阿里云OSS服务端签名C#版片段

1、引用Aliyun.OSS.dll

2、

static string _aliyun_oss_region = ConfigurationManager.AppSettings["aliyun_oss_region"];
static string _aliyun_oss_accessKeyId = ConfigurationManager.AppSettings["aliyun_oss_accessKeyId"];
static string _aliyun_oss_accessKeySecret = ConfigurationManager.AppSettings["aliyun_oss_accessKeySecret"];
static string _aliyun_oss_bucket = ConfigurationManager.AppSettings["aliyun_oss_bucket"];

public static dynamic GeneratePostPolicy()
{
    string dir = "user_note/";
    string host = "http://" + _aliyun_oss_bucket + "." + _aliyun_oss_region;
    OssClient client = new OssClient(host, _aliyun_oss_accessKeyId, _aliyun_oss_accessKeySecret);

    //过期时间
    DateTime expiration = DateTime.Now.AddHours(24);

    PolicyConditions policyConds = new PolicyConditions();

    //请求长度限制1024X1024X1000
    policyConds.AddConditionItem(PolicyConditions.CondContentLengthRange, 0, 1048576000);
    policyConds.AddConditionItem(MatchMode.StartWith, PolicyConditions.CondKey, dir);

    string postPolicy = client.GeneratePostPolicy(expiration, policyConds);

    byte[] binaryData = System.Text.Encoding.UTF8.GetBytes(postPolicy);
    string encodedPolicy = Convert.ToBase64String(binaryData);

    var hmac = new HMACSHA1(Encoding.UTF8.GetBytes(_aliyun_oss_accessKeySecret));
    byte[] hashBytes = hmac.ComputeHash(Encoding.UTF8.GetBytes(encodedPolicy));
    string postSignature = Convert.ToBase64String(hashBytes);

    return new
    {
        accessid = _aliyun_oss_accessKeyId,
        policy = encodedPolicy,
        signature = postSignature,
        dir = dir,
        host = host,
        expire = (expiration.ToUniversalTime().Ticks - 621355968000000000) / 10000
    };
}