crypto: add RSA support
Taken from U-Boot and adopted to barebox with little changes. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Sascha Hauer
parent
fedba5aaef
commit
6e686491a5
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@ -87,6 +87,9 @@ config CRYPTO_PBKDF2
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select DIGEST_SHA1_GENERIC
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bool
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config CRYPTO_RSA
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bool
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config CRYPTO_KEYSTORE
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bool "Keystore"
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help
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@ -11,4 +11,5 @@ obj-$(CONFIG_DIGEST_SHA384_GENERIC) += sha4.o
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obj-$(CONFIG_DIGEST_SHA512_GENERIC) += sha4.o
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obj-$(CONFIG_CRYPTO_PBKDF2) += pbkdf2.o
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obj-$(CONFIG_CRYPTO_RSA) += rsa.o
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obj-$(CONFIG_CRYPTO_KEYSTORE) += keystore.o
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@ -0,0 +1,422 @@
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/*
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* Copyright (c) 2013, Google Inc.
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*
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* This code is ported from U-Boot code.
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <common.h>
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#include <malloc.h>
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#include <of.h>
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#include <digest.h>
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#include <asm/types.h>
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#include <asm/byteorder.h>
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#include <errno.h>
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#include <rsa.h>
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#include <asm/types.h>
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#include <asm/unaligned.h>
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#define UINT64_MULT32(v, multby) (((uint64_t)(v)) * ((uint32_t)(multby)))
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#define get_unaligned_be32(a) fdt32_to_cpu(*(uint32_t *)a)
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#define put_unaligned_be32(a, b) (*(uint32_t *)(b) = cpu_to_fdt32(a))
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/* Default public exponent for backward compatibility */
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#define RSA_DEFAULT_PUBEXP 65537
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/* This is the minimum/maximum key size we support, in bits */
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#define RSA_MIN_KEY_BITS 1024
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#define RSA_MAX_KEY_BITS 4096
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/**
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* subtract_modulus() - subtract modulus from the given value
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*
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* @key: Key containing modulus to subtract
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* @num: Number to subtract modulus from, as little endian word array
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*/
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static void subtract_modulus(const struct rsa_public_key *key, uint32_t num[])
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{
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int64_t acc = 0;
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uint i;
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for (i = 0; i < key->len; i++) {
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acc += (uint64_t)num[i] - key->modulus[i];
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num[i] = (uint32_t)acc;
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acc >>= 32;
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}
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}
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/**
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* greater_equal_modulus() - check if a value is >= modulus
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*
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* @key: Key containing modulus to check
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* @num: Number to check against modulus, as little endian word array
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* @return 0 if num < modulus, 1 if num >= modulus
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*/
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static int greater_equal_modulus(const struct rsa_public_key *key,
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uint32_t num[])
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{
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int i;
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for (i = (int)key->len - 1; i >= 0; i--) {
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if (num[i] < key->modulus[i])
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return 0;
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if (num[i] > key->modulus[i])
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return 1;
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}
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return 1; /* equal */
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}
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/**
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* montgomery_mul_add_step() - Perform montgomery multiply-add step
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*
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* Operation: montgomery result[] += a * b[] / n0inv % modulus
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*
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* @key: RSA key
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* @result: Place to put result, as little endian word array
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* @a: Multiplier
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* @b: Multiplicand, as little endian word array
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*/
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static void montgomery_mul_add_step(const struct rsa_public_key *key,
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uint32_t result[], const uint32_t a, const uint32_t b[])
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{
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uint64_t acc_a, acc_b;
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uint32_t d0;
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uint i;
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acc_a = (uint64_t)a * b[0] + result[0];
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d0 = (uint32_t)acc_a * key->n0inv;
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acc_b = (uint64_t)d0 * key->modulus[0] + (uint32_t)acc_a;
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for (i = 1; i < key->len; i++) {
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acc_a = (acc_a >> 32) + (uint64_t)a * b[i] + result[i];
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acc_b = (acc_b >> 32) + (uint64_t)d0 * key->modulus[i] +
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(uint32_t)acc_a;
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result[i - 1] = (uint32_t)acc_b;
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}
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acc_a = (acc_a >> 32) + (acc_b >> 32);
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result[i - 1] = (uint32_t)acc_a;
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if (acc_a >> 32)
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subtract_modulus(key, result);
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}
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/**
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* montgomery_mul() - Perform montgomery mutitply
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*
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* Operation: montgomery result[] = a[] * b[] / n0inv % modulus
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*
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* @key: RSA key
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* @result: Place to put result, as little endian word array
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* @a: Multiplier, as little endian word array
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* @b: Multiplicand, as little endian word array
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*/
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static void montgomery_mul(const struct rsa_public_key *key,
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uint32_t result[], uint32_t a[], const uint32_t b[])
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{
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uint i;
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for (i = 0; i < key->len; ++i)
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result[i] = 0;
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for (i = 0; i < key->len; ++i)
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montgomery_mul_add_step(key, result, a[i], b);
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}
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/**
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* num_pub_exponent_bits() - Number of bits in the public exponent
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*
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* @key: RSA key
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* @num_bits: Storage for the number of public exponent bits
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*/
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static int num_public_exponent_bits(const struct rsa_public_key *key,
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int *num_bits)
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{
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uint64_t exponent;
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int exponent_bits;
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const uint max_bits = (sizeof(exponent) * 8);
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exponent = key->exponent;
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exponent_bits = 0;
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if (!exponent) {
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*num_bits = exponent_bits;
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return 0;
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}
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for (exponent_bits = 1; exponent_bits < max_bits + 1; ++exponent_bits)
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if (!(exponent >>= 1)) {
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*num_bits = exponent_bits;
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return 0;
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}
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return -EINVAL;
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}
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/**
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* is_public_exponent_bit_set() - Check if a bit in the public exponent is set
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*
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* @key: RSA key
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* @pos: The bit position to check
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*/
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static int is_public_exponent_bit_set(const struct rsa_public_key *key,
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int pos)
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{
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return key->exponent & (1ULL << pos);
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}
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/**
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* pow_mod() - in-place public exponentiation
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*
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* @key: RSA key
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* @inout: Big-endian word array containing value and result
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*/
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static int pow_mod(const struct rsa_public_key *key, void *__inout)
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{
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uint32_t *inout = __inout;
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uint32_t *result, *ptr;
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uint i;
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int j, k;
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uint32_t val[RSA_MAX_KEY_BITS / 32], acc[RSA_MAX_KEY_BITS / 32], tmp[RSA_MAX_KEY_BITS / 32];
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uint32_t a_scaled[RSA_MAX_KEY_BITS / 32];
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/* Sanity check for stack size - key->len is in 32-bit words */
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if (key->len > RSA_MAX_KEY_BITS / 32) {
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debug("RSA key words %u exceeds maximum %d\n", key->len,
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RSA_MAX_KEY_BITS / 32);
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return -EINVAL;
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}
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result = tmp; /* Re-use location. */
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/* Convert from big endian byte array to little endian word array. */
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for (i = 0, ptr = inout + key->len - 1; i < key->len; i++, ptr--)
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val[i] = get_unaligned_be32(ptr);
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if (0 != num_public_exponent_bits(key, &k))
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return -EINVAL;
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if (k < 2) {
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debug("Public exponent is too short (%d bits, minimum 2)\n",
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k);
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return -EINVAL;
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}
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if (!is_public_exponent_bit_set(key, 0)) {
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debug("LSB of RSA public exponent must be set.\n");
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return -EINVAL;
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}
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/* the bit at e[k-1] is 1 by definition, so start with: C := M */
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montgomery_mul(key, acc, val, key->rr); /* acc = a * RR / R mod n */
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/* retain scaled version for intermediate use */
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memcpy(a_scaled, acc, key->len * sizeof(a_scaled[0]));
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for (j = k - 2; j > 0; --j) {
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montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */
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if (is_public_exponent_bit_set(key, j)) {
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/* acc = tmp * val / R mod n */
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montgomery_mul(key, acc, tmp, a_scaled);
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} else {
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/* e[j] == 0, copy tmp back to acc for next operation */
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memcpy(acc, tmp, key->len * sizeof(acc[0]));
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}
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}
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/* the bit at e[0] is always 1 */
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montgomery_mul(key, tmp, acc, acc); /* tmp = acc^2 / R mod n */
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montgomery_mul(key, acc, tmp, val); /* acc = tmp * a / R mod M */
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memcpy(result, acc, key->len * sizeof(result[0]));
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/* Make sure result < mod; result is at most 1x mod too large. */
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if (greater_equal_modulus(key, result))
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subtract_modulus(key, result);
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/* Convert to bigendian byte array */
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for (i = key->len - 1, ptr = inout; (int)i >= 0; i--, ptr++)
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put_unaligned_be32(result[i], ptr);
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return 0;
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}
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/*
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* Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
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*/
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static const u8 RSA_digest_info_MD5[] = {
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0x30, 0x20, 0x30, 0x0C, 0x06, 0x08,
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0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x02, 0x05, /* OID */
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0x05, 0x00, 0x04, 0x10
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};
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static const u8 RSA_digest_info_SHA1[] = {
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0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
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0x2B, 0x0E, 0x03, 0x02, 0x1A,
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0x05, 0x00, 0x04, 0x14
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};
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static const u8 RSA_digest_info_RIPE_MD_160[] = {
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0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
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0x2B, 0x24, 0x03, 0x02, 0x01,
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0x05, 0x00, 0x04, 0x14
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};
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static const u8 RSA_digest_info_SHA224[] = {
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0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
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0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
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0x05, 0x00, 0x04, 0x1C
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};
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static const u8 RSA_digest_info_SHA256[] = {
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0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
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0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
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0x05, 0x00, 0x04, 0x20
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};
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static const u8 RSA_digest_info_SHA384[] = {
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0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
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0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
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0x05, 0x00, 0x04, 0x30
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};
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static const u8 RSA_digest_info_SHA512[] = {
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0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
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0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
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0x05, 0x00, 0x04, 0x40
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};
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static const struct {
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const u8 *data;
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size_t size;
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} RSA_ASN1_templates[] = {
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#define _(X) { RSA_digest_info_##X, sizeof(RSA_digest_info_##X) }
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[HASH_ALGO_MD5] = _(MD5),
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[HASH_ALGO_SHA1] = _(SHA1),
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[HASH_ALGO_RIPE_MD_160] = _(RIPE_MD_160),
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[HASH_ALGO_SHA256] = _(SHA256),
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[HASH_ALGO_SHA384] = _(SHA384),
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[HASH_ALGO_SHA512] = _(SHA512),
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[HASH_ALGO_SHA224] = _(SHA224),
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#undef _
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};
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int rsa_verify(const struct rsa_public_key *key, const uint8_t *sig,
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const uint32_t sig_len, const uint8_t *hash,
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enum hash_algo algo)
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{
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int ret = 0;
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uint8_t buf[RSA_MAX_SIG_BITS / 8];
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int i;
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unsigned PS_end, T_offset;
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const u8 *asn1_template = RSA_ASN1_templates[algo].data;
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size_t asn1_size = RSA_ASN1_templates[algo].size;
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struct digest *d = digest_alloc_by_algo(algo);
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if (!d)
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return -EOPNOTSUPP;
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if (sig_len != (key->len * sizeof(uint32_t))) {
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debug("Signature is of incorrect length %d, should be %d\n", sig_len,
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key->len * sizeof(uint32_t));
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ret = -EINVAL;
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goto out_free_digest;
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}
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/* Sanity check for stack size */
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if (sig_len > RSA_MAX_SIG_BITS / 8) {
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debug("Signature length %u exceeds maximum %d\n", sig_len,
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RSA_MAX_SIG_BITS / 8);
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ret = -EINVAL;
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goto out_free_digest;
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}
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memcpy(buf, sig, sig_len);
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ret = pow_mod(key, buf);
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if (ret)
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goto out_free_digest;
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T_offset = sig_len - (asn1_size + digest_length(d));
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PS_end = T_offset - 1;
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if (buf[PS_end] != 0x00) {
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pr_err(" = -EBADMSG [EM[T-1] == %02u]", buf[PS_end]);
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ret = -EBADMSG;
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goto out_free_digest;
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}
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for (i = 2; i < PS_end; i++) {
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if (buf[i] != 0xff) {
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pr_err(" = -EBADMSG [EM[PS%x] == %02u]", i - 2, buf[i]);
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ret = -EBADMSG;
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goto out_free_digest;
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}
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}
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if (memcmp(asn1_template, buf + T_offset, asn1_size) != 0) {
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pr_err(" = -EBADMSG [EM[T] ASN.1 mismatch]");
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ret = -EBADMSG;
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goto out_free_digest;
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}
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if (memcmp(hash, buf + T_offset + asn1_size, digest_length(d)) != 0) {
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pr_err(" = -EKEYREJECTED [EM[T] hash mismatch]");
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ret = -EKEYREJECTED;
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goto out_free_digest;
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}
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out_free_digest:
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digest_free(d);
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return ret;
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}
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static void rsa_convert_big_endian(uint32_t *dst, const uint32_t *src, int len)
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{
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int i;
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for (i = 0; i < len; i++)
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dst[i] = fdt32_to_cpu(src[len - 1 - i]);
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}
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int rsa_of_read_key(struct device_node *node, struct rsa_public_key *key)
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{
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const void *modulus, *rr;
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const uint64_t *public_exponent;
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int length;
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of_property_read_u32(node, "rsa,num-bits", &key->len);
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of_property_read_u32(node, "rsa,n0-inverse", &key->n0inv);
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public_exponent = of_get_property(node, "rsa,exponent", &length);
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if (!public_exponent || length < sizeof(*public_exponent))
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key->exponent = RSA_DEFAULT_PUBEXP;
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else
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key->exponent = fdt64_to_cpu(*public_exponent);
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modulus = of_get_property(node, "rsa,modulus", NULL);
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rr = of_get_property(node, "rsa,r-squared", NULL);
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if (!key->len || !modulus || !rr) {
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debug("%s: Missing RSA key info", __func__);
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return -EFAULT;
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}
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/* Sanity check for stack size */
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if (key->len > RSA_MAX_KEY_BITS || key->len < RSA_MIN_KEY_BITS) {
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debug("RSA key bits %u outside allowed range %d..%d\n",
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key->len, RSA_MIN_KEY_BITS, RSA_MAX_KEY_BITS);
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return -EFAULT;
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}
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key->len /= sizeof(uint32_t) * 8;
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key->modulus = xzalloc(RSA_MAX_KEY_BITS / 8);
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key->rr = xzalloc(RSA_MAX_KEY_BITS / 8);
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rsa_convert_big_endian(key->modulus, modulus, key->len);
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rsa_convert_big_endian(key->rr, rr, key->len);
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return 0;
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}
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|
|
@ -126,6 +126,11 @@
|
|||
|
||||
#define ENOMEDIUM 123 /* No medium found */
|
||||
#define EMEDIUMTYPE 124 /* Wrong medium type */
|
||||
#define ECANCELED 125 /* Operation Canceled */
|
||||
#define ENOKEY 126 /* Required key not available */
|
||||
#define EKEYEXPIRED 127 /* Key has expired */
|
||||
#define EKEYREVOKED 128 /* Key has been revoked */
|
||||
#define EKEYREJECTED 129 /* Key was rejected by service */
|
||||
|
||||
/* Should never be seen by user programs */
|
||||
#define ERESTARTSYS 512
|
||||
|
|
|
|||
|
|
@ -0,0 +1,54 @@
|
|||
/*
|
||||
* Copyright (c) 2013, Google Inc.
|
||||
*
|
||||
* (C) Copyright 2008 Semihalf
|
||||
*
|
||||
* (C) Copyright 2000-2006
|
||||
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
|
||||
*
|
||||
* SPDX-License-Identifier: GPL-2.0+
|
||||
*/
|
||||
|
||||
#ifndef _RSA_H
|
||||
#define _RSA_H
|
||||
|
||||
#include <errno.h>
|
||||
#include <digest.h>
|
||||
|
||||
/**
|
||||
* struct rsa_public_key - holder for a public key
|
||||
*
|
||||
* An RSA public key consists of a modulus (typically called N), the inverse
|
||||
* and R^2, where R is 2^(# key bits).
|
||||
*/
|
||||
|
||||
struct rsa_public_key {
|
||||
uint len; /* len of modulus[] in number of uint32_t */
|
||||
uint32_t n0inv; /* -1 / modulus[0] mod 2^32 */
|
||||
uint32_t *modulus; /* modulus as little endian array */
|
||||
uint32_t *rr; /* R^2 as little endian array */
|
||||
uint64_t exponent; /* public exponent */
|
||||
};
|
||||
|
||||
/**
|
||||
* rsa_verify() - Verify a signature against some data
|
||||
*
|
||||
* Verify a RSA PKCS1.5 signature against an expected hash.
|
||||
*
|
||||
* @info: Specifies key and FIT information
|
||||
* @data: Pointer to the input data
|
||||
* @data_len: Data length
|
||||
* @sig: Signature
|
||||
* @sig_len: Number of bytes in signature
|
||||
* @return 0 if verified, -ve on error
|
||||
*/
|
||||
int rsa_verify(const struct rsa_public_key *key, const uint8_t *sig,
|
||||
const uint32_t sig_len, const uint8_t *hash,
|
||||
enum hash_algo algo);
|
||||
|
||||
/* This is the maximum signature length that we support, in bits */
|
||||
#define RSA_MAX_SIG_BITS 4096
|
||||
|
||||
int rsa_of_read_key(struct device_node *node, struct rsa_public_key *key);
|
||||
|
||||
#endif
|
||||
Loading…
Reference in New Issue