aboutsummaryrefslogtreecommitdiff
path: root/modexp.c
diff options
context:
space:
mode:
Diffstat (limited to 'modexp.c')
-rw-r--r--modexp.c300
1 files changed, 198 insertions, 102 deletions
diff --git a/modexp.c b/modexp.c
index bad492b..37f5e0e 100644
--- a/modexp.c
+++ b/modexp.c
@@ -11,7 +11,7 @@
* enough that this module is no longer needed, it will go away.
*
* Authors: Rob Austein
- * Copyright (c) 2015, NORDUnet A/S
+ * Copyright (c) 2015-2017, NORDUnet A/S
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@@ -43,7 +43,6 @@
#include <stdio.h>
#include <stdint.h>
-#include <assert.h>
#include "hal.h"
#include "hal_internal.h"
@@ -60,173 +59,270 @@ void hal_modexp_set_debug(const int onoff)
}
/*
- * Check a result, report on failure if debugging, pass failures up
- * the chain.
+ * Get value of an ordinary register.
*/
-#define check(_expr_) \
- do { \
- hal_error_t _err = (_expr_); \
- if (_err != HAL_OK && debug) \
- printf("%s failed: %s\n", #_expr_, hal_error_string(_err)); \
- if (_err != HAL_OK) \
- return _err; \
- } while (0)
+static inline hal_error_t get_register(const hal_core_t *core,
+ const hal_addr_t addr,
+ uint32_t *value)
+{
+ hal_error_t err;
+ uint8_t w[4];
+
+ if (value == NULL)
+ return HAL_ERROR_IMPOSSIBLE;
+
+ if ((err = hal_io_read(core, addr, w, sizeof(w))) != HAL_OK)
+ return err;
+
+ *value = (w[0] << 0) | (w[1] << 8) | (w[2] << 16) | (w[3] << 24);
+
+ return HAL_OK;
+}
/*
- * Set an ordinary register.
+ * Set value of an ordinary register.
*/
-static hal_error_t set_register(const hal_core_t *core,
- const hal_addr_t addr,
- uint32_t value)
+static inline hal_error_t set_register(const hal_core_t *core,
+ const hal_addr_t addr,
+ const uint32_t value)
{
- uint8_t w[4];
- int i;
-
- for (i = 3; i >= 0; i--) {
- w[i] = value & 0xFF;
- value >>= 8;
- }
+ const uint8_t w[4] = {
+ ((value >> 24) & 0xFF),
+ ((value >> 16) & 0xFF),
+ ((value >> 8) & 0xFF),
+ ((value >> 0) & 0xFF)
+ };
return hal_io_write(core, addr, w, sizeof(w));
}
/*
* Get value of a data buffer. We reverse the order of 32-bit words
- * in the buffer during the transfer to match what the modexps6 core
+ * in the buffer during the transfer to match what the modexpa7 core
* expects.
*/
-static hal_error_t get_buffer(const hal_core_t *core,
- const hal_addr_t data_addr,
- uint8_t *value,
- const size_t length)
+static inline hal_error_t get_buffer(const hal_core_t *core,
+ const hal_addr_t data_addr,
+ uint8_t *value,
+ const size_t length)
{
+ hal_error_t err;
size_t i;
- assert(value != NULL && length % 4 == 0);
+ if (value == NULL || length % 4 != 0)
+ return HAL_ERROR_IMPOSSIBLE;
for (i = 0; i < length; i += 4)
- check(hal_io_read(core, data_addr + i/4, &value[length - 4 - i], 4));
+ if ((err = hal_io_read(core, data_addr + i/4, &value[length - 4 - i], 4)) != HAL_OK)
+ return err;
return HAL_OK;
}
/*
* Set value of a data buffer. We reverse the order of 32-bit words
- * in the buffer during the transfer to match what the modexps6 core
+ * in the buffer during the transfer to match what the modexpa7 core
* expects.
+ *
+ * Do we need to zero the portion of the buffer we're not using
+ * explictly (that is, the portion between `length` and the value of
+ * the core's MODEXPA7_ADDR_BUFFER_BITS register)? We've gotten away
+ * without doing this so far, but the core doesn't take an explicit
+ * length parameter for the message itself, instead it assumes that
+ * the message is either as long as or twice as long as the exponent,
+ * depending on the setting of the CRT mode bit. Maybe initializing
+ * the core clears the excess bits so there's no issue? Dunno. Have
+ * never seen a problem with this yet, just dont' know why not.
*/
-static hal_error_t set_buffer(const hal_core_t *core,
- const hal_addr_t data_addr,
- const uint8_t * const value,
- const size_t length)
+static inline hal_error_t set_buffer(const hal_core_t *core,
+ const hal_addr_t data_addr,
+ const uint8_t * const value,
+ const size_t length)
{
+ hal_error_t err;
size_t i;
- assert(value != NULL && length % 4 == 0);
+ if (value == NULL || length % 4 != 0)
+ return HAL_ERROR_IMPOSSIBLE;
for (i = 0; i < length; i += 4)
- check(hal_io_write(core, data_addr + i/4, &value[length - 4 - i], 4));
+ if ((err = hal_io_write(core, data_addr + i/4, &value[length - 4 - i], 4)) != HAL_OK)
+ return err;
return HAL_OK;
}
/*
- * Run one modexp operation.
+ * Stuff moved out of modexp so we can run two cores in parallel more
+ * easily. We have to return to the jacket routine every time we kick
+ * a core into doing something, since only the jacket routines know
+ * how many cores we're running for any particular calculation.
+ *
+ * In theory we could do something clever where we don't wait for both
+ * cores to finish precalc before starting either of them on the main
+ * computation, but that way probably lies madness.
*/
-hal_error_t hal_modexp(hal_core_t *core,
- const uint8_t * const msg, const size_t msg_len, /* Message */
- const uint8_t * const exp, const size_t exp_len, /* Exponent */
- const uint8_t * const mod, const size_t mod_len, /* Modulus */
- uint8_t *result, const size_t result_len)
+static inline hal_error_t check_args(hal_modexp_arg_t *a)
+{
+ /*
+ * All data pointers must be set, exponent may not be longer than
+ * modulus, message may not be longer than twice the modulus (CRT
+ * mode), result buffer must not be shorter than modulus, and all
+ * input lengths must be a multiple of four bytes (the core is all
+ * about 32-bit words).
+ */
+
+ if (a == NULL ||
+ a->msg == NULL || a->msg_len > MODEXPA7_OPERAND_BYTES || a->msg_len > a->mod_len * 2 ||
+ a->exp == NULL || a->exp_len > MODEXPA7_OPERAND_BYTES || a->exp_len > a->mod_len ||
+ a->mod == NULL || a->mod_len > MODEXPA7_OPERAND_BYTES ||
+ a->result == NULL || a->result_len > MODEXPA7_OPERAND_BYTES || a->result_len < a->mod_len ||
+ a->coeff == NULL || a->coeff_len > MODEXPA7_OPERAND_BYTES ||
+ a->mont == NULL || a->mont_len > MODEXPA7_OPERAND_BYTES ||
+ ((a->msg_len | a->exp_len | a->mod_len) & 3) != 0)
+ return HAL_ERROR_BAD_ARGUMENTS;
+
+ return HAL_OK;
+}
+
+static inline hal_error_t setup_precalc(const int precalc, hal_modexp_arg_t *a)
{
hal_error_t err;
/*
- * All pointers must be set, neither message nor exponent may be
- * longer than modulus, result buffer must not be shorter than
- * modulus, and all input lengths must be a multiple of four.
- *
- * The multiple-of-four restriction is a pain, but the rest of the
- * HAL code currently enforces the same restriction, and allowing
- * arbitrary lengths would require some tedious shuffling to deal
- * with alignment issues, so it's not worth trying to fix only here.
+ * Check that operand size is compatabible with the core.
*/
- if (msg == NULL || exp == NULL || mod == NULL || result == NULL ||
- msg_len > mod_len || exp_len > mod_len || result_len < mod_len ||
- ((msg_len | exp_len | mod_len) & 3) != 0)
+ uint32_t operand_max = 0;
+
+ if ((err = get_register(a->core, MODEXPA7_ADDR_BUFFER_BITS, &operand_max)) != HAL_OK)
+ return err;
+
+ operand_max /= 8;
+
+ if (a->msg_len > operand_max ||
+ a->exp_len > operand_max ||
+ a->mod_len > operand_max ||
+ a->coeff_len > operand_max ||
+ a->mont_len > operand_max)
return HAL_ERROR_BAD_ARGUMENTS;
- if (((err = hal_core_alloc(MODEXPS6_NAME, &core)) == HAL_ERROR_CORE_NOT_FOUND) &&
- ((err = hal_core_alloc(MODEXPA7_NAME, &core)) != HAL_OK))
+ /*
+ * Set the modulus, then initiate calculation of modulus-dependent
+ * speedup factors if necessary, by edge-triggering the "init" bit,
+ * then return to caller so it can wait for precalc.
+ */
+
+ if ((err = set_register(a->core, MODEXPA7_ADDR_MODULUS_BITS, a->mod_len * 8)) != HAL_OK ||
+ (err = set_buffer(a->core, MODEXPA7_ADDR_MODULUS, a->mod, a->mod_len)) != HAL_OK ||
+ (precalc && (err = hal_io_zero(a->core)) != HAL_OK) ||
+ (precalc && (err = hal_io_init(a->core)) != HAL_OK))
return err;
-#undef check
-#define check(_expr_) \
- do { \
- hal_error_t _err = (_expr_); \
- if (_err != HAL_OK && debug) \
- printf("%s failed: %s\n", #_expr_, hal_error_string(_err)); \
- if (_err != HAL_OK) { \
- hal_core_free(core); \
- return _err; \
- } \
- } while (0)
+ return HAL_OK;
+}
+
+static inline hal_error_t setup_calc(const int precalc, hal_modexp_arg_t *a)
+{
+ hal_error_t err;
/*
- * We probably ought to take the mode (fast vs constant-time) as an
- * argument, but for the moment we just guess that really short
- * exponent means we're using the public key and can use fast mode,
- * all other cases are something to do with the private key and
- * therefore must use constant-time mode.
- *
- * Unclear whether it's worth trying to figure out exactly how long
- * the operands are: assuming a multiple of eight is safe, but makes
- * a bit more work for the core; checking to see how many bits are
- * really set leaves the core sitting idle while the main CPU does
- * these checks. No way to know which is faster without testing;
- * take simple approach for the moment.
+ * Select CRT mode if and only if message is longer than exponent.
*/
- /* Select mode (1 = fast, 0 = safe) */
- check(set_register(core, MODEXPS6_ADDR_MODE, (exp_len <= 4)));
+ const uint32_t mode = a->msg_len > a->mod_len ? MODEXPA7_MODE_CRT : MODEXPA7_MODE_PLAIN;
- /* Set modulus size in bits */
- check(set_register(core, MODEXPS6_ADDR_MODULUS_WIDTH, mod_len * 8));
+ /*
+ * Copy out precalc results if necessary, then load everything and
+ * start the calculation by edge-triggering the "next" bit. If
+ * everything works, return to caller so it can wait for the
+ * calculation to complete.
+ */
- /* Write new modulus */
- check(set_buffer(core, MODEXPS6_ADDR_MODULUS, mod, mod_len));
+ if ((precalc &&
+ (err = get_buffer(a->core, MODEXPA7_ADDR_MODULUS_COEFF_OUT, a->coeff, a->coeff_len)) != HAL_OK) ||
+ (precalc &&
+ (err = get_buffer(a->core, MODEXPA7_ADDR_MONTGOMERY_FACTOR_OUT, a->mont, a->mont_len)) != HAL_OK) ||
+ (err = set_buffer(a->core, MODEXPA7_ADDR_MODULUS_COEFF_IN, a->coeff, a->coeff_len)) != HAL_OK ||
+ (err = set_buffer(a->core, MODEXPA7_ADDR_MONTGOMERY_FACTOR_IN, a->mont, a->mont_len)) != HAL_OK ||
+ (err = set_register(a->core, MODEXPA7_ADDR_MODE, mode)) != HAL_OK ||
+ (err = set_buffer(a->core, MODEXPA7_ADDR_MESSAGE, a->msg, a->msg_len)) != HAL_OK ||
+ (err = set_buffer(a->core, MODEXPA7_ADDR_EXPONENT, a->exp, a->exp_len)) != HAL_OK ||
+ (err = set_register(a->core, MODEXPA7_ADDR_EXPONENT_BITS, a->exp_len * 8)) != HAL_OK ||
+ (err = hal_io_zero(a->core)) != HAL_OK ||
+ (err = hal_io_next(a->core)) != HAL_OK)
+ return err;
- /* Pre-calcuate speed-up coefficient */
- check(hal_io_init(core));
+ return HAL_OK;
+}
- /* Wait for calculation to complete */
- check(hal_io_wait_ready(core));
+static inline hal_error_t extract_result(hal_modexp_arg_t *a)
+{
+ /*
+ * Extract results from the main calculation and we're done.
+ * Hardly seems worth making this a separate function.
+ */
- /* Write new message */
- check(set_buffer(core, MODEXPS6_ADDR_MESSAGE, msg, msg_len));
+ return get_buffer(a->core, MODEXPA7_ADDR_RESULT, a->result, a->mod_len);
+}
- /* Set new exponent length in bits */
- check(set_register(core, MODEXPS6_ADDR_EXPONENT_WIDTH, exp_len * 8));
+/*
+ * Run one modexp operation.
+ */
- /* Set new exponent */
- check(set_buffer(core, MODEXPS6_ADDR_EXPONENT, exp, exp_len));
+hal_error_t hal_modexp(const int precalc, hal_modexp_arg_t *a)
+{
+ hal_error_t err;
- /* Start calculation */
- check(hal_io_next(core));
+ if ((err = check_args(a)) != HAL_OK)
+ return err;
- /* Wait for result */
- check(hal_io_wait_valid(core));
+ if ((err = hal_core_alloc(MODEXPA7_NAME, &a->core)) == HAL_OK &&
+ (err = setup_precalc(precalc, a)) == HAL_OK &&
+ (!precalc ||
+ (err = hal_io_wait_ready(a->core)) == HAL_OK) &&
+ (err = setup_calc(precalc, a)) == HAL_OK &&
+ (err = hal_io_wait_valid(a->core)) == HAL_OK &&
+ (err = extract_result(a)) == HAL_OK)
+ err = HAL_OK;
+
+ hal_core_free(a->core);
+ return err;
+}
- /* Extract result */
- check(get_buffer(core, MODEXPS6_ADDR_RESULT, result, mod_len));
+/*
+ * Run two modexp operations in parallel.
+ */
- return HAL_OK;
+hal_error_t hal_modexp2(const int precalc, hal_modexp_arg_t *a1, hal_modexp_arg_t *a2)
+{
+ hal_error_t err;
+
+ if ((err = check_args(a1)) != HAL_OK ||
+ (err = check_args(a2)) != HAL_OK)
+ return err;
+
+ if ((err = hal_core_alloc2(MODEXPA7_NAME, &a1->core,
+ MODEXPA7_NAME, &a2->core)) == HAL_OK &&
+ (err = setup_precalc(precalc, a1)) == HAL_OK &&
+ (err = setup_precalc(precalc, a2)) == HAL_OK &&
+ (!precalc ||
+ (err = hal_io_wait_ready2(a1->core, a2->core)) == HAL_OK) &&
+ (err = setup_calc(precalc, a1)) == HAL_OK &&
+ (err = setup_calc(precalc, a2)) == HAL_OK &&
+ (err = hal_io_wait_valid2(a1->core, a2->core)) == HAL_OK &&
+ (err = extract_result(a1)) == HAL_OK &&
+ (err = extract_result(a2)) == HAL_OK)
+ err = HAL_OK;
+
+ hal_core_free(a1->core);
+ hal_core_free(a2->core);
+ return err;
}
/*