return partSize, err
	}

	configuredPartSize := minPartSize
	// Use floats for part size for all calculations to avoid
	// overflows during float64 to int64 conversions.
	partSizeFlt := float64(objectSize / maxPartsCount)
	partSizeFlt = math.Ceil(partSizeFlt/float64(configuredPartSize)) * float64(configuredPartSize)

	// Part size.
	partSize = int64(partSizeFlt)
	if partSize == 0 {
		return minPartSize, nil
	}

ciphertext  := sealed_chunk_0   ||       sealed_chunk_1   ||       sealed_chunk_2   ||       ...
```

In case of a S3 multi-part operation each part is en/decrypted with the scheme shown in Figure 1. However, for each part a unique secret key is derived from the OEK and the part number using a PRF. So in case of multi-part not the OEK but the output of `PRF(OEK, part_id)` is used as secret key.

#### Cryptographic Primitives

					otherPart := getPartNum(other[0])
					if part != otherPart {
						fmt.Println("part ", part, " != other part", otherPart, other[0])
						continue
					}
					// fmt.Println("part ", part, "other part", otherPart, other[0])
					fmt.Printf("Reading version %q Part %d.\n", otherKey, otherPart)
					// os.Exit(0)
					otherM, err := readAndMap(other, part, block)
					if err != nil {
						fmt.Println(err)

	arns := []string{}
	if evnot == nil {
		return arns
	}
	region := globalSite.Region()
	for targetID := range evnot.targetList.TargetMap() {
		// httpclient target is part of ListenNotification
		// which doesn't need to be listed as part of the ARN list
		// This list is only meant for external targets, filter
		// this out pro-actively.
		if !strings.HasPrefix(targetID.ID, "httpclient+") {

	// Read part checksums from serializedOut
	readParts := ReadPartCheckSums(serializedOut)
	expectedChecksums := []string{
		part1Checksum.Encoded,
		part2Checksum.Encoded,
		part3Checksum.Encoded,
	}
	for i, expected := range expectedChecksums {
		if got := readParts[i][ChecksumCRC32C.String()]; got != expected {
			t.Fatalf("want part%dChecksum.Encoded %s, got %s", i+1, expected, got)
		}

	// The ETag of a multi-part object is always:
	//   ETag := MD5(ETag_p1, ETag_p2, ...)+"-N"   (N being the number of parts)
	//
	// This is independent of encryption. An encrypted multipart
	// object also has an ETag that is the MD5 of its part ETags.
	// The fact the in case of encryption the ETag of a part is
	// not the MD5 of the part content does not change that.
	var completeETags []etag.ETag

			continue
		}
		switch header {
		case "expect":
			// Golang http server strips off 'Expect' header, if the
			// client sent this as part of signed headers we need to
			// handle otherwise we would see a signature mismatch.
			// `aws-cli` sets this as part of signed headers.
			//
			// According to
			// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.20
			// Expect header is always of form:

		parts := make([]CompletePart, len(oi.Parts))
		for i, part := range oi.Parts {
			hr, err := hash.NewReader(ctx, io.LimitReader(gr, part.Size), part.Size, "", "", part.ActualSize)
			if err != nil {
				return fmt.Errorf("rebalanceObject: hash.NewReader() %w", err)
			}
			pi, err := z.PutObjectPart(ctx, bucket, oi.Name, res.UploadID,
				part.Number,
				NewPutObjReader(hr),
				ObjectOptions{

// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful

	listPartsResponse.Parts = make([]Part, len(partsInfo.Parts))
	for index, part := range partsInfo.Parts {
		newPart := Part{}
		newPart.PartNumber = part.PartNumber
		newPart.ETag = "\"" + part.ETag + "\""
		newPart.Size = part.Size
		newPart.LastModified = amztime.ISO8601Format(part.LastModified.UTC())
		newPart.ChecksumCRC32 = part.ChecksumCRC32
		newPart.ChecksumCRC32C = part.ChecksumCRC32C