new line appending on my encrypted string

I may be late in answering this, but came across with same problem. Actually problem lies here Base64.encodeBase64String(hashPassword)

Change that line to look like this it should work: Base64.encodeBase64String(hashPassword,Base64.NO_WRAP)

By default the Android Base64 util adds a newline character to the end of the encoded string. The Base64.NO_WRAP flag tells the util to create the encoded string without the newline character.

Check here

In case anyone needs this for any libraries using OkHttp, there's a Credentials class you can use for Base64 encoding your username/pass

String credentials = Credentials.basic("username", "password");

request.header(HttpHeaders.AUTHORIZATION, credentials);