[osanderson]

Batch H of the 2026-10-18 review: L8 and L14, as decided. Both are breaking. Each has a section under ## v0.58.0 in UPGRADING.md.

L8: sealing keys must not be text

The gap: pairwise keys refused a key made entirely of printable text (a passphrase, or a hex or base64 key passed without decoding). The other sealers accepted one and sealed everything under it:

• token sets;
• CIBA sessions;
• client/sessioncookie;
• server/interactioncookie.

The fix:

• sealkeys.Check, which every sealer uses, now refuses such a key, and pairwise's own copy of the check is gone.
• A random 32-byte key is all printable with probability about 4×10⁻¹⁴.
• Test fixtures that used text keys now end in a non-printable byte.

L14: outbound TLS 1.2 cipher suites

The spec: FAPI-CIBA §7.9 (as FAPI 1.0 Part 2 §8.5) permits only the ECDHE AES-GCM suites under TLS 1.2. fapihttp.NewClient offered Go's defaults, CBC included.

The fix:

• The transport now offers exactly the four ECDHE AES-GCM suites under TLS 1.2. Go has no DHE suites, the other two the specs list. TLS 1.3 is unaffected.
• HardeningOf counts a transport as hardened only while its TLS 1.2 suites are some of those four. Adding a CBC suite, or clearing the list back to Go's defaults, makes it unhardened.

Behaviour change: a server offering only CBC suites under TLS 1.2 is no longer reachable through a NewClient client.

Testing

• L8:
  • sealkeys cases for a passphrase and an undecoded hex key;
  • the pairwise text-key tests still pass through the shared check.
• L14:
  • real handshakes against a TLS 1.2 server: an ECDHE-GCM suite is reached, a CBC-only one isn't;
  • HardeningOf refuses an added CBC suite and cleared defaults, and accepts a subset of the permitted suites.
• Checks:
  • go vet, go test ./..., and go test -race on Go 1.26.9 for the affected packages;
  • golangci-lint (0 issues);
  • arm vet;
  • every demo module.
• Downstream: OID4VCgo's whole test suite passes against this branch. Its only sealer key, passport-vdc's interaction cookie key, comes from crypto/rand.

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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