(PHP 4 >= 4.2.0, PHP 5, PHP 7)
openssl_csr_export — Exports a CSR as a string
$csr
   , string &$out
   [, bool $notext = true
  ] )
   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.
  
csr
out
notext
可选参数 notext 影响输出的冗余度。如果设为
FALSE,输出内容将包含附加的人类可读信息。notext 的缺省值为 TRUE。
   成功时返回 TRUE, 或者在失败时返回 FALSE。