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@@ -748,19 +748,23 @@ crypto_pk_public_exponent_ok(crypto_pk_t *env)
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return BN_is_word(env->key->e, 65537);
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}
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-/** Compare the public-key components of a and b. Return -1 if a\<b, 0
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- * if a==b, and 1 if a\>b.
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+/** Compare the public-key components of a and b. Return -1 if a\<b,
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+ * 0 if a==b, and 1 if a\>b. A NULL key is considered to be less than
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+ * all non-NULL keys, and equal to itself.
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+ *
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+ * Note that this may leak information about the keys through timing.
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*/
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int
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crypto_pk_cmp_keys(crypto_pk_t *a, crypto_pk_t *b)
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{
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int result;
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+ char a_is_non_null = (a != NULL) && (a->key != NULL);
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+ char b_is_non_null = (b != NULL) && (b->key != NULL);
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+ char an_argument_is_null = !a_is_non_null | !b_is_non_null;
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- if (!a || !b)
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- return -1;
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-
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- if (!a->key || !b->key)
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- return -1;
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+ result = tor_memcmp(&a_is_non_null, &b_is_non_null, sizeof(a_is_non_null));
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+ if (an_argument_is_null)
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+ return result;
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tor_assert(PUBLIC_KEY_OK(a));
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tor_assert(PUBLIC_KEY_OK(b));
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