Java MessageDigest result does not stay constant
I've got this function for en开发者_开发技巧crypting passwords in Java, but somehow when I call MessageDigest, it returns a different result every time even though I call it with the same password. I wonder if I am initializing it wrong somehow.
public String encrypt (String password) {
MessageDigest md = MessageDigest.getInstance("SHA-1");
md.reset();
md.update(password.getBytes(Charset.forName("utf-8")),0,password.length());
String res = md.digest().toString();
}
This simple code produces three different results :
MessageDigest digest = MessageDigest.getInstance("MD5");
System.out.println("test1 ");
System.out.println(digest.digest("test".getBytes("UTF-8")));
Thread.sleep(10000);
System.out.println("test2 ");
System.out.println(digest.digest("test".getBytes("UTF-8")));
Thread.sleep(10000);
System.out.println("test3 ");
System.out.println(digest.digest("test".getBytes("UTF-8")));
The .toString()
method on the byte[]
that is the return value of .digest()
just gives you the representation of the array, not of its contents.
See this answer on how to convert your byte array to a hex string.
Another approach is using Arrays.toString(byte[]) although that probably does not give you the format you want.
You could change the method signature:
public byte[] encrypt (String password) {
MessageDigest md = MessageDigest.getInstance("SHA-1");
md.reset();
md.update(password.getBytes(Charset.forName("utf-8")), 0, password.length());
return md.digest();
}
... and use Arrays.equals(byte[], byte[])
to compare digests.
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