1 files changed, 31 insertions, 0 deletions
diff --git a/openpgp/src/crypto/backend/openssl/kdf.rs b/openpgp/src/crypto/backend/openssl/kdf.rs
new file mode 100644
index 00000000..11c48667
--- /dev/null
+++ b/openpgp/src/crypto/backend/openssl/kdf.rs
@@ -0,0 +1,31 @@
+use openssl::{
+    md::Md,
+    pkey::Id,
+    pkey_ctx::PkeyCtx,
+};
+
+use crate::{
+    Result,
+    crypto::{
+        SessionKey,
+        backend::interface::Kdf,
+    },
+};
+
+impl Kdf for super::Backend {
+    fn hkdf_sha256(ikm: &SessionKey, salt: Option<&[u8]>, info: &[u8],
+                   okm: &mut SessionKey)
+                   -> Result<()>
+    {
+        let mut pkey = PkeyCtx::new_id(Id::HKDF)?;
+        pkey.derive_init()?;
+        pkey.set_hkdf_md(Md::sha256())?;
+        pkey.set_hkdf_key(&ikm)?;
+        if let Some(salt) = salt {
+            pkey.set_hkdf_salt(salt)?;
+        }
+        pkey.add_hkdf_info(info)?;
+        pkey.derive(Some(okm))?;
+        Ok(())
+    }
+}