Torch Object Storage
Torch Object Storage
Torch Object Storage
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- Documentation
Torch Object StorageBest PracticesChecking data integrityVerifying the integrity of downloaded objects
Copy page
Download PDFChecking data integrity
Verifying the integrity of downloaded objects
Copy pageDownload PDFVerifying the integrity of downloaded objects
This topic illustrates the validation workflow and provides sample codes for validating the integrity of downloaded objects using the CRC-64 algorithm.
How it works
In scenarios where an entire object is downloaded in a single operation, the client calculates a CRC-64 checksum while receiving the data. This value is then compared to the CRC-64 checksum stored on the server to ensure the integrity of the downloaded data.
When an object is downloaded in segments using the Range header, a composite checksum is calculated based on the individual checksums of each segment. This value is then compared to the checksum of the entire object that the server returns to ensure the integrity of the final downloaded object.
Flowchart
Code examples
Golang
Python
package main
import (
"context"
"hash"
"io"
"io/ioutil"
"github.com/volcengine/ve-tos-golang-sdk/v2/tos"
)
type crc64Reader struct {
r io.Reader
h hash.Hash64
}
func (cr *crc64Reader) Read(p []byte) (n int, err error) {
n, err = cr.r.Read(p)
cr.h.Write(p[:n])
return n, err
}
func main() {
var (
accessKey = "your access key"
secretKey = "your secret key"
endpoint = "your endpoint"
region = "your region"
bucket = "bucketname"
key = "objectname"
)
client, err := tos.NewClientV2(endpoint, tos.WithRegion(region), tos.WithCredentials(tos.NewStaticCredentials(accessKey, secretKey)))
if err != nil {
panic(err)
}
output, err := client.GetObjectV2(context.Background(), &tos.GetObjectV2Input{
Bucket: bucket,
Key: key,
})
defer output.Content.Close()
p := make([]byte, 1024)
crc64Hash := tos.NewCRC(tos.DefaultCrcTable(), 0)
reader := &crc64Reader{
r: output.Content,
h: crc64Hash,
}
for {
_, err = reader.Read(p)
if err != nil {
if err == io.EOF{
break
}
panic(err)
}
}
if output.HashCrc64ecma != crc64Hash.Sum64() {
panic("crc64 not match")
}
}
import tos
endpoint = 'your endpoint'
access_key = 'your access key'
secret_key = 'your secret key'
region = 'your region'
bucket = 'bucketname'
key = 'objectname'
crc64 = tos.utils.Crc64()
client = tos.TosClientV2(access_key, secret_key, endpoint, region)
try:
resp = client.get_object(bucket, key)
print(resp.status_code)
while True:
chunk = resp.content.read(65536)
if not chunk:
break
crc64.update(chunk)
if resp.hash_crc64_ecma != crc64.crc:
raise Exception('crc64 not match')
except Exception as e:
print(e)
Last updated: 2026.08.25 10:39:45
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