add more ProtectionProfile

webrtc-rs · Jun 29, 2024 · f5dd5fd · f5dd5fd
1 parent 3190812
commit f5dd5fd
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Showing 7 changed files with 105 additions and 43 deletions.
diff --git a/rtc-srtp/src/cipher/cipher_aead_aes_gcm.rs b/rtc-srtp/src/cipher/cipher_aead_aes_gcm.rs
@@ -7,6 +7,7 @@ use bytes::BytesMut;
 
 use super::Cipher;
 use crate::key_derivation::*;
+use crate::protection_profile::ProtectionProfile;
 use shared::{
     error::{Error, Result},
     marshal::*,
@@ -18,15 +19,27 @@ const RTCP_ENCRYPTION_FLAG: u8 = 0x80;
 
 /// AEAD Cipher based on AES.
 pub(crate) struct CipherAeadAesGcm {
+    profile: ProtectionProfile,
     srtp_cipher: aes_gcm::Aes128Gcm,
     srtcp_cipher: aes_gcm::Aes128Gcm,
     srtp_session_salt: Vec<u8>,
     srtcp_session_salt: Vec<u8>,
 }
 
 impl Cipher for CipherAeadAesGcm {
-    fn auth_tag_len(&self) -> usize {
-        CIPHER_AEAD_AES_GCM_AUTH_TAG_LEN
+    /// Get RTP authenticated tag length.
+    fn rtp_auth_tag_len(&self) -> usize {
+        self.profile.rtp_auth_tag_len()
+    }
+
+    /// Get RTCP authenticated tag length.
+    fn rtcp_auth_tag_len(&self) -> usize {
+        self.profile.rtcp_auth_tag_len()
+    }
+
+    /// Get AEAD auth key length of the cipher.
+    fn aead_auth_tag_len(&self) -> usize {
+        self.profile.aead_auth_tag_len()
     }
 
     fn encrypt_rtp(
@@ -36,8 +49,9 @@ impl Cipher for CipherAeadAesGcm {
         roc: u32,
     ) -> Result<BytesMut> {
         // Grow the given buffer to fit the output.
-        let mut writer =
-            BytesMut::with_capacity(header.marshal_size() + payload.len() + self.auth_tag_len());
+        let mut writer = BytesMut::with_capacity(
+            header.marshal_size() + payload.len() + self.aead_auth_tag_len(),
+        );
 
         let data = header.marshal()?;
         writer.extend(data);
@@ -62,7 +76,7 @@ impl Cipher for CipherAeadAesGcm {
         header: &rtp::header::Header,
         roc: u32,
     ) -> Result<BytesMut> {
-        if ciphertext.len() < self.auth_tag_len() {
+        if ciphertext.len() < self.aead_auth_tag_len() {
             return Err(Error::ErrFailedToVerifyAuthTag);
         }
 
@@ -114,7 +128,7 @@ impl Cipher for CipherAeadAesGcm {
         srtcp_index: usize,
         ssrc: u32,
     ) -> Result<BytesMut> {
-        if encrypted.len() < self.auth_tag_len() + SRTCP_INDEX_SIZE {
+        if encrypted.len() < self.aead_auth_tag_len() + SRTCP_INDEX_SIZE {
             return Err(Error::ErrFailedToVerifyAuthTag);
         }
 
@@ -146,7 +160,11 @@ impl Cipher for CipherAeadAesGcm {
 
 impl CipherAeadAesGcm {
     /// Create a new AEAD instance.
-    pub(crate) fn new(master_key: &[u8], master_salt: &[u8]) -> Result<CipherAeadAesGcm> {
+    pub(crate) fn new(
+        profile: ProtectionProfile,
+        master_key: &[u8],
+        master_salt: &[u8],
+    ) -> Result<CipherAeadAesGcm> {
         let srtp_session_key = aes_cm_key_derivation(
             LABEL_SRTP_ENCRYPTION,
             master_key,
@@ -188,6 +206,7 @@ impl CipherAeadAesGcm {
         )?;
 
         Ok(CipherAeadAesGcm {
+            profile,
             srtp_cipher,
             srtcp_cipher,
             srtp_session_salt,

diff --git a/rtc-srtp/src/cipher/cipher_aes_cm_hmac_sha1.rs b/rtc-srtp/src/cipher/cipher_aes_cm_hmac_sha1.rs
@@ -22,6 +22,7 @@ type Aes128Ctr = ctr::Ctr128BE<aes::Aes128>;
 pub const CIPHER_AES_CM_HMAC_SHA1AUTH_TAG_LEN: usize = 10;
 
 pub(crate) struct CipherAesCmHmacSha1 {
+    profile: ProtectionProfile,
     srtp_session_key: Vec<u8>,
     srtp_session_salt: Vec<u8>,
     srtp_session_auth: HmacSha1,
@@ -33,7 +34,7 @@ pub(crate) struct CipherAesCmHmacSha1 {
 }
 
 impl CipherAesCmHmacSha1 {
-    pub fn new(master_key: &[u8], master_salt: &[u8]) -> Result<Self> {
+    pub fn new(profile: ProtectionProfile, master_key: &[u8], master_salt: &[u8]) -> Result<Self> {
         let srtp_session_key = aes_cm_key_derivation(
             LABEL_SRTP_ENCRYPTION,
             master_key,
@@ -87,6 +88,7 @@ impl CipherAesCmHmacSha1 {
             .map_err(|e| Error::Other(e.to_string()))?;
 
         Ok(CipherAesCmHmacSha1 {
+            profile,
             srtp_session_key,
             srtp_session_salt,
             srtp_session_auth,
@@ -130,7 +132,7 @@ impl CipherAesCmHmacSha1 {
         let code_bytes = result.into_bytes();
 
         // Truncate the hash to the first AUTH_TAG_SIZE bytes.
-        Ok(code_bytes[0..self.auth_tag_len()].to_vec())
+        Ok(code_bytes[0..self.rtp_auth_tag_len()].to_vec())
     }
 
     /// https://tools.ietf.org/html/rfc3711#section-4.2
@@ -153,17 +155,28 @@ impl CipherAesCmHmacSha1 {
         let code_bytes = result.into_bytes();
 
         // Truncate the hash to the first AUTH_TAG_SIZE bytes.
-        code_bytes[0..self.auth_tag_len()].to_vec()
+        code_bytes[0..self.rtcp_auth_tag_len()].to_vec()
     }
 }
 
 impl Cipher for CipherAesCmHmacSha1 {
-    fn auth_tag_len(&self) -> usize {
-        CIPHER_AES_CM_HMAC_SHA1AUTH_TAG_LEN
+    /// Get RTP authenticated tag length.
+    fn rtp_auth_tag_len(&self) -> usize {
+        self.profile.rtp_auth_tag_len()
+    }
+
+    /// Get RTCP authenticated tag length.
+    fn rtcp_auth_tag_len(&self) -> usize {
+        self.profile.rtcp_auth_tag_len()
+    }
+
+    /// Get AEAD auth key length of the cipher.
+    fn aead_auth_tag_len(&self) -> usize {
+        self.profile.aead_auth_tag_len()
     }
 
     fn get_rtcp_index(&self, input: &[u8]) -> usize {
-        let tail_offset = input.len() - (self.auth_tag_len() + SRTCP_INDEX_SIZE);
+        let tail_offset = input.len() - (self.rtcp_auth_tag_len() + SRTCP_INDEX_SIZE);
         (BigEndian::read_u32(&input[tail_offset..tail_offset + SRTCP_INDEX_SIZE]) & !(1 << 31))
             as usize
     }
@@ -174,8 +187,9 @@ impl Cipher for CipherAesCmHmacSha1 {
         header: &rtp::header::Header,
         roc: u32,
     ) -> Result<BytesMut> {
-        let mut writer =
-            BytesMut::with_capacity(header.marshal_size() + payload.len() + self.auth_tag_len());
+        let mut writer = BytesMut::with_capacity(
+            header.marshal_size() + payload.len() + self.rtp_auth_tag_len(),
+        );
 
         // Copy the header unencrypted.
         let data = header.marshal()?;
@@ -210,15 +224,18 @@ impl Cipher for CipherAesCmHmacSha1 {
         header: &rtp::header::Header,
         roc: u32,
     ) -> Result<BytesMut> {
-        if encrypted.len() < self.auth_tag_len() {
-            return Err(Error::SrtpTooSmall(encrypted.len(), self.auth_tag_len()));
+        if encrypted.len() < self.rtp_auth_tag_len() {
+            return Err(Error::SrtpTooSmall(
+                encrypted.len(),
+                self.rtp_auth_tag_len(),
+            ));
         }
 
-        let mut writer = BytesMut::with_capacity(encrypted.len() - self.auth_tag_len());
+        let mut writer = BytesMut::with_capacity(encrypted.len() - self.rtp_auth_tag_len());
 
         // Split the auth tag and the cipher text into two parts.
-        let actual_tag = &encrypted[encrypted.len() - self.auth_tag_len()..];
-        let cipher_text = &encrypted[..encrypted.len() - self.auth_tag_len()];
+        let actual_tag = &encrypted[encrypted.len() - self.rtp_auth_tag_len()..];
+        let cipher_text = &encrypted[..encrypted.len() - self.rtp_auth_tag_len()];
 
         // Generate the auth tag we expect to see from the ciphertext.
         let expected_tag = self.generate_srtp_auth_tag(cipher_text, roc)?;
@@ -257,7 +274,7 @@ impl Cipher for CipherAesCmHmacSha1 {
         ssrc: u32,
     ) -> Result<BytesMut> {
         let mut writer =
-            BytesMut::with_capacity(decrypted.len() + SRTCP_INDEX_SIZE + self.auth_tag_len());
+            BytesMut::with_capacity(decrypted.len() + SRTCP_INDEX_SIZE + self.rtcp_auth_tag_len());
 
         // Write the decrypted to the destination buffer.
         writer.extend_from_slice(decrypted);
@@ -294,14 +311,14 @@ impl Cipher for CipherAesCmHmacSha1 {
         srtcp_index: usize,
         ssrc: u32,
     ) -> Result<BytesMut> {
-        if encrypted.len() < self.auth_tag_len() + SRTCP_INDEX_SIZE {
+        if encrypted.len() < self.rtcp_auth_tag_len() + SRTCP_INDEX_SIZE {
             return Err(Error::SrtcpTooSmall(
                 encrypted.len(),
-                self.auth_tag_len() + SRTCP_INDEX_SIZE,
+                self.rtcp_auth_tag_len() + SRTCP_INDEX_SIZE,
             ));
         }
 
-        let tail_offset = encrypted.len() - (self.auth_tag_len() + SRTCP_INDEX_SIZE);
+        let tail_offset = encrypted.len() - (self.rtcp_auth_tag_len() + SRTCP_INDEX_SIZE);
 
         let mut writer = BytesMut::with_capacity(tail_offset);
 
@@ -313,8 +330,8 @@ impl Cipher for CipherAesCmHmacSha1 {
         }
 
         // Split the auth tag and the cipher text into two parts.
-        let actual_tag = &encrypted[encrypted.len() - self.auth_tag_len()..];
-        let cipher_text = &encrypted[..encrypted.len() - self.auth_tag_len()];
+        let actual_tag = &encrypted[encrypted.len() - self.rtcp_auth_tag_len()..];
+        let cipher_text = &encrypted[..encrypted.len() - self.rtcp_auth_tag_len()];
 
         // Generate the auth tag we expect to see from the ciphertext.
         let expected_tag = self.generate_srtcp_auth_tag(cipher_text);

diff --git a/rtc-srtp/src/cipher/mod.rs b/rtc-srtp/src/cipher/mod.rs
@@ -31,8 +31,14 @@ use shared::error::Result;
 /// Cipher represents a implementation of one
 /// of the SRTP Specific ciphers.
 pub(crate) trait Cipher {
-    /// Get authenticated tag length.
-    fn auth_tag_len(&self) -> usize;
+    /// Get RTP authenticated tag length.
+    fn rtp_auth_tag_len(&self) -> usize;
+
+    /// Get RTCP authenticated tag length.
+    fn rtcp_auth_tag_len(&self) -> usize;
+
+    /// Get AEAD auth key length of the cipher.
+    fn aead_auth_tag_len(&self) -> usize;
 
     /// Retrieved RTCP index.
     fn get_rtcp_index(&self, input: &[u8]) -> usize;

diff --git a/rtc-srtp/src/context/mod.rs b/rtc-srtp/src/context/mod.rs
@@ -130,12 +130,12 @@ impl Context {
         }
 
         let cipher: Box<dyn Cipher> = match profile {
-            ProtectionProfile::Aes128CmHmacSha1_80 => {
-                Box::new(CipherAesCmHmacSha1::new(master_key, master_salt)?)
+            ProtectionProfile::Aes128CmHmacSha1_32 | ProtectionProfile::Aes128CmHmacSha1_80 => {
+                Box::new(CipherAesCmHmacSha1::new(profile, master_key, master_salt)?)
             }
 
-            ProtectionProfile::AeadAes128Gcm => {
-                Box::new(CipherAeadAesGcm::new(master_key, master_salt)?)
+            ProtectionProfile::AeadAes128Gcm | ProtectionProfile::AeadAes256Gcm => {
+                Box::new(CipherAeadAesGcm::new(profile, master_key, master_salt)?)
             }
         };
 

diff --git a/rtc-srtp/src/context/srtcp_test.rs b/rtc-srtp/src/context/srtcp_test.rs
@@ -130,7 +130,7 @@ fn test_rtcp_lifecycle() -> Result<()> {
 
 #[test]
 fn test_rtcp_invalid_auth_tag() -> Result<()> {
-    let auth_tag_len = ProtectionProfile::Aes128CmHmacSha1_80.auth_tag_len();
+    let auth_tag_len = ProtectionProfile::Aes128CmHmacSha1_80.rtcp_auth_tag_len();
 
     let mut decrypt_context = Context::new(
         &RTCP_TEST_MASTER_KEY,
@@ -217,7 +217,7 @@ fn test_encrypt_rtcp_separation() -> Result<()> {
         None,
     )?;
 
-    let auth_tag_len = ProtectionProfile::Aes128CmHmacSha1_80.auth_tag_len();
+    let auth_tag_len = ProtectionProfile::Aes128CmHmacSha1_80.rtcp_auth_tag_len();
 
     let mut decrypt_context = Context::new(
         &RTCP_TEST_MASTER_KEY,

diff --git a/rtc-srtp/src/context/srtp_test.rs b/rtc-srtp/src/context/srtp_test.rs
@@ -121,7 +121,7 @@ fn test_rtp_invalid_auth() -> Result<()> {
 fn test_rtp_lifecyle() -> Result<()> {
     let mut encrypt_context = build_test_context()?;
     let mut decrypt_context = build_test_context()?;
-    let auth_tag_len = ProtectionProfile::Aes128CmHmacSha1_80.auth_tag_len();
+    let auth_tag_len = ProtectionProfile::Aes128CmHmacSha1_80.rtp_auth_tag_len();
 
     for test_case in RTP_TEST_CASES.iter() {
         let decrypted_pkt = rtp::packet::Packet {

diff --git a/rtc-srtp/src/protection_profile.rs b/rtc-srtp/src/protection_profile.rs
@@ -4,34 +4,54 @@
 pub enum ProtectionProfile {
     #[default]
     Aes128CmHmacSha1_80 = 0x0001,
+    Aes128CmHmacSha1_32 = 0x0002,
     AeadAes128Gcm = 0x0007,
+    AeadAes256Gcm = 0x0008,
 }
 
 impl ProtectionProfile {
     pub(crate) fn key_len(&self) -> usize {
         match *self {
-            ProtectionProfile::Aes128CmHmacSha1_80 | ProtectionProfile::AeadAes128Gcm => 16,
+            ProtectionProfile::Aes128CmHmacSha1_32
+            | ProtectionProfile::Aes128CmHmacSha1_80
+            | ProtectionProfile::AeadAes128Gcm => 16,
+            ProtectionProfile::AeadAes256Gcm => 32,
         }
     }
 
     pub(crate) fn salt_len(&self) -> usize {
         match *self {
-            ProtectionProfile::Aes128CmHmacSha1_80 => 14,
-            ProtectionProfile::AeadAes128Gcm => 12,
+            ProtectionProfile::Aes128CmHmacSha1_32 | ProtectionProfile::Aes128CmHmacSha1_80 => 14,
+            ProtectionProfile::AeadAes128Gcm | ProtectionProfile::AeadAes256Gcm => 12,
         }
     }
 
-    pub(crate) fn auth_tag_len(&self) -> usize {
+    pub(crate) fn rtp_auth_tag_len(&self) -> usize {
         match *self {
-            ProtectionProfile::Aes128CmHmacSha1_80 => 10, //CIPHER_AES_CM_HMAC_SHA1AUTH_TAG_LEN,
-            ProtectionProfile::AeadAes128Gcm => 16,       //CIPHER_AEAD_AES_GCM_AUTH_TAG_LEN,
+            ProtectionProfile::Aes128CmHmacSha1_80 => 10,
+            ProtectionProfile::Aes128CmHmacSha1_32 => 4,
+            ProtectionProfile::AeadAes128Gcm | ProtectionProfile::AeadAes256Gcm => 0,
+        }
+    }
+
+    pub(crate) fn rtcp_auth_tag_len(&self) -> usize {
+        match *self {
+            ProtectionProfile::Aes128CmHmacSha1_80 | ProtectionProfile::Aes128CmHmacSha1_32 => 10,
+            ProtectionProfile::AeadAes128Gcm | ProtectionProfile::AeadAes256Gcm => 0,
+        }
+    }
+
+    pub(crate) fn aead_auth_tag_len(&self) -> usize {
+        match *self {
+            ProtectionProfile::Aes128CmHmacSha1_80 | ProtectionProfile::Aes128CmHmacSha1_32 => 0,
+            ProtectionProfile::AeadAes128Gcm | ProtectionProfile::AeadAes256Gcm => 16,
         }
     }
 
     pub(crate) fn auth_key_len(&self) -> usize {
         match *self {
-            ProtectionProfile::Aes128CmHmacSha1_80 => 20,
-            ProtectionProfile::AeadAes128Gcm => 0,
+            ProtectionProfile::Aes128CmHmacSha1_80 | ProtectionProfile::Aes128CmHmacSha1_32 => 20,
+            ProtectionProfile::AeadAes128Gcm | ProtectionProfile::AeadAes256Gcm => 0,
         }
     }
 }