```
mc admin tier add s3 source S3TIER --bucket s3bucket --prefix testprefix/ --use-aws-role
```

## Description of `xl.meta`

`xl.meta` is a new self describing backend format used by MinIO to support AWS S3 compatible versioning.
This file is the source of truth for each `version` at rest. `xl.meta` is a msgpack file serialized from a
well defined data structure. To understand `xl.meta` here are the few things to start with

	export AWS_ACCESS_KEY_ID=minio
	export AWS_SECRET_ACCESS_KEY=minio123
	aws --endpoint-url http://localhost:"$start_port" s3api create-multipart-upload --bucket bucket --key obj-1 >upload-id.json
	uploadId=$(jq -r '.UploadId' upload-id.json)

	truncate -s 5MiB file-5mib
	for i in {1..2}; do
		aws --endpoint-url http://localhost:"$start_port" s3api upload-part \
			--upload-id "$uploadId" --bucket bucket --key obj-1 \

         "Principal":"*",
         "Action":"s3:PutObject",
         "Resource":"arn:aws:s3:::multi-key-poc/*",
         "Condition":{
            "Null":{
               "s3:x-amz-server-side-encryption-aws-kms-key-id":"true"
            }
         }
      }
   ]

 * ⬜️ [Moshi](https://github.com/square/moshi): A modern JSON library for Android and Java.
 * [Ok2Curl](https://github.com/mrmike/Ok2Curl): Convert OkHttp requests into curl logs.
 * [OkHttp AWS Signer](https://github.com/babbel/okhttp-aws-signer): AWS V4 signing algorithm for OkHttp requests
 * [okhttp-digest](https://github.com/rburgst/okhttp-digest): A digest authenticator for OkHttp.

}

// Verify if request has AWS PreSign Version '4'.
func isRequestPresignedSignatureV4(r *http.Request) bool {
	_, ok := r.Form[xhttp.AmzCredential]
	return ok
}

// Verify request has AWS PreSign Version '2'.
func isRequestPresignedSignatureV2(r *http.Request) bool {
	_, ok := r.Form[xhttp.AmzAccessKeyID]
	return ok
}

// Verify if request has AWS Post policy Signature Version '4'.

//
// In this implementation, account-id is empty.
//
// Reference: https://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html

const (
	arnPrefixArn        = "arn"
	arnPartitionMinio   = "minio"
	arnServiceIAM       = "iam"
	arnResourceTypeRole = "role"
)

// ARN - representation of resources based on AWS ARNs.
type ARN struct {
	Partition    string
	Service      string
	Region       string

- [MinIO Erasure Code Overview](https://min.io/docs/minio/linux/operations/concepts/erasure-coding.html)
- [Use `mc` with MinIO Server](https://min.io/docs/minio/linux/reference/minio-mc.html)
- [Use `aws-cli` with MinIO Server](https://min.io/docs/minio/linux/integrations/aws-cli-with-minio.html)
- [Use `minio-go` SDK with MinIO Server](https://min.io/docs/minio/linux/developers/go/minio-go.html)

stat_out1=$(./mc stat --no-list minio1/test-bucket/encrypted --insecure --json)
src_obj1_algo=$(echo "${stat_out1}" | jq '.metadata."X-Amz-Server-Side-Encryption"')
src_obj1_keyid=$(echo "${stat_out1}" | jq '.metadata."X-Amz-Server-Side-Encryption-Aws-Kms-Key-Id"')
echo "Stat minio1/test-bucket/defpartsize"
./mc stat --no-list minio1/test-bucket/defpartsize --insecure --json
stat_out2=$(./mc stat --no-list minio1/test-bucket/defpartsize --insecure --json)

//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

// Package cmd This file implements helper functions to validate Streaming AWS
// Signature Version '4' authorization header.
package cmd

import (
	"bufio"
	"bytes"
	"encoding/hex"
	"errors"
	"fmt"
	"hash"
	"io"
	"net/http"
	"strings"
	"time"