openpgp: Add `MPIs::Unknown` for parameters of unknown algorithms.

  - Fixes #8.

3 files changed, 72 insertions, 8 deletions

diff --git a/openpgp/src/mpis.rs b/openpgp/src/mpis.rs
index d72740c2..ab9d8bae 100644
--- a/openpgp/src/mpis.rs
+++ b/openpgp/src/mpis.rs
@@ -212,6 +212,14 @@ pub enum MPIs {
         /// Symmetrically encrypted poition.
         key: Box<[u8]>
     },
+
+    /// Unknown number of MPIs for an unknown algorithm.
+    Unknown {
+        /// The successfully parsed MPIs.
+        mpis: Box<[MPI]>,
+        /// Any data that failed to parse.
+        rest: Box<[u8]>,
+    },
 }
 
 impl MPIs {
@@ -280,6 +288,10 @@ impl MPIs {
                 2 + e.value.len() +
                 // one length octet plus ephemeral key
                 1 + key.len(),
+
+            &Unknown { ref mpis, ref rest } =>
+                mpis.iter().map(|m| 2 + m.value.len()).sum::<usize>()
+                + rest.len(),
         }
     }
 
@@ -399,6 +411,13 @@ impl MPIs {
                 hash.update(&[key.len() as u8]);
                 hash.update(&key);
             }
+
+            &Unknown { ref mpis, ref rest } => {
+                for mpi in mpis.iter() {
+                    mpi.hash(hash);
+                }
+                hash.update(rest);
+            }
         }
     }
 }
@@ -580,6 +599,8 @@ mod tests {
                         ElgamalEncrypt, cur.into_inner()).unwrap(),
                 MPIs::ECDHCiphertext { .. } =>
                     MPIs::parse_ciphertext_naked(ECDH, cur.into_inner()).unwrap(),
+
+                MPIs::Unknown { .. } => unreachable!(),
             };
 
             mpis == mpis2
diff --git a/openpgp/src/parse/mpis.rs b/openpgp/src/parse/mpis.rs
index bf82caa8..99311dc7 100644
--- a/openpgp/src/parse/mpis.rs
+++ b/openpgp/src/parse/mpis.rs
@@ -125,8 +125,17 @@ impl MPIs {
                 })
             }
 
-            Unknown(p) | Private(p) => {
-                Err(Error::UnknownPublicKeyAlgorithm(p.into()).into())
+            Unknown(_) | Private(_) => {
+                let mut mpis = Vec::new();
+                while let Ok(mpi) = MPI::parse("unknown_parameter", php) {
+                    mpis.push(mpi);
+                }
+                let mut rest = php.parse_bytes_eof("rest")?;
+
+                Ok(MPIs::Unknown {
+                    mpis: mpis.into_boxed_slice(),
+                    rest: rest.into_boxed_slice(),
+                })
             }
         }
     }
@@ -243,8 +252,17 @@ impl MPIs {
                     scalar: MPI::parse("ecdh_secret", php)? })
             }
 
-            Unknown(p) | Private(p) => {
-                Err(Error::UnknownPublicKeyAlgorithm(p.into()).into())
+            Unknown(_) | Private(_) => {
+                let mut mpis = Vec::new();
+                while let Ok(mpi) = MPI::parse("unknown_parameter", php) {
+                    mpis.push(mpi);
+                }
+                let mut rest = php.parse_bytes_eof("rest")?;
+
+                Ok(MPIs::Unknown {
+                    mpis: mpis.into_boxed_slice(),
+                    rest: rest.into_boxed_slice(),
+                })
             }
         }
     }
@@ -308,8 +326,17 @@ impl MPIs {
                 })
             }
 
-            Unknown(p) | Private(p) => {
-                Err(Error::UnknownPublicKeyAlgorithm(p.into()).into())
+            Unknown(_) | Private(_) => {
+                let mut mpis = Vec::new();
+                while let Ok(mpi) = MPI::parse("unknown_parameter", php) {
+                    mpis.push(mpi);
+                }
+                let mut rest = php.parse_bytes_eof("rest")?;
+
+                Ok(MPIs::Unknown {
+                    mpis: mpis.into_boxed_slice(),
+                    rest: rest.into_boxed_slice(),
+                })
             }
 
             RSASign | DSA | EdDSA | ECDSA => {
@@ -398,8 +425,17 @@ impl MPIs {
                 })
             }
 
-            Unknown(p) | Private(p) => {
-                Err(Error::UnknownPublicKeyAlgorithm(p.into()).into())
+            Unknown(_) | Private(_) => {
+                let mut mpis = Vec::new();
+                while let Ok(mpi) = MPI::parse("unknown_parameter", php) {
+                    mpis.push(mpi);
+                }
+                let mut rest = php.parse_bytes_eof("rest")?;
+
+                Ok(MPIs::Unknown {
+                    mpis: mpis.into_boxed_slice(),
+                    rest: rest.into_boxed_slice(),
+                })
             }
 
             RSAEncrypt | ElgamalEncrypt | ECDH => {
diff --git a/openpgp/src/serialize/mod.rs b/openpgp/src/serialize/mod.rs
index e133ab1b..a53ed048 100644
--- a/openpgp/src/serialize/mod.rs
+++ b/openpgp/src/serialize/mod.rs
@@ -285,6 +285,13 @@ impl Serialize for mpis::MPIs {
             }
 
             &None => unreachable!(),
+
+            &Unknown { ref mpis, ref rest } => {
+                for mpi in mpis.iter() {
+                    mpi.serialize(w)?;
+                }
+                w.write_all(rest)?;
+            }
         }
 
         Ok(())