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Diffstat (limited to 'aes_keywrap.c')
-rw-r--r--aes_keywrap.c176
1 files changed, 141 insertions, 35 deletions
diff --git a/aes_keywrap.c b/aes_keywrap.c
index 144ad68..b849304 100644
--- a/aes_keywrap.c
+++ b/aes_keywrap.c
@@ -4,8 +4,9 @@
* Implementation of RFC 5649 over Cryptech AES core.
*
* Authors: Rob Austein
- * Copyright (c) 2015-2017, NORDUnet A/S
- * All rights reserved.
+ * Copyright (c) 2015-2018, NORDUnet A/S All rights reserved.
+ * Copyright: 2020, The Commons Conservancy Cryptech Project
+ * SPDX-License-Identifier: BSD-3-Clause
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
@@ -17,9 +18,9 @@
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
- * - Neither the name of the NORDUnet nor the names of its contributors may
- * be used to endorse or promote products derived from this software
- * without specific prior written permission.
+ * - Neither the name of the copyright holder nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
@@ -50,7 +51,21 @@
#include "hal_internal.h"
/*
+ * Enable use of the experimental keywrap core, if present.
+ */
+
+static int use_keywrap_core = 0;
+
+int hal_aes_use_keywrap_core(int onoff)
+{
+ use_keywrap_core = (onoff && hal_core_find(KEYWRAP_NAME, NULL) != NULL);
+ return use_keywrap_core;
+}
+
+
+/*
* How long the ciphertext will be for a given plaintext length.
+ * This rounds up the length to a multiple of 8, and adds 8 for the IV.
*/
size_t hal_aes_keywrap_ciphertext_length(const size_t plaintext_length)
@@ -62,6 +77,8 @@ size_t hal_aes_keywrap_ciphertext_length(const size_t plaintext_length)
/*
* Check the KEK, then load it into the AES core.
* Note that our AES core only supports 128 and 256 bit keys.
+ *
+ * This should work without modification for the experimental keywrap core.
*/
typedef enum { KEK_encrypting, KEK_decrypting } kek_action_t;
@@ -114,6 +131,57 @@ static hal_error_t load_kek(const hal_core_t *core, const uint8_t *K, const size
/*
+ * Use the experimental keywrap core to wrap/unwrap n 64-bit blocks of plaintext.
+ * The wrapped/unwrapped key is returned in the same buffer.
+ */
+
+static hal_error_t do_keywrap_core(const hal_core_t *core, uint8_t * const C, const size_t n)
+{
+#ifndef min
+#define min(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
+ hal_error_t err;
+
+ hal_assert(core != NULL && C != NULL && n > 0);
+
+ /* n is the number of 64-bit (8-byte) blocks in the input.
+ * KEYWRAP_LEN_R_DATA is the number of 4-byte data registers in the core.
+ */
+ if (n == 0 || n > KEYWRAP_LEN_R_DATA * 2)
+ return HAL_ERROR_BAD_ARGUMENTS;
+
+ /* write the AIV to A */
+ if ((err = hal_io_write(core, KEYWRAP_ADDR_A0, C, 8)) != HAL_OK)
+ return err;
+
+ /* write the length to RLEN */
+ uint32_t nn = htonl(n);
+ if ((err = hal_io_write(core, KEYWRAP_ADDR_RLEN, (const uint8_t *)&nn, 4)) != HAL_OK)
+ return err;
+
+ /* write the data to R_DATA */
+ if ((err = hal_io_write(core, KEYWRAP_ADDR_R_DATA, C + 8, 8 * n)) != HAL_OK)
+ return err;
+
+ /* start the wrap/unwrap operation, and wait for it to complete */
+ if ((err = hal_io_next(core)) != HAL_OK ||
+ (err = hal_io_wait_ready(core)) != HAL_OK)
+ return err;
+
+ /* read the A registers */
+ if ((err = hal_io_read(core, KEYWRAP_ADDR_A0, C, 8)) != HAL_OK)
+ return err;
+
+ /* read the data to R_DATA */
+ if ((err = hal_io_read(core, KEYWRAP_ADDR_R_DATA, C + 8, 8 * n)) != HAL_OK)
+ return err;
+
+ return HAL_OK;
+}
+
+
+/*
* Process one block. Since AES Key Wrap always deals with 64-bit
* half blocks and since the bus is going to break this up into 32-bit
* words no matter what we do, we can eliminate a few gratuitous
@@ -163,7 +231,7 @@ hal_error_t hal_aes_keywrap(hal_core_t *core,
size_t *C_len)
{
const size_t calculated_C_len = hal_aes_keywrap_ciphertext_length(m);
- const int free_core = core == NULL;
+ const int free_core = (core == NULL);
hal_error_t err;
size_t n;
@@ -172,8 +240,22 @@ hal_error_t hal_aes_keywrap(hal_core_t *core,
if (Q == NULL || C == NULL || C_len == NULL || *C_len < calculated_C_len)
return HAL_ERROR_BAD_ARGUMENTS;
- if (free_core && (err = hal_core_alloc(AES_CORE_NAME, &core, NULL)) != HAL_OK)
- return err;
+ /* If we're passed a core, we should figure out which one it is.
+ * In practice, core is always NULL, so this is UNTESTED CODE.
+ */
+ if (core) {
+ const hal_core_info_t *info = hal_core_info(core);
+ if (memcmp(info->name, KEYWRAP_NAME, 8) == 0)
+ use_keywrap_core = 1;
+ else if (memcmp(info->name, AES_CORE_NAME, 8) != 0)
+ /* I have no idea what this is */
+ return HAL_ERROR_BAD_ARGUMENTS;
+ }
+ else {
+ const char *core_name = (use_keywrap_core ? KEYWRAP_NAME : AES_CORE_NAME);
+ if ((err = hal_core_alloc(core_name, &core, NULL)) != HAL_OK)
+ return err;
+ }
if ((err = load_kek(core, K, K_len, KEK_encrypting)) != HAL_OK)
goto out;
@@ -195,21 +277,26 @@ hal_error_t hal_aes_keywrap(hal_core_t *core,
n = calculated_C_len/8 - 1;
- if (n == 1) {
- if ((err = do_block(core, C, C + 8)) != HAL_OK)
- goto out;
+ if (use_keywrap_core) {
+ err = do_keywrap_core(core, C, n);
}
-
else {
- for (size_t j = 0; j <= 5; j++) {
- for (size_t i = 1; i <= n; i++) {
- uint32_t t = n * j + i;
- if ((err = do_block(core, C, C + i * 8)) != HAL_OK)
+ if (n == 1) {
+ if ((err = do_block(core, C, C + 8)) != HAL_OK)
+ goto out;
+ }
+
+ else {
+ for (size_t j = 0; j <= 5; j++) {
+ for (size_t i = 1; i <= n; i++) {
+ uint32_t t = n * j + i;
+ if ((err = do_block(core, C, C + i * 8)) != HAL_OK)
goto out;
- C[7] ^= t & 0xFF; t >>= 8;
- C[6] ^= t & 0xFF; t >>= 8;
- C[5] ^= t & 0xFF; t >>= 8;
- C[4] ^= t & 0xFF;
+ C[7] ^= t & 0xFF; t >>= 8;
+ C[6] ^= t & 0xFF; t >>= 8;
+ C[5] ^= t & 0xFF; t >>= 8;
+ C[4] ^= t & 0xFF;
+ }
}
}
}
@@ -242,8 +329,22 @@ hal_error_t hal_aes_keyunwrap(hal_core_t *core,
if (C == NULL || Q == NULL || C_len % 8 != 0 || C_len < 16 || Q_len == NULL || *Q_len < C_len)
return HAL_ERROR_BAD_ARGUMENTS;
- if (free_core && (err = hal_core_alloc(AES_CORE_NAME, &core, NULL)) != HAL_OK)
- return err;
+ /* If we're passed a core, we should figure out which one it is.
+ * In practice, core is always NULL, so this is UNTESTED CODE.
+ */
+ if (core) {
+ const hal_core_info_t *info = hal_core_info(core);
+ if (memcmp(info->name, KEYWRAP_NAME, 8) == 0)
+ use_keywrap_core = 1;
+ else if (memcmp(info->name, AES_CORE_NAME, 8) != 0)
+ /* I have no idea what this is */
+ return HAL_ERROR_BAD_ARGUMENTS;
+ }
+ else {
+ const char *core_name = (use_keywrap_core ? KEYWRAP_NAME : AES_CORE_NAME);
+ if ((err = hal_core_alloc(core_name, &core, NULL)) != HAL_OK)
+ return err;
+ }
if ((err = load_kek(core, K, K_len, KEK_decrypting)) != HAL_OK)
goto out;
@@ -253,21 +354,26 @@ hal_error_t hal_aes_keyunwrap(hal_core_t *core,
if (Q != C)
memmove(Q, C, C_len);
- if (n == 1) {
- if ((err = do_block(core, Q, Q + 8)) != HAL_OK)
- goto out;
+ if (use_keywrap_core) {
+ err = do_keywrap_core(core, Q, n);
}
-
else {
- for (long j = 5; j >= 0; j--) {
- for (size_t i = n; i >= 1; i--) {
- uint32_t t = n * j + i;
- Q[7] ^= t & 0xFF; t >>= 8;
- Q[6] ^= t & 0xFF; t >>= 8;
- Q[5] ^= t & 0xFF; t >>= 8;
- Q[4] ^= t & 0xFF;
- if ((err = do_block(core, Q, Q + i * 8)) != HAL_OK)
- goto out;
+ if (n == 1) {
+ if ((err = do_block(core, Q, Q + 8)) != HAL_OK)
+ goto out;
+ }
+
+ else {
+ for (long j = 5; j >= 0; j--) {
+ for (size_t i = n; i >= 1; i--) {
+ uint32_t t = n * j + i;
+ Q[7] ^= t & 0xFF; t >>= 8;
+ Q[6] ^= t & 0xFF; t >>= 8;
+ Q[5] ^= t & 0xFF; t >>= 8;
+ Q[4] ^= t & 0xFF;
+ if ((err = do_block(core, Q, Q + i * 8)) != HAL_OK)
+ goto out;
+ }
}
}
}