for them under contract. Private and commercial organizations may adopt it voluntarily unless a law, contract, procurement term or other authority makes it applicable.
Does implementing FIPS 186-5 make a product FIPS certified?
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No. FIPS 186-5 specifies digital-signature algorithms and requirements; it is not a standalone product certification. Federal use commonly depends on a cryptographic module validated under FIPS 140-3 through the CMVP, with the actual module version, operational environment and validation status checked.
What changed after the 2023 publication?
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The one-year FIPS 186-4 transition ended on 3 February 2024. On 12 May 2025, NIST added a planning note stating that identified issues are intended to be corrected in a future update or revision and linked an errata spreadsheet. FIPS 186-5 remains the published standard while those potential updates are monitored.
Is a valid signature enough to prove a person's legal identity?
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No. Cryptographic verification shows that a signature is valid for the tested data and public key. Identity binding, certificate status, authorization, trusted time, key custody, policy and legal effect require additional controls outside the signature equation itself.
Official Documentation
Official PDF for FIPS 186-5
Official publication or summary for FIPS 186-5
Official online resource
National Institute of Standards and Technology (NIST) guidance and reference material
Implementation toolkit
Templates, guidance, or companion resources for FIPS 186-5