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do not offer gcm as the preferred cipher suite

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Move the GCM srtp cipher suites below the default SRTP_AES128_CM_SHA1_80 one.
This will not negotiate them by default since they have an impact on packet overhead for audio-only calls.
GCM can still be negotiated if the peer offers it as preferred cipher suite or answers with just that cipher suite.

BUG=chromium:713701

Change-Id: I79bd4ab827e5c7f55f5550d14db3f4217a7eff86
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/158404
Reviewed-by: Justin Uberti <juberti@google.com>
Reviewed-by: Justin Uberti <juberti@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Justin Uberti <juberti@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29672}
This commit is contained in:
Philipp Hancke
2019-10-26 06:12:55 +02:00
committed by Commit Bot
parent 3ce44a3540
commit 2ebbff83ee
3 changed files with 32 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
api/crypto/crypto_options.cc
View File

@ -32,10 +32,6 @@ CryptoOptions CryptoOptions::NoGcm() {
std::vector<int> CryptoOptions::GetSupportedDtlsSrtpCryptoSuites() const {
std::vector<int> crypto_suites;
if (srtp.enable_gcm_crypto_suites) {
crypto_suites.push_back(rtc::SRTP_AEAD_AES_256_GCM);
crypto_suites.push_back(rtc::SRTP_AEAD_AES_128_GCM);
}
// Note: SRTP_AES128_CM_SHA1_80 is what is required to be supported (by
// draft-ietf-rtcweb-security-arch), but SRTP_AES128_CM_SHA1_32 is allowed as
// well, and saves a few bytes per packet if it ends up selected.
@ -44,7 +40,18 @@ std::vector<int> CryptoOptions::GetSupportedDtlsSrtpCryptoSuites() const {
if (srtp.enable_aes128_sha1_32_crypto_cipher) {
crypto_suites.push_back(rtc::SRTP_AES128_CM_SHA1_32);
}
if (srtp.enable_aes128_sha1_80_crypto_cipher) {
crypto_suites.push_back(rtc::SRTP_AES128_CM_SHA1_80);
}
// Note: GCM cipher suites are not the top choice since they increase the
// packet size. In order to negotiate them the other side must not support
// SRTP_AES128_CM_SHA1_80.
if (srtp.enable_gcm_crypto_suites) {
crypto_suites.push_back(rtc::SRTP_AEAD_AES_256_GCM);
crypto_suites.push_back(rtc::SRTP_AEAD_AES_128_GCM);
}
RTC_CHECK(!crypto_suites.empty());
return crypto_suites;
}
@ -53,6 +60,7 @@ bool CryptoOptions::operator==(const CryptoOptions& other) const {
struct Srtp {
bool enable_gcm_crypto_suites;
bool enable_aes128_sha1_32_crypto_cipher;
bool enable_aes128_sha1_80_crypto_cipher;
bool enable_encrypted_rtp_header_extensions;
} srtp;
struct SFrame {
@ -66,6 +74,8 @@ bool CryptoOptions::operator==(const CryptoOptions& other) const {
return srtp.enable_gcm_crypto_suites == other.srtp.enable_gcm_crypto_suites &&
srtp.enable_aes128_sha1_32_crypto_cipher ==
other.srtp.enable_aes128_sha1_32_crypto_cipher &&
srtp.enable_aes128_sha1_80_crypto_cipher ==
other.srtp.enable_aes128_sha1_80_crypto_cipher &&
srtp.enable_encrypted_rtp_header_extensions ==
other.srtp.enable_encrypted_rtp_header_extensions &&
sframe.require_frame_encryption ==

4
api/crypto/crypto_options.h
View File

@ -49,6 +49,10 @@ struct RTC_EXPORT CryptoOptions {
// other ciphers get preferred.
bool enable_aes128_sha1_32_crypto_cipher = false;
// The most commonly used cipher. Can be disabled, mostly for testing
// purposes.
bool enable_aes128_sha1_80_crypto_cipher = true;
// If set to true, encrypted RTP header extensions as defined in RFC 6904
// will be negotiated. They will only be used if both peers support them.
bool enable_encrypted_rtp_header_extensions = false;

37
pc/peer_connection_integrationtest.cc
View File

@ -1635,13 +1635,18 @@ class PeerConnectionIntegrationBaseTest : public ::testing::Test {
void TestGcmNegotiationUsesCipherSuite(bool local_gcm_enabled,
bool remote_gcm_enabled,
bool aes_ctr_enabled,
int expected_cipher_suite) {
PeerConnectionFactory::Options caller_options;
caller_options.crypto_options.srtp.enable_gcm_crypto_suites =
local_gcm_enabled;
caller_options.crypto_options.srtp.enable_aes128_sha1_80_crypto_cipher =
aes_ctr_enabled;
PeerConnectionFactory::Options callee_options;
callee_options.crypto_options.srtp.enable_gcm_crypto_suites =
remote_gcm_enabled;
callee_options.crypto_options.srtp.enable_aes128_sha1_80_crypto_cipher =
aes_ctr_enabled;
TestNegotiatedCipherSuite(caller_options, callee_options,
expected_cipher_suite);
}
@ -3110,38 +3115,21 @@ TEST_P(PeerConnectionIntegrationTest, Aes128Sha1_32_CipherUsedWhenSupported) {
TEST_P(PeerConnectionIntegrationTest, NonGcmCipherUsedWhenGcmNotSupported) {
bool local_gcm_enabled = false;
bool remote_gcm_enabled = false;
bool aes_ctr_enabled = true;
int expected_cipher_suite = kDefaultSrtpCryptoSuite;
TestGcmNegotiationUsesCipherSuite(local_gcm_enabled, remote_gcm_enabled,
expected_cipher_suite);
aes_ctr_enabled, expected_cipher_suite);
}
// Test that a GCM cipher is used if both ends support it.
TEST_P(PeerConnectionIntegrationTest, GcmCipherUsedWhenGcmSupported) {
// Test that a GCM cipher is used if both ends support it and non-GCM is
// disabled.
TEST_P(PeerConnectionIntegrationTest, GcmCipherUsedWhenOnlyGcmSupported) {
bool local_gcm_enabled = true;
bool remote_gcm_enabled = true;
bool aes_ctr_enabled = false;
int expected_cipher_suite = kDefaultSrtpCryptoSuiteGcm;
TestGcmNegotiationUsesCipherSuite(local_gcm_enabled, remote_gcm_enabled,
expected_cipher_suite);
}
// Test that GCM isn't used if only the offerer supports it.
TEST_P(PeerConnectionIntegrationTest,
NonGcmCipherUsedWhenOnlyCallerSupportsGcm) {
bool local_gcm_enabled = true;
bool remote_gcm_enabled = false;
int expected_cipher_suite = kDefaultSrtpCryptoSuite;
TestGcmNegotiationUsesCipherSuite(local_gcm_enabled, remote_gcm_enabled,
expected_cipher_suite);
}
// Test that GCM isn't used if only the answerer supports it.
TEST_P(PeerConnectionIntegrationTest,
NonGcmCipherUsedWhenOnlyCalleeSupportsGcm) {
bool local_gcm_enabled = false;
bool remote_gcm_enabled = true;
int expected_cipher_suite = kDefaultSrtpCryptoSuite;
TestGcmNegotiationUsesCipherSuite(local_gcm_enabled, remote_gcm_enabled,
expected_cipher_suite);
aes_ctr_enabled, expected_cipher_suite);
}
// Verify that media can be transmitted end-to-end when GCM crypto suites are
@ -3151,6 +3139,7 @@ TEST_P(PeerConnectionIntegrationTest,
TEST_P(PeerConnectionIntegrationTest, EndToEndCallWithGcmCipher) {
PeerConnectionFactory::Options gcm_options;
gcm_options.crypto_options.srtp.enable_gcm_crypto_suites = true;
gcm_options.crypto_options.srtp.enable_aes128_sha1_80_crypto_cipher = false;
ASSERT_TRUE(
CreatePeerConnectionWrappersWithOptions(gcm_options, gcm_options));
ConnectFakeSignaling();