MessageDigest digest() method
Shouldn't the digest() method in MessageDigest always give the same hash value for the same input?
I tried this a开发者_如何学JAVAnd I am getting different set of hashvalues for the same input everytime
md5 = MessageDigest.getInstance("MD5");
System.out.println(md5.digest("stringtodigest".getBytes()));
System.out.println(md5.digest("stringtodigest".getBytes()));
System.out.println(md5.digest("stringtodigest".getBytes()));
Update: Changed the param to digest() method
You're seeing the results of calling byte[].toString()
- which isn't showing you the actual hash of the data. You're basically getting a string which shows that you've called toString
on a byte array (that's the [B
part) and then the hash returned by Object.hashCode()
(that's the hex value after the @
). That hash code doesn't take the data in the array into account.
Try
System.out.println(Arrays.toString(md5.digest(byteArrayToDigest)));
to see the actual data.
EDIT: Quick note about creating an MD5 digest from string data - you should always use the same encoding, explicitly, when hashing. For example:
byte[] hash = md5.digest(text.getBytes("UTF-8"));
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