Expose a safe interface for EVP_AEAD

boring/src/aead.rs

@@ -0,0 +1,357 @@
+//! High level interface to certain AEAD schemes.
+//!
+//! # Examples
+//!
+//! Encrypt data with AES128-GCM-SIV.
+//!
+//! ```
+//! use boring::aead::{encrypt_aead, Aead};
+//!
+//! let aead = Aead::aes_128_gcm_siv();
+//! let data = b"Some Crypto Text";
+//! let aad = b"Some Crypto Context";
+//! let key = b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F";
+//! let nonce = b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x10\x11";
+//! let sealed_data = encrypt_aead(
+//!     aead,
+//!     key,
+//!     nonce,
+//!     aad,
+//!     data).unwrap();
+//!
+//! assert_eq!(
+//!     b"\x3D\xCC\xF8\x9A\x2B\xC1\x91\x15\xCD\x19\xD2\xC2\xB1\x13\x01\x38\xC5\
+//!       \x7D\xF5\xEE\x5B\x37\xD1\x44\x05\xD2\x1A\xDA\x3F\x69\x97\x5D",
+//!     &sealed_data[..]);
+//! ```
+
+use crate::ffi;
+use libc::c_int;
+
+use crate::error::ErrorStack;
+use crate::{cvt, cvt_p};
+
+use ffi::{
+    EVP_AEAD_CTX_new, EVP_AEAD_key_length, EVP_AEAD_max_overhead, EVP_AEAD_max_tag_len,
+    EVP_AEAD_nonce_length,
+};
+
+/// Represents a particular AEAD algorithm.
+///
+/// For more information see the BoringSSL documentation on [`aead.h`].
+///
+/// [`aead.h`]: https://commondatastorage.googleapis.com/chromium-boringssl-docs/aead.h.html
+#[derive(Copy, Clone, PartialEq, Eq)]
+pub struct Aead(*const ffi::EVP_AEAD);
+
+impl Aead {
+    pub fn aes_128_gcm() -> Aead {
+        unsafe { Aead(ffi::EVP_aead_aes_128_gcm()) }
+    }
+
+    pub fn aes_192_gcm() -> Aead {
+        unsafe { Aead(ffi::EVP_aead_aes_192_gcm()) }
+    }
+
+    pub fn aes_256_gcm() -> Aead {
+        unsafe { Aead(ffi::EVP_aead_aes_256_gcm()) }
+    }
+
+    pub fn chacha20_poly1305() -> Aead {
+        unsafe { Aead(ffi::EVP_aead_chacha20_poly1305()) }
+    }
+
+    pub fn xchacha20_poly1305() -> Aead {
+        unsafe { Aead(ffi::EVP_aead_xchacha20_poly1305()) }
+    }
+
+    pub fn aes_128_ctr_hmac_sha256() -> Aead {
+        unsafe { Aead(ffi::EVP_aead_aes_128_ctr_hmac_sha256()) }
+    }
+
+    pub fn aes_256_ctr_hmac_sha256() -> Aead {
+        unsafe { Aead(ffi::EVP_aead_aes_256_ctr_hmac_sha256()) }
+    }
+
+    pub fn aes_128_gcm_siv() -> Aead {
+        unsafe { Aead(ffi::EVP_aead_aes_128_gcm_siv()) }
+    }
+
+    pub fn aes_256_gcm_siv() -> Aead {
+        unsafe { Aead(ffi::EVP_aead_aes_256_gcm_siv()) }
+    }
+
+    /// Returns the length of keys used with this AEAD.
+    pub fn key_len(&self) -> usize {
+        unsafe { EVP_AEAD_key_length(self.0) as usize }
+    }
+
+    /// Returns the length of nonces used with this AEAD.
+    pub fn nonce_len(&self) -> usize {
+        unsafe { EVP_AEAD_nonce_length(self.0) as usize }
+    }
+
+    /// Returns the maximum ciphertext overhead with this AEAD.
+    pub fn max_ciphertext_overhead(&self) -> usize {
+        unsafe { EVP_AEAD_max_overhead(self.0) as usize }
+    }
+
+    /// Returns the maximum tag length with this AEAD.
+    pub fn max_tag_length(&self) -> usize {
+        unsafe { EVP_AEAD_max_tag_len(self.0) as usize }
+    }
+
+    pub fn as_ptr(&self) -> *const ffi::EVP_AEAD {
+        self.0
+    }
+}
+
+unsafe impl Sync for Aead {}
+unsafe impl Send for Aead {}
+
+/// Represents an AEAD context.
+pub struct AeadCrypter {
+    ctx: *mut ffi::EVP_AEAD_CTX,
+    max_overhead: usize,
+}
+
+impl AeadCrypter {
+    /// Creates a new `AeadCrypter`.
+    pub fn new(aead: Aead, key: &[u8]) -> Result<AeadCrypter, ErrorStack> {
+        ffi::init();
+
+        unsafe {
+            let ctx = cvt_p(EVP_AEAD_CTX_new(
+                aead.as_ptr(),
+                key.as_ptr(),
+                key.len(),
+                0, // supply tag_len = 0 so it picks the default one.
+            ))?;
+            let aeadcrypter = AeadCrypter {
+                ctx,
+                max_overhead: aead.max_ciphertext_overhead(),
+            };
+            Ok(aeadcrypter)
+        }
+    }
+
+    /// Seals data by encrypting and authenticating the provided data and authenticating the provided aad.
+    ///
+    /// Returns the number of bytes written to output.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `output.len() > c_int::max_value()`.
+    ///
+    /// Panics if `output.len() < data.len() + aead.max_overhead()`.
+    pub fn seal(
+        &mut self,
+        nonce: &[u8],
+        aad: &[u8],
+        data: &[u8],
+        output: &mut [u8],
+    ) -> Result<usize, ErrorStack> {
+        unsafe {
+            assert!(output.len() <= c_int::max_value() as usize);
+            assert!(output.len() >= data.len() + self.max_overhead);
+
+            let mut output_len = output.len();
+            let nonce_len = nonce.len();
+            let data_len = data.len();
+            let aad_len = aad.len();
+
+            cvt(ffi::EVP_AEAD_CTX_seal(
+                self.ctx,
+                output.as_mut_ptr(),
+                &mut output_len,
+                output_len,
+                nonce.as_ptr(),
+                nonce_len,
+                data.as_ptr(),
+                data_len,
+                aad.as_ptr(),
+                aad_len,
+            ))?;
+
+            Ok(output_len as usize)
+        }
+    }
+
+    /// Opens data by authenticating the provided aad and authenticating and decrypting the provided data.
+    ///
+    /// Returns the number of bytes written to output.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `output.len() > c_int::max_value()`.
+    ///
+    /// Panics if `output.len() < data.len()`.
+    pub fn open(
+        &mut self,
+        nonce: &[u8],
+        aad: &[u8],
+        data: &[u8],
+        output: &mut [u8],
+    ) -> Result<usize, ErrorStack> {
+        unsafe {
+            assert!(output.len() <= c_int::max_value() as usize);
+            assert!(output.len() >= data.len());
+
+            let mut output_len = output.len();
+            let nonce_len = nonce.len();
+            let data_len = data.len();
+            let aad_len = aad.len();
+
+            cvt(ffi::EVP_AEAD_CTX_open(
+                self.ctx,
+                output.as_mut_ptr(),
+                &mut output_len,
+                output_len,
+                nonce.as_ptr(),
+                nonce_len,
+                data.as_ptr(),
+                data_len,
+                aad.as_ptr(),
+                aad_len,
+            ))?;
+
+            Ok(output_len)
+        }
+    }
+}
+
+impl Drop for AeadCrypter {
+    fn drop(&mut self) {
+        unsafe {
+            ffi::EVP_AEAD_CTX_free(self.ctx);
+        }
+    }
+}
+
+/// Encrypts the provided data and authenticates the ciphertext and the provided aad.
+///
+/// Returns the sealed data as a vector.
+pub fn encrypt_aead(
+    aead: Aead,
+    key: &[u8],
+    nonce: &[u8],
+    aad: &[u8],
+    data: &[u8],
+) -> Result<Vec<u8>, ErrorStack> {
+    let mut aeadcrypter = AeadCrypter::new(aead, key)?;
+    let mut output = vec![0u8; data.len() + aead.max_ciphertext_overhead()];
+    let bytes_written_to_output = aeadcrypter.seal(nonce, aad, data, &mut output)?;
+    Ok(output[..bytes_written_to_output].to_vec())
+}
+
+/// Authenticates the provided data and aad and decrypts the provided data.
+///
+/// Returns the unsealed data as a vector.
+pub fn decrypt_aead(
+    aead: Aead,
+    key: &[u8],
+    nonce: &[u8],
+    aad: &[u8],
+    data: &[u8],
+) -> Result<Vec<u8>, ErrorStack> {
+    let mut aeadcrypter = AeadCrypter::new(aead, key)?;
+    let mut output = vec![0u8; data.len()];
+    let bytes_written_to_output = aeadcrypter.open(nonce, aad, data, &mut output)?;
+    Ok(output[..bytes_written_to_output].to_vec())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use hex::{self, FromHex};
+
+    #[test]
+    fn test_aead_encrypt_decrypt() {
+        let key = [0u8; 16];
+        let nonce = [0u8; 16];
+        let aad = [0u8; 16];
+        let data = [0u8; 16];
+
+        let encrypted_data = encrypt_aead(Aead::aes_128_gcm(), &key, &nonce, &aad, &data).unwrap();
+        let decrypted_data =
+            decrypt_aead(Aead::aes_128_gcm(), &key, &nonce, &aad, &encrypted_data).unwrap();
+        assert_eq!(decrypted_data, data);
+    }
+
+    #[test]
+    fn test_xchacha20_poly1305_rfc_test_vector() {
+        // Test Vector from https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-xchacha#appendix-A.1
+        let key = Vec::from_hex("808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9f")
+            .unwrap();
+        let nonce = Vec::from_hex("404142434445464748494a4b4c4d4e4f5051525354555657").unwrap();
+        let aad = Vec::from_hex("50515253c0c1c2c3c4c5c6c7").unwrap();
+        let data = Vec::from_hex("4c616469657320616e642047656e746c656d656e206f662074686520636c617373206f66202739393a204966204920636f756c64206f6666657220796f75206f6e6c79206f6e652074697020666f7220746865206675747572652c2073756e73637265656e20776f756c642062652069742e").unwrap();
+
+        let expected_tag = Vec::from_hex("c0875924c1c7987947deafd8780acf49").unwrap();
+        let expected_encrypted_data = Vec::from_hex("bd6d179d3e83d43b9576579493c0e939572a1700252bfaccbed2902c21396cbb731c7f1b0b4aa6440bf3a82f4eda7e39ae64c6708c54c216cb96b72e1213b4522f8c9ba40db5d945b11b69b982c1bb9e3f3fac2bc369488f76b2383565d3fff921f9664c97637da9768812f615c68b13b52e").unwrap();
+
+        let encrypted_data =
+            encrypt_aead(Aead::xchacha20_poly1305(), &key, &nonce, &aad, &data).unwrap();
+        assert_eq!(
+            encrypted_data,
+            [expected_encrypted_data, expected_tag].concat()
+        );
+
+        let decrypted_data = decrypt_aead(
+            Aead::xchacha20_poly1305(),
+            &key,
+            &nonce,
+            &aad,
+            &encrypted_data,
+        )
+        .unwrap();
+        assert_eq!(decrypted_data, data);
+    }
+
+    #[test]
+    fn test_aes_128_gcm_siv_rfc_test_vector() {
+        // Test Vector from https://datatracker.ietf.org/doc/html/rfc8452#appendix-C.1
+        let key = Vec::from_hex("f901cfe8a69615a93fdf7a98cad48179").unwrap();
+        let nonce = Vec::from_hex("6245709fb18853f68d833640").unwrap();
+        let aad =
+            Vec::from_hex("7576f7028ec6eb5ea7e298342a94d4b202b370ef9768ec6561c4fe6b7e7296fa859c21")
+                .unwrap();
+        let data = Vec::from_hex("e42a3c02c25b64869e146d7b233987bddfc240871d").unwrap();
+
+        let expected_encrypted_data = Vec::from_hex(
+            "391cc328d484a4f46406181bcd62efd9b3ee197d052d15506c84a9edd65e13e9d24a2a6e70",
+        )
+        .unwrap();
+
+        let encrypted_data =
+            encrypt_aead(Aead::aes_128_gcm_siv(), &key, &nonce, &aad, &data).unwrap();
+        assert_eq!(encrypted_data, expected_encrypted_data);
+
+        let decrypted_data =
+            decrypt_aead(Aead::aes_128_gcm_siv(), &key, &nonce, &aad, &encrypted_data).unwrap();
+        assert_eq!(decrypted_data, data);
+    }
+
+    #[test]
+    fn test_aes_256_gcm_nist_test_vector() {
+        // A NIST AES-GCM Test Vector from https://csrc.nist.gov/projects/cryptographic-algorithm-validation-program/CAVP-TESTING-BLOCK-CIPHER-MODES#GCMVS
+
+        let key = Vec::from_hex("78e53ed07c0f162406ee17c54344e2ae").unwrap();
+        let nonce = Vec::from_hex("6ed7b5bb11c6a939cd89ace4").unwrap();
+        let aad = Vec::from_hex("64cc7dadca51bdcfa9fd03969c19b356fcea6b81").unwrap();
+        let data = Vec::from_hex("85ca499a25cc7a85b22a8208f48f6316f6d06af9ef8589dca095d58e2a75ce9d41e9c4260327799f43de4939a9ca3b3fc66d26").unwrap();
+
+        let expected_tag = Vec::from_hex("64dd1120250dfca1efd3a3043f0a1c33").unwrap(); // Note: the original NIST test vector had a 13-byte tag (because of course it did), I added the last "0a1c33" to make it the expected 16 bytes.
+        let expected_encrypted_data = Vec::from_hex("070a337a3d84f6a6feea1d941c8287c2705a4b3af3e47f90e51303b7d37b9b9d7f977c2759a74ac6545f38d4022b642a6758de").unwrap();
+
+        let encrypted_data = encrypt_aead(Aead::aes_128_gcm(), &key, &nonce, &aad, &data).unwrap();
+        assert_eq!(
+            encrypted_data,
+            [expected_encrypted_data, expected_tag].concat()
+        );
+
+        let decrypted_data =
+            decrypt_aead(Aead::aes_128_gcm(), &key, &nonce, &aad, &encrypted_data).unwrap();
+        assert_eq!(decrypted_data, data);
+    }
+}

boring/src/lib.rs

@@ -27,6 +27,7 @@ mod macros;
 mod bio;
 #[macro_use]
 mod util;
+pub mod aead;
 pub mod aes;
 pub mod asn1;
 pub mod base64;