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7658c9bf0a
The call to memset_s() was supposed to replace the use of ZERO_ARRAY_LEN(), but somehow both lines have crept in. Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz> Reviewed-by: Andrew Bartlett <abartlet@samba.org>
231 lines
5.9 KiB
C
231 lines
5.9 KiB
C
/*
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Unix SMB/CIFS implementation.
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Wrapper for gnutls key derivation functions
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Copyright (C) Stefan Metzmacher 2009
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Copyright (C) Catalyst.Net Ltd 2023
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "includes.h"
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#include <gnutls/gnutls.h>
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#include <gnutls/crypto.h>
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#include "gnutls_helpers.h"
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static NTSTATUS samba_gnutls_sp800_108_derive_key_part(
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const gnutls_hmac_hd_t hmac_hnd,
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const uint8_t *FixedData,
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const size_t FixedData_len,
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const uint8_t *Label,
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const size_t Label_len,
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const uint8_t *Context,
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const size_t Context_len,
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const uint32_t L,
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const uint32_t i,
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uint8_t *digest)
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{
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uint8_t buf[4];
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static const uint8_t zero = 0;
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int rc;
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PUSH_BE_U32(buf, 0, i);
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rc = gnutls_hmac(hmac_hnd, buf, sizeof(buf));
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if (rc < 0) {
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return gnutls_error_to_ntstatus(rc,
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NT_STATUS_HMAC_NOT_SUPPORTED);
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}
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if (FixedData != NULL) {
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rc = gnutls_hmac(hmac_hnd, FixedData, FixedData_len);
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if (rc < 0) {
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return gnutls_error_to_ntstatus(
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rc, NT_STATUS_HMAC_NOT_SUPPORTED);
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}
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} else {
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rc = gnutls_hmac(hmac_hnd, Label, Label_len);
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if (rc < 0) {
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return gnutls_error_to_ntstatus(
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rc, NT_STATUS_HMAC_NOT_SUPPORTED);
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}
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rc = gnutls_hmac(hmac_hnd, &zero, 1);
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if (rc < 0) {
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return gnutls_error_to_ntstatus(
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rc, NT_STATUS_HMAC_NOT_SUPPORTED);
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}
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rc = gnutls_hmac(hmac_hnd, Context, Context_len);
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if (rc < 0) {
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return gnutls_error_to_ntstatus(
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rc, NT_STATUS_HMAC_NOT_SUPPORTED);
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}
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PUSH_BE_U32(buf, 0, L);
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rc = gnutls_hmac(hmac_hnd, buf, sizeof(buf));
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if (rc < 0) {
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return gnutls_error_to_ntstatus(
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rc, NT_STATUS_HMAC_NOT_SUPPORTED);
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}
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}
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gnutls_hmac_output(hmac_hnd, digest);
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return NT_STATUS_OK;
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}
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static size_t ceiling_div(const size_t a, const size_t b)
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{
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return a / b + (a % b != 0);
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}
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/**
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* @brief Derive a key using the NIST SP 800‐108 algorithm.
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*
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* The details of the algorithm can be found at
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* https://csrc.nist.gov/pubs/sp/800/108/r1/final.
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*
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* @param KI The key‐derivation key used as input.
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*
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* @param KI_len The length of the key‐derivation key.
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*
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* @param FixedData If non‐NULL, specifies fixed data to be used in place of
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* that constructed from the Label and Context parameters.
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*
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* @param FixedData_len The length of the fixed data, if it is present.
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*
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* @param Label A label that identifies the purpose for the derived key.
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* Ignored if FixedData is non‐NULL.
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*
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* @param Label_len The length of the label.
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*
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* @param Context Information related to the derived key. Ignored if
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* FixedData is non‐NULL.
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*
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* @param Context_len The length of the context data.
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*
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* @param algorithm The HMAC algorithm to use.
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*
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* @param KO A buffer to receive the derived key.
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*
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* @param KO_len The length of the key to be derived.
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*
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* @return NT_STATUS_OK on success, an NT status error code otherwise.
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*/
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NTSTATUS samba_gnutls_sp800_108_derive_key(
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const uint8_t *KI,
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size_t KI_len,
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const uint8_t *FixedData,
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size_t FixedData_len,
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const uint8_t *Label,
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size_t Label_len,
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const uint8_t *Context,
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size_t Context_len,
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const gnutls_mac_algorithm_t algorithm,
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uint8_t *KO,
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size_t KO_len)
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{
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gnutls_hmac_hd_t hmac_hnd = NULL;
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const size_t digest_len = gnutls_hmac_get_len(algorithm);
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uint32_t i;
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uint32_t L = KO_len * 8;
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size_t KO_idx;
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NTSTATUS status = NT_STATUS_OK;
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int rc;
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if (KO_len > UINT32_MAX / 8) {
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/* The calculation of L has overflowed. */
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return NT_STATUS_INTERNAL_ERROR;
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}
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if (digest_len == 0) {
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return NT_STATUS_HMAC_NOT_SUPPORTED;
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}
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{
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const size_t n_iterations = ceiling_div(KO_len, digest_len);
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/*
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* To ensure that the counter values are distinct, n shall not
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* be larger than 2ʳ−1, where r = 32. We have made sure that
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* |KO| × 8 < 2³², and we know that n ≤ |KO| from its
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* definition. Thus n ≤ |KO| ≤ |KO| × 8 < 2³², and so the
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* requirement n ≤ 2³² − 1 must always hold.
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*/
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SMB_ASSERT(n_iterations <= UINT32_MAX);
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}
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/*
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* a simplified version of
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* "NIST Special Publication 800-108" section 5.1.
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*/
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rc = gnutls_hmac_init(&hmac_hnd,
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algorithm,
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KI,
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KI_len);
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if (rc < 0) {
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return gnutls_error_to_ntstatus(rc,
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NT_STATUS_HMAC_NOT_SUPPORTED);
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}
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/* (This loop would make an excellent candidate for parallelization.) */
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for (KO_idx = 0, i = 1; KO_len - KO_idx >= digest_len;
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KO_idx += digest_len, ++i)
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{
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status = samba_gnutls_sp800_108_derive_key_part(hmac_hnd,
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FixedData,
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FixedData_len,
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Label,
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Label_len,
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Context,
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Context_len,
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L,
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i,
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KO + KO_idx);
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if (!NT_STATUS_IS_OK(status)) {
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goto out;
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}
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}
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if (KO_idx < KO_len) {
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/* Get the last little bit. */
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uint8_t digest[digest_len];
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status = samba_gnutls_sp800_108_derive_key_part(hmac_hnd,
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FixedData,
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FixedData_len,
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Label,
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Label_len,
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Context,
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Context_len,
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L,
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i,
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digest);
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if (!NT_STATUS_IS_OK(status)) {
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goto out;
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}
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memcpy(KO + KO_idx, digest, KO_len - KO_idx);
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ZERO_ARRAY(digest);
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}
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out:
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if (hmac_hnd != NULL) {
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gnutls_hmac_deinit(hmac_hnd, NULL);
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}
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if (!NT_STATUS_IS_OK(status)) {
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/* Hide the evidence. */
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memset_s(KO, KO_len, 0, KO_idx);
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}
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return status;
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}
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