I have some old archives that are basically stored preferences created with NSArchiver. I want to be able to decode them with NSKeyedUnarchiver since the NSArchiver/NSUnarchiver are deprecated in favor of their keyed counterparts.
Is there any way to make this work?
You cannot decode an NSArchiver archive with NSKeyedUnarchiver. The NSArchiver format is deprecated, not just the classes. If you have data in the old format, you may have to use a deprecated class to decode it. The point is that you would then re-encode the data using NSKeyedArchiver (or one of the other options like Codable in Swift) and store it in a modern format.
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With the Autoloader feature, As per the documentation the configuration cloudFiles.format supports json, csv, text, parquet, binary and so on. Wanted to know if there is support for XML ?
For streaming file data sources supported file formats are text, CSV, JSON, ORC, Parquet. My assumption is that only streaming file formats are supported.
Not sure if you got a chance to go through https://github.com/databricks/spark-xml for more complex xml-files with the spark-xml library . If you want to make use of this, auto loader won' t help.
Without any encryption, if the recipient has the serialized Protobuf file but does not have the generated Protobuf class (they don't have access to the .proto file that define its structure), is it possible for them to get any data in the Protobuf file from the binary?
If they have access to a part of the .proto file (for example, just one related message in the file) can they get a part of that data out from the entire file while skipping other unknown parts?
yes, absolutely; the protoc tool can help with this (see: --decode_raw), as can https://protogen.marcgravell.com/decode - so it should not be treated as "secure" at all
yes, absolutely - that's a key part built into the protocol that allows messages to be extensible such that they can decode the bits they understand and either ignore or just store (for round-trip or "extension" fields) the bits they don't understand
protobuf is not a security device; to someone with the right tools it is just as readable as xml or json, with the slight issue that it can be uncertain how to interpret some values; but: you can infer and guess and reverse engineer
Ok, I have found this page https://developers.google.com/protocol-buffers/docs/encoding
The message discards all the names and is just a pair of key number and values. The generated class might offer some protection for safely reading these data and could not read unknown data. (Sure enough because the generated class was generated from known structure, .proto file)
But if I am an attacker I could reference that Encoding page and try to figure out which area in the binary corresponds to which data. For example, varint might be easy to spot after changing some data. And proceed to write my own .proto file to attack this unknown data or even a custom binary reader that can selectively read part of the binary.
I want to store large amount of data in a protobuf format in which include time-stamp parameter. And I want to retrieve the data based on the time-stamp value.
Thanks.
Protobuf is a sequential-access format. There's no way to jump into the middle of a message looking for data; you have to parse through the whole thing.
Some options:
Devise a framing format that allows you to break up your datastore into many small chunks, each of which is a separate protobuf message. This is a fairly large project.
Use SQLite or even an actual database.
Use a random-access-fieldly format like Cap'n Proto instead. (Disclosure: I'm the author of Cap'n Proto, and also of Protobufs v2 (Google's open source release).)
I downloaded big point cloud file with extension .pts and I want to convert it into .pcd format. What is the simplest and easiest way to do it?
Is .pts ASCII?
If so, you can easily write a parser for it and save it as a .pcd.
Or, if you are looking for a tool, meshlab can read in plain XYZ data and save it to .ply format (remove all header content, if there is any). .ply files are supported by the Point Cloud Library, you can either convert it or just read in the .ply.
I'd like to create a Base16 encoder and decoder for Lion's new Security.framework to complement kSecBase32Encoding and kSecBase64Encoding. Apple's documentation shows how to write a custom transform (Caesar cipher) using SecTransformRegister. As far as I can tell, custom transforms registered this way have to operate symmetrically on the data and can't be used to encode and decode data differently. Does anyone know if writing a custom encoder/decoder is possible, and if so, how?
I don't see a way to tie custom encoders into SecEncodeTransformCreate(), which is what kSecBase32Encoding and the others are based on. But it's easy to create a transform that accepts a "encoding" bool and makes use of that to decide whether to encode or decode. In the CaesarTransform example, they attach an attribute called key with SecTransformSetAttribute(). You'd do the same thing, but with a bool encode.
And of course you could just create an encoding transform and a decoding transform.