openpgp: Make list of supported algorithms backend-dependent.

3 files changed, 81 insertions, 22 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,
+        }
+    }
+}
diff --git a/openpgp/src/types/mod.rs b/openpgp/src/types/mod.rs
index 750ef2ca..09b79f9d 100644
--- a/openpgp/src/types/mod.rs
+++ b/openpgp/src/types/mod.rs
@@ -195,14 +195,7 @@ impl PublicKeyAlgorithm {
     /// assert!(!PublicKeyAlgorithm::Private(101).is_supported());
     /// ```
     pub fn is_supported(&self) -> bool {
-        use self::PublicKeyAlgorithm::*;
-        #[allow(deprecated)]
-        match &self {
-            RSAEncryptSign | RSAEncrypt | RSASign | DSA | ECDH | ECDSA | EdDSA
-                => true,
-            ElGamalEncrypt | ElGamalEncryptSign | Private(_) | Unknown(_)
-                => false,
-        }
+        self.is_supported_by_backend()
     }
 }
 
@@ -491,13 +484,7 @@ impl Curve {
     /// assert!(!Curve::Unknown(Box::new([0x2B, 0x11])).is_supported());
     /// ```
     pub fn is_supported(&self) -> bool {
-        use self::Curve::*;
-        match &self {
-            NistP256 | NistP384 | NistP521 | Ed25519 | Cv25519
-                => true,
-            BrainpoolP256 | BrainpoolP512 | Unknown(_)
-                => false,
-        }
+        self.is_supported_by_backend()
     }
 }
 
@@ -738,13 +725,7 @@ impl AEADAlgorithm {
     /// assert!(!AEADAlgorithm::OCB.is_supported());
     /// ```
     pub fn is_supported(&self) -> bool {
-        use self::AEADAlgorithm::*;
-        match &self {
-            EAX
-                => true,
-            OCB | Private(_) | Unknown(_)
-                => false,
-        }
+        self.is_supported_by_backend()
     }
 }