(Objective-C) Streaming Decrypt HTTP Response

If the an encrypted file was previously uploaded, this example demonstrates how to download and decrypt in a streaming way.

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#import <CkoRest.h>
#import <NSString.h>
#import <CkoCrypt2.h>
#import <CkoStream.h>
#import <CkoTask.h>

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

CkoRest *rest = [[CkoRest alloc] init];

BOOL bTls = YES;
int port = 443;
BOOL bAutoReconnect = YES;
BOOL success = [rest Connect: @"chilkatdownload.com" port: [NSNumber numberWithInt: port] tls: bTls autoReconnect: bAutoReconnect];

// Send the request to download a file.
success = [rest SendReqNoBody: @"GET" uriPath: @"/9.5.0.83/chilkat-9.5.0-python-3.8-x64.zip"];
if (success != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

// Read the response header.
int responseStatusCode = [[rest ReadResponseHeader] intValue];
if (responseStatusCode < 0) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

NSLog(@"%@%d",@"Response status code = ",responseStatusCode);

// We expect a 200 response status if the JPG data is coming.
// Otherwise, we'll get a string response body with an error message(or no response body).
if (responseStatusCode != 200) {
    NSString *errResponse = [rest ReadRespBodyString];
    if (rest.LastMethodSuccess != YES) {
        NSLog(@"%@",rest.LastErrorText);
    }
    else {
        NSLog(@"%@",errResponse);
    }

    return;
}

// Create an object for decrypting.
// This example will use "none" for the encryption algorithm, which means it's just a pass-through.
// Typically you would set the decrypt properties, such as secret key, IV, key length, padding scheme, cipher mode..
CkoCrypt2 *crypt = [[CkoCrypt2 alloc] init];
crypt.CryptAlgorithm = @"none";

// The following settings are ignored in this test because our CryptAlgorithm is "none".
// However, if you were truly decrypting, you might set CryptAlgorithm = "aes".
crypt.CipherMode = @"cbc";
crypt.KeyLength = [NSNumber numberWithInt:128];
[crypt SetEncodedKey: @"000102030405060708090A0B0C0D0E0F" encoding: @"hex"];
[crypt SetEncodedIV: @"000102030405060708090A0B0C0D0E0F" encoding: @"hex"];

CkoStream *receiveStream = [[CkoStream alloc] init];
// The decryptStream's source will be the receiveStream.
CkoStream *decryptStream = [[CkoStream alloc] init];

// The decrypt stream's sink will be a file.
decryptStream.SinkFile = @"qa_output/chilkat-9.5.0-python-3.8-x64.zip";
[decryptStream SetSourceStream: receiveStream];

// Create and run a background async task to decrypt incoming data and write to a file.
CkoTask *decryptStreamTask = [crypt DecryptStreamAsync: decryptStream];
success = [decryptStreamTask Run];

success = [rest ReadRespBodyStream: receiveStream autoSetStreamCharset: YES];
if (success != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

NSLog(@"%@",@"Successfully received the .zip file.");