Signature Comparator API

Endpoint Overview

POST /api/v1/ocr/signature-comparator

Description

The Signature Comparator API provides advanced biometric signature verification capabilities by comparing two signature images and generating an accuracy score. This endpoint leverages sophisticated image processing and machine learning algorithms to analyze signature characteristics, patterns, and features to determine authenticity and matching probability.

The API returns a comprehensive comparison result including a numerical score (0-100), a threshold-based matching decision, and detailed metadata about the comparison process. This service is essential for document verification, identity authentication, and fraud prevention workflows.

Key Benefits

High Accuracy: Advanced ML algorithms provide precise signature matching with customizable threshold settings

Multiple Input Formats: Supports file uploads, Base64 encoded images, and direct URL links for maximum flexibility

PDF Support: Native capability to extract and compare signatures from PDF documents

Real-time Processing: Fast response times suitable for real-time verification workflows

Use Cases

Financial Services

Legal & Compliance

Healthcare & Insurance

Document Authentication: Verify signatures on loan applications, account opening forms, and financial agreements

Check Verification: Authenticate signatures on checks and payment instruments to prevent fraud

Digital Onboarding: Streamline customer onboarding by automatically verifying signature consistency across documents

Compliance Verification: Ensure regulatory compliance by maintaining audit trails of signature verification processes

Technical Implementation

Authentication

All API requests require authentication using a JWT Bearer token. Authentication follows these steps:

Obtain API Credentials: Register with Surepass to receive your API key.

Generate JWT Token: Use your API key to generate a JWT token.

Include in Requests: Add the token to the Authorization header as Bearer TOKEN.

Different authentication tokens are used for sandbox and production environments:

Sandbox: https://sandbox.surepass.io

Production: https://kyc-api.surepass.io

Request Parameters

Request Headers

Header	Required	Description
Authorization	Yes	Bearer token for API authentication (JWT)
Content-Type	Yes	multipart/form-data for file uploads

Request Body

Parameter	Type	Required	Description
file_1	File	Conditional*	First signature image file for comparison
file_2	File	Conditional*	Second signature image file for comparison
base64_1	String	Conditional*	Base64 encoded first signature image
base64_2	String	Conditional*	Base64 encoded second signature image
link_1	String	Conditional*	URL link to first signature image
link_2	String	Conditional*	URL link to second signature image
use_pdf	Boolean	No	Set to true when comparing signatures from PDF files (default: false)

Note: You must provide exactly one pair of inputs: either (file_1, file_2), (base64_1, base64_2), or (link_1, link_2).

Example Request

{
    "file_1": "[signature_image_1.jpg]",
    "file_2": "[signature_image_2.jpg]",
    "use_pdf": false
}

Process Response

Response Parameters

Parameter	Type	Description
data	Object	Container for comparison results
data.client_id	String	Unique identifier for the comparison request
data.threshold	Number	Threshold value used for matching decision (0-100)
data.score	Number	Similarity score between signatures (0-100)
data.matched	Boolean	Whether signatures match based on threshold
status_code	Number	HTTP status code of the response
success	Boolean	Indicates if the request was processed successfully
message	String	Human-readable response message
message_code	String	Machine-readable message code

Example Successful Response

{
    "data": {
        "client_id": "signature_comparator_vqSwPxeFzaWroCYrfqoS",
        "threshold": 90,
        "score": 100.0,
        "matched": true
    },
    "status_code": 200,
    "success": true,
    "message": "success",
    "message_code": "success"
}

Possible Error Responses

Authentication Error

Invalid File Format

Server Error

{
    "error": null,
    "message": "Your token is invalid. Please ensure that correct token is being used.",
    "status_code": 401,
    "success": false,
    "message_code": "invalid_token"
}

Occurs when the Bearer token is missing, invalid, or expired.

Integration Best Practices

Security Recommendations

Secure Token Storage: Store JWT tokens securely and implement token refresh mechanisms

HTTPS Only: Always use HTTPS endpoints to encrypt data transmission

Input Validation: Validate file types and sizes before sending to prevent malicious uploads

Rate Limiting: Implement client-side rate limiting to avoid exceeding API quotas

User Experience Guidelines

Image Quality Guidelines: Provide users with clear guidelines for signature image quality and resolution

Progress Indicators: Show processing status for signature comparison requests

Error Handling: Implement user-friendly error messages and retry mechanisms

Batch Processing: Consider implementing batch processing for multiple signature comparisons

Code Samples

cURL

Python

Node.js

Related APIs

Document OCR API: Extract text and data from various document types including signatures

ID Verification API: Comprehensive identity verification using government-issued documents

Face Match API: Biometric face comparison and verification services

Document Classification API: Automatically classify and categorize document types

Compliance and Legal Considerations

Data Privacy: Signature images are processed securely and not stored permanently on servers

GDPR Compliance: API processing complies with GDPR requirements for biometric data handling

Industry Standards: Signature comparison algorithms meet industry standards for biometric verification

Audit Trails: All API requests generate audit logs for compliance and security monitoring

Legal Validity: While the API provides technical verification, legal signature validity may require additional context and jurisdiction-specific considerations

Provide your bearer token in the

Authorization

header when making requests to protected resources.

Example:

Authorization: Bearer ********************

curl --location --request POST 'https://kyc-api.surepass.app/api/v1/ocr/signature-comparator' \ --header 'Authorization: Bearer <token>' \ --form 'file_1=@""' \ --form 'file_2=@""' \ --form 'use_pdf=""'

{ "data": { "client_id": "signature_comparator_vqSwPxeFzaWroCYrfqoS", "threshold": 90, "score": 100.0, "matched": true }, "status_code": 200, "success": true, "message": "success", "message_code": "success" }

Signature Comparator

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