openssl_csr_export() takes the
Certificate Signing Request represented by csr and stores it as ascii-armoured
text into out, which is
passed by reference. 成功回傳TRUE失敗回傳FALSE。 The optional notext affects the verbosity of the
output; if it is FALSE then
additional human-readable information is included in the
output. The default value of
notext is TRUE
See also openssl_csr_export_to_file(),
openssl_csr_new() and
openssl_csr_sign().