Sender-Constrained Tokens: How DPoP Solves the Bearer Token Security Crisis in Production Carrier API Integrations
Bearer tokens in carrier API integrations present a fundamental security vulnerability: once stolen, they become a "golden ticket" for attackers who can impersonate legitimate clients without any additional verification. FedEx requires OAuth access tokens that expire every 60 minutes, while UPS phased out access key-based authentication in 2024,