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[dice] refactor dice lib to reduce code size
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This refactors the dice lib to optimize code reuse and follow lib asset
naming conventions.

Signed-off-by: Tim Trippel <[email protected]>
(cherry picked from commit b217f41)
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@timothytrippel
timothytrippel committed May 3, 2024
1 parent c321102 commit 60135fc
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Showing 5 changed files with 72 additions and 94 deletions.
11 changes: 5 additions & 6 deletions sw/device/silicon_creator/lib/BUILD
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Original file line number Diff line number Diff line change
Expand Up @@ -489,12 +489,11 @@ cc_library(
opentitan_test(
name = "otbn_boot_services_functest",
srcs = ["otbn_boot_services_functest.c"],
exec_env = dicts.add(
EARLGREY_TEST_ENVS,
{
"//hw/top_earlgrey:fpga_cw310_sival": None,
},
),
exec_env = {
"//hw/top_earlgrey:fpga_cw310_sival": None,
"//hw/top_earlgrey:sim_dv": None,
"//hw/top_earlgrey:sim_verilator": None,
},
# This target uses OTBN pointers internally, so it cannot work host-side.
deps = [
":otbn_boot_services",
Expand Down
106 changes: 43 additions & 63 deletions sw/device/silicon_creator/lib/dice.c
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Original file line number Diff line number Diff line change
Expand Up @@ -95,93 +95,70 @@ static void curr_pubkey_le_to_be_convert(attestation_public_key_t *pubkey) {
le_be_buf_format((unsigned char *)pubkey->y, kAttestationPublicKeyCoordBytes);
}

/**
* Function generating a DICE or TPM certificate key pair. If successful, the
* generated public key is saved at pubkey.
*/
static rom_error_t common_attestation_keygen(
otbn_boot_attestation_key_type_t key_type,
const keymgr_diversification_t *diversifier, attestation_key_seed_t seed,
keymgr_state_t desired_keymgr_state, hmac_digest_t *pubkey_id,
attestation_public_key_t *pubkey) {
HARDENED_RETURN_IF_ERROR(keymgr_state_check(desired_keymgr_state));

// Generate / sideload key material into OTBN, and generate the ECC keypair.
HARDENED_RETURN_IF_ERROR(
otbn_boot_attestation_keygen(seed, key_type, *diversifier, pubkey));

// Keys are represented in certificates in big endian format, but the key is
// output from OTBN in little endian format, so we convert the key to
// big endian format.
curr_pubkey_le_to_be_convert(pubkey);

// Generate the key ID.
hmac_sha256(pubkey, kAttestationPublicKeyCoordBytes * 2, pubkey_id);

return kErrorOk;
}

/**
* Function preparing parameters for generating DICE attestation keys.
*/
rom_error_t dice_attestation_keygen(dice_key_t desired_key,
hmac_digest_t *pubkey_id,
attestation_public_key_t *pubkey) {
otbn_boot_attestation_key_type_t key_type;
attestation_key_seed_t otbn_ecc_keygen_seed;
const keymgr_diversification_t *keymgr_diversifier;
keymgr_state_t desired_state;
keymgr_state_t desired_keymgr_state;

switch (desired_key) {
case kDiceKeyUds:
desired_state = kKeymgrStateCreatorRootKey;
desired_keymgr_state = kKeymgrStateCreatorRootKey;
key_type = kOtbnBootAttestationKeyTypeDice;
keymgr_diversifier = &kUdsKeymgrDiversifier;
otbn_ecc_keygen_seed = kUdsAttestationKeySeed;
break;
case kDiceKeyCdi0:
desired_state = kKeymgrStateOwnerIntermediateKey;
desired_keymgr_state = kKeymgrStateOwnerIntermediateKey;
key_type = kOtbnBootAttestationKeyTypeDice;
keymgr_diversifier = &kCdi0KeymgrDiversifier;
otbn_ecc_keygen_seed = kCdi0AttestationKeySeed;
break;
case kDiceKeyCdi1:
desired_state = kKeymgrStateOwnerKey;
desired_keymgr_state = kKeymgrStateOwnerKey;
key_type = kOtbnBootAttestationKeyTypeDice;
keymgr_diversifier = &kCdi1KeymgrDiversifier;
otbn_ecc_keygen_seed = kCdi1AttestationKeySeed;
break;
default:
return kErrorDiceInvalidArgument;
};
return common_attestation_keygen(kOtbnBootAttestationKeyTypeDice,
keymgr_diversifier, otbn_ecc_keygen_seed,
desired_state, pubkey_id, pubkey);
}

/**
* Function preparing parameters for generating TPM keys.
*/
rom_error_t tpm_cert_keygen(tpm_key_t desired_key, hmac_digest_t *pubkey_id,
attestation_public_key_t *pubkey) {
attestation_key_seed_t otbn_ecc_keygen_seed;
const keymgr_diversification_t *keymgr_diversifier;

switch (desired_key) {
case kTpmKeyEk:
case kDiceKeyTpmEk:
desired_keymgr_state = kKeymgrStateOwnerKey;
key_type = kOtbnBootAttestationKeyTypeTpm;
keymgr_diversifier = &kTpmEkKeymgrDiversifier;
otbn_ecc_keygen_seed = kTpmEkAttestationKeySeed;
break;
case kTpmKeyCek:
case kDiceKeyTpmCek:
desired_keymgr_state = kKeymgrStateOwnerKey;
key_type = kOtbnBootAttestationKeyTypeTpm;
keymgr_diversifier = &kTpmCekKeymgrDiversifier;
otbn_ecc_keygen_seed = kTpmCekAttestationKeySeed;
break;
case kTpmKeyCik:
case kDiceKeyTpmCik:
desired_keymgr_state = kKeymgrStateOwnerKey;
key_type = kOtbnBootAttestationKeyTypeTpm;
keymgr_diversifier = &kTpmCikKeymgrDiversifier;
otbn_ecc_keygen_seed = kTpmCikAttestationKeySeed;
break;
default:
return kErrorDiceInvalidArgument;
return kErrorDiceInvalidKeyType;
};
return common_attestation_keygen(kOtbnBootAttestationKeyTypeTpm,
keymgr_diversifier, otbn_ecc_keygen_seed,
kKeymgrStateOwnerKey, pubkey_id, pubkey);

HARDENED_RETURN_IF_ERROR(keymgr_state_check(desired_keymgr_state));

// Generate / sideload key material into OTBN, and generate the ECC keypair.
HARDENED_RETURN_IF_ERROR(otbn_boot_attestation_keygen(
otbn_ecc_keygen_seed, key_type, *keymgr_diversifier, pubkey));

// Keys are represented in certificates in big endian format, but the key is
// output from OTBN in little endian format, so we convert the key to
// big endian format.
curr_pubkey_le_to_be_convert(pubkey);

// Generate the key ID.
hmac_sha256(pubkey, kAttestationPublicKeyCoordBytes * 2, pubkey_id);

return kErrorOk;
}

/**
Expand Down Expand Up @@ -351,7 +328,8 @@ rom_error_t dice_cdi_1_cert_build(hmac_digest_t *owner_measurement,

rom_error_t dice_tpm_ek_cert_build(manuf_certgen_inputs_t *inputs,
attestation_public_key_t *tpm_ek_pubkey,
hmac_digest_t *digest, uint8_t *tpm_ek_tbs,
hmac_digest_t *pubkey_id,
uint8_t *tpm_ek_tbs,
size_t *tpm_ek_tbs_size) {
tpm_ek_tbs_values_t tpm_ek_tbs_params = {
.auth_key_key_id = inputs->auth_key_key_id,
Expand All @@ -360,7 +338,7 @@ rom_error_t dice_tpm_ek_cert_build(manuf_certgen_inputs_t *inputs,
.tpm_ek_pub_key_ec_x_size = kAttestationPublicKeyCoordBytes,
.tpm_ek_pub_key_ec_y = (unsigned char *)tpm_ek_pubkey->y,
.tpm_ek_pub_key_ec_y_size = kAttestationPublicKeyCoordBytes,
.tpm_ek_pub_key_id = (unsigned char *)digest->digest, // Nobody cares.
.tpm_ek_pub_key_id = (unsigned char *)pubkey_id->digest,
.tpm_ek_pub_key_id_size = kDiceCertKeyIdSizeInBytes,
.tpm_version = "0.0.1",
.tpm_version_len = 5,
Expand All @@ -378,7 +356,8 @@ rom_error_t dice_tpm_ek_cert_build(manuf_certgen_inputs_t *inputs,

rom_error_t dice_tpm_cek_cert_build(manuf_certgen_inputs_t *inputs,
attestation_public_key_t *tpm_cek_pubkey,
hmac_digest_t *digest, uint8_t *tpm_cek_tbs,
hmac_digest_t *pubkey_id,
uint8_t *tpm_cek_tbs,
size_t *tpm_cek_tbs_size) {
tpm_cek_tbs_values_t tpm_cek_tbs_params = {
.auth_key_key_id = inputs->auth_key_key_id,
Expand All @@ -387,7 +366,7 @@ rom_error_t dice_tpm_cek_cert_build(manuf_certgen_inputs_t *inputs,
.tpm_cek_pub_key_ec_x_size = kAttestationPublicKeyCoordBytes,
.tpm_cek_pub_key_ec_y = (unsigned char *)tpm_cek_pubkey->y,
.tpm_cek_pub_key_ec_y_size = kAttestationPublicKeyCoordBytes,
.tpm_cek_pub_key_id = (unsigned char *)digest->digest,
.tpm_cek_pub_key_id = (unsigned char *)pubkey_id->digest,
.tpm_cek_pub_key_id_size = kDiceCertKeyIdSizeInBytes,
};

Expand All @@ -399,7 +378,8 @@ rom_error_t dice_tpm_cek_cert_build(manuf_certgen_inputs_t *inputs,

rom_error_t dice_tpm_cik_cert_build(manuf_certgen_inputs_t *inputs,
attestation_public_key_t *tpm_cik_pubkey,
hmac_digest_t *digest, uint8_t *tpm_cik_tbs,
hmac_digest_t *pubkey_id,
uint8_t *tpm_cik_tbs,
size_t *tpm_cik_tbs_size) {
tpm_cik_tbs_values_t tpm_cik_tbs_params = {
.auth_key_key_id = inputs->auth_key_key_id,
Expand All @@ -408,7 +388,7 @@ rom_error_t dice_tpm_cik_cert_build(manuf_certgen_inputs_t *inputs,
.tpm_cik_pub_key_ec_x_size = kAttestationPublicKeyCoordBytes,
.tpm_cik_pub_key_ec_y = (unsigned char *)tpm_cik_pubkey->y,
.tpm_cik_pub_key_ec_y_size = kAttestationPublicKeyCoordBytes,
.tpm_cik_pub_key_id = (unsigned char *)digest->digest,
.tpm_cik_pub_key_id = (unsigned char *)pubkey_id->digest,
.tpm_cik_pub_key_id_size = kDiceCertKeyIdSizeInBytes,
};

Expand Down
46 changes: 22 additions & 24 deletions sw/device/silicon_creator/lib/dice.h
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Original file line number Diff line number Diff line change
Expand Up @@ -26,23 +26,35 @@ enum {
};

/**
* Supported DICE attestation keys.
* Supported DICE/TPM attestation keys.
*/
typedef enum dice_key {
/**
* DICE UDS key.
*/
kDiceKeyUds = 0,
/**
* DICE CDI0 key.
*/
kDiceKeyCdi0 = 1,
/**
* DICE CDI1 key.
*/
kDiceKeyCdi1 = 2,
/**
* TPM EK key.
*/
kDiceKeyTpmEk = 3,
/**
* TPM CEK key.
*/
kDiceKeyTpmCek = 4,
/**
* TPM CIK key.
*/
kDiceKeyTpmCik = 5,
} dice_key_t;

/**
* Supported TPM attestation keys.
*/
typedef enum tpm_key {
kTpmKeyEk = 0,
kTpmKeyCek = 1,
kTpmKeyCik = 2,
} tpm_key_t;

/**
* A set of public key IDs required to generate an X.509 certificate.
*/
Expand Down Expand Up @@ -131,20 +143,6 @@ rom_error_t dice_cdi_1_cert_build(hmac_digest_t *owner_measurement,
attestation_public_key_t *cdi_1_pubkey,
uint8_t *cert, size_t *cert_size);

/**
* Generates the requested TPM ECC keypair, returning the public key and
* a key ID (which is a SHA256 digest of the public key).
*
* Preconditions: keymgr has been initialized and cranked to the desired stage.
*
* @param desired_key The desired attestation key to generate.
* @param[out] pubkey_id The public key ID (for embedding into certificates).
* @param[out] pubkey The public key.
*/
OT_WARN_UNUSED_RESULT
rom_error_t tpm_cert_keygen(tpm_key_t desired_key, hmac_digest_t *pubkey_id,
attestation_public_key_t *pubkey);

/**
* Generates an X.509 TBS section of a TPM EK certificate.
*
Expand Down
2 changes: 1 addition & 1 deletion sw/device/silicon_creator/lib/error.h
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Original file line number Diff line number Diff line change
Expand Up @@ -192,7 +192,7 @@ enum module_ {
X(kErrorRescueBadMode, ERROR_(1, kModuleRescue, kInvalidArgument)), \
X(kErrorRescueImageTooBig, ERROR_(2, kModuleRescue, kFailedPrecondition)), \
\
X(kErrorDiceInvalidArgument, ERROR_(0, kModuleDice, kInvalidArgument)), \
X(kErrorDiceInvalidKeyType, ERROR_(0, kModuleDice, kInvalidArgument)), \
\
X(kErrorCertInternal, ERROR_(0, kModuleCert, kInternal)), \
X(kErrorCertInvalidArgument, ERROR_(1, kModuleCert, kInvalidArgument)), \
Expand Down
1 change: 1 addition & 0 deletions sw/device/silicon_creator/manuf/skus/earlgrey_a0/sival_bringup/ft_personalize_3.c
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Original file line number Diff line number Diff line change
Expand Up @@ -152,6 +152,7 @@ static status_t personalize(ujson_t *uj) {
keymgr_advance_state();
TRY(dice_attestation_keygen(kDiceKeyUds, &uds_pubkey_id, &curr_pubkey));
TRY(otbn_boot_attestation_key_save(kUdsAttestationKeySeed,
kOtbnBootAttestationKeyTypeDice,
kUdsKeymgrDiversifier));
// We copy over the UDS endorsement key ID to an SHA256 digest type, since
// this is the format of key IDs generated on-dice.
Expand Down

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