Java DigestUtils doesn't calculate SHA-256 correcly?

I have a file called test.sha256, which contains:

5891b5b522d5df086d0ff0b110fbd9d21bb4fc7163af34d08286a2e846f6be03

I have another file called data.txt, which contains:

hello

I know that when using Files.readAllBytes(Path.of(data.txt)); the result is an array of signed bytes. However what if I should do following:

1. Read test.sha256, which contains sha256 hash of data.txt
2. Read data.txt and create sha256 hash from that file
3. Compare (1) and (2)

Problem is that when I use:

DigestUtils.getDigest("SHA-256").digest(Files.readAllBytes(data.txt))

Result differs from the content of test.sha256 file. And that is because Java cannot iterpret unsigned bytes using Files.readAllBytes, but can do that using DigestUtils.getDigest().digest.

Note though, that "SHA-256" is configurable, i.e I don't hardcode it in real code (it is passed as an argument to the method).

My question is how I can compare hash "A" that has been red from a file and the hash that is generated from a data of file "B" ? Where "A" is the actual hash of "B".

UPD: I confirm that they differ:

Arrays.equals(DigestUtils.sha256(Files.readAllBytes(data.txt)), Files.readAllBytes(test.sha256));

Java class being used: import org.apache.commons.codec.digest.DigestUtils

The problem you have is that the output of DigestUtils.getDigest("SHA-256").digest(..) is a byte array of the raw bytes of the digest, while your test.sha256 file contains a hex encoded value.

To address this problem, you'll need to encode the raw bytes to hex, for example using HexFormat (introduced in Java 17), or the DigestUtil.sha256Hex(..) method which will perform the digest and then produce a hex-encoded string.

For example:

System.out.println(DigestUtils.sha256Hex(Files.readAllBytes(data)));

and

Objects.equals(
        DigestUtils.sha256Hex(Files.readAllBytes(data)),
        Files.readString(test.sha256));

Or, if you want to keep the hash parameterized and you cannot use HexFormat of Java 17:

Hex.encodeHexString(
        DigestUtils.getDigest("SHA-256")
                .digest(Files.readAllBytes(data)));

where Hex is org.apache.commons.codec.binary.Hex.