Adding TripleDhKem key exchange (#404)

Author: kevinlewi

.github/workflows/main.yml

@@ -15,6 +15,7 @@ jobs:
         backend_feature:
           -
           - --features ristretto255
+          - --features ristretto255,kem
           - --features curve25519
           - --features ecdsa
           - --features ed25519
@@ -73,6 +74,7 @@ jobs:
         backend_feature:
           -
           - --features ristretto255
+          - --features ristretto255,kem
           - --features curve25519
           - --features ecdsa
           - --features ed25519
@@ -167,6 +169,7 @@ jobs:
       matrix:
         backend_feature:
           - --features ristretto255
+          - --features ristretto255,kem
           -
     steps:
       - name: Checkout sources
@@ -204,7 +207,7 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: clippy
-          args: --all-targets --features argon2,std,curve25519,ecdsa,ed25519 -- -D warnings
+          args: --all-targets --features argon2,std,curve25519,ecdsa,ed25519,kem -- -D warnings
 
   format:
     name: cargo fmt
@@ -233,7 +236,7 @@ jobs:
           RUSTDOCFLAGS: -D warnings
         with:
           command: doc
-          args: --no-deps --document-private-items --features argon2,std,curve25519,ecdsa,ed25519
+          args: --no-deps --document-private-items --features argon2,std,curve25519,ecdsa,ed25519,kem
 
   taplo:
     name: Taplo

Cargo.toml

@@ -18,6 +18,7 @@ curve25519 = ["dep:curve25519-dalek"]
 default = ["ristretto255", "serde"]
 ecdsa = ["dep:ecdsa", "dep:rfc6979"]
 ed25519 = ["dep:curve25519-dalek", "dep:ed25519-dalek"]
+kem = ["dep:ml-kem"]
 ristretto255 = ["dep:curve25519-dalek", "voprf/ristretto255-ciphersuite"]
 serde = [
   "dep:serde",
@@ -53,6 +54,9 @@ elliptic-curve = { version = "0.13", features = ["hash2curve", "sec1"] }
 generic-array = "=0.14.7" # pinned to avoid deprecation warnings
 hkdf = "0.12"
 hmac = "0.12"
+ml-kem = { version = "0.2", default-features = false, features = [
+  "zeroize",
+], optional = true }
 rand = { version = "0.8", default-features = false }
 rfc6979 = { version = "0.4", optional = true }
 serde = { version = "1", default-features = false, features = [

src/errors.rs

@@ -24,6 +24,8 @@ pub enum InternalError {
     HmacError,
     /// Computing the key stretching function failed
     KsfError,
+    /// Error while performing a KEM operation
+    KemError,
     /** This error occurs when the envelope seal open hmac check fails
     HMAC check in seal open failed. */
     SealOpenHmacError,
@@ -43,6 +45,7 @@ impl Debug for InternalError {
             Self::HkdfError => f.debug_tuple("HkdfError").finish(),
             Self::HmacError => f.debug_tuple("HmacError").finish(),
             Self::KsfError => f.debug_tuple("KsfError").finish(),
+            Self::KemError => f.debug_tuple("KemError").finish(),
             Self::SealOpenHmacError => f.debug_tuple("SealOpenHmacError").finish(),
             Self::IncompatibleEnvelopeModeError => {
                 f.debug_tuple("IncompatibleEnvelopeModeError").finish()

src/key_exchange/mod.rs

@@ -13,6 +13,8 @@ pub mod group;
 pub(crate) mod shared;
 pub mod sigma_i;
 pub mod tripledh;
+#[cfg(feature = "kem")]
+pub mod tripledh_kem;
 
 use core::iter;
 use core::ops::Add;