UVF: use 64 bit keys for HMAC-SHA256

see encryption-alliance/unified-vault-format#31

Author: overheadhunter

src/main/java/org/cryptomator/cryptolib/v3/FileNameCryptorImpl.java

@@ -36,7 +36,7 @@ class FileNameCryptorImpl implements FileNameCryptor {
 	 */
 	FileNameCryptorImpl(RevolvingMasterkey masterkey, int revision) throws IllegalArgumentException {
 		this.sivKey = masterkey.subKey(revision, 64, "siv".getBytes(StandardCharsets.US_ASCII), "AES");
-		this.hmacKey = masterkey.subKey(revision, 32, "hmac".getBytes(StandardCharsets.US_ASCII), "HMAC");
+		this.hmacKey = masterkey.subKey(revision, 64, "hmac".getBytes(StandardCharsets.US_ASCII), "HMAC");
 	}
 
 	@Override

src/test/java/org/cryptomator/cryptolib/v3/FileNameCryptorImplTest.java

@@ -79,7 +79,7 @@ public void testDeterministicEncryptionOf128bitFilename() throws AuthenticationF
 	public void testHashRootDirId() {
 		final byte[] rootDirId = Base64.getDecoder().decode("24UBEDeGu5taq7U4GqyA0MXUXb9HTYS6p3t9vvHGJAc=");
 		final String hashedRootDirId = filenameCryptor.hashDirectoryId(rootDirId);
-		Assertions.assertEquals("CRAX3I7DP4HQHA6TDQDMJQUTDKDJ7QG5", hashedRootDirId);
+		Assertions.assertEquals("6DYU3E5BTPAZ4DWEQPQK3AIHX2DXSPHG", hashedRootDirId);
 	}
 
 	@DisplayName("hash directory id for random directory ids")

src/test/java/org/cryptomator/cryptolib/v3/UVFIntegrationTest.java

@@ -56,7 +56,7 @@ public void testRootDirId() {
 	public void testRootDirHash() {
 		byte[] rootDirId = Base64.getDecoder().decode("5WEGzwKkAHPwVSjT2Brr3P3zLz7oMiNpMn/qBvht7eM=");
 		String dirHash = cryptor.fileNameCryptor(masterkey.firstRevision()).hashDirectoryId(rootDirId);
-		Assertions.assertEquals("RKHZLENL3PQIW6GZHE3KRRRGLFBHWHRU", dirHash);
+		Assertions.assertEquals("RZK7ZH7KBXULNEKBMGX3CU42PGUIAIX4", dirHash);
 	}
 
 	@Test