1 files changed, 92 insertions, 0 deletions
diff --git a/third_party/rust/ohttp/src/hpke.rs b/third_party/rust/ohttp/src/hpke.rs
new file mode 100644
index 0000000000..7bca571923
--- /dev/null
+++ b/third_party/rust/ohttp/src/hpke.rs
@@ -0,0 +1,92 @@
+macro_rules! convert_enum {
+    ($(#[$meta:meta])* $vis:vis enum $name:ident {
+        $($(#[$vmeta:meta])* $vname:ident $(= $val:expr)?,)*
+    }) => {
+        $(#[$meta])*
+        #[derive(Clone, Copy, Debug, PartialEq, Eq)]
+        $vis enum $name {
+            $($(#[$vmeta])* $vname $(= $val)?,)*
+        }
+
+        impl std::convert::TryFrom<u16> for $name {
+            type Error = crate::Error;
+
+            fn try_from(v: u16) -> Result<Self, Self::Error> {
+                match v {
+                    $(x if x == $name::$vname as u16 => Ok($name::$vname),)*
+                    _ => Err(crate::Error::Unsupported),
+                }
+            }
+        }
+
+        impl std::convert::From<$name> for u16 {
+            fn from(v: $name) -> u16 {
+                v as u16
+            }
+        }
+    }
+}
+
+convert_enum! {
+pub enum Kem {
+    X25519Sha256 = 32,
+}
+}
+
+impl Kem {
+    #[must_use]
+    pub fn n_enc(self) -> usize {
+        match self {
+            Kem::X25519Sha256 => 32,
+        }
+    }
+
+    #[must_use]
+    pub fn n_pk(self) -> usize {
+        match self {
+            Kem::X25519Sha256 => 32,
+        }
+    }
+}
+
+convert_enum! {
+    pub enum Kdf {
+        HkdfSha256 = 1,
+        HkdfSha384 = 2,
+        HkdfSha512 = 3,
+    }
+}
+
+convert_enum! {
+    pub enum Aead {
+        Aes128Gcm = 1,
+        Aes256Gcm = 2,
+        ChaCha20Poly1305 = 3,
+    }
+}
+
+impl Aead {
+    /// The size of the key for this AEAD.
+    #[must_use]
+    pub fn n_k(self) -> usize {
+        match self {
+            Aead::Aes128Gcm => 16,
+            Aead::Aes256Gcm | Aead::ChaCha20Poly1305 => 32,
+        }
+    }
+
+    /// The size of the nonce for this AEAD.
+    #[must_use]
+    pub fn n_n(self) -> usize {
+        match self {
+            Aead::Aes128Gcm | Aead::Aes256Gcm | Aead::ChaCha20Poly1305 => 12,
+        }
+    }
+
+    /// The size of the tag for this AEAD.
+    #[must_use]
+    #[allow(clippy::unused_self)] // This is only presently constant.
+    pub fn n_t(self) -> usize {
+        16
+    }
+}