In public key infrastructure (PKI) systems, a certificate signing request (also CSR or certification request) is a message sent from an applicant to a registration authority of the public key infrastructure in order to apply for a digital identity certificate. It usually contains the public key for which the certificate should be issued, identifying information (such as a domain name) and integrity protection (e.g., a digital signature). The most common format for CSRs is the PKCS #10 specification; another is the Signed Public Key and Challenge SPKAC format generated by some web browsers.
