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author | Gavin Andresen <gavinandresen@gmail.com> | 2013-08-08 19:58:57 +1000 |
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committer | Gavin Andresen <gavinandresen@gmail.com> | 2013-08-20 12:19:40 +1000 |
commit | cdb3441b5cd2c1bae49fae671dc4a496f7c96322 (patch) | |
tree | 920b43f3e70c3801375c10ab728070a8eaaa320e | |
parent | 38863afbcc6ddb8a247210ac1d7c5d9717265339 (diff) | |
download | bitcoin-cdb3441b5cd2c1bae49fae671dc4a496f7c96322.tar.xz |
Make RPC password resistant to timing attacks
Fixes issue#2838; this is a tweaked version of pull#2845 that
should not leak the length of the password and is more generic,
in case we run into other situations where we need
timing-attack-resistant comparisons.
-rw-r--r-- | src/bitcoinrpc.cpp | 2 | ||||
-rw-r--r-- | src/test/util_tests.cpp | 11 | ||||
-rw-r--r-- | src/util.h | 15 |
3 files changed, 27 insertions, 1 deletions
diff --git a/src/bitcoinrpc.cpp b/src/bitcoinrpc.cpp index 2c4744a579..31452fa1e7 100644 --- a/src/bitcoinrpc.cpp +++ b/src/bitcoinrpc.cpp @@ -479,7 +479,7 @@ bool HTTPAuthorized(map<string, string>& mapHeaders) return false; string strUserPass64 = strAuth.substr(6); boost::trim(strUserPass64); string strUserPass = DecodeBase64(strUserPass64); - return strUserPass == strRPCUserColonPass; + return TimingResistantEqual(strUserPass, strRPCUserColonPass); } // diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp index 1b0ccad511..9ca0eef7aa 100644 --- a/src/test/util_tests.cpp +++ b/src/test/util_tests.cpp @@ -323,4 +323,15 @@ BOOST_AUTO_TEST_CASE(util_seed_insecure_rand) } } +BOOST_AUTO_TEST_CASE(util_TimingResistantEqual) +{ + BOOST_CHECK(TimingResistantEqual(std::string(""), std::string(""))); + BOOST_CHECK(!TimingResistantEqual(std::string("abc"), std::string(""))); + BOOST_CHECK(!TimingResistantEqual(std::string(""), std::string("abc"))); + BOOST_CHECK(!TimingResistantEqual(std::string("a"), std::string("aa"))); + BOOST_CHECK(!TimingResistantEqual(std::string("aa"), std::string("a"))); + BOOST_CHECK(TimingResistantEqual(std::string("abc"), std::string("abc"))); + BOOST_CHECK(!TimingResistantEqual(std::string("abc"), std::string("aba"))); +} + BOOST_AUTO_TEST_SUITE_END() diff --git a/src/util.h b/src/util.h index 3f3dd0f487..9b7e2573da 100644 --- a/src/util.h +++ b/src/util.h @@ -433,6 +433,21 @@ static inline uint32_t insecure_rand(void) */ void seed_insecure_rand(bool fDeterministic=false); +/** + * Timing-attack-resistant comparison. + * Takes time proportional to length + * of first argument. + */ +template <typename T> +bool TimingResistantEqual(const T& a, const T& b) +{ + if (b.size() == 0) return a.size() == 0; + size_t accumulator = a.size() ^ b.size(); + for (size_t i = 0; i < a.size(); i++) + accumulator |= a[i] ^ b[i%b.size()]; + return accumulator == 0; +} + /** Median filter over a stream of values. * Returns the median of the last N numbers */ |