The traditional class-based SSL certificate system (Class 1-5) was originally defined in the X.509 standard, but modern certificate authorities have largely moved to validation level-based classification (DV, OV, EV). Let's examine the technical differences:

// Example: Checking cert validation level in Node.js
const https = require('https');
const tls = require('tls');

https.get('https://example.com', (res) => {
  const cert = res.socket.getPeerCertificate();
  console.log('Validation Level:', cert.subject.O ? 'OV/EV' : 'DV');
  console.log('EV Fields:', cert.subject.organizationName);
});

While EV validation shares similarities with Class 3 requirements, it's actually more stringent:

• EV requires legal existence verification (Class 3 doesn't)
• EV mandates physical address confirmation
• EV certificates trigger browser UI indicators (green bar)

For your SOAP-based B2B communication, here's what modern security best practices recommend:

// Sample Java code enforcing mutual TLS for B2B
SSLContext sslContext = SSLContextBuilder
    .create()
    .loadTrustMaterial(trustStore, trustStrategy)
    .loadKeyMaterial(keyStore, keyPassword)
    .build();

WSClient client = WSClient.builder()
    .sslContext(sslContext)
    .requireHostnameVerification()
    .build();

Major CAs and their offerings:

The actual cryptographic protection is identical across certificate types - the difference lies in validation:

# OpenSSL command to verify cert strength
openssl x509 -in certificate.crt -text -noout | grep -E "Signature Algorithm|Public Key Algorithm"

# Sample output:
# Signature Algorithm: sha256WithRSAEncryption
# Public-Key: (2048 bit)

Certificate authorities must undergo WebTrust audits to issue higher-class certificates. Key requirements:

• Class 3/EV: Annual third-party audits
• Physical security controls for HSMs
• Strict identity verification procedures

The classification system for SSL certificates (Class 1-5) represents varying levels of validation and use cases. While modern terminology often focuses on DV, OV, and EV certificates, understanding these legacy classes remains important for backward compatibility and certain business requirements.

Extended Validation (EV) certificates represent the highest level of validation in current CA/Browser Forum standards, while Class 3 was a historical designation for similar high-assurance certificates. Key differences:

• EV requires more rigorous business verification (legal existence, operational status)
• Class 3 didn't mandate the strict organizational checks of EV
• Modern browsers don't display "Class 3" indicators like they do with EV green bars

For business-to-business SOAP APIs, the technical requirements differ from visual trust indicators:

// Java example - SSL context setup for mutual authentication
SSLContext sslContext = SSLContextBuilder.create()
    .loadTrustMaterial(trustStore, new TrustSelfSignedStrategy())
    .loadKeyMaterial(keyStore, keyPassword)
    .build();

CloseableHttpClient client = HttpClients.custom()
    .setSSLContext(sslContext)
    .build();

Class 4 certificates (for inter-company transactions) typically add:

• Additional legal entity verification
• Higher warranty amounts
• Audit requirements for CAs issuing them

CA authorization to issue different classes depends on:

All certificate classes provide identical cryptographic strength when:

• Using same key lengths (2048-bit RSA or equivalent)
• Employing modern TLS versions (1.2+)
• Properly configured servers

The Mozilla CA Certificate Program maintains the most comprehensive list:

# Fetch current trusted root program
curl https://ccadb-public.secure.force.com/mozilla/IncludedRootsPEMTxt?trustBitsInclude=Websites

Key resources include:

• CA/Browser Forum baseline requirements
• Mozilla root store policy
• Microsoft root certificate program