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SSKDF with KMAC should return SIZE_MAX when EVP_KDF_CTX_get_kdf_size() 

is used.

Fixes #19934

The existing code was looking for the digest size, and then returned
zero.

The example code in EVP_KDF-SS.pod has been corrected to not use a
digest.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19935)
This commit is contained in:
slontis 2022-12-20 13:44:18 +10:00 committed by Tomas Mraz
parent 5adca946c3
commit e8add4d379
3 changed files with 33 additions and 11 deletions
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6
doc/man7/EVP_KDF-SS.pod
View File

@ -43,6 +43,8 @@ The supported parameters are:
=item "digest" (B<OSSL_KDF_PARAM_DIGEST>) <UTF8 string>
This parameter is ignored for KMAC.
=item "mac" (B<OSSL_KDF_PARAM_MAC>) <UTF8 string>
=item "maclen" (B<OSSL_KDF_PARAM_MAC_SIZE>) <unsigned integer>
@ -133,7 +135,7 @@ fixedinfo value "label", salt of "salt" and KMAC outlen of 20:
EVP_KDF *kdf;
EVP_KDF_CTX *kctx;
unsigned char out[10];
OSSL_PARAM params[7], *p = params;
OSSL_PARAM params[6], *p = params;
kdf = EVP_KDF_fetch(NULL, "SSKDF", NULL);
kctx = EVP_KDF_CTX_new(kdf);
@ -141,8 +143,6 @@ fixedinfo value "label", salt of "salt" and KMAC outlen of 20:
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC,
SN_kmac128, strlen(SN_kmac128));
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
SN_sha256, strlen(SN_sha256));
*p++ = OSSL_PARAM_construct_octet_string(EVP_KDF_CTRL_SET_KEY,
"secret", (size_t)6);
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,

25
providers/implementations/kdfs/sskdf.c
View File

@ -62,6 +62,7 @@ typedef struct {
unsigned char *salt;
size_t salt_len;
size_t out_len; /* optional KMAC parameter */
int is_kmac;
} KDF_SSKDF;
#define SSKDF_MAX_INLEN (1<<30)
@ -340,6 +341,7 @@ static void *sskdf_dup(void *vctx)
|| !ossl_prov_digest_copy(&dest->digest, &src->digest))
goto err;
dest->out_len = src->out_len;
dest->is_kmac = src->is_kmac;
}
return dest;
@ -361,8 +363,12 @@ static int sskdf_set_buffer(unsigned char **out, size_t *out_len,
static size_t sskdf_size(KDF_SSKDF *ctx)
{
int len;
const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
const EVP_MD *md = NULL;
if (ctx->is_kmac)
return SIZE_MAX;
md = ossl_prov_digest_md(&ctx->digest);
if (md == NULL) {
ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
return 0;
@ -402,8 +408,7 @@ static int sskdf_derive(void *vctx, unsigned char *key, size_t keylen,
default_salt_len = EVP_MD_get_size(md);
if (default_salt_len <= 0)
return 0;
} else if (EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC128)
|| EVP_MAC_is_a(mac, OSSL_MAC_NAME_KMAC256)) {
} else if (ctx->is_kmac) {
/* H(x) = KMACzzz(x, salt, custom) */
custom = kmac_custom_str;
custom_len = sizeof(kmac_custom_str);
@ -479,12 +484,20 @@ static int sskdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
if (params == NULL)
return 1;
if (!ossl_prov_digest_load_from_params(&ctx->digest, params, libctx))
return 0;
if (!ossl_prov_macctx_load_from_params(&ctx->macctx, params,
NULL, NULL, NULL, libctx))
return 0;
if (ctx->macctx != NULL) {
if (EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->macctx),
OSSL_MAC_NAME_KMAC128)
|| EVP_MAC_is_a(EVP_MAC_CTX_get0_mac(ctx->macctx),
OSSL_MAC_NAME_KMAC256)) {
ctx->is_kmac = 1;
}
}
if (!ossl_prov_digest_load_from_params(&ctx->digest, params, libctx))
return 0;
if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL
|| (p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL)

13
test/evp_kdf_test.c
View File

@ -1528,6 +1528,7 @@ static int test_kdf_kbkdf_kmac(void)
kctx = get_kdfbyname("KBKDF");
ret = TEST_ptr(kctx)
&& TEST_size_t_eq(EVP_KDF_CTX_get_kdf_size(kctx), SIZE_MAX)
&& TEST_int_gt(EVP_KDF_derive(kctx, result, sizeof(result), params), 0)
&& TEST_mem_eq(result, sizeof(result), output, sizeof(output));
@ -1580,7 +1581,7 @@ static int test_kdf_ss_kmac(void)
{
int ret;
EVP_KDF_CTX *kctx;
OSSL_PARAM params[6], *p = params;
OSSL_PARAM params[7], *p = params;
unsigned char out[64];
size_t mac_size = 20;
static unsigned char z[] = {
@ -1603,6 +1604,9 @@ static int test_kdf_ss_kmac(void)
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC,
(char *)OSSL_MAC_NAME_KMAC128, 0);
/* The digest parameter is not needed here and should be ignored */
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
(char *)"SHA256", 0);
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY, z, sizeof(z));
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO, other,
sizeof(other));
@ -1613,7 +1617,12 @@ static int test_kdf_ss_kmac(void)
ret =
TEST_ptr(kctx = get_kdfbyname(OSSL_KDF_NAME_SSKDF))
&& TEST_int_gt(EVP_KDF_derive(kctx, out, sizeof(out), params), 0)
&& TEST_size_t_eq(EVP_KDF_CTX_get_kdf_size(kctx), 0)
&& TEST_int_eq(EVP_KDF_CTX_set_params(kctx, params), 1)
/* The bug fix for KMAC returning SIZE_MAX was added in 3.0.8 */
&& (fips_provider_version_lt(NULL, 3, 0, 8)
|| TEST_size_t_eq(EVP_KDF_CTX_get_kdf_size(kctx), SIZE_MAX))
&& TEST_int_gt(EVP_KDF_derive(kctx, out, sizeof(out), NULL), 0)
&& TEST_mem_eq(out, sizeof(out), expected, sizeof(expected));
EVP_KDF_CTX_free(kctx);