[media-types] [IANA #1425698] application/vnd.g3pix. g3fc registration request

Hi Alexey, 

Sending a reminder for this request from July 29th.

thanks,
Amanda

On Tue Jul 29 00:21:17 2025, david.dong wrote:
> Hi Alexey,
> 
> Would you be able to review this new media type request by August 11th?
> 
> Thank you!
> 
> Best regards,
> 
> David Dong
> IANA Services Sr. Specialist
> 
> On Mon Jul 28 02:42:23 2025, [email protected] wrote:
> > 
> > Name: Lucas Guimarães
> > 
> > Email: [email protected]
> > 
> > Media type name: application
> > 
> > Media subtype name: vnd.g3pix.g3fc
> > 
> > Required parameters: N/A
> > 
> > Optional parameters: N/A
> > 
> > Encoding considerations: binary
> > 
> > 
> > 
> > Security considerations: This media type does not contain any active
> > or executable content. The G3FC format is a container for passive data
> > files and metadata only.
> > 
> > The G3FC format provides optional, built-in services for
> > confidentiality and integrity through robust, password-based
> > encryption. When enabled, the file index and all data blocks are
> > encrypted using AES-256-GCM. The GCM mode is significant as it
> > provides both confidentiality (encryption) and authentication
> > (integrity checking via an authentication tag), protecting against
> > unauthorized access and modification of the archive's content. Keys
> > are derived from user-supplied passwords using PBKDF2 with HMAC-
> > SHA256, which mitigates dictionary and brute-force attacks. If the
> > native encryption is not used, these security services must be
> > provided by external means, such as by transporting the file over a
> > secure channel like TLS.
> > 
> > Compression
> > The media type employs Zstandard compression. As with any format that
> > uses compression, G3FC files are susceptible to "compression bomb"
> > denial-of-service attacks, where a small file decompresses to an
> > extremely large size, potentially exhausting system memory or disk
> > space. Implementations that parse this format SHOULD mitigate this
> > risk by first checking the uncompressed_size field in the file's
> > metadata index and enforcing reasonable limits on resource allocation
> > before attempting decompression.
> > 
> > Container Format
> > As a container format, G3FC stores internal file and directory paths.
> > A maliciously crafted archive could contain paths intended to
> > overwrite sensitive system files (e.g., a path traversal attack using
> > ../../..). Implementations MUST rigorously validate and sanitize all
> > path information from the file index before writing any data to the
> > local filesystem. File paths MUST be treated as relative to the
> > designated extraction directory, and any attempts to write outside of
> > this directory must be prevented.
> > 
> > Password-Based Encryption Considerations
> > Password Strength: The security of an encrypted archive is entirely
> > dependent on the strength of the user's password. Implementations
> > SHOULD encourage or enforce strong password policies.
> > 
> > KDF Iterations: The number of PBKDF2 iterations (kdf_iterations) is
> > critical for resisting brute-force attacks. The recommended value of
> > 100,000 is a baseline and SHOULD be increased over time as computing
> > power grows.
> > 
> > Salt: The use of a unique, randomly generated salt for each archive is
> > crucial to prevent rainbow table attacks. The read_salt MUST be
> > cryptographically random.
> > 
> > Interoperability considerations: This document specifies format
> > version 1.0.  All fields use little-endian byte order.
> > 
> > Published specification:
> > https://g3pix.com.br/g3fc/g3fc_file_format_specification.txt
> > https://g3pix.com.br/g3fc/g3fc_file_format_specification.html
> > https://g3pix.com.br/g3fc/g3fc_file_format_specification.xml
> > https://github.com/guimaraeslucas/g3fc
> > 
> > Applications which use this media: G3FC Archiver Tool and other
> > compatible archiving utilities.
> > 
> > Fragment identifier considerations: N/A
> > 
> > Restrictions on usage: None
> > 
> > Provisional registration? (standards tree only): No
> > 
> > Additional information:
> > 
> > 1. Deprecated alias names for this type: N/A
> > 2. Magic number(s): The first 4 bytes are 0x47 0x33 0x46 0x43 (ASCII
> > "G3FC")
> > 3. File extension(s): .g3fc, .g3fc<n>
> > 4. Macintosh file type code: N/A
> > 5. Object Identifiers: N/A
> > 
> > General Comments:
> > 
> > Person to contact for further information:
> > 
> > 1. Name: Lucas Guimarães
> > 2. Email: [email protected]
> > 
> > Intended usage: COMMON
> > 
> > 
> > 
> > Author/Change controller: G3Pix

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