Verification code

The verification code displayed to the user is calculated based on the actual digest_value as
follows.

integer(SHA256(hash)[-2:-1]) mod 10000

Calculate SHA256 from the actual digest_value , extract 2 rightmost bytes from the result, interpret them as a big-endian unsigned integer and take the last 4 digits in decimal form for display.
SHA256 is always used here, no matter what algorithm was used to calculate the original hash.