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Remove limit on MAC protected headers; MAC code size smaller #276

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merged 7 commits into from
Nov 16, 2023
Merged

Remove limit on MAC protected headers; MAC code size smaller #276

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180f949
Rework of crypto adaptor layer for MAC
Nov 16, 2023
4199d1f
Merge branch 'dev' of github.com:laurencelundblade/t_cose into better…
Nov 16, 2023
4691ae3
A little more tidying up
Nov 16, 2023
a0c1abe
Improve comments; re order
Nov 16, 2023
157ab33
More code formatting and comments
Nov 16, 2023
e9e54cb
More code formatting and comments
Nov 16, 2023
2055ce7
More code formatting and comments
Nov 16, 2023
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68 changes: 18 additions & 50 deletions crypto_adapters/t_cose_openssl_crypto.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1052,7 +1052,7 @@ t_cose_crypto_hash_finish(struct t_cose_crypto_hash *hash_ctx,
* See documentation in t_cose_crypto.h
*/
enum t_cose_err_t
t_cose_crypto_hmac_compute_setup(struct t_cose_crypto_hmac *hmac_ctx,
t_cose_crypto_hmac_setup(struct t_cose_crypto_hmac *hmac_ctx,
struct t_cose_key signing_key,
const int32_t cose_alg_id)
{
Expand Down Expand Up @@ -1104,46 +1104,51 @@ t_cose_crypto_hmac_compute_setup(struct t_cose_crypto_hmac *hmac_ctx,
return T_COSE_ERR_HMAC_GENERAL_FAIL;
}

hmac_ctx->update_error = 1; /* 1 is success in OpenSSL */

return T_COSE_SUCCESS;
}


/*
* See documentation in t_cose_crypto.h
*/
enum t_cose_err_t
void
t_cose_crypto_hmac_update(struct t_cose_crypto_hmac *hmac_ctx,
struct q_useful_buf_c payload)
{
int ossl_result;

ossl_result = EVP_DigestSignUpdate(hmac_ctx->evp_ctx, payload.ptr, payload.len);
if(ossl_result != 1) {
return T_COSE_ERR_HMAC_GENERAL_FAIL;
if(hmac_ctx->update_error) { /* 1 is no error, 0 means error for OpenSSL */
if(payload.ptr) {
hmac_ctx->update_error = EVP_DigestSignUpdate(hmac_ctx->evp_ctx,
payload.ptr,
payload.len);
}
}

return T_COSE_SUCCESS;
}



/*
* See documentation in t_cose_crypto.h
*/
enum t_cose_err_t
t_cose_crypto_hmac_compute_finish(struct t_cose_crypto_hmac *hmac_ctx,
t_cose_crypto_hmac_finish(struct t_cose_crypto_hmac *hmac_ctx,
struct q_useful_buf tag_buf,
struct q_useful_buf_c *tag)
{
int ossl_result;
size_t in_out_len;

in_out_len = tag_buf.len;
ossl_result = EVP_DigestSignFinal(hmac_ctx->evp_ctx, tag_buf.ptr, &in_out_len);
if(hmac_ctx->update_error) {
hmac_ctx->update_error = EVP_DigestSignFinal(hmac_ctx->evp_ctx,
tag_buf.ptr,
&in_out_len);
}

EVP_MD_CTX_free(hmac_ctx->evp_ctx);
EVP_PKEY_free(hmac_ctx->evp_pkey);

if(ossl_result != 1) {
if(hmac_ctx->update_error != 1) {
return T_COSE_ERR_HMAC_GENERAL_FAIL;
}

Expand All @@ -1154,43 +1159,6 @@ t_cose_crypto_hmac_compute_finish(struct t_cose_crypto_hmac *hmac_ctx,
}


/*
* See documentation in t_cose_crypto.h
*/
// TODO: argument order alignment with t_cose_crypto_hmac_compute_setup
enum t_cose_err_t
t_cose_crypto_hmac_validate_setup(struct t_cose_crypto_hmac *hmac_ctx,
const int32_t cose_alg_id,
struct t_cose_key validation_key)
{
return t_cose_crypto_hmac_compute_setup(hmac_ctx, validation_key, cose_alg_id);
}


/*
* See documentation in t_cose_crypto.h
*/
enum t_cose_err_t
t_cose_crypto_hmac_validate_finish(struct t_cose_crypto_hmac *hmac_ctx,
struct q_useful_buf_c input_tag)
{
Q_USEFUL_BUF_MAKE_STACK_UB( tag_buf, T_COSE_CRYPTO_HMAC_TAG_MAX_SIZE);
struct q_useful_buf_c computed_tag;
enum t_cose_err_t result;

result = t_cose_crypto_hmac_compute_finish(hmac_ctx, tag_buf, &computed_tag);
if(result != T_COSE_SUCCESS) {
return result;
}

if(q_useful_buf_compare(computed_tag, input_tag)) {
return T_COSE_ERR_HMAC_VERIFY;
}

return T_COSE_SUCCESS;
}


/*
* See documentation in t_cose_crypto.h
*/
Expand Down
110 changes: 34 additions & 76 deletions crypto_adapters/t_cose_psa_crypto.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -552,12 +552,12 @@ psa_status_to_t_cose_error_hmac(psa_status_t status)
* See documentation in t_cose_crypto.h
*/
enum t_cose_err_t
t_cose_crypto_hmac_compute_setup(struct t_cose_crypto_hmac *hmac_ctx,
struct t_cose_key signing_key,
const int32_t cose_alg_id)
t_cose_crypto_hmac_setup(struct t_cose_crypto_hmac *hmac_ctx,
struct t_cose_key signing_key,
const int32_t cose_alg_id)
{
psa_algorithm_t psa_alg;
psa_status_t psa_ret;
psa_status_t psa_ret;

/* Map the algorithm ID */
psa_alg = cose_hmac_alg_id_to_psa(cose_alg_id);
Expand All @@ -582,103 +582,61 @@ t_cose_crypto_hmac_compute_setup(struct t_cose_crypto_hmac *hmac_ctx,
(psa_key_id_t)signing_key.key.handle,
psa_alg);

hmac_ctx->status = PSA_SUCCESS;

return psa_status_to_t_cose_error_hmac(psa_ret);
}


/*
* See documentation in t_cose_crypto.h
*/
enum t_cose_err_t
void
t_cose_crypto_hmac_update(struct t_cose_crypto_hmac *hmac_ctx,
struct q_useful_buf_c payload)
{
psa_status_t psa_ret;

psa_ret = psa_mac_update(&hmac_ctx->op_ctx,
payload.ptr, payload.len);

return psa_status_to_t_cose_error_hmac(psa_ret);
}

/*
* See documentation in t_cose_crypto.h
*/
enum t_cose_err_t
t_cose_crypto_hmac_compute_finish(struct t_cose_crypto_hmac *hmac_ctx,
struct q_useful_buf tag_buf,
struct q_useful_buf_c *tag)
{
psa_status_t psa_ret;

psa_ret = psa_mac_sign_finish(&hmac_ctx->op_ctx,
tag_buf.ptr, tag_buf.len,
&(tag->len));
if(psa_ret == PSA_SUCCESS) {
tag->ptr = tag_buf.ptr;
if(hmac_ctx->status != PSA_SUCCESS) {
/* In error state. Nothing to do. */
return;
}

return psa_status_to_t_cose_error_hmac(psa_ret);
hmac_ctx->status = psa_mac_update(&hmac_ctx->op_ctx,
payload.ptr,
payload.len);
}


/*
* See documentation in t_cose_crypto.h
*/
enum t_cose_err_t
t_cose_crypto_hmac_validate_setup(struct t_cose_crypto_hmac *hmac_ctx,
const int32_t cose_alg_id,
struct t_cose_key validation_key)
t_cose_crypto_hmac_finish(struct t_cose_crypto_hmac *hmac_ctx,
struct q_useful_buf tag_buf,
struct q_useful_buf_c *tag)
{
psa_algorithm_t psa_alg;
psa_status_t psa_ret;

if(!hmac_ctx) {
return T_COSE_ERR_INVALID_ARGUMENT;
}

/* Map the algorithm ID */
psa_alg = cose_hmac_alg_id_to_psa(cose_alg_id);
if(!PSA_ALG_IS_MAC(psa_alg)) {
return T_COSE_ERR_UNSUPPORTED_HMAC_ALG;
}

/*
* Verify if HMAC algorithm is valid.
* According to COSE (RFC 9053), only SHA-256, SHA-384 and SHA-512 are
* supported in HMAC.
*/
if((psa_alg != PSA_ALG_HMAC(PSA_ALG_SHA_256)) &&
(psa_alg != PSA_ALG_HMAC(PSA_ALG_SHA_384)) &&
(psa_alg != PSA_ALG_HMAC(PSA_ALG_SHA_512))) {
return T_COSE_ERR_UNSUPPORTED_HMAC_ALG;
if(hmac_ctx->status != PSA_SUCCESS) {
/* Error state. Nothing to do */
goto done;
}

hmac_ctx->op_ctx = psa_mac_operation_init();
hmac_ctx->status = psa_mac_sign_finish(&hmac_ctx->op_ctx,
tag_buf.ptr,
tag_buf.len,
&(tag->len));
tag->ptr = tag_buf.ptr;

psa_ret = psa_mac_verify_setup(&hmac_ctx->op_ctx,
(psa_key_id_t)validation_key.key.handle,
psa_alg);

return psa_status_to_t_cose_error_hmac(psa_ret);
done:
return psa_status_to_t_cose_error_hmac(hmac_ctx->status);
}


/*
* See documentation in t_cose_crypto.h
/* The PSA API for MAC validation is not used because it results
* in larger code size overall and because OSSL doesn't have that
* API. There is no issue with a crypto service API that isolates
* the MAC key in an HSM or such by making this choice. It is still
* possible to to do. The MAC tag is a public value so it doesn't
* need to in the HSM.
*/
enum t_cose_err_t
t_cose_crypto_hmac_validate_finish(struct t_cose_crypto_hmac *hmac_ctx,
struct q_useful_buf_c tag)
{
psa_status_t psa_ret;

if(!hmac_ctx) {
return T_COSE_ERR_INVALID_ARGUMENT;
}

psa_ret = psa_mac_verify_finish(&hmac_ctx->op_ctx, tag.ptr, tag.len);

return psa_status_to_t_cose_error_hmac(psa_ret);
}


enum t_cose_err_t
Expand Down
36 changes: 7 additions & 29 deletions crypto_adapters/t_cose_test_crypto.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -301,57 +301,35 @@ t_cose_crypto_hash_finish(struct t_cose_crypto_hash *hash_ctx,


enum t_cose_err_t
t_cose_crypto_hmac_compute_setup(struct t_cose_crypto_hmac *hmac_ctx,
struct t_cose_key signing_key,
const int32_t cose_alg_id)
t_cose_crypto_hmac_setup(struct t_cose_crypto_hmac *hmac_ctx,
struct t_cose_key signing_key,
const int32_t cose_alg_id)
{
(void)hmac_ctx;
(void)signing_key;
(void)cose_alg_id;
return T_COSE_ERR_UNSUPPORTED_SIGNING_ALG;
}

enum t_cose_err_t
void
t_cose_crypto_hmac_update(struct t_cose_crypto_hmac *hmac_ctx,
struct q_useful_buf_c payload)
{
(void)hmac_ctx;
(void)payload;
return T_COSE_ERR_UNSUPPORTED_SIGNING_ALG;
}

enum t_cose_err_t
t_cose_crypto_hmac_compute_finish(struct t_cose_crypto_hmac *hmac_ctx,
struct q_useful_buf tag_buf,
struct q_useful_buf_c *tag)
t_cose_crypto_hmac_finish(struct t_cose_crypto_hmac *hmac_ctx,
struct q_useful_buf tag_buf,
struct q_useful_buf_c *tag)
{
(void)hmac_ctx;
(void)tag_buf;
(void)tag;
return T_COSE_ERR_UNSUPPORTED_SIGNING_ALG;
}

enum t_cose_err_t
t_cose_crypto_hmac_validate_setup(struct t_cose_crypto_hmac *hmac_ctx,
const int32_t cose_alg_id,
struct t_cose_key validation_key)
{
(void)hmac_ctx;
(void)cose_alg_id;
(void)validation_key;
return T_COSE_ERR_UNSUPPORTED_SIGNING_ALG;
}

enum t_cose_err_t
t_cose_crypto_hmac_validate_finish(struct t_cose_crypto_hmac *hmac_ctx,
struct q_useful_buf_c tag)
{
(void)hmac_ctx;
(void)tag;
return T_COSE_ERR_UNSUPPORTED_SIGNING_ALG;
}



/*
* See documentation in t_cose_crypto.h
Expand Down
14 changes: 0 additions & 14 deletions inc/t_cose/t_cose_common.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -250,20 +250,6 @@ enum t_cose_key_usage_flags {
};



/* Private value. Intentionally not documented for Doxygen.
* This is the size allocated for the encoded protected headers. It
* needs to be big enough for make_protected_header() to succeed. It
* currently sized for one header with an algorithm ID up to 32 bits
* long -- one byte for the wrapping map, one byte for the label, 5
* bytes for the ID. If this is made accidentially too small, QCBOR will
* only return an error, and not overrun any buffers.
*
* 9 extra bytes are added, rounding it up to 16 total, in case some
* other protected header is to be added.
*/
#define T_COSE_MAC0_MAX_SIZE_PROTECTED_PARAMETERS (1 + 1 + 5 + 9)

/* Six: an alg id, a kid, an iv, a content type, one custom, crit list
* or: 2 alg IDs, an IV, a kid, a supp_pub_info, one custom. If
* this is not enough use t_cose_encrypt_add_param_storage() or
Expand Down
4 changes: 1 addition & 3 deletions inc/t_cose/t_cose_mac_compute.h
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Original file line number Diff line number Diff line change
Expand Up @@ -23,12 +23,10 @@ extern "C" {
/**
* This is the context for creating a \c COSE_Mac structure. The caller
* should allocate it and pass it to the functions here. This is
* about 32 bytes so it fits easily on the stack.
* about 72 bytes so it fits easily on the stack.
*/
struct t_cose_mac_calculate_ctx {
/* Private data structure */
uint8_t protected_parameters_buffer[
T_COSE_MAC0_MAX_SIZE_PROTECTED_PARAMETERS];
struct q_useful_buf_c protected_parameters; /* The encoded protected parameters */
int32_t cose_algorithm_id;
struct t_cose_key mac_key;
Expand Down
2 changes: 2 additions & 0 deletions inc/t_cose/t_cose_standard_constants.h
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Original file line number Diff line number Diff line change
Expand Up @@ -742,4 +742,6 @@
*/
#define COSE_MAC_CONTEXT_STRING_MAC0 "MAC0"

#define COSE_MAC_CONTEXT_STRING_MAC "MAC"

#endif /* __T_COSE_STANDARD_CONSTANTS_H__ */
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