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-rw-r--r--firmware/bdb/rsa.c337
1 files changed, 0 insertions, 337 deletions
diff --git a/firmware/bdb/rsa.c b/firmware/bdb/rsa.c
deleted file mode 100644
index 35bfcb47..00000000
--- a/firmware/bdb/rsa.c
+++ /dev/null
@@ -1,337 +0,0 @@
-/* Copyright 2016 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.
- *
- * Boot descriptor block firmware RSA
- */
-
-#include <string.h>
-#include "bdb.h"
-
-/* Public key structure in RAM */
-struct public_key {
- uint32_t arrsize; /* Size of n[] and rr[] arrays in elements */
- uint32_t n0inv; /* -1 / n[0] mod 2^32 */
- const uint32_t *n; /* Modulus as little endian array */
- const uint32_t *rr; /* R^2 as little endian array */
-};
-
-/**
- * a[] -= mod
- */
-static void subM(const struct public_key *key, uint32_t *a)
-{
- int64_t A = 0;
- uint32_t i;
- for (i = 0; i < key->arrsize; ++i) {
- A += (uint64_t)a[i] - key->n[i];
- a[i] = (uint32_t)A;
- A >>= 32;
- }
-}
-
-/**
- * Return a[] >= mod
- */
-static int mont_ge(const struct public_key *key, uint32_t *a)
-{
- uint32_t i;
- for (i = key->arrsize; i;) {
- --i;
- if (a[i] < key->n[i])
- return 0;
- if (a[i] > key->n[i])
- return 1;
- }
- return 1; /* equal */
-}
-
-/**
- * Montgomery c[] += a * b[] / R % mod
- */
-static void montMulAdd(const struct public_key *key,
- uint32_t *c,
- const uint32_t a,
- const uint32_t *b)
-{
- uint64_t A = (uint64_t)a * b[0] + c[0];
- uint32_t d0 = (uint32_t)A * key->n0inv;
- uint64_t B = (uint64_t)d0 * key->n[0] + (uint32_t)A;
- uint32_t i;
-
- for (i = 1; i < key->arrsize; ++i) {
- A = (A >> 32) + (uint64_t)a * b[i] + c[i];
- B = (B >> 32) + (uint64_t)d0 * key->n[i] + (uint32_t)A;
- c[i - 1] = (uint32_t)B;
- }
-
- A = (A >> 32) + (B >> 32);
-
- c[i - 1] = (uint32_t)A;
-
- if (A >> 32) {
- subM(key, c);
- }
-}
-
-/**
- * Montgomery c[] = a[] * b[] / R % mod
- */
-static void montMul(const struct public_key *key,
- uint32_t *c,
- const uint32_t *a,
- const uint32_t *b)
-{
- uint32_t i;
- for (i = 0; i < key->arrsize; ++i) {
- c[i] = 0;
- }
- for (i = 0; i < key->arrsize; ++i) {
- montMulAdd(key, c, a[i], b);
- }
-}
-
-static int safe_memcmp(const void *s1, const void *s2, size_t size)
-{
- const unsigned char *us1 = s1;
- const unsigned char *us2 = s2;
- int result = 0;
-
- if (0 == size)
- return 0;
-
- /*
- * Code snippet without data-dependent branch due to Nate Lawson
- * (nate@root.org) of Root Labs.
- */
- while (size--)
- result |= *us1++ ^ *us2++;
-
- return result != 0;
-}
-
-/*
- * PKCS 1.5 padding (from the RSA PKCS#1 v2.1 standard)
- *
- * Depending on the RSA key size and hash function, the padding is calculated
- * as follows:
- *
- * 0x00 || 0x01 || PS || 0x00 || T
- *
- * T: DER Encoded DigestInfo value which depends on the hash function used.
- *
- * SHA-256: (0x)30 31 30 0d 06 09 60 86 48 01 65 03 04 02 01 05 00 04 20 || H.
- *
- * Length(T) = 51 octets for SHA-256
- *
- * PS: octet string consisting of {Length(RSA Key) - Length(T) - 3} 0xFF
- */
-static const uint8_t sha256_tail[] = {
- 0x00,0x30,0x31,0x30,0x0d,0x06,0x09,0x60,
- 0x86,0x48,0x01,0x65,0x03,0x04,0x02,0x01,
- 0x05,0x00,0x04,0x20
-};
-
-static int check_padding(const uint8_t *sig, const struct public_key *key,
- uint32_t pad_size)
-{
- /* Determine padding to use depending on the signature type */
- const uint32_t tail_size = sizeof(sha256_tail);
- int result = 0;
- int i;
-
- /* First 2 bytes are always 0x00 0x01 */
- result |= *sig++ ^ 0x00;
- result |= *sig++ ^ 0x01;
-
- /* Then 0xff bytes until the tail */
- for (i = 0; i < pad_size - tail_size - 2; i++)
- result |= *sig++ ^ 0xff;
-
- /*
- * Then the tail. Even though there are probably no timing issues
- * here, we use safe_memcmp() just to be on the safe side.
- */
- result |= safe_memcmp(sig, sha256_tail, tail_size);
-
- return result ? BDB_ERROR_DIGEST : BDB_SUCCESS;
-}
-
-/* Array size for RSA4096 */
-#define ARRSIZE4096 (4096 / 32)
-
-/**
- * In-place public exponentiation. (exponent 65537, key size 4096 bits)
- *
- * @param key Key to use in signing
- * @param inout Input and output big-endian byte array
- */
-static void modpowF4(const struct public_key *key, uint8_t *inout)
-{
- uint32_t a[ARRSIZE4096];
- uint32_t aR[ARRSIZE4096];
- uint32_t aaR[ARRSIZE4096];
- uint32_t *aaa = aaR; /* Re-use location. */
- int i;
-
- /* Convert from big endian byte array to little endian word array. */
- for (i = 0; i < ARRSIZE4096; ++i) {
- uint32_t tmp =
- (inout[((ARRSIZE4096 - 1 - i) * 4) + 0] << 24) |
- (inout[((ARRSIZE4096 - 1 - i) * 4) + 1] << 16) |
- (inout[((ARRSIZE4096 - 1 - i) * 4) + 2] << 8) |
- (inout[((ARRSIZE4096 - 1 - i) * 4) + 3] << 0);
- a[i] = tmp;
- }
-
- montMul(key, aR, a, key->rr); /* aR = a * RR / R mod M */
- for (i = 0; i < 16; i+=2) {
- montMul(key, aaR, aR, aR); /* aaR = aR * aR / R mod M */
- montMul(key, aR, aaR, aaR); /* aR = aaR * aaR / R mod M */
- }
- montMul(key, aaa, aR, a); /* aaa = aR * a / R mod M */
-
- /* Make sure aaa < mod; aaa is at most 1x mod too large. */
- if (mont_ge(key, aaa)) {
- subM(key, aaa);
- }
-
- /* Convert to bigendian byte array */
- for (i = ARRSIZE4096 - 1; i >= 0; --i) {
- uint32_t tmp = aaa[i];
- *inout++ = (uint8_t)(tmp >> 24);
- *inout++ = (uint8_t)(tmp >> 16);
- *inout++ = (uint8_t)(tmp >> 8);
- *inout++ = (uint8_t)(tmp >> 0);
- }
-}
-
-int bdb_rsa4096_verify(const uint8_t *key_data,
- const uint8_t *sig,
- const uint8_t *digest)
-{
- const uint32_t *kdata32 = (const uint32_t *)key_data;
- struct public_key key;
- uint8_t sig_work[BDB_RSA4096_SIG_SIZE];
- uint32_t pad_size;
- int rv;
-
- /* Unpack key */
- if (kdata32[0] != ARRSIZE4096)
- return BDB_ERROR_DIGEST; /* Wrong key size */
-
- key.arrsize = kdata32[0];
- key.n0inv = kdata32[1];
- key.n = kdata32 + 2;
- key.rr = kdata32 + 2 + key.arrsize;
-
- /* Copy signature to work buffer */
- memcpy(sig_work, sig, sizeof(sig_work));
-
- modpowF4(&key, sig_work);
-
- /*
- * Check padding. Continue on to check the digest even if error to
- * reduce the risk of timing based attacks.
- */
- pad_size = key.arrsize * sizeof(uint32_t) - BDB_SHA256_DIGEST_SIZE;
- rv = check_padding(sig_work, &key, pad_size);
-
- /*
- * Check digest. Even though there are probably no timing issues here,
- * use safe_memcmp() just to be on the safe side. (That's also why
- * we don't return before this check if the padding check failed.)
- */
- if (safe_memcmp(sig_work + pad_size, digest, BDB_SHA256_DIGEST_SIZE))
- rv = BDB_ERROR_DIGEST;
-
- return rv;
-}
-
-/* Array size for RSA3072B */
-#define ARRSIZE3072B (3072 / 32)
-
-/**
- * In-place public exponentiation. (exponent 3, key size 3072 bits)
- *
- * @param key Key to use in signing
- * @param inout Input and output big-endian byte array
- */
-static void modpow3(const struct public_key *key, uint8_t *inout)
-{
- uint32_t a[ARRSIZE3072B];
- uint32_t aR[ARRSIZE3072B];
- uint32_t aaR[ARRSIZE3072B];
- uint32_t *aaa = aR; /* Re-use location */
- int i;
-
- /* Convert from big endian byte array to little endian word array. */
- for (i = 0; i < ARRSIZE3072B; ++i) {
- uint32_t tmp =
- (inout[((ARRSIZE3072B - 1 - i) * 4) + 0] << 24) |
- (inout[((ARRSIZE3072B - 1 - i) * 4) + 1] << 16) |
- (inout[((ARRSIZE3072B - 1 - i) * 4) + 2] << 8) |
- (inout[((ARRSIZE3072B - 1 - i) * 4) + 3] << 0);
- a[i] = tmp;
- }
-
- montMul(key, aR, a, key->rr); /* aR = a * RR / R mod M */
- montMul(key, aaR, aR, aR); /* aaR = aR * aR / R mod M */
- montMul(key, aaa, aaR, a); /* aaa = aaR * a / R mod M */
-
- /* Make sure aaa < mod; aaa is at most 1x mod too large. */
- if (mont_ge(key, aaa)) {
- subM(key, aaa);
- }
-
- /* Convert to bigendian byte array */
- for (i = ARRSIZE3072B - 1; i >= 0; --i) {
- uint32_t tmp = aaa[i];
- *inout++ = (uint8_t)(tmp >> 24);
- *inout++ = (uint8_t)(tmp >> 16);
- *inout++ = (uint8_t)(tmp >> 8);
- *inout++ = (uint8_t)(tmp >> 0);
- }
-}
-
-int bdb_rsa3072b_verify(const uint8_t *key_data,
- const uint8_t *sig,
- const uint8_t *digest)
-{
- const uint32_t *kdata32 = (const uint32_t *)key_data;
- struct public_key key;
- uint8_t sig_work[BDB_RSA3072B_SIG_SIZE];
- uint32_t pad_size;
- int rv;
-
- /* Unpack key */
- if (kdata32[0] != ARRSIZE3072B)
- return BDB_ERROR_DIGEST; /* Wrong key size */
-
- key.arrsize = kdata32[0];
- key.n0inv = kdata32[1];
- key.n = kdata32 + 2;
- key.rr = kdata32 + 2 + key.arrsize;
-
- /* Copy signature to work buffer */
- memcpy(sig_work, sig, sizeof(sig_work));
-
- modpow3(&key, sig_work);
-
- /*
- * Check padding. Continue on to check the digest even if error to
- * reduce the risk of timing based attacks.
- */
- pad_size = key.arrsize * sizeof(uint32_t) - BDB_SHA256_DIGEST_SIZE;
- rv = check_padding(sig_work, &key, pad_size);
-
- /*
- * Check digest. Even though there are probably no timing issues here,
- * use safe_memcmp() just to be on the safe side. (That's also why
- * we don't return before this check if the padding check failed.)
- */
- if (safe_memcmp(sig_work + pad_size, digest, BDB_SHA256_DIGEST_SIZE))
- rv = BDB_ERROR_DIGEST;
-
- return rv;
-}
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