php 如何获取 公钥钥格式为cer，私钥格式为pfx的证书

Question

1.对接一个接口,对方的接口是java写的,我是php,对方给了两个文件,一个公钥.cer,一个私钥.pfx,
我用openssl_pkcs12_read() 读取pfx进行签名.

openssl_pkcs12_read(file_get_contents('./private.pfx'), $certs, "sft12#");
if(!$certs) exit(0);
openssl_sign($data, $signature, $certs['pkey']);
$signature = base64_encode($signature);

该怎么读取.cer进行验签呢

$cer_key = file_get_contents('./public.cer'); 
 $cer = openssl_x509_read($cer_key);

openssl_x509_read这个函数会报错误
openssl_x509_read(): supplied parameter cannot be coerced into an X509 certificate!

用openssl_x509_read 应该是不对的,那应该怎么做呢.还是说用openssl命令转换成pem呢! 希望得到指导
x509 -inform der -in test.cer -out test.pem

Answer 1

pfx后缀证书（私钥+公钥）、cer证书（仅有公钥）
openssl_pkcs12_read(file_get_contents('./private.pfx'), $certs, "sft12#");

print_r([
$certs['cert'],
$certs['pkey']
]);