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authorDenys Vlasenko <vda.linux@googlemail.com>2021-10-05 17:31:33 +0200
committerDenys Vlasenko <vda.linux@googlemail.com>2021-10-05 17:31:33 +0200
commit81d8af1970e70f2bffa9e67acb10e732cba555a6 (patch)
treecd4f4c2cc3c1d947685453d7c4107b568a6d4a81
parent92402d5e0a2b8e0692b2eebd15b893bdbe4c3a34 (diff)
tls: fix (what looks like) a rare corner case bug in P256
function old new delta static.sp_256_mont_sub_10 30 46 +16 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--networking/tls_sp_c32.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/networking/tls_sp_c32.c b/networking/tls_sp_c32.c
index 7c6229ffd..99f9c6839 100644
--- a/networking/tls_sp_c32.c
+++ b/networking/tls_sp_c32.c
@@ -96,11 +96,13 @@ static void sp_256_to_bin_10(sp_digit* r, uint8_t* a)
a[j] = 0;
for (i = 0; i < 10 && j >= 0; i++) {
b = 0;
- a[j--] |= r[i] << s; b += 8 - s;
+ a[j--] |= r[i] << s;
+ b += 8 - s;
if (j < 0)
break;
while (b < 26) {
- a[j--] = r[i] >> b; b += 8;
+ a[j--] = r[i] >> b;
+ b += 8;
if (j < 0)
break;
}
@@ -297,6 +299,7 @@ static void sp_256_mont_sub_10(sp_digit* r, const sp_digit* a, const sp_digit* b
if (r[9] >> 22)
sp_256_add_10(r, r, m);
sp_256_norm_10(r);
+ r[9] &= 0x03fffff; /* truncate to 22 bits */
}
/* Double a Montgomery form number (r = a + a % m) */
@@ -864,8 +867,8 @@ static void sp_ecc_secret_gen_256(const sp_digit priv[10], const uint8_t *pub2x3
dump_hex(" %s\n", pub2x32 + 32, 32);
sp_256_point_from_bin2x32(point, pub2x32);
- dump_hex("point->x %s\n", point->x, sizeof(point->x));
- dump_hex("point->y %s\n", point->y, sizeof(point->y));
+ dump_512("point->x %s\n", point->x);
+ dump_512("point->y %s\n", point->y);
sp_256_ecc_mulmod_10(point, point, priv);