56 lines
2 KiB
Diff
56 lines
2 KiB
Diff
https://github.com/LibVNC/libvncserver/commit/b686f379c34114cf938fe88291f58014337558f6
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https://bugs.gentoo.org/893608
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From b686f379c34114cf938fe88291f58014337558f6 Mon Sep 17 00:00:00 2001
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From: Gaurav Ujjwal <gujjwal00@gmail.com>
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Date: Mon, 23 Jan 2023 00:03:03 +0530
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Subject: [PATCH] common/crypto_openssl: pad DH key buffers with leading zeros
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for smaller keys
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Re: https://github.com/LibVNC/libvncserver/issues/493
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Re: https://github.com/bk138/multivnc/issues/202
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--- a/common/crypto_openssl.c
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+++ b/common/crypto_openssl.c
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@@ -156,6 +156,15 @@ int encrypt_aes128ecb(void *out, int *out_len, const unsigned char key[16], cons
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return result;
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}
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+static void pad_leading_zeros(uint8_t *out, const size_t current_len, const size_t expected_len) {
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+ if (current_len >= expected_len || expected_len < 1)
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+ return;
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+
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+ size_t diff = expected_len - current_len;
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+ memmove(out + diff, out, current_len);
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+ memset(out, 0, diff);
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+}
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+
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int dh_generate_keypair(uint8_t *priv_out, uint8_t *pub_out, const uint8_t *gen, const size_t gen_len, const uint8_t *prime, const size_t keylen)
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{
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int result = 0;
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@@ -184,6 +193,9 @@ int dh_generate_keypair(uint8_t *priv_out, uint8_t *pub_out, const uint8_t *gen,
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goto out;
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if(BN_bn2bin(dh->pub_key, pub_out) == 0)
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goto out;
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+
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+ pad_leading_zeros(priv_out, BN_num_bytes(dh->priv_key), keylen);
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+ pad_leading_zeros(pub_out, BN_num_bytes(dh->pub_key), keylen);
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#else
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DH_get0_key(dh, &pub_key, &priv_key);
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if(BN_bn2binpad(priv_key, priv_out, keylen) == -1)
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@@ -216,9 +228,11 @@ int dh_compute_shared_key(uint8_t *shared_out, const uint8_t *priv, const uint8_
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if(!DH_set0_key(dh, NULL, BN_bin2bn(priv, keylen, NULL)))
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goto out;
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#endif
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- if(DH_compute_key(shared_out, BN_bin2bn(pub, keylen, NULL), dh) == -1)
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- goto out;
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+ int shared_len = DH_compute_key(shared_out, BN_bin2bn(pub, keylen, NULL), dh);
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+ if(shared_len == -1)
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+ goto out;
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+ pad_leading_zeros(shared_out, shared_len, keylen);
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result = 1;
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out:
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--
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2.39.2
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