in main/src/main/java/org/apache/james/jdkim/DKIMVerifier.java [337:350]
public List<SignatureRecord> verify(Headers messageHeaders,
InputStream bodyInputStream) throws IOException, FailException {
BodyHasher bh = newBodyHasher(messageHeaders);
if (bh == null) return null;
CompoundBodyHasher cbh = validateBodyHasher(bh);
// simultaneous computation of all the hashes.
DKIMCommon.streamCopy(bodyInputStream, cbh.getOutputStream());
return verify(cbh);
}