Convert signature to rsa signatures

Signed-off-by: Arthur Gautier <[email protected]>

Author: baloo

tss-esapi/src/abstraction/signatures.rs

@@ -1,7 +1,10 @@
 // Copyright 2024 Contributors to the Parsec project.
 // SPDX-License-Identifier: Apache-2.0
 
-use crate::{structures::EccSignature, Error, Result, WrapperErrorKind};
+use crate::{
+    structures::{EccSignature, Signature},
+    Error, Result, WrapperErrorKind,
+};
 
 use std::convert::TryFrom;
 
@@ -38,5 +41,32 @@ where
     }
 }
 
-// TODO(baloo): impl TryFrom<RsaSignature> for rsa::pkcs1v15::Signature
-// TODO(baloo): impl TryFrom<RsaSignature> for rsa::pss::Signature
+// Note: this does not implement `TryFrom<RsaSignature>` because `RsaSignature` does not carry the
+// information whether the signatures was generated using PKCS#1v1.5 or PSS.
+impl TryFrom<Signature> for rsa::pkcs1v15::Signature {
+    type Error = Error;
+
+    fn try_from(signature: Signature) -> Result<Self> {
+        let Signature::RsaSsa(signature) = signature else {
+            return Err(Error::local_error(WrapperErrorKind::InvalidParam));
+        };
+
+        Self::try_from(signature.signature().as_bytes())
+            .map_err(|_| Error::local_error(WrapperErrorKind::InvalidParam))
+    }
+}
+
+// Note: this does not implement `TryFrom<RsaSignature>` because `RsaSignature` does not carry the
+// information whether the signatures was generated using PKCS#1v1.5 or PSS.
+impl TryFrom<Signature> for rsa::pss::Signature {
+    type Error = Error;
+
+    fn try_from(signature: Signature) -> Result<Self> {
+        let Signature::RsaPss(signature) = signature else {
+            return Err(Error::local_error(WrapperErrorKind::InvalidParam));
+        };
+
+        Self::try_from(signature.signature().as_bytes())
+            .map_err(|_| Error::local_error(WrapperErrorKind::InvalidParam))
+    }
+}