CODEWITHSUNDEEP
javacryptographymd5
daydreamer
daydreamer

Reputation: 91949

Java Different MD5 output for same input?

My code to generate md5 looks like 

@Nonnull
static String getAuthCode(@Nonnull final String email, @Nonnull final String memberExternalId,
                          @Nonnull final String clientId, @Nonnull final String clientSecret) {
    final MessageDigest messageDigest = getMessageDigest("MD5");
    final String stringForHashCode = email + ":" + memberExternalId + ":" + clientId + ":" + clientSecret;
    messageDigest.update(stringForHashCode.getBytes());
    return new BigInteger(1, messageDigest.digest()).toString();
}

I run the test as 

@Test
public void test() {
    System.out.println(getAuthCode("a", "b", "c", "d"));
}

and I get the output as 

306937959255909402080036399104389354327

When I run the same test on online website, I get the output as 

e6ea19c62a3763c7b78c475652c51357

for same input a:b:c:d

Question

Upvotes: 1

Views: 913

Answers (1)

Jon Skeet
Jon Skeet

Reputation: 1499760

The problem pointed out in comments is a problem - you should define which encoding you want to use. I'd recommend using UTF-8, e.g.

messageDigest.update(stringForHashCode.getBytes(StandardCharsets.UTF_8));

A bigger problem, however, is that you're printing out a BigInteger created from the digest - which is printing it out in decimal. The result you're getting from the online tool is in hexadecimal instead.

While you could convert the BigInteger into hex, I would personally avoid creating a BigInteger in the first place - you'd need to work out padding etc. Instead, just use one of the many libraries available for converting a byte[] to hex, e.g. Apache Commons Codec with its Hex class.

Upvotes: 3

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