Function VerifyClaimCode

internal/server/claim_codes.go:127–144

VerifyClaimCode returns true if code matches the derived code for (userID, workspaceID) at the current OR previous time bucket — the sliding 5–10 minute lifetime described in IDEA-1517 §4. Constant-time compare prevents timing oracles from leaking which of the two derivations failed (which would re

(secret []byte, userID, workspaceID, code string, at time.Time)

// Empty code, empty userID, or empty workspaceID always return false —
// no need to even derive in those cases.
func VerifyClaimCode(secret []byte, userID, workspaceID, code string, at time.Time) bool {
	if code == "" || userID == "" || workspaceID == "" || len(secret) < 16 {
		return false
	}
	if len(code) != claimCodeDigits {
		return false
	}
	bucket := at.UTC().Unix() / claimBucketSeconds
	current := deriveClaimCodeForBucket(secret, userID, workspaceID, bucket)
	previous := deriveClaimCodeForBucket(secret, userID, workspaceID, bucket-1)
	codeBytes := []byte(code)
	// ConstantTimeCompare returns 1 on match. OR the two results so
	// either matching bucket passes; subtle's compare doesn't panic
	// on equal-length operands so length-mismatch isn't a concern
	// here (we already gated on claimCodeDigits above).
	return subtle.ConstantTimeCompare(codeBytes, []byte(current)) == 1 ||
		subtle.ConstantTimeCompare(codeBytes, []byte(previous)) == 1
}