try {
    $result = $cosClient->putObject(array(
            'Bucket' => 'examplebucket-125000000', //存储桶名称，由BucketName-Appid 组成，可以在COS控制台查看 https://console.tencentcloud.com/cos5/bucket
            'Key' => 'exampleobject'
            'Body' => 'string',
            'ServerSideEncryption' => 'AES256',	//SSE-COS加密
        ),
    );
    print_r ($result);
} catch (Qcloud\\Cos\\Exception\\ServiceResponseException $e) {
    echo $e;
}

<?php

require dirname(__FILE__) . '/../vendor/autoload.php';

$secretId = "SECRETID"; //替换为用户的 secretId，请登录访问管理控制台进行查看和管理，https://console.tencentcloud.com/cam/capi
$secretKey = "SECRETKEY"; //替换为用户的 secretKey，请登录访问管理控制台进行查看和管理，https://console.tencentcloud.com/cam/capi
$region = "ap-beijing"; //替换为用户的 region，已创建桶归属的region可以在控制台查看，https://console.tencentcloud.com/cos5/bucket
$cosClient = new Qcloud\\Cos\\Client(
    array(
        'region' => $region,
        'schema' => 'https', //协议头部，默认为http
        'credentials'=> array(
            'secretId'  => $secretId ,
            'secretKey' => $secretKey)));

$bucket = 'examplebucket-125000000'; //存储桶名称，由BucketName-Appid 组成，可以在COS控制台查看 https://console.tencentcloud.com/cos5/bucket
$key = 'exampleobject';
try {
    $customerKey = 'abcdefghijklmnopqrstuvwxyz123456'; //32字节的字符串，支持数字、字母、字符的组合，不支持中文
    $SSECustomerKey = base64_encode($customerKey);
    $SSECustomerKeyMd5 = base64_encode(md5($customerKey, true));
    $result = $cosClient->putObject(array(
            'Bucket' => $bucket, 
            'Key' => $key,
            'Body' => 'string',
            'SSECustomerAlgorithm' => 'AES256',
            'SSECustomerKey' => $SSECustomerKey,
            'SSECustomerKeyMD5' => $SSECustomerKeyMd5,
        )); 
    print_r ($result);
} catch (Qcloud\\Cos\\Exception\\ServiceResponseException $e) {
    echo $e; 
}