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/* Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* Miscellaneous functions for userspace vboot utilities.
*/
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "2common.h"
#include "2sha.h"
#include "2sysincludes.h"
#include "host_common.h"
#include "host_key2.h"
#include "openssl_compat.h"
#include "util_misc.h"
#include "vb2_common.h"
const char *packed_key_sha1_string(const struct vb2_packed_key *key)
{
uint8_t *buf = ((uint8_t *)key) + key->key_offset;
uint32_t buflen = key->key_size;
uint8_t digest[VB2_SHA1_DIGEST_SIZE];
static char dest[VB2_SHA1_DIGEST_SIZE * 2 + 1];
vb2_digest_buffer(buf, buflen, VB2_HASH_SHA1, digest, sizeof(digest));
char *dnext = dest;
int i;
for (i = 0; i < sizeof(digest); i++)
dnext += sprintf(dnext, "%02x", digest[i]);
return dest;
}
const char *private_key_sha1_string(const struct vb2_private_key *key)
{
uint8_t *buf;
uint32_t buflen;
uint8_t digest[VB2_SHA1_DIGEST_SIZE];
static char dest[VB2_SHA1_DIGEST_SIZE * 2 + 1];
if (!key->rsa_private_key ||
vb_keyb_from_rsa(key->rsa_private_key, &buf, &buflen)) {
return "<error>";
}
vb2_digest_buffer(buf, buflen, VB2_HASH_SHA1, digest, sizeof(digest));
char *dnext = dest;
int i;
for (i = 0; i < sizeof(digest); i++)
dnext += sprintf(dnext, "%02x", digest[i]);
free(buf);
return dest;
}
int vb_keyb_from_rsa(struct rsa_st *rsa_private_key,
uint8_t **keyb_data, uint32_t *keyb_size)
{
uint32_t i, nwords;
BIGNUM *N = NULL;
BIGNUM *Big1 = NULL, *Big2 = NULL, *Big32 = NULL, *BigMinus1 = NULL;
BIGNUM *B = NULL;
BIGNUM *N0inv = NULL, *R = NULL, *RR = NULL;
BIGNUM *RRTemp = NULL, *NnumBits = NULL;
BIGNUM *n = NULL, *rr = NULL;
const BIGNUM *rsa_private_key_n;
BN_CTX *bn_ctx = BN_CTX_new();
uint32_t n0invout;
uint32_t bufsize;
uint32_t *outbuf;
int retval = 1;
/* Size of RSA key in 32-bit words */
nwords = RSA_size(rsa_private_key) / 4;
bufsize = (2 + nwords + nwords) * sizeof(uint32_t);
outbuf = malloc(bufsize);
if (!outbuf)
goto done;
*keyb_data = (uint8_t *)outbuf;
*keyb_size = bufsize;
*outbuf++ = nwords;
/* Initialize BIGNUMs */
#define NEW_BIGNUM(x) do { x = BN_new(); if (!x) goto done; } while (0)
NEW_BIGNUM(N);
NEW_BIGNUM(Big1);
NEW_BIGNUM(Big2);
NEW_BIGNUM(Big32);
NEW_BIGNUM(BigMinus1);
NEW_BIGNUM(N0inv);
NEW_BIGNUM(R);
NEW_BIGNUM(RR);
NEW_BIGNUM(RRTemp);
NEW_BIGNUM(NnumBits);
NEW_BIGNUM(n);
NEW_BIGNUM(rr);
NEW_BIGNUM(B);
#undef NEW_BIGNUM
RSA_get0_key(rsa_private_key, &rsa_private_key_n, NULL, NULL);
BN_copy(N, rsa_private_key_n);
BN_set_word(Big1, 1L);
BN_set_word(Big2, 2L);
BN_set_word(Big32, 32L);
BN_sub(BigMinus1, Big1, Big2);
BN_exp(B, Big2, Big32, bn_ctx); /* B = 2^32 */
/* Calculate and output N0inv = -1 / N[0] mod 2^32 */
BN_mod_inverse(N0inv, N, B, bn_ctx);
BN_sub(N0inv, B, N0inv);
n0invout = BN_get_word(N0inv);
*outbuf++ = n0invout;
/* Calculate R = 2^(# of key bits) */
BN_set_word(NnumBits, BN_num_bits(N));
BN_exp(R, Big2, NnumBits, bn_ctx);
/* Calculate RR = R^2 mod N */
BN_copy(RR, R);
BN_mul(RRTemp, RR, R, bn_ctx);
BN_mod(RR, RRTemp, N, bn_ctx);
/* Write out modulus as little endian array of integers. */
for (i = 0; i < nwords; ++i) {
uint32_t nout;
BN_mod(n, N, B, bn_ctx); /* n = N mod B */
nout = BN_get_word(n);
*outbuf++ = nout;
BN_rshift(N, N, 32); /* N = N/B */
}
/* Write R^2 as little endian array of integers. */
for (i = 0; i < nwords; ++i) {
uint32_t rrout;
BN_mod(rr, RR, B, bn_ctx); /* rr = RR mod B */
rrout = BN_get_word(rr);
*outbuf++ = rrout;
BN_rshift(RR, RR, 32); /* RR = RR/B */
}
outbuf = NULL;
retval = 0;
done:
free(outbuf);
/* Free BIGNUMs. */
BN_free(Big1);
BN_free(Big2);
BN_free(Big32);
BN_free(BigMinus1);
BN_free(N0inv);
BN_free(R);
BN_free(RRTemp);
BN_free(NnumBits);
BN_free(n);
BN_free(rr);
return retval;
}
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