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Add support for the enrollment algorithm on volatile keys #48

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08a95e6
Add support for the enrollment algorithm on volatile keys
padelsbach Nov 4, 2026
2c097eb
Check enrollment algorithm in key wrap, KEM and one-shot AEAD
padelsbach Nov 4, 2026
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9 changes: 7 additions & 2 deletions .gitignore
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Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,8 @@ test/psa_devid_cryptocb_test
test/build-probe
test/build-cryptocb
test/build-cryptocb-asan
test/build-enroll
test/build-enroll-asan
test/psa_store_commit_test
test/psa_store_dir_validation_test
test/psa_store_read_open_test
Expand All @@ -80,6 +82,9 @@ test/psa_kdf_psk_to_ms_size_test
test/psa_kdf_zeroize_output_test
test/psa_import_zero_length_test
test/psa_copy_key_cross_lifetime_test
build-test/out/
test/psa_zero_capacity_buffer_test
test/psa_tf_psa_extra_test
test/psa_zero_capacity_buffer_test
test/psa_enrollment_alg_test
build-test/out/
.cache/
compile_commands.json
5 changes: 5 additions & 0 deletions Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,10 @@ endif
ifeq ($(AES_FAST),1)
CPPFLAGS += -DWOLFPSA_AES_FAST
endif
# ENROLLMENT_ALG=1 allows the Mbed TLS enrollment algorithm on volatile keys
ifeq ($(ENROLLMENT_ALG),1)
CPPFLAGS += -DWOLFPSA_ENROLLMENT_ALG
endif
CFLAGS += $(DEBUG_FLAGS) $(SANITIZE_FLAGS)
LDFLAGS += $(SANITIZE_FLAGS)

Expand Down Expand Up @@ -204,6 +208,7 @@ UNIT_TESTS := psa_api_test \
psa_store_read_open_test \
psa_store_dir_validation_test \
psa_devid_cryptocb_test \
psa_enrollment_alg_test \
psa_kdf_zeroize_output_test \
psa_import_zero_length_test \
psa_copy_key_cross_lifetime_test \
Expand Down
97 changes: 33 additions & 64 deletions src/psa_aead.c
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Original file line number Diff line number Diff line change
Expand Up @@ -152,6 +152,33 @@ static psa_status_t wolfpsa_aead_gcm_check_tag_size(size_t tag_length)
}
#endif

/* Whether permitted algorithm key_alg allows AEAD alg and its tag length */
static int wolfpsa_aead_alg_permitted(psa_algorithm_t key_alg,
psa_algorithm_t alg)
{
size_t key_tag_len = wolfpsa_aead_tag_length(key_alg);
size_t req_tag_len = wolfpsa_aead_tag_length(alg);

if (key_tag_len == 0 ||
PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG(key_alg) !=
PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG(alg)) {
return 0;
}
if ((key_alg & PSA_ALG_AEAD_AT_LEAST_THIS_LENGTH_FLAG) != 0) {
return req_tag_len >= key_tag_len;
}
return req_tag_len == key_tag_len;
}

/* Whether the permitted or enrollment algorithm allows AEAD alg */
static int wolfpsa_aead_key_permits_alg(const psa_key_attributes_t *attributes,
psa_algorithm_t alg)
{
return wolfpsa_aead_alg_permitted(psa_get_key_algorithm(attributes), alg) ||
wolfpsa_aead_alg_permitted(
psa_get_key_enrollment_algorithm(attributes), alg);
}

static psa_status_t wolfpsa_aead_check_key(psa_key_id_t key,
psa_key_usage_t usage,
psa_algorithm_t alg,
Expand All @@ -161,11 +188,6 @@ static psa_status_t wolfpsa_aead_check_key(psa_key_id_t key,
{
psa_status_t status;
psa_key_usage_t key_usage;
psa_algorithm_t key_alg;
psa_algorithm_t key_base;
psa_algorithm_t req_base;
size_t key_tag_len;
size_t req_tag_len;

status = wolfpsa_get_key_data(key, attributes, key_data, key_data_length);
if (status != PSA_SUCCESS) {
Expand Down Expand Up @@ -207,43 +229,14 @@ static psa_status_t wolfpsa_aead_check_key(psa_key_id_t key,
return PSA_ERROR_NOT_PERMITTED;
}

key_alg = psa_get_key_algorithm(attributes);
if (key_alg == PSA_ALG_NONE) {
wolfpsa_forcezero_free_key_data(*key_data, *key_data_length);
*key_data = NULL;
*key_data_length = 0;
return PSA_ERROR_NOT_PERMITTED;
}

/* Algorithm match checks */
key_base = PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG(key_alg);
req_base = PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG(alg);
key_tag_len = wolfpsa_aead_tag_length(key_alg);
req_tag_len = wolfpsa_aead_tag_length(alg);

if (key_tag_len == 0 || req_tag_len == 0) {
if (wolfpsa_aead_tag_length(alg) == 0) {
wolfpsa_forcezero_free_key_data(*key_data, *key_data_length);
*key_data = NULL;
*key_data_length = 0;
return PSA_ERROR_INVALID_ARGUMENT;
}

if (key_base != req_base) {
wolfpsa_forcezero_free_key_data(*key_data, *key_data_length);
*key_data = NULL;
*key_data_length = 0;
return PSA_ERROR_NOT_PERMITTED;
}

if ((key_alg & PSA_ALG_AEAD_AT_LEAST_THIS_LENGTH_FLAG) != 0) {
if (req_tag_len < key_tag_len) {
wolfpsa_forcezero_free_key_data(*key_data, *key_data_length);
*key_data = NULL;
*key_data_length = 0;
return PSA_ERROR_NOT_PERMITTED;
}
}
else if (req_tag_len != key_tag_len) {
if (!wolfpsa_aead_key_permits_alg(attributes, alg)) {
wolfpsa_forcezero_free_key_data(*key_data, *key_data_length);
*key_data = NULL;
*key_data_length = 0;
Expand Down Expand Up @@ -1525,7 +1518,6 @@ static psa_status_t wolfpsa_xchacha_oneshot_encrypt(
size_t key_data_length = 0;
psa_status_t status;
psa_key_usage_t key_usage;
psa_algorithm_t key_alg;
int ret;
/* Encrypt produces plaintext_length bytes of ciphertext plus 16-byte tag. */
size_t out_len;
Expand Down Expand Up @@ -1569,12 +1561,7 @@ static psa_status_t wolfpsa_xchacha_oneshot_encrypt(
return PSA_ERROR_NOT_PERMITTED;
}

key_alg = psa_get_key_algorithm(&attributes);
if (!PSA_ALG_AEAD_EQUAL(key_alg, PSA_ALG_XCHACHA20_POLY1305)) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
if (!PSA_ALG_AEAD_EQUAL(key_alg, alg)) {
if (!wolfpsa_aead_key_permits_alg(&attributes, alg)) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
Expand Down Expand Up @@ -1611,7 +1598,6 @@ static psa_status_t wolfpsa_xchacha_oneshot_decrypt(
size_t key_data_length = 0;
psa_status_t status;
psa_key_usage_t key_usage;
psa_algorithm_t key_alg;
int ret;
size_t pt_len;

Expand Down Expand Up @@ -1652,12 +1638,7 @@ static psa_status_t wolfpsa_xchacha_oneshot_decrypt(
return PSA_ERROR_NOT_PERMITTED;
}

key_alg = psa_get_key_algorithm(&attributes);
if (!PSA_ALG_AEAD_EQUAL(key_alg, PSA_ALG_XCHACHA20_POLY1305)) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
if (!PSA_ALG_AEAD_EQUAL(key_alg, alg)) {
if (!wolfpsa_aead_key_permits_alg(&attributes, alg)) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
Expand Down Expand Up @@ -1701,7 +1682,6 @@ static psa_status_t wolfpsa_ascon_oneshot_encrypt(
size_t key_data_length = 0;
psa_status_t status;
psa_key_usage_t key_usage;
psa_algorithm_t key_alg;
wc_AsconAEAD128 ascon;
int ret;
size_t out_len;
Expand Down Expand Up @@ -1749,12 +1729,7 @@ static psa_status_t wolfpsa_ascon_oneshot_encrypt(
return PSA_ERROR_NOT_PERMITTED;
}

key_alg = psa_get_key_algorithm(&attributes);
if (!PSA_ALG_AEAD_EQUAL(key_alg, PSA_ALG_ASCON_AEAD128)) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
if (!PSA_ALG_AEAD_EQUAL(key_alg, alg)) {
if (!wolfpsa_aead_key_permits_alg(&attributes, alg)) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
Expand Down Expand Up @@ -1807,7 +1782,6 @@ static psa_status_t wolfpsa_ascon_oneshot_decrypt(
size_t key_data_length = 0;
psa_status_t status;
psa_key_usage_t key_usage;
psa_algorithm_t key_alg;
wc_AsconAEAD128 ascon;
int ret;
size_t ct_len; /* ciphertext body length (without tag) */
Expand Down Expand Up @@ -1854,12 +1828,7 @@ static psa_status_t wolfpsa_ascon_oneshot_decrypt(
return PSA_ERROR_NOT_PERMITTED;
}

key_alg = psa_get_key_algorithm(&attributes);
if (!PSA_ALG_AEAD_EQUAL(key_alg, PSA_ALG_ASCON_AEAD128)) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
if (!PSA_ALG_AEAD_EQUAL(key_alg, alg)) {
if (!wolfpsa_aead_key_permits_alg(&attributes, alg)) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
Expand Down
36 changes: 17 additions & 19 deletions src/psa_asymmetric_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -275,6 +275,19 @@ static int wolfpsa_sign_alg_permitted(psa_algorithm_t key_alg,
return 0;
}

static int wolfpsa_asymmetric_alg_permitted(psa_algorithm_t key_alg,
psa_algorithm_t alg,
psa_key_usage_t usage)
{
if (key_alg == PSA_ALG_NONE) {
return 0;
}
if (PSA_ALG_IS_KEY_AGREEMENT(alg) && PSA_ALG_IS_KEY_AGREEMENT(key_alg)) {
return wolfpsa_key_agreement_alg_permitted(key_alg, alg);
}
return wolfpsa_sign_alg_permitted(key_alg, alg, usage);
}

static psa_status_t wolfpsa_asymmetric_check_key(psa_key_id_t key,
psa_key_usage_t usage,
psa_algorithm_t alg,
Expand All @@ -284,7 +297,6 @@ static psa_status_t wolfpsa_asymmetric_check_key(psa_key_id_t key,
{
psa_status_t status;
psa_key_usage_t key_usage;
psa_algorithm_t key_alg;

status = wolfpsa_get_key_data(key, attributes, key_data, key_data_length);
if (status != PSA_SUCCESS) {
Expand All @@ -299,24 +311,10 @@ static psa_status_t wolfpsa_asymmetric_check_key(psa_key_id_t key,
return PSA_ERROR_NOT_PERMITTED;
}

key_alg = psa_get_key_algorithm(attributes);
if (key_alg == PSA_ALG_NONE) {
wolfpsa_forcezero_free_key_data(*key_data, *key_data_length);
*key_data = NULL;
*key_data_length = 0;
return PSA_ERROR_NOT_PERMITTED;
}

/* Algorithm match checks */
if (PSA_ALG_IS_KEY_AGREEMENT(alg) && PSA_ALG_IS_KEY_AGREEMENT(key_alg)) {
if (!wolfpsa_key_agreement_alg_permitted(key_alg, alg)) {
wolfpsa_forcezero_free_key_data(*key_data, *key_data_length);
*key_data = NULL;
*key_data_length = 0;
return PSA_ERROR_NOT_PERMITTED;
}
}
else if (!wolfpsa_sign_alg_permitted(key_alg, alg, usage)) {
if (!wolfpsa_asymmetric_alg_permitted(psa_get_key_algorithm(attributes),
alg, usage) &&
!wolfpsa_asymmetric_alg_permitted(
psa_get_key_enrollment_algorithm(attributes), alg, usage)) {
wolfpsa_forcezero_free_key_data(*key_data, *key_data_length);
*key_data = NULL;
*key_data_length = 0;
Expand Down
4 changes: 1 addition & 3 deletions src/psa_cipher.c
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Expand Up @@ -161,7 +161,6 @@ static psa_status_t wolfpsa_cipher_check_key(
{
psa_status_t status;
psa_key_usage_t key_usage;
psa_algorithm_t key_alg;

status = wolfpsa_get_key_data(key, attributes, key_data, key_data_length);
if (status != PSA_SUCCESS) {
Expand Down Expand Up @@ -228,8 +227,7 @@ static psa_status_t wolfpsa_cipher_check_key(
return PSA_ERROR_NOT_PERMITTED;
}

key_alg = psa_get_key_algorithm(attributes);
if (key_alg == PSA_ALG_NONE || key_alg != alg) {
if (!wolfpsa_key_permits_alg(attributes, alg)) {
wolfpsa_forcezero_free_key_data(*key_data, *key_data_length);
*key_data = NULL;
*key_data_length = 0;
Expand Down
16 changes: 2 additions & 14 deletions src/psa_kem.c
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Expand Up @@ -88,7 +88,6 @@ psa_status_t psa_encapsulate(psa_key_id_t key,
psa_key_type_t key_type;
size_t key_bits;
psa_key_usage_t key_usage;
psa_algorithm_t key_alg;
psa_status_t status;
uint8_t ss[WOLFPSA_MLKEM_SS_SIZE];
/* Staging buffer: ciphertext is written here before the output key is
Expand Down Expand Up @@ -129,7 +128,6 @@ psa_status_t psa_encapsulate(psa_key_id_t key,
key_type = psa_get_key_type(&key_attr);
key_bits = psa_get_key_bits(&key_attr);
key_usage = psa_get_key_usage_flags(&key_attr);
key_alg = psa_get_key_algorithm(&key_attr);

if (key_type != PSA_KEY_TYPE_ML_KEM_KEY_PAIR &&
key_type != PSA_KEY_TYPE_ML_KEM_PUBLIC_KEY) {
Expand All @@ -142,11 +140,7 @@ psa_status_t psa_encapsulate(psa_key_id_t key,
return PSA_ERROR_NOT_PERMITTED;
}

if (key_alg != alg && key_alg != PSA_ALG_NONE) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
if (key_alg == PSA_ALG_NONE) {
if (!wolfpsa_key_permits_alg(&key_attr, alg)) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
Expand Down Expand Up @@ -207,7 +201,6 @@ psa_status_t psa_decapsulate(psa_key_id_t key,
psa_key_type_t key_type;
size_t key_bits;
psa_key_usage_t key_usage;
psa_algorithm_t key_alg;
psa_status_t status;
uint8_t ss[WOLFPSA_MLKEM_SS_SIZE];

Expand Down Expand Up @@ -240,7 +233,6 @@ psa_status_t psa_decapsulate(psa_key_id_t key,
key_type = psa_get_key_type(&key_attr);
key_bits = psa_get_key_bits(&key_attr);
key_usage = psa_get_key_usage_flags(&key_attr);
key_alg = psa_get_key_algorithm(&key_attr);

/* Decapsulate requires the key pair (private key). */
if (key_type != PSA_KEY_TYPE_ML_KEM_KEY_PAIR) {
Expand All @@ -253,11 +245,7 @@ psa_status_t psa_decapsulate(psa_key_id_t key,
return PSA_ERROR_NOT_PERMITTED;
}

if (key_alg != alg && key_alg != PSA_ALG_NONE) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
if (key_alg == PSA_ALG_NONE) {
if (!wolfpsa_key_permits_alg(&key_attr, alg)) {
wolfpsa_forcezero_free_key_data(key_data, key_data_length);
return PSA_ERROR_NOT_PERMITTED;
}
Expand Down
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