openpgp: Make list of supported algorithms backend-dependent.

2 files changed, 78 insertions, 0 deletions

diff --git a/openpgp/src/crypto/backend/cng.rs b/openpgp/src/crypto/backend/cng.rs
index 9947f3a2..8bf01b02 100644
--- a/openpgp/src/crypto/backend/cng.rs
+++ b/openpgp/src/crypto/backend/cng.rs
@@ -1,5 +1,7 @@
 //! Implementation of crypto primitives using the Windows CNG (Cryptographic API: Next Generation).
 
+use crate::types::*;
+
 use win_crypto_ng::random::RandomNumberGenerator;
 
 pub mod aead;
@@ -14,3 +16,40 @@ pub fn random<B: AsMut<[u8]>>(mut buf: B) {
         .gen_random(buf.as_mut())
         .expect("system-preferred RNG not to fail")
 }
+
+impl PublicKeyAlgorithm {
+    pub(crate) fn is_supported_by_backend(&self) -> bool {
+        use PublicKeyAlgorithm::*;
+        #[allow(deprecated)]
+        match &self {
+            RSAEncryptSign | RSAEncrypt | RSASign | DSA | ECDH | ECDSA | EdDSA
+                => true,
+            ElGamalEncrypt | ElGamalEncryptSign | Private(_) | Unknown(_)
+                => false,
+        }
+    }
+}
+
+impl Curve {
+    pub(crate) fn is_supported_by_backend(&self) -> bool {
+        use self::Curve::*;
+        match &self {
+            NistP256 | NistP384 | NistP521 | Ed25519 | Cv25519
+                => true,
+            BrainpoolP256 | BrainpoolP512 | Unknown(_)
+                => false,
+        }
+    }
+}
+
+impl AEADAlgorithm {
+    pub(crate) fn is_supported_by_backend(&self) -> bool {
+        use self::AEADAlgorithm::*;
+        match &self {
+            EAX
+                => true,
+            OCB | Private(_) | Unknown(_)
+                => false,
+        }
+    }
+}
diff --git a/openpgp/src/crypto/backend/nettle.rs b/openpgp/src/crypto/backend/nettle.rs
index a07e7824..9bf737c0 100644
--- a/openpgp/src/crypto/backend/nettle.rs
+++ b/openpgp/src/crypto/backend/nettle.rs
@@ -1,5 +1,7 @@
 //! Implementation of Sequoia crypto API using the Nettle cryptographic library.
 
+use crate::types::*;
+
 use nettle::random::{Random, Yarrow};
 
 pub mod aead;
@@ -20,3 +22,40 @@ pub mod symmetric;
 pub fn random<B: AsMut<[u8]>>(mut buf: B) {
     Yarrow::default().random(buf.as_mut());
 }
+
+impl PublicKeyAlgorithm {
+    pub(crate) fn is_supported_by_backend(&self) -> bool {
+        use PublicKeyAlgorithm::*;
+        #[allow(deprecated)]
+        match &self {
+            RSAEncryptSign | RSAEncrypt | RSASign | DSA | ECDH | ECDSA | EdDSA
+                => true,
+            ElGamalEncrypt | ElGamalEncryptSign | Private(_) | Unknown(_)
+                => false,
+        }
+    }
+}
+
+impl Curve {
+    pub(crate) fn is_supported_by_backend(&self) -> bool {
+        use self::Curve::*;
+        match &self {
+            NistP256 | NistP384 | NistP521 | Ed25519 | Cv25519
+                => true,
+            BrainpoolP256 | BrainpoolP512 | Unknown(_)
+                => false,
+        }
+    }
+}
+
+impl AEADAlgorithm {
+    pub(crate) fn is_supported_by_backend(&self) -> bool {
+        use self::AEADAlgorithm::*;
+        match &self {
+            EAX
+                => true,
+            OCB | Private(_) | Unknown(_)
+                => false,
+        }
+    }
+}