The branch master has been updated
via a766aab93a282774e63ba918d0bb1c6680a5f292 (commit)
from 27232cc3385260311e7fd2f6cd78db967cae650d (commit)
- Log -----------------------------------------------------------------
commit a766aab93a282774e63ba918d0bb1c6680a5f292
Author: Billy Brumley <bbrum...@gmail.com>
Date: Wed Jun 20 10:56:37 2018 +0300
[crypto/ec] don't assume points are of order group->order
Reviewed-by: Paul Dale <paul.d...@oracle.com>
Reviewed-by: Richard Levitte <levi...@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6535)
-----------------------------------------------------------------------
Summary of changes:
crypto/ec/ec_mult.c | 29 +++++++++++++++--------------
test/recipes/30-test_evp_data/evppkey.txt | 29 +++++++++++++++++++++++++++++
2 files changed, 44 insertions(+), 14 deletions(-)
diff --git a/crypto/ec/ec_mult.c b/crypto/ec/ec_mult.c
index b668e87..c821cb8 100644
--- a/crypto/ec/ec_mult.c
+++ b/crypto/ec/ec_mult.c
@@ -132,10 +132,11 @@ static int ec_mul_consttime(const EC_GROUP *group,
EC_POINT *r,
const BIGNUM *scalar, const EC_POINT *point,
BN_CTX *ctx)
{
- int i, order_bits, group_top, kbit, pbit, Z_is_one;
+ int i, cardinality_bits, group_top, kbit, pbit, Z_is_one;
EC_POINT *s = NULL;
BIGNUM *k = NULL;
BIGNUM *lambda = NULL;
+ BIGNUM *cardinality = NULL;
BN_CTX *new_ctx = NULL;
int ret = 0;
@@ -144,8 +145,6 @@ static int ec_mul_consttime(const EC_GROUP *group, EC_POINT
*r,
BN_CTX_start(ctx);
- order_bits = BN_num_bits(group->order);
-
s = EC_POINT_new(group);
if (s == NULL)
goto err;
@@ -160,18 +159,20 @@ static int ec_mul_consttime(const EC_GROUP *group,
EC_POINT *r,
EC_POINT_BN_set_flags(s, BN_FLG_CONSTTIME);
+ cardinality = BN_CTX_get(ctx);
lambda = BN_CTX_get(ctx);
k = BN_CTX_get(ctx);
- if (k == NULL)
+ if (k == NULL || !BN_mul(cardinality, group->order, group->cofactor, ctx))
goto err;
/*
- * Group orders are often on a word boundary.
+ * Group cardinalities are often on a word boundary.
* So when we pad the scalar, some timing diff might
* pop if it needs to be expanded due to carries.
* So expand ahead of time.
*/
- group_top = bn_get_top(group->order);
+ cardinality_bits = BN_num_bits(cardinality);
+ group_top = bn_get_top(cardinality);
if ((bn_wexpand(k, group_top + 1) == NULL)
|| (bn_wexpand(lambda, group_top + 1) == NULL))
goto err;
@@ -181,25 +182,25 @@ static int ec_mul_consttime(const EC_GROUP *group,
EC_POINT *r,
BN_set_flags(k, BN_FLG_CONSTTIME);
- if ((BN_num_bits(k) > order_bits) || (BN_is_negative(k))) {
+ if ((BN_num_bits(k) > cardinality_bits) || (BN_is_negative(k))) {
/*-
* this is an unusual input, and we don't guarantee
* constant-timeness
*/
- if (!BN_nnmod(k, k, group->order, ctx))
+ if (!BN_nnmod(k, k, cardinality, ctx))
goto err;
}
- if (!BN_add(lambda, k, group->order))
+ if (!BN_add(lambda, k, cardinality))
goto err;
BN_set_flags(lambda, BN_FLG_CONSTTIME);
- if (!BN_add(k, lambda, group->order))
+ if (!BN_add(k, lambda, cardinality))
goto err;
/*
- * lambda := scalar + order
- * k := scalar + 2*order
+ * lambda := scalar + cardinality
+ * k := scalar + 2*cardinality
*/
- kbit = BN_is_bit_set(lambda, order_bits);
+ kbit = BN_is_bit_set(lambda, cardinality_bits);
BN_consttime_swap(kbit, k, lambda, group_top + 1);
group_top = bn_get_top(group->field);
@@ -300,7 +301,7 @@ static int ec_mul_consttime(const EC_GROUP *group, EC_POINT
*r,
* This is XOR. pbit tracks the previous bit of k.
*/
- for (i = order_bits - 1; i >= 0; i--) {
+ for (i = cardinality_bits - 1; i >= 0; i--) {
kbit = BN_is_bit_set(k, i) ^ pbit;
EC_POINT_CSWAP(kbit, r, s, group_top, Z_is_one);
if (!EC_POINT_add(group, s, r, s, ctx))
diff --git a/test/recipes/30-test_evp_data/evppkey.txt
b/test/recipes/30-test_evp_data/evppkey.txt
index e191b6f..7435125 100644
--- a/test/recipes/30-test_evp_data/evppkey.txt
+++ b/test/recipes/30-test_evp_data/evppkey.txt
@@ -17257,6 +17257,35 @@ PeerKey=KAS-ECC-CDH_B-571_C24-Peer-PUBLIC
Ctrl=ecdh_cofactor_mode:1
SharedSecret=02da266a269bdc8d8b2a0c6bb5762f102fc801c8d5394a9271539136bd81d4b69cfbb7525cd0a983fb7f7e9deec583b8f8e574c6184b2d79831ec770649e484dc006fa35b0bffd0b
+# for cofactor-order points, ECC CDH (co-factor ECDH) should fail. Test that.
+
+PrivateKey=ALICE_cf_sect283k1
+-----BEGIN PRIVATE KEY-----
+MIGQAgEAMBAGByqGSM49AgEGBSuBBAAQBHkwdwIBAQQkAHtPwRfQZ9pWgSctyHdt
+xt3pd8ESMI3ugVx8MDLkiVB8GkCRoUwDSgAEA+xpY5sDcgM2yYxoWOrzH7WUH+b3
+n68A32kODgcKu8PXRYEKBH8Xzbr974982ZJW1sGrDs+P81sIFH8tdp45Jkr+OtfM
+8uKr
+-----END PRIVATE KEY-----
+
+PublicKey=ALICE_cf_sect283k1_PUB
+-----BEGIN PUBLIC KEY-----
+MF4wEAYHKoZIzj0CAQYFK4EEABADSgAEA+xpY5sDcgM2yYxoWOrzH7WUH+b3n68A
+32kODgcKu8PXRYEKBH8Xzbr974982ZJW1sGrDs+P81sIFH8tdp45Jkr+OtfM8uKr
+-----END PUBLIC KEY-----
+
+PublicKey=BOB_cf_sect283k1_PUB
+-----BEGIN PUBLIC KEY-----
+MF4wEAYHKoZIzj0CAQYFK4EEABADSgAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
+AAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAB
+-----END PUBLIC KEY-----
+
+PrivPubKeyPair = ALICE_cf_sect283k1:ALICE_cf_sect283k1_PUB
+
+# ECDH Alice with Bob peer
+Derive=ALICE_cf_sect283k1
+PeerKey=BOB_cf_sect283k1_PUB
+Ctrl=ecdh_cofactor_mode:1
+Result = DERIVE_ERROR
Title = Test keypair mistmatches
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