wolfTPM Firmware TPM (fwTPM / fTPM / swtpm) Server
June 8, 2026 · View on GitHub
A portable firmware TPM 2.0 implementation built entirely on wolfCrypt. The fwTPM provides a standards-compliant TPM 2.0 command processor that can replace a hardware TPM on embedded platforms without a discrete TPM chip, or serve as a drop-in development and CI/CD replacement for external simulators. Supports TCP socket transport (Microsoft TPM simulator protocol, compatible with wolfTPM examples and tpm2-tools) and TIS register-level transport over shared memory or SPI/I2C for bare-metal integration. Implements 105 of 113 TPM 2.0 v1.38 commands (93% coverage) with HAL abstractions for IO and NV storage portability.
Post-quantum cryptography support is available with --enable-pqc (alias for
--enable-v185), adding ML-DSA (FIPS 204) signing and ML-KEM (FIPS 203) key
encapsulation per TCG TPM 2.0 Library Specification v1.85. Configure
auto-detects PQC and enables it when --enable-fwtpm is built against a
wolfCrypt that has both. See docs/FWTPM.md
for algorithm and command details.
Building
wolfSSL must be built with --enable-keygen and WC_RSA_NO_PADDING:
cd wolfssl
./configure --enable-wolftpm --enable-pkcallbacks --enable-keygen CFLAGS="-DWC_RSA_NO_PADDING"
make && make install
Then build wolfTPM with the fwTPM server:
cd wolftpm
./configure --enable-fwtpm --enable-swtpm
make
Running
# Listens on localhost:2321 (cmd) and :2322 (platform)
src/fwtpm/fwtpm_server
# Optionally start with clear NV
src/fwtpm/fwtpm_server --clear
Testing with tpm2-tools
In socket mode (--enable-swtpm), the fwTPM server supports both the mssim
(Microsoft TPM simulator) and swtpm (Stefan Berger) TCTI protocols via
auto-detection on the command port. Either TCTI works:
# Using mssim TCTI (default for wolfTPM test scripts)
export TPM2TOOLS_TCTI="mssim:host=localhost,port=2321"
tpm2_startup -c
# Using swtpm TCTI (also works — auto-detected)
export TPM2TOOLS_TCTI="swtpm:host=localhost,port=2321"
tpm2_getrandom 8
The --port and --platform-port options are socket-mode only and not
available in TIS builds (--enable-fwtpm without --enable-swtpm).
Testing with wolfTPM examples
wolfTPM examples use the built-in swtpm client which speaks the mssim protocol automatically:
./examples/wrap/caps
./examples/keygen/keygen
Test Suite
# Full test: unit.test + run_examples.sh + tpm2-tools (311 tests)
make check
# tpm2-tools only
scripts/tpm2_tools_test.sh
make check runs tests/fwtpm_check.sh, which manages the
fwtpm_server lifecycle automatically.
CI Tests (fwtpm-test.yml)
All tests below run in GitHub Actions CI. Run manually before PR submission.
Runtime Tests (build + run_examples.sh + make check)
| Name | wolfTPM Config | Extra | Notes |
|---|---|---|---|
| fwtpm-socket | --enable-fwtpm --enable-swtpm --enable-debug | Primary test | |
| fwtpm-tis | --enable-fwtpm --enable-debug | TIS/SHM transport | |
| fwtpm-asan | --enable-fwtpm --enable-swtpm --enable-debug | -fsanitize=address | Memory errors |
| fwtpm-ubsan | --enable-fwtpm --enable-swtpm --enable-debug | -fsanitize=undefined | UB detection |
Build-Only Tests
| Name | wolfTPM Config | wolfSSL Config | Extra CFLAGS |
|---|---|---|---|
| fwtpm-no-rsa | --enable-fwtpm --enable-swtpm | --disable-rsa | |
| fwtpm-no-ecc | --enable-fwtpm --enable-swtpm | --disable-ecc | |
| fwtpm-only | --enable-fwtpm-only --enable-swtpm | No client library | |
| fwtpm-minimal | --enable-fwtpm --enable-swtpm | -DFWTPM_NO_ATTESTATION -DFWTPM_NO_NV -DFWTPM_NO_POLICY -DFWTPM_NO_CREDENTIAL -DFWTPM_NO_DA -DFWTPM_NO_PARAM_ENC | |
| fwtpm-no-policy | --enable-fwtpm --enable-swtpm | -DFWTPM_NO_POLICY | |
| fwtpm-no-nv | --enable-fwtpm --enable-swtpm | -DFWTPM_NO_NV | |
| fwtpm-no-attestation | --enable-fwtpm --enable-swtpm | -DFWTPM_NO_ATTESTATION | |
| fwtpm-no-credential | --enable-fwtpm --enable-swtpm | -DFWTPM_NO_CREDENTIAL | |
| fwtpm-no-da | --enable-fwtpm --enable-swtpm | -DFWTPM_NO_DA | |
| fwtpm-no-param-enc | --enable-fwtpm --enable-swtpm | -DFWTPM_NO_PARAM_ENC | |
| fwtpm-no-rsa-no-policy | --enable-fwtpm --enable-swtpm | --disable-rsa | -DFWTPM_NO_POLICY |
| fwtpm-no-ecc-no-nv | --enable-fwtpm --enable-swtpm | --disable-ecc | -DFWTPM_NO_NV |
| fwtpm-small-stack | --enable-fwtpm --enable-swtpm | -DWOLFTPM_SMALL_STACK |
Pedantic Builds (build-only, -Werror)
| Name | Compiler | Config |
|---|---|---|
| fwtpm-pedantic-gcc | gcc | --enable-fwtpm --enable-swtpm |
| fwtpm-pedantic-clang | clang | --enable-fwtpm --enable-swtpm |
| fwtpm-pedantic-only | gcc | --enable-fwtpm-only |
Separate Job: tpm2-tools (311 tests)
scripts/tpm2_tools_test.sh
Build Options and Feature Macros
See docs/FWTPM.md for the full list of configure options, compile-time macros (feature groups, algorithm flags, size limits, stack/heap control), spec version targeting, and HAL abstraction details.
Key options: --enable-fwtpm, --enable-fwtpm-only, --enable-swtpm,
--enable-fwtpm-small-ctx, --enable-fuzz. Feature disable macros:
FWTPM_NO_ATTESTATION, FWTPM_NO_NV, FWTPM_NO_POLICY, FWTPM_NO_CREDENTIAL,
FWTPM_NO_DA, FWTPM_NO_PARAM_ENC.
SPDM Responder Mode
fwtpm_server ships an SPDM 1.3 responder so the SPDM stack (TCG cert
handshake + DSP0274 PSK) can be tested without real silicon. When SPDM
is on, the responder sits above the existing transport HAL and dispatches
TCG-framed messages (tags 0x8101 clear, 0x8201 secured) into the SPDM
state machine; plaintext TPM frames fall through to the regular dispatcher
until the requester issues SPDMONLY LOCK, after which only GetCapability
is allowed through in plaintext (matching Nuvoton/Nations silicon).
Build with --enable-fwtpm --enable-spdm plus at least one of
--enable-tcg / --enable-psk. Start in one of two modes:
./src/fwtpm/fwtpm_server --spdm-tcg # TCG cert handshake
./src/fwtpm/fwtpm_server --spdm-psk \
--spdm-psk-hex dbc2192291d807742441b963f6712841... # PSK handshake
./src/fwtpm/fwtpm_server --no-spdm # plaintext only (default)
The responder generates a fresh P-384 identity keypair at startup (used
for GET_PUBK/KEY_EXCHANGE signing); the private key never leaves
fwtpm_server memory and the stack copy is zeroed with wc_ForceZero
after handoff to the responder context.
End-to-end coverage runs via the same script that drives real silicon:
./examples/spdm/spdm_test.sh ./examples/spdm/spdm_ctrl fwtpm-tcg
./examples/spdm/spdm_test.sh ./examples/spdm/spdm_ctrl fwtpm-psk
CI exercises 7 build-only configure permutations + the two e2e modes on
ubuntu-latest via spdm-test.yml, against the fwTPM SPDM responder.
TPM 2.0 Command Coverage
Currently Implemented (105 commands)
The fwTPM implements 105 of 113 commands from the v1.38 baseline (93% coverage).
Always enabled (47 commands): Startup, Shutdown, SelfTest, IncrementalSelfTest, GetTestResult, GetRandom, StirRandom, GetCapability, TestParms, PCR_Read, PCR_Extend, PCR_Reset, PCR_Event, PCR_Allocate, PCR_SetAuthPolicy, PCR_SetAuthValue, ReadClock, ClockSet, ClockRateAdjust, CreatePrimary, FlushContext, ContextSave, ContextLoad, ReadPublic, Clear, ClearControl, ChangeEPS, ChangePPS, HierarchyControl, HierarchyChangeAuth, SetPrimaryPolicy, EvictControl, Create, ObjectChangeAuth, Load, Sign, VerifySignature, Hash, HMAC, HMAC_Start, HashSequenceStart, SequenceUpdate, SequenceComplete, EventSequenceComplete, StartAuthSession, Unseal, LoadExternal, Import, Duplicate, Rewrap, CreateLoaded, Vendor_TCG_Test
Conditional on algorithm (NO_RSA / HAVE_ECC / NO_AES):
RSA_Encrypt, RSA_Decrypt, ECDH_KeyGen, ECDH_ZGen, ECC_Parameters,
EC_Ephemeral, ZGen_2Phase,
EncryptDecrypt, EncryptDecrypt2
Conditional on feature macros:
FWTPM_NO_POLICY: PolicyGetDigest, PolicyRestart, PolicyPCR, PolicyPassword, PolicyAuthValue, PolicyCommandCode, PolicyOR, PolicySecret, PolicyAuthorize, PolicyLocality, PolicySigned, PolicyNV, PolicyPhysicalPresence, PolicyCpHash, PolicyNameHash, PolicyDuplicationSelect, PolicyNvWritten, PolicyTemplate, PolicyCounterTimer, PolicyTicket, PolicyAuthorizeNV (21 commands)FWTPM_NO_NV: NV_DefineSpace, NV_UndefineSpace, NV_UndefineSpaceSpecial, NV_ReadPublic, NV_Write, NV_Read, NV_Extend, NV_Increment, NV_WriteLock, NV_ReadLock, NV_SetBits, NV_ChangeAuth, NV_GlobalWriteLock (13 commands). Also gates PolicyNV and PolicyAuthorizeNV when policy is enabled.FWTPM_NO_ATTESTATION: Quote, Certify, CertifyCreation, GetTime, NV_CertifyFWTPM_NO_CREDENTIAL: MakeCredential, ActivateCredentialFWTPM_NO_DA: DictionaryAttackLockReset, DictionaryAttackParameters (2 commands)FWTPM_NO_PARAM_ENC: Disables parameter encryption/decryption for command and response parameters. Sessions still work for HMAC auth, but encrypted transport is disabled. Reduces code size by removing AES-CFB and XOR param encryption.
Missing Commands -- TODO
v1.38 Baseline (8 missing commands)
Medium (moderate logic, builds on existing infrastructure)
| Command | Spec Section | Difficulty | Notes |
|---|---|---|---|
TPM2_SetCommandCodeAuditStatus | 21.2 | Medium | Manage list of commands that are audited. Needs audit bitmap in context |
TPM2_PP_Commands | 26.2 | Medium | Manage physical presence command list. Needs PP command bitmap |
Hard (complex crypto or new subsystems)
| Command | Spec Section | Difficulty | Notes |
|---|---|---|---|
TPM2_GetSessionAuditDigest | 18.5 | Hard | Sign session audit digest. Requires session audit tracking (running hash of all commands in session). New subsystem |
TPM2_GetCommandAuditDigest | 18.6 | Hard | Sign command audit digest. Requires command audit log with running hash. New subsystem |
TPM2_Commit | 19.2 | Hard | DAA/anonymous attestation ephemeral key. Complex ECC point math (K,L,E generation). Needs DAA support in wolfCrypt |
TPM2_SetAlgorithmSet | 26.3 | Hard | Vendor-specific algorithm configuration. Rarely implemented, can return TPM_RC_COMMAND_CODE |
TPM2_FieldUpgradeStart | 27.2 | Hard | Firmware upgrade initiation. Vendor-specific, requires secure update infrastructure |
TPM2_FieldUpgradeData | 27.3 | Hard | Firmware upgrade data blocks. Vendor-specific |
TPM2_FirmwareRead | 27.4 | Hard | Read firmware for backup. Vendor-specific |
v1.59 Additions (7 commands)
| Command | Spec Section | Difficulty | Notes |
|---|---|---|---|
TPM2_MAC | 15.6 | Medium | Block cipher MAC (CMAC). Like HMAC but uses symmetric key. Needs wolfCrypt CMAC |
TPM2_MAC_Start | 17.3 | Medium | Start MAC sequence. Mirrors HMAC_Start for CMAC |
TPM2_CertifyX509 | 18.8 | Hard | Generate partial X.509 certificate. Complex ASN.1 construction, caller provides tbsCert template. Deprecated in v1.84 |
TPM2_AC_GetCapability | 32.2 | Hard | Attached component capability query. Hardware-specific, rarely needed for software TPM |
TPM2_AC_Send | 32.3 | Hard | Send data to attached component. Hardware-specific |
TPM2_Policy_AC_SendSelect | 32.4 | Medium | Policy for AC_Send. Like other policy commands |
TPM2_ACT_SetTimeout | 33.2 | Medium | Set authenticated countdown timer. Needs ACT state + timer infrastructure |
v1.84 Additions (9 commands)
| Command | Spec Section | Difficulty | Notes |
|---|---|---|---|
TPM2_ECC_Encrypt | 14.8 | Medium | ECC-based encryption (ECIES/ElGamal). wolfCrypt ECIES support available |
TPM2_ECC_Decrypt | 14.9 | Medium | ECC-based decryption. Paired with ECC_Encrypt |
TPM2_PolicyCapability | 23.x | Easy | Assert TPM capability value in policy session |
TPM2_PolicyParameters | 23.x | Easy | Assert command parameters in policy session |
TPM2_SetCapability | 30.x | Medium | Modify TPM capability settings. Platform auth required |
TPM2_NV_DefineSpace2 | 31.x | Medium | Extended NV space definition (larger attribute field). Extends existing NV_DefineSpace |
TPM2_NV_ReadPublic2 | 31.x | Easy | Extended NV public read. Extends existing NV_ReadPublic |
TPM2_ReadOnlyControl | 24.x | Easy | Toggle TPM read-only mode. Simple flag |
TPM2_PolicyTransportSPDM | 23.x | Hard | SPDM transport policy. Requires SPDM protocol support |
Coverage Summary
The eight v1.85 PQC commands (TPM2_Encapsulate, TPM2_Decapsulate,
TPM2_SignDigest, TPM2_VerifyDigestSignature, TPM2_SignSequenceStart,
TPM2_SignSequenceComplete, TPM2_VerifySequenceStart,
TPM2_VerifySequenceComplete) are implemented under --enable-pqc
(alias --enable-v185). See "v1.85 Limitations / Scope" below for the
documented PQC-only restriction.
| Spec Version | Total Commands | Implemented | Missing | Coverage |
|---|---|---|---|---|
| v1.38 | 113 | 105 | 8 | 93% |
| v1.59 | 120 | 105 | 15 | 88% |
| v1.84 | 129 | 105 | 24 | 81% |
| v1.85 | 137 | 113 | 24 | 82% |
v1.85 Limitations / Scope
The following v1.85 commands are implemented for post-quantum keys only;
non-PQC key types are rejected with TPM_RC_KEY / TPM_RC_SCHEME even when
the v1.85 spec defines them generically:
TPM2_Encapsulate/TPM2_Decapsulate— ML-KEM only. ECC DHKEM (Table 100ecdharm with non-NULL KDF) is not implemented.TPM2_SignSequenceStart/VerifySequenceStart/SignSequenceComplete/VerifySequenceComplete— ML-DSA and Hash-ML-DSA only. Classical schemes (RSASSA, RSAPSS, ECDSA, SM2, ECSCHNORR, HMAC) that the spec also permits via these commands are not supported.TPM2_SignDigest/TPM2_VerifyDigestSignature— ML-DSA and Hash-ML-DSA only. Classical digest signing (RSASSA, RSAPSS, ECDSA) over these new commands is not supported; use the existingTPM2_Sign/TPM2_VerifySignaturecommands for those schemes.