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[PM-18938] Isolate decryption support for type 0 user keys #585

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[PM-18938] Isolate decryption support for type 0 user keys #585

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60dfd44
[PM-18938] isolate decryption support for 32 byte user keys
eligrubb Nov 5, 2025
ae9ba48
Fix error returned from decrypt_user_key
eligrubb Dec 1, 2025
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20 changes: 15 additions & 5 deletions crates/bitwarden-crypto/src/enc_string/symmetric.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -332,8 +332,10 @@ impl KeyEncryptableWithContentType<SymmetricCryptoKey, EncString> for &[u8] {
impl KeyDecryptable<SymmetricCryptoKey, Vec<u8>> for EncString {
fn decrypt_with_key(&self, key: &SymmetricCryptoKey) -> Result<Vec<u8>> {
match (self, key) {
(EncString::Aes256Cbc_B64 { iv, data }, SymmetricCryptoKey::Aes256CbcKey(key)) => {
crate::aes::decrypt_aes256(iv, data.clone(), &key.enc_key)
(EncString::Aes256Cbc_B64 { .. }, SymmetricCryptoKey::Aes256CbcKey(_)) => {
Err(CryptoError::OperationNotSupported(
UnsupportedOperationError::DecryptionNotImplementedForKey,
))
}
(
EncString::Aes256Cbc_HmacSha256_B64 { iv, mac, data },
Expand Down Expand Up @@ -578,16 +580,24 @@ mod tests {
}

#[test]
fn test_decrypt_cbc256() {
fn test_decrypt_fails_for_cbc256_keys() {
let key = "hvBMMb1t79YssFZkpetYsM3deyVuQv4r88Uj9gvYe08=".to_string();
let key = SymmetricCryptoKey::try_from(key).unwrap();

let enc_str = "0.NQfjHLr6za7VQVAbrpL81w==|wfrjmyJ0bfwkQlySrhw8dA==";
let enc_string: EncString = enc_str.parse().unwrap();
assert_eq!(enc_string.enc_type(), 0);

let dec_str: String = enc_string.decrypt_with_key(&key).unwrap();
assert_eq!(dec_str, "EncryptMe!");
let result: Result<String, CryptoError> = enc_string.decrypt_with_key(&key);
assert!(
matches!(
result,
Err(CryptoError::OperationNotSupported(
crate::error::UnsupportedOperationError::DecryptionNotImplementedForKey
)),
),
"Expected decrypt to fail when using deprecated type 0 key",
);
}

#[test]
Expand Down
2 changes: 2 additions & 0 deletions crates/bitwarden-crypto/src/error.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -79,6 +79,8 @@ pub enum CryptoError {
pub enum UnsupportedOperationError {
#[error("Encryption is not implemented for key")]
EncryptionNotImplementedForKey,
#[error("Decryption is not implemented for key")]
DecryptionNotImplementedForKey,
}

#[derive(Debug, Error)]
Expand Down
44 changes: 38 additions & 6 deletions crates/bitwarden-crypto/src/keys/master_key.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -143,19 +143,17 @@ pub(super) fn decrypt_user_key(
// Legacy. user_keys were encrypted using `Aes256Cbc_B64` a long time ago. We've since
// moved to using `Aes256Cbc_HmacSha256_B64`. However, we still need to support
// decrypting these old keys.
EncString::Aes256Cbc_B64 { .. } => {
let legacy_key = SymmetricCryptoKey::Aes256CbcKey(super::Aes256CbcKey {
enc_key: Box::pin(GenericArray::clone_from_slice(key)),
});
user_key.decrypt_with_key(&legacy_key)?
EncString::Aes256Cbc_B64 { iv, ref data } => {
let legacy_key = Box::pin(GenericArray::clone_from_slice(key));
crate::aes::decrypt_aes256(&iv, data.clone(), &legacy_key)?
}
EncString::Aes256Cbc_HmacSha256_B64 { .. } => {
let stretched_key = SymmetricCryptoKey::Aes256CbcHmacKey(stretch_key(key)?);
user_key.decrypt_with_key(&stretched_key)?
}
EncString::Cose_Encrypt0_B64 { .. } => {
return Err(CryptoError::OperationNotSupported(
crate::error::UnsupportedOperationError::EncryptionNotImplementedForKey,
crate::error::UnsupportedOperationError::DecryptionNotImplementedForKey,
));
}
};
Expand Down Expand Up @@ -330,4 +328,38 @@ mod tests {
]
);
}

#[test]
fn test_decrypt_cbc256() {
let master_key = "hvBMMb1t79YssFZkpetYsM3deyVuQv4r88Uj9gvYe08=".to_string();
let master_key = SymmetricCryptoKey::try_from(master_key).unwrap();
let SymmetricCryptoKey::Aes256CbcKey(master_key) = &master_key else {
panic!("Incorrect key type for test used");
};

let master_key = MasterKey::KdfKey(KdfDerivedKeyMaterial(master_key.enc_key.clone()));

let enc_str = "0.tn/heK4HLbbEe+yEkC+kvw==|8QM94f7aVTtjm/bmvRdVxOxiLiiZtHYYO7+oBdjFCkilncesx0iVrXPl+tMKqW+Jo7+FtZdPNsTrL6RdoG7i5QbCRVwK+9010+xm7MTQY8s=";
let enc_string: EncString = enc_str.parse().unwrap();

let decrypted = master_key.decrypt_user_key(enc_string).unwrap();
let SymmetricCryptoKey::Aes256CbcHmacKey(decrypted) = &decrypted else {
panic!("Failed to decrypt Aes256CbcHmacKey from Aes256CbcKey encrypted EncString")
};

assert_eq!(
decrypted.enc_key.as_slice(),
[
116, 170, 187, 43, 80, 212, 193, 202, 234, 181, 57, 66, 151, 249, 59, 47, 70, 16,
57, 4, 170, 78, 85, 241, 152, 232, 91, 57, 9, 87, 209, 245,
]
);
assert_eq!(
decrypted.mac_key.as_slice(),
[
40, 245, 106, 140, 2, 225, 138, 213, 98, 223, 92, 168, 135, 208, 22, 194, 31, 21,
178, 252, 203, 198, 35, 174, 53, 218, 254, 151, 235, 57, 7, 98,
]
);
}
}
105 changes: 97 additions & 8 deletions crates/bitwarden-crypto/src/store/context.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -169,10 +169,10 @@ impl<Ids: KeyIds> KeyStoreContext<'_, Ids> {
let wrapping_key = self.get_symmetric_key(wrapping_key)?;

let key = match (wrapped_key, wrapping_key) {
(EncString::Aes256Cbc_B64 { iv, data }, SymmetricCryptoKey::Aes256CbcKey(key)) => {
SymmetricCryptoKey::try_from(&BitwardenLegacyKeyBytes::from(
crate::aes::decrypt_aes256(iv, data.clone(), &key.enc_key)?,
))?
(EncString::Aes256Cbc_B64 { .. }, SymmetricCryptoKey::Aes256CbcKey(_)) => {
return Err(CryptoError::OperationNotSupported(
UnsupportedOperationError::DecryptionNotImplementedForKey,
));
}
(
EncString::Aes256Cbc_HmacSha256_B64 { iv, mac, data },
Expand Down Expand Up @@ -517,8 +517,10 @@ impl<Ids: KeyIds> KeyStoreContext<'_, Ids> {
let key = self.get_symmetric_key(key)?;

match (data, key) {
(EncString::Aes256Cbc_B64 { iv, data }, SymmetricCryptoKey::Aes256CbcKey(key)) => {
crate::aes::decrypt_aes256(iv, data.clone(), &key.enc_key)
(EncString::Aes256Cbc_B64 { .. }, SymmetricCryptoKey::Aes256CbcKey(_)) => {
Err(CryptoError::OperationNotSupported(
UnsupportedOperationError::DecryptionNotImplementedForKey,
))
}
(
EncString::Aes256Cbc_HmacSha256_B64 { iv, mac, data },
Expand Down Expand Up @@ -605,8 +607,8 @@ mod tests {

use crate::{
AsymmetricCryptoKey, AsymmetricPublicCryptoKey, CompositeEncryptable, CoseKeyBytes,
CoseSerializable, CryptoError, Decryptable, KeyDecryptable, LocalId, Pkcs8PrivateKeyBytes,
SignatureAlgorithm, SigningKey, SigningNamespace, SymmetricCryptoKey,
CoseSerializable, CryptoError, Decryptable, EncString, KeyDecryptable, LocalId,
Pkcs8PrivateKeyBytes, SignatureAlgorithm, SigningKey, SigningNamespace, SymmetricCryptoKey,
store::{
KeyStore,
tests::{Data, DataView},
Expand Down Expand Up @@ -894,4 +896,91 @@ mod tests {
"Expected encrypt to fail with KeyOperationNotSupported",
);
}

#[test]
fn test_encrypt_decrypt_data_fails_when_key_is_type_0() {
let store = KeyStore::<TestIds>::default();
let mut ctx = store.context_mut();

let key_id = TestSymmKey::A(0);
let key = SymmetricCryptoKey::Aes256CbcKey(crate::Aes256CbcKey {
enc_key: Box::pin([0u8; 32].into()),
});
ctx.set_symmetric_key_internal(key_id, key).unwrap();

let data_to_encrypt: Vec<u8> = vec![1, 2, 3, 4, 5];
let result = ctx.encrypt_data_with_symmetric_key(
key_id,
&data_to_encrypt,
crate::ContentFormat::OctetStream,
);
assert!(
matches!(
result,
Err(CryptoError::OperationNotSupported(
crate::error::UnsupportedOperationError::EncryptionNotImplementedForKey
))
),
"Expected encrypt to fail when using deprecated type 0 keys",
);

let data_to_decrypt = EncString::Aes256Cbc_B64 {
iv: [0; 16],
data: data_to_encrypt,
}; // dummy value; shouldn't matter
let result = ctx.decrypt_data_with_symmetric_key(key_id, &data_to_decrypt);
assert!(
matches!(
result,
Err(CryptoError::OperationNotSupported(
crate::error::UnsupportedOperationError::DecryptionNotImplementedForKey
))
),
"Expected decrypt to fail when using deprecated type 0 keys",
);
}

#[test]
fn test_wrap_unwrap_key_fails_when_key_is_type_0() {
let store = KeyStore::<TestIds>::default();
let mut ctx = store.context_mut();

let wrapping_key_id = TestSymmKey::A(0);
let wrapping_key = SymmetricCryptoKey::Aes256CbcKey(crate::Aes256CbcKey {
enc_key: Box::pin([0u8; 32].into()),
});
ctx.set_symmetric_key_internal(wrapping_key_id, wrapping_key)
.unwrap();

let key_to_wrap_id = TestSymmKey::A(1);
let key_to_wrap = SymmetricCryptoKey::make_aes256_cbc_hmac_key();
ctx.set_symmetric_key_internal(key_to_wrap_id, key_to_wrap)
.unwrap();

let result = ctx.wrap_symmetric_key(wrapping_key_id, key_to_wrap_id);
assert!(
matches!(
result,
Err(CryptoError::OperationNotSupported(
crate::error::UnsupportedOperationError::EncryptionNotImplementedForKey
))
),
"Expected encrypt to fail when using deprecated type 0 keys",
);

let wrapped_key = &EncString::Aes256Cbc_B64 {
iv: [0; 16],
data: vec![0],
}; // dummy value; shouldn't matter
let result = ctx.unwrap_symmetric_key(wrapping_key_id, wrapped_key);
assert!(
matches!(
result,
Err(CryptoError::OperationNotSupported(
crate::error::UnsupportedOperationError::DecryptionNotImplementedForKey
))
),
"Expected decrypt to fail when using deprecated type 0 keys",
);
}
}
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