Robert Allan JamesandClaude Sonnet 5
431bcb1f34
Root CA + snakeoil intermediate generated entirely offline (/home/rajames/CLionProjects/lithosananke-ca/, outside this repo, private keys chmod 600) per this milestone's own requirement: Ed25519, root self-signed 20-year validity, intermediate real-CA-signed (CA:TRUE, pathlen:0), chain verified via openssl. Snakeoil intermediate embedded as a capsule (capsules/pki/ snakeoil-intermediate.der) -- confirmed the font-capsule precedent needed zero new infrastructure, any non-.4th file under capsules/ embeds verbatim already. New x509_ed25519.c: a from-scratch, narrow DER walker (not general ASN.1/X.509, per this milestone's design decision) extracting the raw Ed25519 pubkey from a cert's SubjectPublicKeyInfo -- handles the optional v3 version field, verifies the AlgorithmIdentifier OID is Ed25519 rather than assuming, handles both DER length forms. Verified against ground truth: the extracted key from the real embedded cert matches openssl's own reported pubkey byte-for-byte; refusal path checked against truncated/garbage/empty/wrong-algorithm (real RSA cert) input. Compiles clean on all three architectures. Still open: mkcapsule signing step, wiring ed25519_verify() into capsule_birth.c's three validate call sites (landing warn-only first, per decision -- a bug here could stop every capsule from birthing, including Mama's own, on all three arches), and the BLOCK_MAP.md signature-status column. Documented in FABRIC-3.md. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01U14ET9CWAtbQMbYqomKgXd
31 lines
1.3 KiB
C
31 lines
1.3 KiB
C
/*
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* x509_ed25519.h -- extract a raw Ed25519 public key from a DER-encoded
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* X.509 certificate's SubjectPublicKeyInfo (RFC 8410).
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*
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* Deliberately NOT a general ASN.1/X.509 parser (Milestone 6 decision,
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* FABRIC-2.md): walks exactly as far into the DER structure as needed
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* to reach SubjectPublicKeyInfo, verifies its AlgorithmIdentifier OID is
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* Ed25519 (1.3.101.112) and rejects anything else, then returns the raw
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* 32-byte key from the trailing BIT STRING. No signature verification,
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* no chain validation, no extension parsing -- this only answers "what
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* public key does this cert claim to hold," matching exactly what
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* ed25519_verify() needs as input.
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*
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* Freestanding C99, no libc beyond memcmp/memcpy (already provided by
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* src/starkernel/vm/host/shim.c in the kernel build).
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*/
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#ifndef STARKERNEL_X509_ED25519_H
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#define STARKERNEL_X509_ED25519_H
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#include <stdint.h>
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#include <stddef.h>
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/* Returns 0 on success (pubkey_out[32] filled), -1 on any malformed
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* encoding, unexpected structure, or non-Ed25519 algorithm. Never
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* faults on malformed input -- every DER length/tag is bounds-checked
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* against der_len before use. */
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int x509_extract_ed25519_pubkey(const uint8_t *der, size_t der_len,
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uint8_t pubkey_out[32]);
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#endif /* STARKERNEL_X509_ED25519_H */
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