age: impl From<[u8; 16]> and ExposeSecret<[u8; 16]> for FileKey

External crates will need to be able to create FileKeys in order to implement the Identity trait, and will need to be able to to read them in order to implement the future Recipient trait.
str4d · Jul 12, 2020 · b7adcca · b7adcca
1 parent ce13b2a
commit b7adcca
Show file tree

Hide file tree

Showing 6 changed files with 56 additions and 43 deletions.
diff --git a/age/src/format/scrypt.rs b/age/src/format/scrypt.rs
@@ -3,9 +3,10 @@ use age_core::{
     primitives::{aead_decrypt, aead_encrypt},
 };
 use rand::{rngs::OsRng, RngCore};
-use secrecy::{ExposeSecret, Secret, SecretString};
+use secrecy::{ExposeSecret, SecretString};
 use std::convert::TryInto;
 use std::time::Duration;
+use zeroize::Zeroize;
 
 use crate::{error::Error, keys::FileKey, primitives::scrypt, util::read::base64_arg};
 
@@ -91,7 +92,7 @@ impl RecipientStanza {
         let enc_key = scrypt(&inner_salt, log_n, passphrase.expose_secret()).expect("log_n < 64");
         let encrypted_file_key = {
             let mut key = [0; ENCRYPTED_FILE_KEY_BYTES];
-            key.copy_from_slice(&aead_encrypt(&enc_key, file_key.0.expose_secret()));
+            key.copy_from_slice(&aead_encrypt(&enc_key, file_key.expose_secret()));
             key
         };
 
@@ -128,11 +129,11 @@ impl RecipientStanza {
                 }
             })?;
         aead_decrypt(&enc_key, &self.encrypted_file_key)
-            .map(|pt| {
+            .map(|mut pt| {
                 // It's ours!
-                let mut file_key = [0; 16];
-                file_key.copy_from_slice(&pt);
-                Some(FileKey(Secret::new(file_key)))
+                let file_key: [u8; 16] = pt[..].try_into().unwrap();
+                pt.zeroize();
+                Some(file_key.into())
             })
             .map_err(Error::from)
     }

diff --git a/age/src/format/ssh_ed25519.rs b/age/src/format/ssh_ed25519.rs
@@ -4,10 +4,11 @@ use age_core::{
 };
 use curve25519_dalek::edwards::EdwardsPoint;
 use rand::rngs::OsRng;
-use secrecy::{ExposeSecret, Secret};
+use secrecy::ExposeSecret;
 use sha2::{Digest, Sha256, Sha512};
 use std::convert::TryInto;
 use x25519_dalek::{EphemeralSecret, PublicKey, StaticSecret};
+use zeroize::Zeroize;
 
 use crate::{
     error::Error, format::x25519::ENCRYPTED_FILE_KEY_BYTES, keys::FileKey, util::read::base64_arg,
@@ -74,7 +75,7 @@ impl RecipientStanza {
         );
         let encrypted_file_key = {
             let mut key = [0; ENCRYPTED_FILE_KEY_BYTES];
-            key.copy_from_slice(&aead_encrypt(&enc_key, file_key.0.expose_secret()));
+            key.copy_from_slice(&aead_encrypt(&enc_key, file_key.expose_secret()));
             key
         };
 
@@ -124,11 +125,11 @@ impl RecipientStanza {
         Some(
             aead_decrypt(&enc_key, &self.rest.encrypted_file_key)
                 .map_err(Error::from)
-                .map(|pt| {
+                .map(|mut pt| {
                     // It's ours!
-                    let mut file_key = [0; 16];
-                    file_key.copy_from_slice(&pt);
-                    FileKey(Secret::new(file_key))
+                    let file_key: [u8; 16] = pt[..].try_into().unwrap();
+                    pt.zeroize();
+                    file_key.into()
                 }),
         )
     }

diff --git a/age/src/format/ssh_rsa.rs b/age/src/format/ssh_rsa.rs
@@ -1,8 +1,10 @@
 use age_core::format::AgeStanza;
 use rand::rngs::OsRng;
 use rsa::{padding::PaddingScheme, PublicKey, RSAPrivateKey, RSAPublicKey};
-use secrecy::{ExposeSecret, Secret};
+use secrecy::ExposeSecret;
 use sha2::{Digest, Sha256};
+use std::convert::TryInto;
+use zeroize::Zeroize;
 
 use crate::{error::Error, keys::FileKey, util::read::base64_arg};
 
@@ -45,7 +47,7 @@ impl RecipientStanza {
             .encrypt(
                 &mut rng,
                 PaddingScheme::new_oaep_with_label::<Sha256, _>(SSH_RSA_OAEP_LABEL),
-                file_key.0.expose_secret(),
+                file_key.expose_secret(),
             )
             .expect("pubkey is valid and file key is not too long");
 
@@ -75,11 +77,11 @@ impl RecipientStanza {
                 &self.encrypted_file_key,
             )
             .map_err(Error::from)
-            .map(|pt| {
+            .map(|mut pt| {
                 // It's ours!
-                let mut file_key = [0; 16];
-                file_key.copy_from_slice(&pt);
-                FileKey(Secret::new(file_key))
+                let file_key: [u8; 16] = pt[..].try_into().unwrap();
+                pt.zeroize();
+                file_key.into()
             }),
         )
     }

diff --git a/age/src/format/x25519.rs b/age/src/format/x25519.rs
@@ -3,9 +3,10 @@ use age_core::{
     primitives::{aead_decrypt, aead_encrypt, hkdf},
 };
 use rand::rngs::OsRng;
-use secrecy::{ExposeSecret, Secret};
+use secrecy::ExposeSecret;
 use std::convert::TryInto;
 use x25519_dalek::{EphemeralSecret, PublicKey, StaticSecret};
+use zeroize::Zeroize;
 
 use crate::{error::Error, keys::FileKey, util::read::base64_arg};
 
@@ -48,7 +49,7 @@ impl RecipientStanza {
         let enc_key = hkdf(&salt, X25519_RECIPIENT_KEY_LABEL, shared_secret.as_bytes());
         let encrypted_file_key = {
             let mut key = [0; ENCRYPTED_FILE_KEY_BYTES];
-            key.copy_from_slice(&aead_encrypt(&enc_key, file_key.0.expose_secret()));
+            key.copy_from_slice(&aead_encrypt(&enc_key, file_key.expose_secret()));
             key
         };
 
@@ -70,11 +71,11 @@ impl RecipientStanza {
 
         aead_decrypt(&enc_key, &self.encrypted_file_key)
             .map_err(Error::from)
-            .map(|pt| {
+            .map(|mut pt| {
                 // It's ours!
-                let mut file_key = [0; 16];
-                file_key.copy_from_slice(&pt);
-                FileKey(Secret::new(file_key))
+                let file_key: [u8; 16] = pt[..].try_into().unwrap();
+                pt.zeroize();
+                file_key.into()
             })
     }
 }
@@ -102,19 +103,18 @@ pub(super) mod write {
 mod tests {
     use quickcheck::TestResult;
     use quickcheck_macros::quickcheck;
-    use secrecy::{ExposeSecret, Secret};
+    use secrecy::ExposeSecret;
     use x25519_dalek::{PublicKey, StaticSecret};
 
     use super::RecipientStanza;
-    use crate::keys::FileKey;
 
     #[quickcheck]
     fn wrap_and_unwrap(sk_bytes: Vec<u8>) -> TestResult {
         if sk_bytes.len() > 32 {
             return TestResult::discard();
         }
 
-        let file_key = FileKey(Secret::new([7; 16]));
+        let file_key = [7; 16].into();
         let sk = {
             let mut tmp = [0; 32];
             tmp[..sk_bytes.len()].copy_from_slice(&sk_bytes);
@@ -125,7 +125,7 @@ mod tests {
         let res = stanza.unwrap_file_key(&sk);
 
         TestResult::from_bool(
-            res.is_ok() && res.unwrap().0.expose_secret() == file_key.0.expose_secret(),
+            res.is_ok() && res.unwrap().expose_secret() == file_key.expose_secret(),
         )
     }
 }
diff --git a/age/src/keys.rs b/age/src/keys.rs
@@ -39,13 +39,25 @@ fn parse_bech32(s: &str, expected_hrp: &str) -> Option<Result<[u8; 32], &'static
 }
 
 /// A file key for encrypting or decrypting an age file.
-pub struct FileKey(pub(crate) Secret<[u8; 16]>);
+pub struct FileKey(Secret<[u8; 16]>);
+
+impl From<[u8; 16]> for FileKey {
+    fn from(file_key: [u8; 16]) -> Self {
+        FileKey(Secret::new(file_key))
+    }
+}
+
+impl ExposeSecret<[u8; 16]> for FileKey {
+    fn expose_secret(&self) -> &[u8; 16] {
+        self.0.expose_secret()
+    }
+}
 
 impl FileKey {
     pub(crate) fn generate() -> Self {
         let mut file_key = [0; 16];
         OsRng.fill_bytes(&mut file_key);
-        FileKey(Secret::new(file_key))
+        file_key.into()
     }
 
     pub(crate) fn mac_key(&self) -> HmacKey {

diff --git a/age/src/ssh/identity.rs b/age/src/ssh/identity.rs
@@ -281,16 +281,13 @@ pub(crate) fn ssh_identity(input: &str) -> IResult<&str, Identity> {
 
 #[cfg(test)]
 pub(crate) mod tests {
-    use secrecy::{ExposeSecret, Secret};
+    use secrecy::ExposeSecret;
     use std::io::BufReader;
 
     use super::Identity;
-    use crate::{
-        keys::FileKey,
-        ssh::recipient::{
-            tests::{TEST_SSH_ED25519_PK, TEST_SSH_RSA_PK},
-            Recipient,
-        },
+    use crate::ssh::recipient::{
+        tests::{TEST_SSH_ED25519_PK, TEST_SSH_RSA_PK},
+        Recipient,
     };
 
     pub(crate) const TEST_SSH_RSA_SK: &str = "-----BEGIN RSA PRIVATE KEY-----
@@ -339,13 +336,13 @@ AAAEADBJvjZT8X6JRJI8xVq/1aU8nMVgOtVnmdwqWwrSlXG3sKLqeplhpW+uObz5dvMgjz
         };
         let pk: Recipient = TEST_SSH_RSA_PK.parse().unwrap();
 
-        let file_key = FileKey(Secret::new([12; 16]));
+        let file_key = [12; 16].into();
 
         let wrapped = pk.wrap_file_key(&file_key);
         let unwrapped = sk.unwrap_file_key(&wrapped);
         assert_eq!(
-            unwrapped.unwrap().unwrap().0.expose_secret(),
-            file_key.0.expose_secret()
+            unwrapped.unwrap().unwrap().expose_secret(),
+            file_key.expose_secret()
         );
     }
 
@@ -359,13 +356,13 @@ AAAEADBJvjZT8X6JRJI8xVq/1aU8nMVgOtVnmdwqWwrSlXG3sKLqeplhpW+uObz5dvMgjz
         };
         let pk: Recipient = TEST_SSH_ED25519_PK.parse().unwrap();
 
-        let file_key = FileKey(Secret::new([12; 16]));
+        let file_key = [12; 16].into();
 
         let wrapped = pk.wrap_file_key(&file_key);
         let unwrapped = sk.unwrap_file_key(&wrapped);
         assert_eq!(
-            unwrapped.unwrap().unwrap().0.expose_secret(),
-            file_key.0.expose_secret()
+            unwrapped.unwrap().unwrap().expose_secret(),
+            file_key.expose_secret()
         );
     }
 }