Key/Certificate parameters
OpenSSL Функции
OpenSSL
PHP Manual

# Certificate Verification

When calling a function that will verify a signature/certificate, the cainfo parameter is an array containing file and directory names that specify the locations of trusted CA files. If a directory is specified, then it must be a correctly formed hashed directory as the openssl command would use.

Key/Certificate parameters
OpenSSL Функции
OpenSSL
PHP Manual