SECOM CO., LTD. Apple, Inc. DigiCert, Inc. sn3rd This specification defines a profile of the Online Certificate Status Protocol (OCSP) that addresses the scalability issues inherent when using OCSP in large scale (high volume) Public Key Infrastructure (PKI) environments and/or in PKI environments that require a lightweight solution to minimize communication bandwidth and client- side processing. This specification obsoletes RFC 5019. The profile specified in RFC 5019 has been updated to allow and recommend the use of SHA-256 over SHA-1.