Crypto: fix aes256ctr decryption and test

The buf of decrypted text should be set the same
length as the ciphertext. This commit also changed
the feature `rust-crypto` and `openssl` to be
compatitable .

When both of them are enabled, uses `openssl`.

Signed-off-by: Xynnn007 <[email protected]>

Cargo.toml

@@ -11,7 +11,7 @@ anyhow = "1.0"
 async-trait = "0.1.56"
 base64 = "0.13.0"
 bincode = { version = "1.3.3", optional = true }
-ctr = "0.9.2"
+ctr = { version = "0.9.2", optional = true }
 foreign-types = { version = "0.5.0", optional = true }
 kbs-types = { git = "https://github.com/virtee/kbs-types" }
 log = "0.4.14"
@@ -38,7 +38,7 @@ tokio = { version = "1.20.1", features = ["macros", "rt-multi-thread"] }
 tonic-build = { version = "0.8.0", optional = true }
 
 [features]
-default = ["sample_kbc"]
+default = ["sample_kbc", "rust-crypto"]
 sample_kbc = []
 cc_kbc = ["rand", "rsa", "sha2", "tdx-attest-rs", "reqwest"]
 eaa_kbc = ["foreign-types"]
@@ -48,9 +48,5 @@ online_sev_kbc = ["tonic", "prost", "uuid", "bincode", "tokio"]
 gen-proto = ["tonic-build"]
 
 # Either `rust-crypto` or `openssl` should be enabled to work as underlying crypto module
-rust-crypto = ["dep:aes-gcm", "crypto"]
-openssl = ["dep:openssl", "crypto"]
-
-crypto = []
-
-crypto-compatibility-test = [ "dep:aes-gcm", "openssl" ]
+rust-crypto = ["dep:aes-gcm", "ctr"]
+openssl = ["dep:openssl"]

Makefile

@@ -25,11 +25,9 @@ RUSTFLAGS_ARGS ?=
 OPENSSL ?=
 
 ifdef KBC
-    feature := --no-default-features --features
     FEATURES := $(KBC)
 else
-    feature := --features
-    FEATURES := default
+    FEATURES := sample_kbc
 endif
 
 ifeq ($(LIBC), musl)
@@ -104,7 +102,7 @@ else
 endif
 
 build:
-	cd app && $(RUST_FLAGS) cargo build $(release) $(feature) $(FEATURES) $(LIBC_FLAG)
+	cd app && $(RUST_FLAGS) cargo build $(release) --no-default-features --features $(FEATURES) $(LIBC_FLAG)
 
 TARGET := app/$(TARGET_DIR)/$(BIN_NAME)
 

src/common/crypto/aes256ctr.rs

@@ -7,18 +7,17 @@
 
 use anyhow::*;
 
-#[cfg(feature = "rust-crypto")]
-use aes_gcm::aes::Aes256;
-#[cfg(feature = "rust-crypto")]
-use ctr::{
-    cipher::{KeyIvInit, StreamCipher},
-    Ctr128BE,
-};
-
-#[cfg(feature = "rust-crypto")]
+#[cfg(all(feature = "rust-crypto", not(feature = "openssl")))]
 pub fn decrypt(encrypted_data: &[u8], key: &[u8], iv: &[u8]) -> Result<Vec<u8>> {
+    use aes_gcm::aes::Aes256;
+    use ctr::{
+        cipher::{KeyIvInit, StreamCipher},
+        Ctr128BE,
+    };
+
     let mut decryptor = Ctr128BE::<Aes256>::new(key.into(), iv.into());
     let mut buf = Vec::new();
+    buf.resize(encrypted_data.len(), b' ');
     decryptor
         .apply_keystream_b2b(encrypted_data, &mut buf)
         .map_err(|e| anyhow!("aes-256-ctr decrypt failed: {:?}", e))?;
@@ -35,3 +34,30 @@ pub fn decrypt(encrypted_data: &[u8], key: &[u8], iv: &[u8]) -> Result<Vec<u8>>
     openssl::symm::decrypt(cipher, key, Some(iv), encrypted_data)
         .map_err(|e| anyhow!(e.to_string()))
 }
+
+#[cfg(all(feature = "rust-crypto", feature = "openssl"))]
+#[cfg(test)]
+mod tests {
+    use ctr::{
+        cipher::{KeyIvInit, StreamCipher},
+        Ctr128BE,
+    };
+
+    #[test]
+    fn compatible_with_openssl() {
+        use aes_gcm::aes::Aes256;
+
+        let plaintext = b"plaintext message";
+        let key = [0x42; 32];
+        let iv = [0x24; 16];
+        let mut cipher = Ctr128BE::<Aes256>::new(&key.into(), &iv.into());
+        let mut cipher_text = Vec::new();
+        cipher_text.resize(plaintext.len(), b' ');
+        cipher
+            .apply_keystream_b2b(plaintext, &mut cipher_text)
+            .expect("encryption failed");
+
+        let decrypted = super::decrypt(&cipher_text, &key, &iv).expect("decrypt failed");
+        assert_eq!(decrypted, plaintext);
+    }
+}

src/common/crypto/aes256gcm.rs

@@ -7,10 +7,10 @@
 
 use anyhow::*;
 
-#[cfg(feature = "rust-crypto")]
+#[cfg(all(feature = "rust-crypto", not(feature = "openssl")))]
 use aes_gcm::{aead::Aead, Aes256Gcm, Key, KeyInit, Nonce};
 
-#[cfg(feature = "rust-crypto")]
+#[cfg(all(feature = "rust-crypto", not(feature = "openssl")))]
 pub fn decrypt(encrypted_data: &[u8], key: &[u8], iv: &[u8]) -> Result<Vec<u8>> {
     let decrypting_key = Key::<Aes256Gcm>::from_slice(key);
     let cipher = Aes256Gcm::new(decrypting_key);
@@ -40,15 +40,14 @@ pub fn decrypt(encrypted_data: &[u8], key: &[u8], iv: &[u8]) -> Result<Vec<u8>>
         .map_err(|e| anyhow!(e.to_string()))
 }
 
+#[cfg(all(feature = "rust-crypto", feature = "openssl"))]
 #[cfg(test)]
 mod tests {
-    #[cfg(feature = "crypto-compatibility-test")]
     use aes_gcm::{
         aead::{Aead, OsRng},
         Aes256Gcm, KeyInit, Nonce,
     };
 
-    #[cfg(feature = "crypto-compatibility-test")]
     #[test]
     fn compatible_with_openssl() {
         let plaintext = b"plaintext message";

src/common/crypto/mod.rs

@@ -11,9 +11,6 @@ use zeroize::Zeroizing;
 mod aes256ctr;
 mod aes256gcm;
 
-#[cfg(all(not(feature = "openssl"), not(feature = "rust-crypto")))]
-compile_error!("One feature of `openssl` and ``rust-crypto` must be enabled.");
-
 /// Supported WrapType, s.t. encryption algorithm using to encrypt the
 /// [PLBCO](https://github.com/confidential-containers/attestation-agent/blob/main/docs/IMPLEMENTATION.md#encryption-and-decryption-of-container-image).
 /// TODO: Support more kinds of en/decryption schemes.