I received the same notice. I opened up a trouble ticket to WPGIVE asking if this is anything we need to be concerned about. Being today is a Saturday (01/12), I am not expecting a response until Monday. We have some time since the elimination of MD5 support does not terminate until the end of January.
To add more detail for WPGIVE Support Team, here is the full email instructions:
To use the Signature Key to validate the value of transHashSHA2:
Step 1. Generate a Signature Key and store it in a secure location on your server.
Step 2. Convert the Signature Key into a byte array.
Step 3. Create a message string that starts with a caret (“^”), followed by the following three fields delimited by carets, and terminated with another caret:
? The API Login ID that you send in createTransactionRequest in the name element.
? The transaction ID that we send in createTransactionResponse in the transId element.
? The transaction amount that we send in createTransactionResponse in the amount element.
For example, if your API Login ID is “ANet123”, the value of transId is “20987654321”, and the value of amount is “9.99”, the message string would look like this:
^ANet123^20987654321^9.99^
Step 4. Use HMAC-SHA512 to hash the byte array form of the Signature Key from Step 2 with the message string from Step 3.
Step 5. Compare the value of transHashSHA2 with the output from the HMAC-SHA512 hash mentioned in Step 4.
For C# users, Authorize.Net provides the following code for converting the Signature Key into a byte array and calculating the HMAC-SHA512 hash.
public string HMACSHA512(string key, string textToHash)
{
if (string.IsNullOrEmpty(key))
throw new ArgumentNullException(“HMACSHA512: key”, “Parameter cannot be empty.”);
if (string.IsNullOrEmpty(textToHash))
throw new ArgumentNullException(“HMACSHA512: textToHash”, “Parameter cannot be empty.”);
if (key.Length % 2 != 0 || key.Trim().Length < 2)
{
throw new ArgumentNullException(“HMACSHA512: key”, “Parameter cannot be odd or less than 2 characters.”);
}
try
{
byte[] k = Enumerable.Range(0, key.Length)
.Where(x => x % 2 == 0)
.Select(x => Convert.ToByte(key.Substring(x, 2), 16))
.ToArray();
HMACSHA512 hmac = new HMACSHA512(k);
byte[] HashedValue = hmac.ComputeHash((new System.Text.ASCIIEncoding()).GetBytes(textToHash));
return BitConverter.ToString(HashedValue).Replace(“-“, string.Empty);
}
catch (Exception ex)
{
throw new Exception(“HMACSHA512: ” + ex.Message);
}
}
The details can be found at: https://developer.authorize.net/support/hash_upgrade/?utm_campaign=19Q2%20MD5%20Hash%20EOL%20Merchant&utm_medium=email&utm_source=Eloqua
