Improve encryption of Server Actions bound values

[shuding]

Removes the constant prefix and action ID from the IV value and makes it a fully random string. Then, we prefix the actual payload with the action ID to avoid submitting the payload from a different action, as well as using it as the checksum of the encryption data to ensure it's not damaged.

[ijjk]

Stats from current PR

Default Build

General

	vercel/next.js canary	vercel/next.js shu/715f	Change
buildDuration	10.7s	10.8s	N/A
buildDurationCached	6.3s	6.4s	N/A
nodeModulesSize	178 MB	177 MB	N/A
nextStartRea..uration (ms)	401ms	404ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js shu/715f	Change
199-HASH.js gzip	27.9 kB	27.9 kB	N/A
3f784ff6-HASH.js gzip	53.2 kB	53.2 kB	N/A
99.HASH.js gzip	182 B	182 B	✓
framework-HASH.js gzip	45.5 kB	45.5 kB	✓
main-app-HASH.js gzip	254 B	251 B	N/A
main-HASH.js gzip	33 kB	33 kB	N/A
webpack-HASH.js gzip	1.75 kB	1.75 kB	N/A
Overall change	45.7 kB	45.7 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js shu/715f	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js shu/715f	Change
_app-HASH.js gzip	206 B	205 B	N/A
_error-HASH.js gzip	182 B	180 B	N/A
amp-HASH.js gzip	506 B	505 B	N/A
css-HASH.js gzip	322 B	323 B	N/A
dynamic-HASH.js gzip	2.59 kB	2.59 kB	✓
edge-ssr-HASH.js gzip	260 B	259 B	N/A
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	369 B	369 B	✓
image-HASH.js gzip	4.38 kB	4.38 kB	N/A
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	2.67 kB	2.67 kB	N/A
routerDirect..HASH.js gzip	316 B	318 B	N/A
script-HASH.js gzip	385 B	384 B	N/A
withRouter-HASH.js gzip	319 B	319 B	✓
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	3.99 kB	3.99 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js shu/715f	Change
_buildManifest.js gzip	484 B	482 B	N/A
Overall change	0 B	0 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js shu/715f	Change
index.html gzip	528 B	530 B	N/A
link.html gzip	541 B	542 B	N/A
withRouter.html gzip	524 B	524 B	✓
Overall change	524 B	524 B	✓

Edge SSR bundle Size

	vercel/next.js canary	vercel/next.js shu/715f	Change
edge-ssr.js gzip	95.3 kB	95.3 kB	N/A
page.js gzip	157 kB	157 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js canary	vercel/next.js shu/715f	Change
middleware-b..fest.js gzip	622 B	626 B	N/A
middleware-r..fest.js gzip	150 B	151 B	N/A
middleware.js gzip	22.9 kB	22.9 kB	✓
edge-runtime..pack.js gzip	1.92 kB	1.92 kB	✓
Overall change	24.8 kB	24.8 kB	✓

Diff details

Diff for page.js

Diff too large to display

Commit: f7d22ff

[ijjk]

Tests Passed

[franky47]

This could be further improved in the following ways:

• Change IV length from 16 to 12 bytes (96 bits), as recommended by the GCM specification (paper)
• Use the AEAD capabilities of AES-GCM to authenticate the actionId by setting it as authenticated additional data (AAD), rather than prepending it to the cleartext and checking for a valid prefix after decryption.

Would you like me to open a PR?