Chilkat Examples

ChilkatHOME.NET Core C#Android™AutoItCC#C++Chilkat2-PythonCkPythonClassic ASPDataFlexDelphi ActiveXDelphi DLLGoJavaLianjaMono C#Node.jsObjective-CPHP ActiveXPHP ExtensionPerlPowerBuilderPowerShellPureBasicRubySQL ServerSwift 2Swift 3,4,5...TclUnicode CUnicode C++VB.NETVBScriptVisual Basic 6.0Visual FoxProXojo Plugin

.NET Core C# Examples

Web API Categories

ASN.1
AWS KMS
AWS Misc
Amazon EC2
Amazon Glacier
Amazon S3
Amazon S3 (new)
Amazon SES
Amazon SNS
Amazon SQS
Async
Azure Cloud Storage
Azure Key Vault
Azure Service Bus
Azure Table Service
Base64
Bounced Email
Box
CAdES
CSR
CSV
Certificates
Cloud Signature CSC
Code Signing
Compression
DKIM / DomainKey
DNS
DSA
Diffie-Hellman
Digital Signatures
Dropbox
Dynamics CRM
EBICS
ECC
Ed25519
Email Object
Encryption
FTP
FileAccess
Firebase
GMail REST API
GMail SMTP/IMAP/POP
Geolocation
Google APIs
Google Calendar
Google Cloud SQL
Google Cloud Storage
Google Drive
Google Photos
Google Sheets
Google Tasks
Gzip
HTML-to-XML/Text
HTTP

HTTP Misc
IMAP
JSON
JSON Web Encryption (JWE)
JSON Web Signatures (JWS)
JSON Web Token (JWT)
Java KeyStore (JKS)
MHT / HTML Email
MIME
MS Storage Providers
Microsoft Graph
Misc
NTLM
OAuth1
OAuth2
OIDC
Office365
OneDrive
OpenSSL
Outlook
Outlook Calendar
Outlook Contact
PDF Signatures
PEM
PFX/P12
PKCS11
POP3
PRNG
REST
REST Misc
RSA
SCP
SCard
SFTP
SMTP
SSH
SSH Key
SSH Tunnel
ScMinidriver
SharePoint
SharePoint Online
Signing in the Cloud
Socket/SSL/TLS
Spider
Stream
Tar Archive
ULID/UUID
Upload
WebSocket
XAdES
XML
XML Digital Signatures
XMP
Zip
curl
uncategorized

 

 

 

(.NET Core C#) Dropbox Content Hash

Demonstrates how to compute the Dropbox content_hash of a file. (This is the "content_hash" found in the Dropbox FileMetadata object.

Note: This example requires Chilkat v9.5.0.79 or greater because it uses the fac.ReadBlockBd method.

For more information, see https://www.dropbox.com/developers/reference/content-hash

Chilkat .NET Downloads

Chilkat .NET Assemblies

Chilkat for .NET Core

Chilkat for Mono

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Chilkat.Crypt2 crypt = new Chilkat.Crypt2();

// To calculate the content_hash of a file:
// Split the file into blocks of 4 MB (4,194,304 or 4 * 1024 * 1024 bytes). The last block (if any) may be smaller than 4 MB.
// Compute the hash of each block using SHA-256.
// Concatenate the hash of all blocks in the binary format to form a single binary string.
// Compute the hash of the concatenated string using SHA-256. Output the resulting hash in hexadecimal format.

crypt.HashAlgorithm = "sha256";
crypt.EncodingMode = "hex_lower";

// We're going to calculate the content_hash for the Milky Way JPG image linked here:  https://www.dropbox.com/developers/reference/content-hash

Chilkat.FileAccess fac = new Chilkat.FileAccess();
Chilkat.BinData bd = new Chilkat.BinData();
Chilkat.BinData bdHashes = new Chilkat.BinData();

bool success = fac.OpenForRead("qa_data/jpg/milky-way-nasa.jpg");
if (success == false) {
    Debug.WriteLine(fac.LastErrorText);
    return;
}

int blockSize = 4194304;
int numBlocks = fac.GetNumBlocks(blockSize);

int i = 0;
while ((i < numBlocks)) {
    // Read the next 4MB block into bd.
    bd.Clear();
    success = fac.ReadBlockBd(i,blockSize,bd);

    string hashHex = crypt.HashBdENC(bd);
    Debug.WriteLine(Convert.ToString(i) + ": " + hashHex);
    bdHashes.AppendEncoded(hashHex,"hex_lower");

    i = i + 1;
}

fac.FileClose();

// Hash the concatenated SHA-256 hashes.
string content_hash = crypt.HashBdENC(bdHashes);
Debug.WriteLine("content_hash = " + content_hash);

 

© 2000-2024 Chilkat Software, Inc. All Rights Reserved.