(PureBasic) Payeezy HMAC Computation

Demonstrates how to calculate the HMAC for a Payeezy REST request.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkStringBuilder.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkPrng.pb"
IncludeFile "CkDateTime.pb"
IncludeFile "CkCrypt2.pb"

Procedure ChilkatExample()

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

    crypt.i = CkCrypt2::ckCreate()
    If crypt.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    prng.i = CkPrng::ckCreate()
    If prng.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success.i

    ; An API key such as y6pWAJNyJyjGv66IsVuWnklkKUPFbb0a
    apiKey.s = "my_api_key"
    ; An API secret such as 86fbae7030253af3cd15faef2a1f4b67353e41fb6799f576b5093ae52901e6f7
    apiSecret.s = "my_api_secret"
    ; A token such as fdoa-a480ce8951daa73262734cf102641994c1e55e7cdf4c02b6
    token.s = "my_merchant_token"

    ; The nonce is a random number (bytes), something like "6057786719490086000"
    nonce.s = CkPrng::ckGenRandom(prng,8,"decimal")
    Debug "nonce = " + nonce

    dtNow.i = CkDateTime::ckCreate()
    If dtNow.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkDateTime::ckSetFromCurrentSystemTime(dtNow)
    sbTimestamp.i = CkStringBuilder::ckCreate()
    If sbTimestamp.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Get the epoch timestamp in seconds
    CkStringBuilder::ckAppend(sbTimestamp,CkDateTime::ckGetAsUnixTimeStr(dtNow,0))
    ; Change it to milliseconds
    CkStringBuilder::ckAppend(sbTimestamp,"000")
    ; The timestamp is a number similar to this: 1546011905000 (which is a timestamp taken on 28-Dec-2018).
    timestamp.s = CkStringBuilder::ckGetAsString(sbTimestamp)
    Debug "timestamp = " + timestamp

    ; Generate the following JSON request body:
    ; 	{
    ; 	  "merchant_ref": "Astonishing-Sale",
    ; 	  "transaction_type": "authorize",
    ; 	  "method": "token",
    ; 	  "amount": "200",
    ; 	  "currency_code": "USD",
    ; 	  "token": {
    ; 	    "token_type": "FDToken",
    ; 	    "token_data": {
    ; 	      "type": "visa",
    ; 	      "value": "2537446225198291",
    ; 	      "cardholder_name": "JohnSmith",
    ; 	      "exp_date": "1030",
    ; 	      "special_payment": "B"
    ; 	    }
    ; 	  }
    ; 	}

    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckUpdateString(json,"merchant_ref","Astonishing-Sale")
    CkJsonObject::ckUpdateString(json,"transaction_type","authorize")
    CkJsonObject::ckUpdateString(json,"method","token")
    CkJsonObject::ckUpdateString(json,"amount","200")
    CkJsonObject::ckUpdateString(json,"currency_code","USD")
    CkJsonObject::ckUpdateString(json,"token.token_type","FDToken")
    CkJsonObject::ckUpdateString(json,"token.token_data.type","visa")
    CkJsonObject::ckUpdateString(json,"token.token_data.value","2537446225198291")
    CkJsonObject::ckUpdateString(json,"token.token_data.cardholder_name","JohnSmith")
    CkJsonObject::ckUpdateString(json,"token.token_data.exp_date","1030")
    CkJsonObject::ckUpdateString(json,"token.token_data.special_payment","B")

    ; string hashData = apiKey + nonce + timestamp + token + jsonString;
    sbHmacData.i = CkStringBuilder::ckCreate()
    If sbHmacData.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sbHmacData,apiKey)
    CkStringBuilder::ckAppend(sbHmacData,nonce)
    CkStringBuilder::ckAppend(sbHmacData,timestamp)
    CkStringBuilder::ckAppend(sbHmacData,token)
    CkStringBuilder::ckAppend(sbHmacData,CkJsonObject::ckEmit(json))

    ; HMAC the data to produce a hex string.
    CkCrypt2::setCkEncodingMode(crypt, "hexlower")
    CkCrypt2::setCkMacAlgorithm(crypt, "hmac")
    CkCrypt2::ckSetMacKeyString(crypt,apiSecret)
    CkCrypt2::setCkHashAlgorithm(crypt, "sha256")
    CkCrypt2::setCkCharset(crypt, "utf-8")
    hexHash.s = CkCrypt2::ckMacStringENC(crypt,CkStringBuilder::ckGetAsString(sbHmacData))

    ; Now base64 encode the hex string:
    sbBase64Hash.i = CkStringBuilder::ckCreate()
    If sbBase64Hash.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sbBase64Hash,hexHash)
    CkStringBuilder::ckEncode(sbBase64Hash,"base64","utf-8")

    Debug "This is the Authorization header to be sent with the payeezy request:"
    Debug "Authorization: " + CkStringBuilder::ckGetAsString(sbBase64Hash)


    CkCrypt2::ckDispose(crypt)
    CkPrng::ckDispose(prng)
    CkDateTime::ckDispose(dtNow)
    CkStringBuilder::ckDispose(sbTimestamp)
    CkJsonObject::ckDispose(json)
    CkStringBuilder::ckDispose(sbHmacData)
    CkStringBuilder::ckDispose(sbBase64Hash)


    ProcedureReturn
EndProcedure