1 files changed, 101 insertions, 0 deletions
diff --git a/openpgp/src/crypto/backend/botan.rs b/openpgp/src/crypto/backend/botan.rs
new file mode 100644
index 00000000..30f42a67
--- /dev/null
+++ b/openpgp/src/crypto/backend/botan.rs
@@ -0,0 +1,101 @@
+//! Implementation of Sequoia crypto API using the Botan cryptographic library.
+
+use crate::types::*;
+
+pub mod aead;
+#[allow(unused_variables)]
+pub mod asymmetric;
+#[allow(unused_variables)]
+pub mod ecdh;
+pub mod hash;
+pub mod symmetric;
+
+/// Returns a short, human-readable description of the backend.
+pub fn backend() -> String {
+    "Botan".to_string()
+}
+
+/// Fills the given buffer with random data.
+pub fn random(buf: &mut [u8]) {
+    let mut rng = botan::RandomNumberGenerator::new_system().unwrap();
+    rng.fill(buf).unwrap();
+}
+
+impl PublicKeyAlgorithm {
+    pub(crate) fn is_supported_by_backend(&self) -> bool {
+        use PublicKeyAlgorithm::*;
+        #[allow(deprecated)]
+        match &self {
+            RSAEncryptSign | RSAEncrypt | RSASign | DSA | ECDH | ECDSA | EdDSA |
+            ElGamalEncrypt | ElGamalEncryptSign
+                => true,
+            Private(_) | Unknown(_)
+                => false,
+        }
+    }
+}
+
+impl Curve {
+    pub(crate) fn is_supported_by_backend(&self) -> bool {
+        use self::Curve::*;
+        match &self {
+            NistP256 | NistP384 | NistP521 | Ed25519 | Cv25519 |
+            BrainpoolP256 | BrainpoolP512
+                => true,
+            Unknown(_) if self.is_brainpoolp384() // XXX
+                => true,
+            Unknown(_)
+                => false,
+        }
+    }
+}
+
+impl AEADAlgorithm {
+    /// Returns the best AEAD mode supported by the backend.
+    ///
+    /// This SHOULD return OCB, which is the mandatory-to-implement
+    /// algorithm and the most performing one, but fall back to any
+    /// supported algorithm.
+    pub(crate) const fn const_default() -> AEADAlgorithm {
+        AEADAlgorithm::OCB
+    }
+
+    pub(crate) fn is_supported_by_backend(&self) -> bool {
+        use self::AEADAlgorithm::*;
+        match &self {
+            EAX | OCB
+                => true,
+            Private(_) | Unknown(_)
+                => false,
+        }
+    }
+
+    #[cfg(test)]
+    pub(crate) fn supports_symmetric_algo(&self, algo: &SymmetricAlgorithm) -> bool {
+        match &self {
+            AEADAlgorithm::EAX =>
+                match algo {
+                    SymmetricAlgorithm::AES128 |
+                    SymmetricAlgorithm::AES192 |
+                    SymmetricAlgorithm::AES256 |
+                    SymmetricAlgorithm::Twofish |
+                    SymmetricAlgorithm::Camellia128 |
+                    SymmetricAlgorithm::Camellia192 |
+                    SymmetricAlgorithm::Camellia256 => true,
+                    _ => false,
+                },
+            AEADAlgorithm::OCB =>
+                match algo {
+                    SymmetricAlgorithm::AES128 |
+                    SymmetricAlgorithm::AES192 |
+                    SymmetricAlgorithm::AES256 |
+                    SymmetricAlgorithm::Twofish |
+                    SymmetricAlgorithm::Camellia128 |
+                    SymmetricAlgorithm::Camellia192 |
+                    SymmetricAlgorithm::Camellia256 => true,
+                    _ => false,
+                },
+            _ => false
+        }
+    }
+}