Class: C2PA::Config

Inherits:
Object
  • Object
show all
Defined in:
lib/c2pa/config.rb

Overview

Settings that govern how c2pa-rs validates.

These reach the SDK through its Context, which is rebuilt whenever they change. Signing already in flight on another thread continues against the settings it started with.

Defaults are c2pa-rs's own, so a gem that never calls C2PA.configure behaves exactly as it did before this existed.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Config

Returns a new instance of Config.



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# File 'lib/c2pa/config.rb', line 62

def initialize
  @trust_anchors = nil
  @trust_list = nil
  @allowed_certificates = nil
  @verify_trust = nil
  @remote_manifest_fetch = nil
  @ocsp_fetch = nil
  @thumbnails = false
  @thumbnail_size = nil
  @thumbnail_format = nil
  @thumbnail_quality = nil
end

Instance Attribute Details

#allowed_certificates ⇒ Object

Explicitly allowed certificates, as a PEM bundle.



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# File 'lib/c2pa/config.rb', line 24

def allowed_certificates
  @allowed_certificates
end

#ocsp_fetch ⇒ Object

Whether to check certificate revocation over OCSP, which also makes network requests.



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# File 'lib/c2pa/config.rb', line 39

def ocsp_fetch
  @ocsp_fetch
end

#remote_manifest_fetch ⇒ Object

Whether reading an asset may fetch a manifest over the network. c2pa-rs defaults this to true, so reading can make an outbound request.



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# File 'lib/c2pa/config.rb', line 35

def remote_manifest_fetch
  @remote_manifest_fetch
end

#thumbnail_format ⇒ Object

:jpeg, :png or :gif. Left unset, c2pa-rs picks the smaller encoding.



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# File 'lib/c2pa/config.rb', line 57

def thumbnail_format
  @thumbnail_format
end

#thumbnail_quality ⇒ Object

:low, :medium or :high. c2pa-rs's default is :medium.



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# File 'lib/c2pa/config.rb', line 60

def thumbnail_quality
  @thumbnail_quality
end

#thumbnail_size ⇒ Object

Longest edge of the thumbnail in pixels. c2pa-rs's default is 1024.



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# File 'lib/c2pa/config.rb', line 54

def thumbnail_size
  @thumbnail_size
end

#thumbnails ⇒ Object

Whether to embed a thumbnail of the asset in its manifest, and of each ingredient supplied as a file.

Off by default, which departs from c2pa-rs. Its thumbnail generation scales to a fixed long edge and upscales to reach it, so a 160x120 image gets a 1024x768 thumbnail ten times its own size. Turn it on for assets that are larger than thumbnail_size, or set thumbnail_size to suit.

Thumbnails are produced for JPEG, PNG, WebP and TIFF. Other formats are signed without one; c2pa-rs treats that as non-fatal.



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# File 'lib/c2pa/config.rb', line 51

def thumbnails
  @thumbnails
end

#trust_anchors ⇒ Object

Additional root certificates to trust, as a PEM bundle. Use this for a private or enterprise CA: a certificate chaining to one of these validates as "Trusted" rather than carrying signingCredential.untrusted.



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# File 'lib/c2pa/config.rb', line 16

def trust_anchors
  @trust_anchors
end

#trust_list ⇒ Object

The trust list proper — normally the C2PA-recognised anchors. Setting this replaces that list rather than adding to it, so prefer trust_anchors unless you mean to substitute the whole thing.



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# File 'lib/c2pa/config.rb', line 21

def trust_list
  @trust_list
end

#verify_trust ⇒ Object

Whether to check certificates against the trust list at all.

Turning this off means nothing is ever reported as untrusted, which in a library for establishing provenance is rarely what you want. It exists for offline and air-gapped environments.



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# File 'lib/c2pa/config.rb', line 31

def verify_trust
  @verify_trust
end

Instance Method Details

#to_json ⇒ String

The settings document c2pa-rs expects.

Only values that were actually set are included, so anything left alone keeps the SDK's default rather than being pinned to ours.

Returns:

  • (String) —

    JSON



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# File 'lib/c2pa/config.rb', line 81

def to_json
  trust = {}
  trust["user_anchors"] = read_pem(@trust_anchors)        unless @trust_anchors.nil?
  trust["trust_anchors"] = read_pem(@trust_list)          unless @trust_list.nil?
  trust["allowed_list"] = read_pem(@allowed_certificates) unless @allowed_certificates.nil?

  verify = {}
  verify["verify_trust"] = @verify_trust                   unless @verify_trust.nil?
  verify["remote_manifest_fetch"] = @remote_manifest_fetch unless @remote_manifest_fetch.nil?
  verify["ocsp_fetch"] = @ocsp_fetch                       unless @ocsp_fetch.nil?

  # enabled is always sent: this gem's default differs from c2pa-rs's, so
  # leaving it out would mean inheriting the wrong one.
  thumbnail = { "enabled" => @thumbnails == true }
  thumbnail["long_edge"] = Integer(@thumbnail_size)          unless @thumbnail_size.nil?
  thumbnail["format"] = @thumbnail_format.to_s.downcase   unless @thumbnail_format.nil?
  thumbnail["quality"] = @thumbnail_quality.to_s.downcase unless @thumbnail_quality.nil?

  settings = { "builder" => { "thumbnail" => thumbnail } }
  settings["trust"] = trust unless trust.empty?
  settings["verify"] = verify unless verify.empty?

  JSON.generate(settings)
end