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Phase 8: zuse cert storage moved out of the dictionary (fuse-blow install)

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Found that a pinned CONSTANT is not actually tamper-proof: ACL-PIN only
blocks redefinition, not a >BODY-then-store on the word's existing data
field. Moves the Zuse cert value into C-only VM struct fields
(zuse_cert_lo/hi + zuse_cert_installed fuse bit) with a one-time
vm_zuse_cert_install() and read-only ZUSE-CERT-LO@/HI@/INSTALLED? FORTH
accessors, closing the tamper path structurally instead of by convention.
Deletes the now-insecure ZUSE-CERT-LO/HI CONSTANT words from zuse.4th.

vm_zuse_cert_install() has no caller yet -- the real mint flow (Milestone
6 CA, the MINT word) is still open; this is storage + accessors only, not
a stand-in mint. Documented in FABRIC-3.md. Verified: hosted build clean,
mkcapsule --lint clean (31/31), clean boot to ok> on amd64/aarch64/riscv64
with Stadium conservation intact and no panics.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01U14ET9CWAtbQMbYqomKgXd
This commit is contained in:
Robert Allan James
2026-08-26 13:58:22 -04:00
co-authored by Claude Sonnet 5
parent 4dd1321ea4
commit 6f5605d479
14 changed files with 27217 additions and 10 deletions
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src/vm.c
+25
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@@ -117,6 +117,31 @@ void vm_set_base(VM* vm, unsigned b)
/* vm_init and vm_cleanup moved to vm_bootstrap.c */
/* vm_tick* and heartbeat functions moved to vm_time.c */
/**
* @brief One-time write of the Zuse cert value (blows the fuse).
*
* Deliberately not backed by a dictionary CONSTANT: ACL-PIN only blocks
* redefinition (vm_create_word shadowing), not a >BODY-then-store on the
* word's data field, so a pinned CONSTANT is not actually immutable against
* FORTH-level tampering. Keeping the value in a VM struct field with no
* corresponding FORTH store word closes that path entirely -- see
* FABRIC-3.md's Milestone 4 mint-then-pin writeup for the finding.
*
* @param vm VM instance.
* @param lo Cert value, low half.
* @param hi Cert value, high half.
* @return 0 on success; -1 if already installed (fuse already blown).
*/
int vm_zuse_cert_install(VM* vm, uint64_t lo, uint64_t hi)
{
if (!vm) return -1;
if (vm->zuse_cert_installed) return -1;
vm->zuse_cert_lo = lo;
vm->zuse_cert_hi = hi;
vm->zuse_cert_installed = 1;
return 0;
}
/* ====================== Parser / number ======================= */
/**