FIPS legacy mix-up testing detects outdated cryptographic algorithms in products that claim conformance to modern security requirements. Test objects include software modules, firmware images, cryptographic libraries, and network-facing devices. It targets four primitive families: DES, 3DES, RSA with insufficient key lengths, and SHA-1. Results are reported as detection rates against defined acceptance criteria.
service
The service covers algorithm inventory, configuration review, and functional verification. It serves products that must demonstrate the absence or containment of legacy cryptographic primitives. An engagement typically follows three phases.
In intake and scoping, the client declares the product boundaries and the cryptographic components in scope. In execution, analysts apply static and dynamic methods to locate legacy algorithm usage. In reporting, findings are mapped to the DES, 3DES, RSA, and SHA-1 categories with evidence traces.
The service accepts various types of samples. These include firmware binaries, application builds, and hardware modules with exposed cryptographic interfaces. Deliverables include an algorithm register, an exposure assessment, and a remediation checklist.
Where a first assessment identifies nonconformities, the laboratory can perform post-remediation validation on resubmitted builds. This validation uses the same method set. Before-and-after results therefore remain directly comparable and auditable. The service gives developers, procurement teams, and auditors a repeatable way to locate residual legacy cryptography and confirm that remediation has succeeded.
Test objects and sample collection
Sample collection determines the evidential quality of the entire assessment. Acceptable test objects include release-build binaries, firmware images extracted from target hardware, source distributions for white-box review, and protocol traces captured from live interfaces.
Each sample must be accompanied by build identification, version designation, and a declaration of the platform and toolchain in use. Algorithm identification results cannot be interpreted without this context.
For hardware modules, the laboratory records device identifiers and firmware checksums at intake. Tested configurations can then be reproduced.
Collection follows chain-of-custody practice. Samples are hashed on receipt and stored in a controlled repository. Any extraction from target hardware is documented step by step.
Mixed-source submissions require separation of first-party code, third-party libraries, and operating-system components. Legacy primitives frequently enter through bundled dependencies rather than through the product's own code. Incomplete submissions are flagged befOre testing begins.
Legacy
algorithm identification by test method
Identification combines static analysis, dynamic probing, and traffic observation.
Static analysis applies binary inspection and disassembly to recovered samples. Constant tables, S-box structures, and distinctive round functions associated with DES-family ciphers are searchable in compiled code. Hash routine signatures reveal SHA-1 implementations. Library and linker maps are also reviewed. They record which cryptographic packages were linked into the build.
Dynamic probing exercises the product's interfaces with crafted inputs. Analysts then observe ciphertext or digest characteristics. Block size, mode-of-operation artifacts, and output length distinguish DES and 3DES from modern block ciphers. Digest length separates SHA-1 from the SHA-2 family.
For key establishment, protocol handshakes are observed. The record shows whether RSA key exchange or RSA-based signatures with short keys appear.
Each method produces a candidate finding. A finding is confirmed only when at least two independent methods agree. This limits false attribution from obfuscated or partially stripped binaries.
Detection
coverage: DES / 3DES / RSA / SHA-1 assessment
Coverage assessment organizes confirmed findings into the four primitive families. Each family is evaluated against the declared scope.
For DES and 3DES, analysts classify the usage. The cipher may be reachable through exposed interfaces, dormant in linked code, or used only for legacy interoperability paths. The distinction matters. Dead code and active encryption channels carry different remediation priorities.
For RSA, the assessment records key lengths in use. It distinguishes encryption usage from signature usage. It also notes whether deprecated padding schemes accompany the modulus.
For SHA-1, coverage work separates hash usage in certificates, in message authentication, and in internal integrity checks. Certificate-chain exposure typically demands earlier correction.
Each family result is cross-referenced against the algorithm register. No confirmed finding may lack a location, an invocation path, and a classification.
Coverage gaps are reported explicitly rather than omitted. Examples include interfaces that could not be exercised and binaries that resisted static inspection. An incomplete register understates residual risk and misleads remediation planning.
Assay
metrics: detection rate and reporting
Two metrics govern the analytical output: per-family detection rate and overall register completeness.
The per-family detection rate is calculated for each of the four families. It expresses the proportion of in-scope interfaces and components for which the applied methods yielded a determinate result. A determinate result means detected present, detected absent, or confirmed not reachable.
Register completeness expresses the proportion of declared scope items for which a determinate conclusion was reached at all.
Both metrics are calculated from the executed test matrix and reported with their denominators. A reader can therefore tell a low rate caused by genuine legacy usage from one caused by untestable interfaces.
Reports present each confirmed finding with its evidence: sample identifier, method combination, location within the build, and observed invocation context. Indeterminate items are listed separately with the technical reason. Examples include packed binaries or interface requirements that could not be met in the laboratory environment. This structure lets the client reproduce each conclusion independently.
Acceptance
criteria and remediation validation
Acceptance is judged against criteria agreed at scoping. A common formulation requires zero active uses of DES, 3DES, and SHA-1 across in-scope interfaces. It also requires no RSA usage below the agreed key-length floor, plus documented justification for any legacy interoperability path that must remain.
Findings are graded by exposure. Active use fails acceptance outright. Dormant linked code may pass conditionally, with a removal or isolation plan and a re-test date. Documented interoperability paths pass only when bounded by configuration controls.
Remediation validation applies the same method set to the corrected build. Results are compared finding by finding against the original register.
A remediation is accepted when three conditions hold. Previously confirmed legacy usage is absent under both static and dynamic methods. The fix introduced no new legacy primitives. Previously indeterminate items either gained determinate results or carry documented limitations.
The closing report states the before-and-after detection rates. It also records any residual conditions attached to acceptance.
Frequently Asked Questions
Can samples be retested if we dispute the FIPS: Legacy Mix-Up findings?
Yes. Retained samples from the FIPS: Legacy Mix-Up assessment can be retested upon request. Disputed results are reviewed against the original assay metrics, the detection rate, and the reporting records. If remediation was already performed, the remediation validation data is reviewed as well. A final determination is issued after this review.
How long does a FIPS: Legacy Mix-Up test take, and how are reports delivered?
Turnaround depends on the test method used and the number of legacy algorithms identified for assessment. Progress follows the workflow of legacy algorithm identification, DES / 3DES / RSA / SHA-1 detection coverage, and reporting. The final report is delivered through the agreed reporting channel.
What
sample requirements apply to FIPS: Legacy Mix-Up submission?
Sample collection must follow the test objects and sample collection requirements defined for the FIPS: Legacy Mix-Up service. Appropriate test objects should be provided. This allows legacy algorithm identification and the subsequent DES / 3DES / RSA / SHA-1 assessments to be performed on representative material.