new, more secure encryption scheme

- fixed flaw reported by Stan Drapkin (SecurityDriven.NET) reducing effective key size to 96 bit
- multiple file content MACs for 1MB blocks, preventing chosen ciphertext attacks, as authentication now happens before decryption
- allowing files bigger than 64GiB

main/crypto-api/src/main/java/org/cryptomator/crypto/AbstractCryptorDecorator.java

@@ -52,11 +52,6 @@ public class AbstractCryptorDecorator implements Cryptor {
 		return cryptor.decryptedContentLength(encryptedFile);
 	}
 
-	@Override
-	public boolean isAuthentic(SeekableByteChannel encryptedFile) throws IOException {
-		return cryptor.isAuthentic(encryptedFile);
-	}
-
 	@Override
 	public Long decryptFile(SeekableByteChannel encryptedFile, OutputStream plaintextFile) throws IOException, DecryptFailedException {
 		return cryptor.decryptFile(encryptedFile, plaintextFile);

main/crypto-api/src/main/java/org/cryptomator/crypto/Cryptor.java

@@ -75,11 +75,6 @@ public interface Cryptor extends Destroyable {
 	 */
 	Long decryptedContentLength(SeekableByteChannel encryptedFile) throws IOException, MacAuthenticationFailedException;
 
-	/**
-	 * @return true, if the stored MAC matches the calculated one.
-	 */
-	boolean isAuthentic(SeekableByteChannel encryptedFile) throws IOException;
-
 	/**
 	 * @return Number of decrypted bytes. This might not be equal to the encrypted file size due to optional metadata written to it.
 	 * @throws DecryptFailedException If decryption failed