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lib:crypto: Have samba_gnutls_sp800_108_derive_key() support various output key lengths

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Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
This commit is contained in:
Joseph Sutton 2023-11-29 12:44:10 +13:00 committed by Andrew Bartlett
parent 6b5ccd2508
commit cd1168a131
2 changed files with 62 additions and 24 deletions
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85
lib/crypto/gnutls_sp800_108.c
View File

@ -72,6 +72,11 @@ static NTSTATUS samba_gnutls_sp800_108_derive_key_part(
return NT_STATUS_OK;
}
static size_t ceiling_div(const size_t a, const size_t b)
{
return a / b + (a % b != 0);
}
/**
* @brief Derive a key using the NIST SP 800‐108 algorithm.
*
@ -113,24 +118,31 @@ NTSTATUS samba_gnutls_sp800_108_derive_key(
{
gnutls_hmac_hd_t hmac_hnd = NULL;
const size_t digest_len = gnutls_hmac_get_len(algorithm);
uint8_t digest[digest_len];
uint32_t i = 1;
uint32_t i;
uint32_t L = KO_len * 8;
size_t KO_idx;
NTSTATUS status = NT_STATUS_OK;
int rc;
if (KO_len > digest_len) {
DBG_ERR("KO_len[%zu] > digest_len[%zu]\n", KO_len, digest_len);
if (KO_len > UINT32_MAX / 8) {
/* The calculation of L has overflowed. */
return NT_STATUS_INTERNAL_ERROR;
}
switch (KO_len) {
case 16:
case 32:
break;
default:
DBG_ERR("KO_len[%zu] not supported\n", KO_len);
return NT_STATUS_INTERNAL_ERROR;
if (digest_len == 0) {
return NT_STATUS_HMAC_NOT_SUPPORTED;
}
{
const size_t n_iterations = ceiling_div(KO_len, digest_len);
/*
* To ensure that the counter values are distinct, n shall not
* be larger than 2ʳ−1, where r = 32. We have made sure that
* |KO| × 8 < 2³², and we know that n ≤ |KO| from its
* definition. Thus n ≤ |KO| ≤ |KO| × 8 < 2³², and so the
* requirement n ≤ 2³² − 1 must always hold.
*/
SMB_ASSERT(n_iterations <= UINT32_MAX);
}
/*
@ -146,26 +158,53 @@ NTSTATUS samba_gnutls_sp800_108_derive_key(
NT_STATUS_HMAC_NOT_SUPPORTED);
}
status = samba_gnutls_sp800_108_derive_key_part(hmac_hnd,
Label,
Label_len,
Context,
Context_len,
L,
i,
digest);
if (!NT_STATUS_IS_OK(status)) {
goto out;
/* (This loop would make an excellent candidate for parallelization.) */
for (KO_idx = 0, i = 1; KO_len - KO_idx >= digest_len;
KO_idx += digest_len, ++i)
{
status = samba_gnutls_sp800_108_derive_key_part(hmac_hnd,
Label,
Label_len,
Context,
Context_len,
L,
i,
KO + KO_idx);
if (!NT_STATUS_IS_OK(status)) {
goto out;
}
}
memcpy(KO, digest, KO_len);
if (KO_idx < KO_len) {
/* Get the last little bit. */
uint8_t digest[digest_len];
status = samba_gnutls_sp800_108_derive_key_part(hmac_hnd,
Label,
Label_len,
Context,
Context_len,
L,
i,
digest);
if (!NT_STATUS_IS_OK(status)) {
goto out;
}
ZERO_ARRAY(digest);
memcpy(KO + KO_idx, digest, KO_len - KO_idx);
ZERO_ARRAY(digest);
}
out:
if (hmac_hnd != NULL) {
gnutls_hmac_deinit(hmac_hnd, NULL);
}
if (!NT_STATUS_IS_OK(status)) {
/* Hide the evidence. */
memset_s(KO, KO_len, 0, KO_idx);
ZERO_ARRAY_LEN(KO, KO_idx);
}
return status;
}

1
selftest/knownfail.d/gnutls-sp800-108
View File

@ -1 +0,0 @@
^samba\.unittests\.test_gnutls_sp800_108\.test_sp800_108_sha512\(none\)$