> Credential Check APIs_

Verify Credentials Instantly.
Protect Users Anonymously.

Check if credentials have been compromised in real-time without exposing sensitive data. Our cryptographically secure API allows anonymous verification against billions of breached records.

Official SDKs

Node.js, Python, Rust, Go, C#, Java

RESTful API Integration

Simple, well-documented endpoints

Cryptographic Privacy

Private k-anonymity checks

Real-time Verification

Lightning-fast responses

Billions of Records Checked

Comprehensive database, updated daily

How It Works

Your users stay protected. Their credentials stay private.

pseudocode
1

User Enters Credentials

Your application receives login credentials: [email protected] : password123

// Hash the credential pair
const hash = SHA256(email + ':' + password)
// → 5baa61e4c9b93f3f0682250b6cf8331b...
Hash: 5baa61e4c9b93f3f0682250b6cf8331b...
pseudocode
2

Send Prefix Only

Extract the first 5 characters of the hash and send only the prefix to our API.

const prefix = hash.substring(0, 5)
// → "5baa6"
await fetch('/credential-check/query', { prefix })
Privacy Layer 1: Only 5 characters of the hash are sent - like checking a library card without revealing your name.
Prefix: 5baa6
pseudocode
3

HMAC Protection Applied

Our API finds all matching hashes and scrambles them with HMAC encryption before sending back.

// Server generates HMAC key
results = matchingHashes.map(h => HMAC(h, key))
return { results, key }
Privacy Layer 2: Results are cryptographically protected with HMAC - even if intercepted, they reveal nothing.
HMAC Results + Key
pseudocode
4

Check Match Locally

Your app applies the same HMAC to your full hash and checks if it's in the results - all client-side.

if (hmacResults.includes(hmac(fullHash, key))) {
  // Credential found in breach database!
  // → Go to Step 5A (Breach Detected)
} else {
  // Credentials are safe
  // → Go to Step 5B (All Clear)
}
5A

Breach Detected

ACTION REQUIRED

SOC analyst response options - automate or trigger manually:

Block Account AccessImmediately prevent login until password is reset
Force Password ResetRequire immediate credential change via email
Alert Security TeamTrigger SIEM/incident response workflow
Notify UserSend breach notification with remediation steps
Log IncidentRecord breach detection in audit trail
5B

All Clear

SAFE TO PROCEED

Credentials not found in any known breaches - proceed safely:

Grant AccessAllow user to proceed with authentication
Log SuccessRecord successful verification in audit trail
Update MetricsTrack verification stats for security analytics
Continue SessionProceed with normal authentication flow

Why This Matters

Zero-Knowledge Verification

Your users' credentials are never exposed to DarkStrata or anyone else. The two-layer privacy approach means even we can't see what you're checking — only you know if there's a match.

No credentials leave your server
Cryptographically impossible to reverse
GDPR compliant by design

Official SDKs

Get up and running in minutes with our open-source SDKs

example.ts
// One call to check if credentials are compromised
const isBreached = await darkstrata.check('[email protected]', password);

Node.js / TypeScript

@darkstrata/credential-check
npm install @darkstrata/credential-check
pip install darkstrata-credential-check
cargo add darkstrata-credential-check
dotnet add package DarkStrata.CredentialCheck
go get github.com/darkstrata/darkstrata-sdks/go
<dependency>io.darkstrata:credential-check</dependency>

Why Choose DarkStrata?

The most private credential verification API available

FeatureDarkStrataTraditional APIsIn-House Database
Privacy ProtectionK-Anonymity + HMACTwo-layer cryptographic privacy
Basic k-anonymity only
Single layer protection
None
Full credential exposure
Data Sent to API5-character prefix1 in 1 million anonymity set
Full hash or email
Linkable across requests
Full credentials
Complete exposure risk
Response Speed<200msHighly optimised edge workers
500ms+
Centralised servers
Variable
Depends on infrastructure
Database CoverageBillions of recordsConstantly updated
Millions of records
Periodic updates
Manual effort required
Expensive to maintain
Maintenance BurdenZeroFully managed service
Low
SaaS integration
HighStorage, updates, security
Official SDKs6 Languages SupportedNode.js, Python, Rust, Go, C#, Java
Limited or none
REST only, DIY integration
N/A
Build everything yourself
Compliance FriendlyGDPR ReadyZero PII transmitted
Depends on implementation
May require DPA
Complex
Full data protection burden
Diff FilesAvailableEnterprise tier only *
Not available
API-only access
Manual processBuild your own system

Get enterprise-grade breach protection without compromising your users' privacy or building expensive infrastructure.

* Diff files enable offline bulk processing for password vaults, enterprise password managers, and large-scale credential audits without API rate limits.

API Use Cases

Protect your users across the entire authentication lifecycle

User Authentication

Verify credentials at login time to detect compromised accounts before they can be exploited. Force password resets for affected users automatically.

Registration Validation

Check new user registrations to ensure they aren't using previously breached credentials. Protect your platform from credential stuffing attacks from day one.

Password Reset Flows

Validate that new passwords haven't been compromised in data breaches. Ensure users choose strong, uncompromised passwords when updating their credentials.

Continuous Monitoring

Periodically check your user database against new breaches. Proactively notify users when their credentials appear in newly discovered data leaks.

Low Friction Integration

Get up and running in minutes with our official SDKs for Node.js, Python, Rust, Go, C#, and Java. Credential checking is a one-liner — no complex setup or cryptography knowledge required.

Enterprise Diff Files

Access large HMAC-anonymised hash files for offline credential checking. Ideal for password vaults, enterprise password managers, and bulk credential audits.

Enterprise Plan Only

SIEM Integration

Export credential exposure intelligence directly to your security tools

Native STIX 2.1 Support

Industry-First for Credential Intelligence

DarkStrata is the only credential exposure platform with native STIX/TAXII support. Feed structured threat intelligence directly into Splunk, Microsoft Sentinel, and other SIEM platforms without custom parsing or transformation.

STIX 2.1 compliant bundles
Splunk ES compatible format
TAXII 2.1 endpoints (coming soon)

Alert Reports

Export credential exposure alerts as STIX Report objects with full context and relationships.

Indicators

Compromised credentials as STIX Indicators with patterns for automated detection in your SIEM.

Identities

Compromised users as STIX Identity objects for correlation with your existing user directories.

STIX Export Endpoints

EndpointSTIX ObjectsDescription
/api/v1/stix/alertsReport, Indicator, Identity, RelationshipAlert bundles with full credential context
/api/v1/stix/alerts/:idReport, Indicator, Identity, RelationshipSingle alert as STIX bundle
/api/v1/stix/indicatorsIndicator, Observed-DataFlat credential indicators for bulk import

Compatible Platforms

Splunk ES

Microsoft Sentinel

IBM QRadar

Any STIX 2.1

Start Building with DarkStrata's APIs

Get your API key and start checking credentials in minutes