nx_tls12_ske_verify.nx

nx_tls12_ske_verify.nx -- TLS 1.2 ECDHE-RSA ServerKeyExchange signature verification (rung 5 of the sovereign TLS 1.2 client; RFC 5246 §7.4.3 + §7.4.1.4.1). The server proves ownership of its certificate's RSA key by signing the ephemeral ECDHE parameters bound to both handshake randoms: signed_data = client_random(32) || server_random(32) || ECDHE_params signature = RSASSA-PKCS1-v1_5( SHA-256(signed_data) ) // leaf RSA key ECDHE_params = curve_type(1=0x03 named_curve) || named_curve(2=0x0017 secp256r1) || point_len(1) || point(point_len, 0x04||X||Y uncompressed) On the TLS 1.2 wire the SKE body additionally carries, AFTER the params, a 2-byte SignatureAndHashAlgorithm (e.g. 0x0401 = {sha256, rsa}) and a 2-byte signature length -- but those frame the signature; the SIGNED bytes are exactly client_random || server_random || ECDHE_params. COMPOSED, not re-implemented (verify-don't-rebuild): - tls12_skx_signed_data -> nx_tls12_parse.nx (signed-data assembly) - tls12_parse_server_key_exchange -> nx_tls12_parse.nx (wire field split) - rsa_pkcs1_v1_5_sha256_verify -> nx_rsa_pkcs1_v1_5_sha256.nx (RSA-2048 PKCS1 v1.5 + SHA-256 verify, hashes signed_data internally) - u2048_load_be -> nx_u2048.nx (modulus load) This rung adds ONLY the glue: assemble -> hash+verify -> sealed verdict. license_tier: INDEPENDENT_REDERIVE genealogy_id: international-research-sources/ietf/rfc_5246 + rfc_8017 lineage_id: nishi_tls12_ske_verify_q1 nx_safety_envelope: intended_use: "TLS 1.2 ECDHE-RSA ServerKeyExchange signature verification (server authentication / anti-MITM)" sil_target: SIL3 (authentication; a forged-accept = MITM) evidence: [composed_from_rsa_pkcs1v15_sha256_verify, openssl_signed_fixture_VERIFIED, neg_control_flipped_sig_and_signed_data_REJECTED] verdict: NOT_YET_EVALUATED