The parameter tampering attack is based on the manipulation of parameters exchanged between client and server in order to modify application data, such as user credentials, amount and quantity of products, etc.
public string ComputeHash(Request _req)
{
string _key= { Secret Key Provided by Casheer}
string datatocomputeHash = $"{_req.amount}{_req.authKey}{_req.currency}{_req.merchantCode}{_req.pc}{_req.referenceID}{_req.sourceCurrency}{_req.timeStamp}{_req.tunnel}{_req.userReference}";
return GetHashValue(datatocomputeHash, _key);
}
public string GetHashValue(String datatocomputeHash, String HashKey)
{
HMACSHA256 hmac = new HMACSHA256(System.Text.Encoding.UTF8.GetBytes(HashKey));
string computedHash = convertToHex(hmac.ComputeHash(System.Text.UTF8Encoding.Default.GetBytes(datatocomputeHash)));
return computedHash;
}
private string convertToHex(byte[] data)
{
System.Text.StringBuilder sb = new System.Text.StringBuilder(data.Length);
foreach (byte b in data)
sb.AppendFormat("{0:X2}", (int)b);
return sb.ToString();
}
Private Function ComputeHash(ByVal _req As Request) As String
Dim _key As Strig={ Secret Key Provided by Casheer}
Dim datatocomputeHash As String = $"{_req.amount}{_req.authKey}{_req.currency}{_req.merchantCode}{_req.pc}{_req.referenceID}{_req.sourceCurrency}{_req.timeStamp}{_req.tunnel}{_req.userReference}"
Return GetHashValue(datatoHash, _key)
End Function
Public Function GetHashValue(ByVal datatocomputeHash As String, ByVal HashKey As String) As String
Dim hmac As HMACSHA256 = New HMACSHA256(System.Text.Encoding.UTF8.GetBytes(HashKey))
Dim computedHash As String = convertToHex(hmac.ComputeHash(System.Text.UTF8Encoding.[Default].GetBytes(datatocomputeHash)))
Return computedHash
End Function
Private Function convertToHex(ByVal data As Byte()) As String
Dim sb As System.Text.StringBuilder = New System.Text.StringBuilder(data.Length)
For Each b As Byte In data
sb.AppendFormat("{0:X2}", CInt(b))
Next
Return sb.ToString()
End Function
private function ComputeHash(Request $req)
{
$_key= {Secret Key Provided by Casheer}
$datatocomputeHash = $_req.amount.$_req.authKey.$_req.currency.$_req.merchantCode.$_req.pc.$_req.referenceID.$_req.sourceCurrency.$_req.timeStamp.$_req.tunnel.$_req.userReference;
return GetHashValue($datatocomputeHash, $_key);
}
public function GetHashValue($datatocomputeHash,$HashKey)
{
$computedHash = strtoupper(hash_hmac("sha256", $datatocomputeHash,$HashKey));
return $computedHash
}
private ComputeHash(_req: Request): string {
let _key={ Secret Key Provided by Casheer}
let datatocomputeHash: string = "{_req.amount}{_req.authKey}{_req.currency}{_req.merchantCode}{_req.pc}{_req.referenceID}{_req.sourceCurrency}{_req.timeStamp}{_req.tunnel}{_req.userReference}";
return GetHashValue(datatocomputeHash, _key);
}
public GetHashValue(datatocomputeHash: String, HashKey: String): string {
let hmac: HMACSHA256 = new HMACSHA256(System.Text.Encoding.UTF8.GetBytes(HashKey));
let computedHash: string = convertToHex(hmac.ComputeHash(System.Text.UTF8Encoding.Default.GetBytes(datatocomputeHash)));
return computedHash;
}
pagecode:` private string convertToHex(byte[] data)
{
System.Text.StringBuilder sb = new System.Text.StringBuilder(data.Length);
foreach (byte b in data)
sb.AppendFormat("{0:X2}", (int)b);
return sb.ToString();
}`;
SubVendor Hash Method
To ensure secure processing and prevent parameter tampering attacks, it is mandatory to generate a hash for each sub-vendor included in the SubVendors array within the request body. This hash must be created using the respective sub-vendor's details and secured using the main merchant's Authkey. The generated hash should be included in the request to verify the integrity and authenticity of each sub-vendor's data. Failure to include a valid hash for each sub-vendor may result in the rejection of the multivendor payment request.
Below is the code sample to create sub nvedor hash
public string ComputeSubvendorHash(SubVendor _subvendor ,Request _req)
{
string _key= {Main merchant Secret Key Provided by Casheer}
string datatocomputeHash = $"{_subvendor.amount}{_subvendor.id}{_subvendor.vendorrefrence}{_req.timeStamp}";
return GetHashValue(datatocomputeHash, _key);
}
public string GetHashValue(String datatocomputeHash, String HashKey)
{
HMACSHA256 hmac = new HMACSHA256(System.Text.Encoding.UTF8.GetBytes(HashKey));
string computedHash = convertToHex(hmac.ComputeHash(System.Text.UTF8Encoding.Default.GetBytes(datatocomputeHash)));
return computedHash;
}
private string convertToHex(byte[] data)
{
System.Text.StringBuilder sb = new System.Text.StringBuilder(data.Length);
foreach (byte b in data)
sb.AppendFormat("{0:X2}", (int)b);
return sb.ToString();
}
Private Function ComputeSubvendorHash(ByVal _subvendor As SubVendor,ByVal _req As Request) As String
Dim _key As Strig={ Main merchant Secret Key Provided by Casheer}
Dim datatocomputeHash As String = $"{_subvendor.amount}{_subvendor.id}{_subvendor.vendorrefrence}{_req.timeStamp}"
Return GetHashValue(datatoHash, _key)
End Function
Public Function GetHashValue(ByVal datatocomputeHash As String, ByVal HashKey As String) As String
Dim hmac As HMACSHA256 = New HMACSHA256(System.Text.Encoding.UTF8.GetBytes(HashKey))
Dim computedHash As String = convertToHex(hmac.ComputeHash(System.Text.UTF8Encoding.[Default].GetBytes(datatocomputeHash)))
Return computedHash
End Function
Private Function convertToHex(ByVal data As Byte()) As String
Dim sb As System.Text.StringBuilder = New System.Text.StringBuilder(data.Length)
For Each b As Byte In data
sb.AppendFormat("{0:X2}", CInt(b))
Next
Return sb.ToString()
End Function
private function ComputeHash(SubVendor $_subvendor,Request $req)
{
$_key= {Main merchant Secret Key Provided by Casheer}
$datatocomputeHash = $_subvendor.amount.$_subvendor.id.$_subvendor.vendorrefrence.$_req.timeStamp;
return GetHashValue($datatocomputeHash, $_key);
}
public function GetHashValue($datatocomputeHash,$HashKey)
{
$computedHash = strtoupper(hash_hmac("sha256", $datatocomputeHash,$HashKey));
return $computedHash
}
