(Objective-C) Adyen HMAC Signature Calculation for Hosted Payment Pages

Demonstrates how to do the HMAC Signature Calculation for a hosted payment page (HPP) in Adyen.

For a C# ASP.NET Razor Pages example showing the HTML Form with HMAC signature code, see Adyen HMAC Signature Calculation in C#

For more information, see https://docs.adyen.com/classic-integration/hosted-payment-pages/hmac-signature-calculation/

Chilkat Objective-C Library Downloads MAC OS X (Cocoa) Libs iOS Libs

#import <NSString.h>
#import <CkoGzip.h>
#import <CkoXml.h>
#import <CkoStringBuilder.h>
#import <CkoCrypt2.h>

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

BOOL success;

NSString *strHtml = @"<table class=\"od\"><tr><th>Description</th><th>Quantity</th><th>Amount</th></tr><tr><td>1 Digital Camera</td><td class=\"r\">1</td><td class=\"r\">100 GBP</td></tr><tr><td class=\"b\">Total</td><td class=\"r\"></td><td class=\"b r\">100.00 GBP</td></tr></table>";

CkoGzip *gzip = [[CkoGzip alloc] init];
NSString *gzOrderData = [gzip CompressStringENC: strHtml charset: @"utf-8" encoding: @"base64"];

CkoXml *xml = [[CkoXml alloc] init];
xml.Tag = @"keyValuePairs";

[xml NewChild2: @"orderData" content: gzOrderData];

// required, The payment deadline; the payment needs to occur within the specified time value.
NSString *sessionValidity = @"2019-08-11T10:30:00Z";
[xml NewChild2: @"sessionValidity" content: sessionValidity];

// optional.  Normally we'll let Adyen automatically know the country based on the IP address.
// By default, the payment methods offered to a shopper are filtered based on the country the shopper's IP address is mapped to. 
// In this way, shoppers are not offered payment methods that are not available in the country they are carrying out the transaction from. 
// This IP-to-country mapping is not 100% accurate, so if you have already established the country of the shopper, you can set it explicitly 
// in the countryCode parameter.
NSString *countryCode = @"GB";
[xml NewChild2: @"countryCode" content: countryCode];

// optional
NSString *shopperLocale = @"en_GB";
// If not specified, the locale preference is set to en_GB   by default.
// When it is not necessary to include the country-specific part, use only the language code.
// For example: it instead of it_IT to set the locale preferences to Italian.
[xml NewChild2: @"shopperLocale" content: shopperLocale];

// required, A reference to uniquely identify the payment. This reference is used in all communication with you about the payment status. 
// We recommend using a unique value per payment; however, it is not a requirement. If you need to provide multiple references for a transaction, 
// you can enter them in this field. Separate each reference value with a hyphen character ("-"). This field has a length restriction: 
// you can enter max. 80 characters.
NSString *merchantReference = @"paymentTest1234";
[xml NewChild2: @"merchantReference" content: merchantReference];

// required, The merchant account identifier you want to process the (transaction) request with.
NSString *merchantAccount = @"ChilkatSoftwareIncCOM";
[xml NewChild2: @"merchantAccount" content: merchantAccount];

// required.  10000 for $100.00
NSString *paymentAmount = @"10000";
[xml NewChild2: @"paymentAmount" content: paymentAmount];

// required, The three-character ISO currency code
NSString *currencyCode = @"GBP";
[xml NewChild2: @"currencyCode" content: currencyCode];

// required.
NSString *skinCode = @"S7uWsvfB";
[xml NewChild2: @"skinCode" content: skinCode];

// optional, A unique identifier for the shopper, for example, a customer ID.
// We recommend providing this information, as it is used in velocity fraud checks. It is also the key in recurring payments.
// This field is mandatory in recurring payments.  
NSString *shopperReference = @"somebody@example.com";
[xml NewChild2: @"shopperReference" content: shopperReference];

// optional
NSString *shopperEmail = @"somebody@example.com";
[xml NewChild2: @"shopperEmail" content: shopperEmail];

// optional, An integer value that adds up to the normal fraud score.
// The value can be either a positive or negative integer.
[xml NewChild2: @"offset" content: @"0"];

// Apparently this is a required field.
NSString *shipBeforeDate = @"2019-06-04";
[xml NewChild2: @"shipBeforeDate" content: shipBeforeDate];

[xml SortByTag: YES];

// Encode...
//  "\" (backslash) as "\\"
//  ":" (colon) as "\:"

CkoStringBuilder *sbTags = [[CkoStringBuilder alloc] init];
CkoStringBuilder *sbValues = [[CkoStringBuilder alloc] init];

CkoStringBuilder *sbContent = [[CkoStringBuilder alloc] init];
int n = [xml.NumChildren intValue];
int i = 0;
while (i < n) {
    if (i > 0) {
        [sbTags Append: @":"];
        [sbValues Append: @":"];
    }

    [xml GetChild2: [NSNumber numberWithInt: i]];
    [sbTags Append: xml.Tag];

    [sbContent SetString: xml.Content];
    int numReplaced = [[sbContent Replace: @"\\" replacement: @"\\\\"] intValue];
    numReplaced = [[sbContent Replace: @":" replacement: @"\\:"] intValue];
    [sbValues AppendSb: sbContent];
    [xml GetParent2];

    i = i + 1;
}

CkoStringBuilder *sbSigningStr = [[CkoStringBuilder alloc] init];
[sbSigningStr AppendSb: sbTags];
[sbSigningStr Append: @":"];
[sbSigningStr AppendSb: sbValues];

CkoCrypt2 *crypt = [[CkoCrypt2 alloc] init];
crypt.HashAlgorithm = @"sha256";
crypt.MacAlgorithm = @"hmac";

NSString *hmacKey = @"934D1E806DDD99595EB430076FD7F8E4D12D0A3F51243A4C0C3897703118E739";
[crypt SetMacKeyEncoded: hmacKey encoding: @"hex"];

crypt.EncodingMode = @"base64";
NSString *merchantSig = [crypt HmacStringENC: [sbSigningStr GetAsString]];

NSLog(@"%@",merchantSig);