GZZ Memorystream到S3桶散列错误

Question

我正在尝试将一个对象序列化为JSON（Newtonsoft.json），并将其存储在GZIP压缩形式的S3存储桶中。我想使用putobjectRequest的MD5Digest属性来确认成功的传输，但是我很难从内存流中正确计算哈希。我猜这与编码有关。

BasicAWSCredentials credentials = new BasicAWSCredentials(<access key>, <secret key>);
AmazonS3Client s3Client = new AmazonS3Client(credentials, <region>);

AmazonS3Client s3Client 
string md5Hash = null;
//Serialize JSON package to be uploaded to AWS
JsonSerializer serializer = new JsonSerializer();
serializer.NullValueHandling = NullValueHandling.Include;
serializer.TypeNameHandling = TypeNameHandling.Auto;
using (MemoryStream memoryStream = new MemoryStream())
{
    //Write JSON to memory stream through compression layer
    using (GZipStream zipStream = new GZipStream(memoryStream, CompressionLevel.Fastest, true))
    using (StreamWriter sw = new StreamWriter(zipStream))
    using (JsonWriter writer = new JsonTextWriter(sw))
    {
        serializer.Serialize(writer, <object to serialize>);
        writer.Flush();
    }
    //Store gzipped JSON package hash to confirm successful upload later
    using (MD5 md5 = MD5.Create())
    {
        byte[] hash = md5.ComputeHash(memoryStream);
        md5Hash = string.Concat(hash.Select(x => x.ToString("x2")));
    }
    //Reset memoryStream to start because ComputeHash has consumed it
    memoryStream.Position = 0;
    //Upload to AWS
    PutObjectRequest request = new PutObjectRequest();
    request.InputStream = memoryStream;
    request.Key = <file name>;
    request.BucketName = <bucket>;
    request.ContentType = "application/gzip";
    request.MD5Digest = md5Hash;
    PutObjectResponse response = s3Client.PutObject(request);
}

Answer 1

我的示例中有2个问题。

Anon Coward正确地确定需要重置内存的位置。

另一个问题是putobjectRequest.md5digest期望base64表示（即使AWS在ETAG中显示MD5 Hash作为HEX）。

代码的哈希部分应该看起来像这样，两个问题已固定

memoryStream.Position = 0;
using (MD5 md5 = MD5.Create())
{
    byte[] hash = md5.ComputeHash(memoryStream);
    md5Hash = Convert.ToBase64String(hash);
}