OpenSEP

An open-source SEP boot ROM for Apple's virtual iPhone and iPad, compatible with AVPSEPBooter. Boots the SEP firmware of iOS 15 through iOS 27 on vphone-cli and iphone-cli.

• Serves the SEP mailbox protocol, from startup through AKE
• Loads and evaluates the personalised SEP firmware (IMG4/DER/X.509), then hands over to it
• Plain C17 and AArch64 assembly, no Apple code inside

Use it in place of AVPSEPBooter as the SEP core's ROM: load build/OpenSEP.bin at 0x02000000.

Not affiliated with Apple Inc. Apple and iPhone are trademarks of Apple Inc.

Compatibility

Host	Device	iOS 15	iOS 16	iOS 17	iOS 18	iOS 26	iOS 27
vphone-cli	iPhone17,3					✅	✅
vphone-cli	iPad15,3					✅	✅
iphone-cli	iPhone14,4	✅	✅	✅	✅	✅	❔

✅ boots  ·  ❔ not verified  ·  blank: not tested

vphone-cli runs on Virtualization.framework and uses the vresearch1 build (make): 26.4 (23E246) and 27.0.1 (24A446) reach SpringBoard on both devices, with OpenAVB as the AP boot ROM. iphone-cli runs on QEMU (d16) and uses the t8110 build (make PLATFORM=t8110): 15.0.1 (19A348), 16.0 (20A362), 17.0 (21A329), 18.6.2 (22G100) and 26.0 (23A341) reach the activation page. The 27.0 (24A437) run on iphone-cli did not complete because of a test-harness failure, so that combination is not yet verified. docs/platforms.md explains how the two builds differ.

Build

The build runs on macOS with the Xcode Command Line Tools and:

brew install llvm lld uv ripgrep

make                   # build/OpenSEP.bin for vresearch1 (the default)
make PLATFORM=t8110    # the same ROM with the t8110 handoff
make verify            # ROM gates plus every host test under tests/
make clean

Set LLVM_PREFIX= or HOST_CC= to use a toolchain outside Homebrew's default paths. OPENSEP_SEPFW_IMAGE and OPENSEP_RESEARCH_DIR enable two optional checks in make verify; see Internals.

Outputs

File	What it is
build/OpenSEP.bin	The ROM: a flat image linked at 0x02000000, at most 0x29000 bytes, with no relocations. build/OpenSEP.elf keeps DWARF for debugging.
build/<name>_tests	Host test binaries, one per tests/**/<name>_tests.c, built from the same sources.

Documentation

• External contract: the memory map, mailbox protocol and SEP firmware image a host must agree on.
• Platforms: the per-platform handoff table, its evidence, and how to add a platform.
• SEP firmware keys: where the per-build keys come from and the planned move to host-supplied keys.
• Internals: the toolchain, the checks in make verify and the source layout.
• Open items: known, deferred work.

Acknowledgements

Thanks to @lbr77 for the initial work this project builds on.

License

OpenSEP is released under the MIT License; see LICENSE.

The cryptographic primitives are implemented from the public specifications: FIPS 197 (AES), FIPS 180-4 (SHA-1/SHA-2), NIST SP 800-38A/B/C (ECB/CBC, CMAC, CCM), RFC 2104 / FIPS 198-1 (HMAC), NIST SP 800-108 (KDF in counter mode), FIPS 186-4, SEC 1 and NIST SP 800-56A (P-384, ECDH), and PKCS #1 v2.2 / RFC 8017 (RSA), whose constants they reproduce. For compatibility, the internal API and ABI -- function names, signatures and structure layouts -- follow the routines used by the SEP ROM interface that OpenSEP replaces, and a few constants (such as fault-detection canaries) are values of that interface.

The IMG4 DER test fixtures in tests/image/img4/img4_der_tests.c are built to the public IMG4 schema as documented by PongoOS lib/img4 (checkra1n/PongoOS, MIT); no PongoOS code is included.

Two pieces of Apple data are embedded: the per-build SEP firmware keys in src/platform/platform.c, which are publicly published (see SEP firmware keys), and the public Apple DDI Secure Boot Root CA - G1 certificate in src/image/img4/img4_chain.c. Both are data, not code.