[WIP] pkcs5: add back support for using AES-GCM in PBES2

This support was originally added in #1433, but reverted in #2292 to
unblock a release of the `pkcs5` crate until such time as there is a
stable release of `aes-gcm`.

TODO: still pending a stable release of `aes-gcm`

Author: tarcieri

Cargo.lock

@@ -21,6 +21,7 @@ spki = "0.8"
 
 # optional dependencies
 aes = { version = "0.9", optional = true, default-features = false }
+aes-gcm = { version = "0.11.0-rc.3", optional = true, default-features = false, features = ["aes"] }
 cbc = { version = "0.2", optional = true }
 des = { version = "0.9", optional = true, default-features = false }
 pbkdf2 = { version = "0.13", optional = true, default-features = false, features = ["hmac"] }
@@ -39,7 +40,7 @@ alloc = []
 3des = ["dep:des", "pbes2"]
 des-insecure = ["dep:des", "pbes2"]
 getrandom = ["dep:getrandom", "rand_core"]
-pbes2 = ["dep:aes", "dep:cbc", "dep:pbkdf2", "dep:scrypt", "dep:sha2"]
+pbes2 = ["dep:aes", "dep:aes-gcm", "dep:cbc", "dep:pbkdf2", "dep:scrypt", "dep:sha2"]
 rand_core = ["dep:rand_core"]
 sha1-insecure = ["dep:sha1", "pbes2"]
 

pkcs5/Cargo.toml

@@ -39,6 +39,14 @@ pub const AES_192_CBC_OID: ObjectIdentifier =
 pub const AES_256_CBC_OID: ObjectIdentifier =
     ObjectIdentifier::new_unwrap("2.16.840.1.101.3.4.1.42");
 
+/// 128-bit Advanced Encryption Standard (AES) algorithm with Galois Counter Mode
+pub const AES_128_GCM_OID: ObjectIdentifier =
+    ObjectIdentifier::new_unwrap("2.16.840.1.101.3.4.1.6");
+
+/// 256-bit Advanced Encryption Standard (AES) algorithm with Galois Counter Mode
+pub const AES_256_GCM_OID: ObjectIdentifier =
+    ObjectIdentifier::new_unwrap("2.16.840.1.101.3.4.1.46");
+
 /// DES operating in CBC mode
 #[cfg(feature = "des-insecure")]
 pub const DES_CBC_OID: ObjectIdentifier = ObjectIdentifier::new_unwrap("1.3.14.3.2.7");
@@ -55,6 +63,12 @@ pub const PBES2_OID: ObjectIdentifier = ObjectIdentifier::new_unwrap("1.2.840.11
 /// AES cipher block size
 const AES_BLOCK_SIZE: usize = 16;
 
+/// GCM nonce size
+///
+/// We could use any value here but GCM is most efficient
+/// with 96 bit nonces
+const GCM_NONCE_SIZE: usize = 12;
+
 /// DES / Triple DES block size
 #[cfg(any(feature = "3des", feature = "des-insecure"))]
 const DES_BLOCK_SIZE: usize = 8;
@@ -255,6 +269,46 @@ impl Parameters {
         Ok(Self { kdf, encryption })
     }
 
+    /// Initialize PBES2 parameters using scrypt as the password-based
+    /// key derivation function and AES-128-GCM as the symmetric cipher.
+    ///
+    /// For more information on scrypt parameters, see documentation for the
+    /// [`scrypt::Params`] struct.
+    ///
+    /// # Errors
+    /// Propagates errors from [`ScryptParams::from_params_and_salt`].
+    // TODO(tarcieri): encapsulate `scrypt::Params`?
+    #[cfg(feature = "pbes2")]
+    pub fn scrypt_aes128gcm(
+        params: scrypt::Params,
+        salt: &[u8],
+        gcm_nonce: [u8; GCM_NONCE_SIZE],
+    ) -> Result<Self> {
+        let kdf = ScryptParams::from_params_and_salt(params, salt)?.into();
+        let encryption = EncryptionScheme::Aes128Gcm { nonce: gcm_nonce };
+        Ok(Self { kdf, encryption })
+    }
+
+    /// Initialize PBES2 parameters using scrypt as the password-based
+    /// key derivation function and AES-256-GCM as the symmetric cipher.
+    ///
+    /// For more information on scrypt parameters, see documentation for the
+    /// [`scrypt::Params`] struct.
+    ///
+    /// # Errors
+    /// Propagates errors from [`ScryptParams::from_params_and_salt`].
+    // TODO(tarcieri): encapsulate `scrypt::Params`?
+    #[cfg(feature = "pbes2")]
+    pub fn scrypt_aes256gcm(
+        params: scrypt::Params,
+        salt: &[u8],
+        gcm_nonce: [u8; GCM_NONCE_SIZE],
+    ) -> Result<Self> {
+        let kdf = ScryptParams::from_params_and_salt(params, salt)?.into();
+        let encryption = EncryptionScheme::Aes256Gcm { nonce: gcm_nonce };
+        Ok(Self { kdf, encryption })
+    }
+
     /// Attempt to decrypt the given ciphertext, allocating and returning a
     /// byte vector containing the plaintext.
     ///
@@ -387,6 +441,18 @@ pub enum EncryptionScheme {
         iv: [u8; AES_BLOCK_SIZE],
     },
 
+    /// AES-128 in CBC mode
+    Aes128Gcm {
+        /// GCM nonce
+        nonce: [u8; GCM_NONCE_SIZE],
+    },
+
+    /// AES-256 in GCM mode
+    Aes256Gcm {
+        /// GCM nonce
+        nonce: [u8; GCM_NONCE_SIZE],
+    },
+
     /// 3-Key Triple DES in CBC mode
     #[cfg(feature = "3des")]
     DesEde3Cbc {
@@ -410,6 +476,8 @@ impl EncryptionScheme {
             Self::Aes128Cbc { .. } => 16,
             Self::Aes192Cbc { .. } => 24,
             Self::Aes256Cbc { .. } => 32,
+            Self::Aes128Gcm { .. } => 16,
+            Self::Aes256Gcm { .. } => 32,
             #[cfg(feature = "des-insecure")]
             Self::DesCbc { .. } => 8,
             #[cfg(feature = "3des")]
@@ -424,6 +492,8 @@ impl EncryptionScheme {
             Self::Aes128Cbc { .. } => AES_128_CBC_OID,
             Self::Aes192Cbc { .. } => AES_192_CBC_OID,
             Self::Aes256Cbc { .. } => AES_256_CBC_OID,
+            Self::Aes128Gcm { .. } => AES_128_GCM_OID,
+            Self::Aes256Gcm { .. } => AES_256_GCM_OID,
             #[cfg(feature = "des-insecure")]
             Self::DesCbc { .. } => DES_CBC_OID,
             #[cfg(feature = "3des")]
@@ -468,6 +538,12 @@ impl TryFrom<AlgorithmIdentifierRef<'_>> for EncryptionScheme {
             AES_256_CBC_OID => Ok(Self::Aes256Cbc {
                 iv: iv.try_into().map_err(|_| Tag::OctetString.value_error())?,
             }),
+            AES_128_GCM_OID => Ok(Self::Aes128Gcm {
+                nonce: iv.try_into().map_err(|_| Tag::OctetString.value_error())?,
+            }),
+            AES_256_GCM_OID => Ok(Self::Aes256Gcm {
+                nonce: iv.try_into().map_err(|_| Tag::OctetString.value_error())?,
+            }),
             #[cfg(feature = "des-insecure")]
             DES_CBC_OID => Ok(Self::DesCbc {
                 iv: iv[0..DES_BLOCK_SIZE]
@@ -493,6 +569,8 @@ impl<'a> TryFrom<&'a EncryptionScheme> for AlgorithmIdentifierRef<'a> {
             EncryptionScheme::Aes128Cbc { iv } => iv.as_slice(),
             EncryptionScheme::Aes192Cbc { iv } => iv.as_slice(),
             EncryptionScheme::Aes256Cbc { iv } => iv.as_slice(),
+            EncryptionScheme::Aes128Gcm { nonce } => nonce.as_slice(),
+            EncryptionScheme::Aes256Gcm { nonce } => nonce.as_slice(),
             #[cfg(feature = "des-insecure")]
             EncryptionScheme::DesCbc { iv } => iv.as_slice(),
             #[cfg(feature = "3des")]

pkcs5/src/pbes2.rs

@@ -2,6 +2,7 @@
 
 use super::{EncryptionScheme, Kdf, Parameters, Pbkdf2Params, Pbkdf2Prf, ScryptParams};
 use crate::{Error, Result};
+use aes_gcm::{KeyInit as GcmKeyInit, Nonce, Tag, aead::AeadInOut};
 use cbc::cipher::{
     BlockCipherDecrypt, BlockCipherEncrypt, BlockModeDecrypt, BlockModeEncrypt, KeyInit, KeyIvInit,
     block_padding::Pkcs7,
@@ -12,7 +13,7 @@ use pbkdf2::{
         digest::{
             FixedOutput, HashMarker, Update,
             block_api::BlockSizeUser,
-            typenum::{IsLess, NonZero, True, U256},
+            typenum::{IsLess, NonZero, True, U12, U16, U256},
         },
     },
     pbkdf2_hmac,
@@ -47,6 +48,65 @@ fn cbc_decrypt<'a, C: BlockCipherDecrypt + KeyInit>(
         .map_err(|_| Error::DecryptFailed)
 }
 
+fn gcm_encrypt<C, NonceSize, TagSize>(
+    es: EncryptionScheme,
+    key: EncryptionKey,
+    nonce: Nonce<NonceSize>,
+    buffer: &mut [u8],
+    pos: usize,
+) -> Result<&[u8]>
+where
+    C: BlockSizeUser<BlockSize = U16> + GcmKeyInit + BlockCipherEncrypt,
+    aes_gcm::AesGcm<C, NonceSize, TagSize>: GcmKeyInit,
+    TagSize: aes_gcm::TagSize,
+    NonceSize: aes::cipher::array::ArraySize,
+{
+    if buffer.len() < TagSize::USIZE + pos {
+        return Err(Error::EncryptFailed);
+    }
+    let gcm =
+        <aes_gcm::AesGcm<C, NonceSize, TagSize> as GcmKeyInit>::new_from_slice(key.as_slice())
+            .map_err(|_| es.to_alg_params_invalid())?;
+    let tag = gcm
+        .encrypt_inout_detached(&nonce, &[], (&mut buffer[..pos]).into())
+        .map_err(|_| Error::EncryptFailed)?;
+    buffer[pos..].copy_from_slice(tag.as_ref());
+    Ok(&buffer[0..pos + TagSize::USIZE])
+}
+
+fn gcm_decrypt<C, NonceSize, TagSize>(
+    es: EncryptionScheme,
+    key: EncryptionKey,
+    nonce: Nonce<NonceSize>,
+    buffer: &mut [u8],
+) -> Result<&[u8]>
+where
+    C: BlockSizeUser<BlockSize = U16> + GcmKeyInit + BlockCipherEncrypt,
+    aes_gcm::AesGcm<C, NonceSize, TagSize>: GcmKeyInit,
+    TagSize: aes_gcm::TagSize,
+    NonceSize: aes::cipher::array::ArraySize,
+{
+    let msg_len = buffer
+        .len()
+        .checked_sub(TagSize::USIZE)
+        .ok_or(Error::DecryptFailed)?;
+
+    let gcm =
+        <aes_gcm::AesGcm<C, NonceSize, TagSize> as GcmKeyInit>::new_from_slice(key.as_slice())
+            .map_err(|_| es.to_alg_params_invalid())?;
+
+    let tag = Tag::try_from(&buffer[msg_len..]).map_err(|_| Error::DecryptFailed)?;
+
+    if gcm
+        .decrypt_inout_detached(&nonce, &[], (&mut buffer[..msg_len]).into(), &tag)
+        .is_err()
+    {
+        return Err(Error::DecryptFailed);
+    }
+
+    Ok(&buffer[..msg_len])
+}
+
 pub fn encrypt_in_place<'b>(
     params: &Parameters,
     password: impl AsRef<[u8]>,
@@ -64,6 +124,12 @@ pub fn encrypt_in_place<'b>(
         EncryptionScheme::Aes128Cbc { iv } => cbc_encrypt::<aes::Aes128Enc>(es, key, &iv, buf, pos),
         EncryptionScheme::Aes192Cbc { iv } => cbc_encrypt::<aes::Aes192Enc>(es, key, &iv, buf, pos),
         EncryptionScheme::Aes256Cbc { iv } => cbc_encrypt::<aes::Aes256Enc>(es, key, &iv, buf, pos),
+        EncryptionScheme::Aes128Gcm { nonce } => {
+            gcm_encrypt::<aes::Aes128Enc, U12, U16>(es, key, Nonce::from(nonce), buf, pos)
+        }
+        EncryptionScheme::Aes256Gcm { nonce } => {
+            gcm_encrypt::<aes::Aes256Enc, U12, U16>(es, key, Nonce::from(nonce), buf, pos)
+        }
         #[cfg(feature = "3des")]
         EncryptionScheme::DesEde3Cbc { iv } => cbc_encrypt::<des::TdesEde3>(es, key, &iv, buf, pos),
         #[cfg(feature = "des-insecure")]
@@ -86,6 +152,12 @@ pub fn decrypt_in_place<'a>(
         EncryptionScheme::Aes128Cbc { iv } => cbc_decrypt::<aes::Aes128Dec>(es, key, &iv, buf),
         EncryptionScheme::Aes192Cbc { iv } => cbc_decrypt::<aes::Aes192Dec>(es, key, &iv, buf),
         EncryptionScheme::Aes256Cbc { iv } => cbc_decrypt::<aes::Aes256Dec>(es, key, &iv, buf),
+        EncryptionScheme::Aes128Gcm { nonce } => {
+            gcm_decrypt::<aes::Aes128Enc, U12, U16>(es, key, Nonce::from(nonce), buf)
+        }
+        EncryptionScheme::Aes256Gcm { nonce } => {
+            gcm_decrypt::<aes::Aes256Enc, U12, U16>(es, key, Nonce::from(nonce), buf)
+        }
         #[cfg(feature = "3des")]
         EncryptionScheme::DesEde3Cbc { iv } => cbc_decrypt::<des::TdesEde3>(es, key, &iv, buf),
         #[cfg(feature = "des-insecure")]