pkcs5: add support for using AES-GCM in PBES2 (#1433)

Interoperable with pycryptodome and botan

Author: randombit

Cargo.toml

@@ -68,6 +68,10 @@ whirlpool = { git = "https://github.com/RustCrypto/hashes.git" }
 cbc = { git = "https://github.com/RustCrypto/block-modes.git" }
 # Pending a release of 0.11.0-pre
 salsa20  = { git = "https://github.com/RustCrypto/stream-ciphers.git" }
+# Pending a release of 0.11.0-pre
+aes-gcm = { git = "https://github.com/RustCrypto/AEADs.git" }
+aead = { git = "https://github.com/RustCrypto/traits.git" }
+ctr = { git = "https://github.com/RustCrypto/block-modes.git" }
 
 # https://github.com/RustCrypto/formats/pull/1055
 # https://github.com/RustCrypto/signatures/pull/809

pkcs5/Cargo.toml

@@ -22,6 +22,7 @@ spki = { version = "=0.8.0-pre.0" }
 # optional dependencies
 cbc = { version = "=0.2.0-pre", optional = true }
 aes = { version = "=0.9.0-pre", optional = true, default-features = false }
+aes-gcm = { version = "=0.11.0-pre", optional = true, default-features = false, features = ["aes"] }
 des = { version = "=0.9.0-pre.0", optional = true, default-features = false }
 pbkdf2 = { version = "=0.13.0-pre.0", optional = true, default-features = false, features = ["hmac"] }
 rand_core = { version = "0.6.4", optional = true, default-features = false }
@@ -37,7 +38,7 @@ alloc = []
 3des = ["dep:des", "pbes2"]
 des-insecure = ["dep:des", "pbes2"]
 getrandom = ["rand_core/getrandom"]
-pbes2 = ["dep:aes", "dep:cbc", "dep:pbkdf2", "dep:scrypt", "dep:sha2"]
+pbes2 = ["dep:aes", "dep:cbc", "dep:pbkdf2", "dep:scrypt", "dep:sha2", "dep:aes-gcm"]
 sha1-insecure = ["dep:sha1", "pbes2"]
 
 [package.metadata.docs.rs]

pkcs5/src/pbes2.rs

@@ -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;
@@ -205,6 +219,40 @@ 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.
+    // 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.
+    // 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.
     #[cfg(all(feature = "alloc", feature = "pbes2"))]
@@ -321,6 +369,18 @@ 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 {
@@ -343,6 +403,8 @@ 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")]
@@ -356,6 +418,8 @@ 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")]
@@ -399,6 +463,12 @@ 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]
@@ -424,6 +494,8 @@ 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/encryption.rs

@@ -2,6 +2,7 @@
 
 use super::{EncryptionScheme, Kdf, Parameters, Pbkdf2Params, Pbkdf2Prf, ScryptParams};
 use crate::{Error, Result};
+use aes_gcm::{AeadInPlace, KeyInit as GcmKeyInit, Nonce, Tag};
 use cbc::cipher::{
     block_padding::Pkcs7, BlockCipher, BlockCipherDecrypt, BlockCipherEncrypt, BlockModeDecrypt,
     BlockModeEncrypt, KeyInit, KeyIvInit,
@@ -11,7 +12,7 @@ use pbkdf2::{
         digest::{
             block_buffer::Eager,
             core_api::{BlockSizeUser, BufferKindUser, FixedOutputCore, UpdateCore},
-            typenum::{IsLess, Le, NonZero, U256},
+            typenum::{IsLess, Le, NonZero, U12, U16, U256},
             HashMarker,
         },
         EagerHash,
@@ -48,6 +49,65 @@ fn cbc_decrypt<'a, C: BlockCipherDecrypt + BlockCipher + KeyInit>(
         .map_err(|_| Error::EncryptFailed)
 }
 
+fn gcm_encrypt<C, NonceSize, TagSize>(
+    es: EncryptionScheme,
+    key: EncryptionKey,
+    nonce: Nonce<NonceSize>,
+    buffer: &mut [u8],
+    pos: usize,
+) -> Result<&[u8]>
+where
+    C: BlockCipher + BlockSizeUser<BlockSize = U16> + GcmKeyInit + BlockCipherEncrypt,
+    aes_gcm::AesGcm<C, NonceSize, TagSize>: GcmKeyInit,
+    TagSize: aes_gcm::TagSize,
+    NonceSize: aes::cipher::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_in_place_detached(&nonce, &[], &mut buffer[..pos])
+        .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: BlockCipher + BlockSizeUser<BlockSize = U16> + GcmKeyInit + BlockCipherEncrypt,
+    aes_gcm::AesGcm<C, NonceSize, TagSize>: GcmKeyInit,
+    TagSize: aes_gcm::TagSize,
+    NonceSize: aes::cipher::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_in_place_detached(&nonce, &[], &mut buffer[..msg_len], &tag)
+        .is_err()
+    {
+        return Err(Error::DecryptFailed);
+    }
+
+    Ok(&buffer[..msg_len])
+}
+
 pub fn encrypt_in_place<'b>(
     params: &Parameters,
     password: impl AsRef<[u8]>,
@@ -65,6 +125,12 @@ 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")]
@@ -87,6 +153,12 @@ 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")]

pkcs8/tests/encrypted_private_key.rs

@@ -46,6 +46,28 @@ const ED25519_DER_AES256_PBKDF2_SHA256_EXAMPLE: &[u8] =
 const ED25519_DER_AES256_SCRYPT_EXAMPLE: &[u8] =
     include_bytes!("examples/ed25519-encpriv-aes256-scrypt.der");
 
+/// Ed25519 PKCS#8 encrypted private key (PBES2 + AES-128-GCM + scrypt) encoded as ASN.1 DER.
+///
+/// Generated using:
+///
+/// ```
+/// $ botan pkcs8  ed25519-priv-pkcs8v1.der --der-out '--pbe=PBES2(AES-128/GCM,Scrypt)' --pass-out=hunter42
+/// ```
+#[cfg(feature = "encryption")]
+const ED25519_DER_AES128_GCM_SCRYPT_EXAMPLE: &[u8] =
+    include_bytes!("examples/ed25519-encpriv-aes128-gcm-scrypt.der");
+
+/// Ed25519 PKCS#8 encrypted private key (PBES2 + AES-256-GCM + scrypt) encoded as ASN.1 DER.
+///
+/// Generated using:
+///
+/// ```
+/// $ botan pkcs8  ed25519-priv-pkcs8v1.der --der-out '--pbe=PBES2(AES-256/GCM,Scrypt)' --pass-out=hunter42
+/// ```
+#[cfg(feature = "encryption")]
+const ED25519_DER_AES256_GCM_SCRYPT_EXAMPLE: &[u8] =
+    include_bytes!("examples/ed25519-encpriv-aes256-gcm-scrypt.der");
+
 /// Ed25519 PKCS#8 encrypted private key encoded as PEM
 #[cfg(feature = "pem")]
 const ED25519_PEM_AES256_PBKDF2_SHA256_EXAMPLE: &str =
@@ -158,6 +180,64 @@ fn decrypt_ed25519_der_encpriv_aes256_scrypt() {
     assert_eq!(pk.as_bytes(), ED25519_DER_PLAINTEXT_EXAMPLE);
 }
 
+#[cfg(feature = "encryption")]
+#[test]
+fn decrypt_ed25519_der_encpriv_aes128_gcm_scrypt() {
+    let enc_pk = EncryptedPrivateKeyInfo::try_from(ED25519_DER_AES128_GCM_SCRYPT_EXAMPLE).unwrap();
+    let pk = enc_pk.decrypt(PASSWORD).unwrap();
+    assert_eq!(pk.as_bytes(), ED25519_DER_PLAINTEXT_EXAMPLE);
+}
+
+#[cfg(feature = "encryption")]
+#[test]
+fn encrypt_ed25519_der_encpriv_aes128_gcm_scrypt() {
+    let scrypt_params = pkcs5::pbes2::Parameters::scrypt_aes128gcm(
+        pkcs5::scrypt::Params::new(14, 8, 1, 16).unwrap(),
+        &hex!("05BE17663E551D120F81308E"),
+        hex!("D7E967A5DF6189471BCC1F49"),
+    )
+    .unwrap();
+
+    let pk_plaintext = PrivateKeyInfo::try_from(ED25519_DER_PLAINTEXT_EXAMPLE).unwrap();
+    let pk_encrypted = pk_plaintext
+        .encrypt_with_params(scrypt_params, PASSWORD)
+        .unwrap();
+
+    assert_eq!(
+        pk_encrypted.as_bytes(),
+        ED25519_DER_AES128_GCM_SCRYPT_EXAMPLE
+    );
+}
+
+#[cfg(feature = "encryption")]
+#[test]
+fn decrypt_ed25519_der_encpriv_aes256_gcm_scrypt() {
+    let enc_pk = EncryptedPrivateKeyInfo::try_from(ED25519_DER_AES256_GCM_SCRYPT_EXAMPLE).unwrap();
+    let pk = enc_pk.decrypt(PASSWORD).unwrap();
+    assert_eq!(pk.as_bytes(), ED25519_DER_PLAINTEXT_EXAMPLE);
+}
+
+#[cfg(feature = "encryption")]
+#[test]
+fn encrypt_ed25519_der_encpriv_aes256_gcm_scrypt() {
+    let scrypt_params = pkcs5::pbes2::Parameters::scrypt_aes256gcm(
+        pkcs5::scrypt::Params::new(15, 8, 1, 32).unwrap(),
+        &hex!("F67F4005A8393BD41F5B4981"),
+        hex!("98B118A950D39E2ECB5B125C"),
+    )
+    .unwrap();
+
+    let pk_plaintext = PrivateKeyInfo::try_from(ED25519_DER_PLAINTEXT_EXAMPLE).unwrap();
+    let pk_encrypted = pk_plaintext
+        .encrypt_with_params(scrypt_params, PASSWORD)
+        .unwrap();
+
+    assert_eq!(
+        pk_encrypted.as_bytes(),
+        ED25519_DER_AES256_GCM_SCRYPT_EXAMPLE
+    );
+}
+
 #[cfg(feature = "encryption")]
 #[test]
 fn encrypt_ed25519_der_encpriv_aes256_pbkdf2_sha256() {