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Allow web applications to select SFrame cipher suite as a parameter provided to SFrameTransform constructor. #257

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Allow web applications to select SFrame cipher suite as a parameter provided to SFrameTransform constructor. #257

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33 changes: 19 additions & 14 deletions index.bs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,11 +19,6 @@ spec:webidl; type:dfn; text:resolve
</pre>
<pre class=biblio>
{
"SFRAME": {
"href":
"https://www.ietf.org/archive/id/draft-ietf-sframe-enc-04.html",
"title": "Secure Frame (SFrame)"
},
"VP9": {
"href":
"https://storage.googleapis.com/downloads.webmproject.org/docs/vp9/vp9-bitstream-specification-v0.6-20160331-draft.pdf",
Expand Down Expand Up @@ -221,7 +216,7 @@ Similarly, if a web application sets the transform synchronously at creation of
# SFrameTransform # {#sframe}

<p>
The API presented in this section allows applications to process SFrame data as defined in [[SFrame]].
The API presented in this section allows applications to process SFrame data as defined in [[RFC9605]].
</p>

<xmp class="idl">
Expand All @@ -230,8 +225,17 @@ enum SFrameTransformRole {
"decrypt"
};

enum SFrameCipherSuite {
"AES_128_CTR_HMAC_SHA256_80",
"AES_128_CTR_HMAC_SHA256_64",
"AES_128_CTR_HMAC_SHA256_32",
"AES_128_GCM_SHA256_128",
"AES_256_GCM_SHA512_128"
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Why these particular ciphersuites? If they're defined by 9605 section 4.5 and no others can be used, we should be sure to say so.

Should there be an MTI ciphersuite?

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These cipher suites are indeed the ones defined by RFC 9605.
No other can be used given we use an enumeration here.

I would think that all cipher suites are MTI if a UA implements SFrameTransform.

};

dictionary SFrameTransformOptions {
SFrameTransformRole role = "encrypt";
required SFrameCipherSuite cipherSuite;
};

typedef [EnforceRange] unsigned long long SmallCryptoKeyID;
Expand Down Expand Up @@ -269,12 +273,13 @@ dictionary SFrameTransformErrorEventInit : EventInit {

The <dfn constructor for="SFrameTransform" lt="SFrameTransform(options)"><code>new SFrameTransform(<var>options</var>)</code></dfn> constructor steps are:
1. Let |transformAlgorithm| be an algorithm which takes a |frame| as input and runs the <a href="#sframe-transform-algorithm">SFrame transform algorithm</a> with |this| and |frame|.
2. Set |this|.`[[transform]]` to a new {{TransformStream}}.
3. <a dfn for="ReadableStream">Set up</a> [=this=].`[[transform]]` with [=TransformStream/set up/transformAlgorithm=] set to |transformAlgorithm|.
4. Let |options| be the method's first argument.
5. Set |this|.`[[role]]` to |options|["{{SFrameTransformOptions/role}}"].
6. Set |this|.`[[readable]]` to |this|.`[[transform]]`.`[[readable]]`.
7. Set |this|.`[[writable]]` to |this|.`[[transform]]`.`[[writable]]`.
1. Set |this|.`[[transform]]` to a new {{TransformStream}}.
1. <a dfn for="ReadableStream">Set up</a> [=this=].`[[transform]]` with [=TransformStream/set up/transformAlgorithm=] set to |transformAlgorithm|.
1. Let |options| be the method's first argument.
1. Set |this|.`[[role]]` to |options|["{{SFrameTransformOptions/role}}"].
1. Set |this|.`[[cipherSuite]]` to |options|["{{SFrameTransformOptions/cipherSuite}}"].
1. Set |this|.`[[readable]]` to |this|.`[[transform]]`.`[[readable]]`.
1. Set |this|.`[[writable]]` to |this|.`[[transform]]`.`[[writable]]`.

## Algorithm ## {#sframe-transform-algorithm}

Expand All @@ -287,7 +292,7 @@ The SFrame transform algorithm, given |sframe| as a SFrameTransform object and |
1. If |frame| is a {{RTCEncodedAudioFrame}}, set |data| to |frame|.{{RTCEncodedAudioFrame/data}}
1. If |frame| is a {{RTCEncodedVideoFrame}}, set |data| to |frame|.{{RTCEncodedVideoFrame/data}}
1. If |data| is undefined, abort these steps.
1. Let |buffer| be the result of running the SFrame algorithm with |data| and |role| as parameters. This algorithm is defined by the <a href="https://datatracker.ietf.org/doc/draft-omara-sframe/">SFrame specification</a> and returns an {{ArrayBuffer}}.
1. Let |buffer| be the result of running the SFrame algorithm with |data|, |sframe|.`[[cipherSuite]]`, and |role| as parameters. This algorithm is defined by [[RFC9605]] and returns an {{ArrayBuffer}}.
1. If the SFrame algorithm exits abruptly with an error, [=queue a task=] to run the following sub steps:
1. If the processing fails on decryption side due to |data| not following the SFrame format, [=fire an event=] named {{SFrameTransform/onerror|error}} at |sframe|,
using the {{SFrameTransformErrorEvent}} interface with its {{SFrameTransformErrorEvent/errorType}} attribute set to {{SFrameTransformErrorEventType/syntax}}
Expand All @@ -309,7 +314,7 @@ The <dfn method for="SFrameTransform">setEncryptionKey(|key|, |keyID|)</dfn> met
1. Let |promise| be [=a new promise=].
2. If |keyID| is a {{bigint}} which cannot be represented as a integer between 0 and 2<sup>64</sup>-1 inclusive, [=reject=] |promise| with a {{RangeError}} exception.
3. Otherwise, [=in parallel=], run the following steps:
1. Set |key| with its optional |keyID| as key material to use for the SFrame transform algorithm, as defined by the <a href="https://datatracker.ietf.org/doc/draft-omara-sframe/">SFrame specification</a>.
1. Set |key| with its optional |keyID| as key material to use for the SFrame transform algorithm, as defined by [[RFC9605]].
2. If setting the key material fails, [=reject=] |promise| with an {{InvalidModificationError}} exception and abort these steps.
3. [=Resolve=] |promise| with undefined.
4. Return |promise|.
Expand Down