| // Copyright (c) 2012 The Chromium OS Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| // Crypto - class for handling the keyset key management functions relating to |
| // cryptohome. This includes wrapping/unwrapping the vault keyset (and |
| // supporting functions) and setting/clearing the user keyring for use with |
| // ecryptfs. |
| |
| #ifndef CRYPTOHOME_CRYPTO_H_ |
| #define CRYPTOHOME_CRYPTO_H_ |
| |
| #include <stdint.h> |
| |
| #include <memory> |
| #include <string> |
| #include <utility> |
| #include <vector> |
| |
| #include <base/files/file_path.h> |
| #include <base/macros.h> |
| #include <brillo/secure_blob.h> |
| |
| #include "cryptohome/le_credential_manager.h" |
| #include "cryptohome/tpm.h" |
| #include "cryptohome/tpm_init.h" |
| |
| #include "vault_keyset.pb.h" // NOLINT(build/include) |
| |
| namespace cryptohome { |
| |
| class VaultKeyset; |
| |
| extern const char kSystemSaltFile[]; |
| |
| class Crypto { |
| public: |
| enum CryptoError { |
| CE_NONE = 0, |
| CE_TPM_FATAL, |
| CE_TPM_COMM_ERROR, |
| CE_TPM_DEFEND_LOCK, |
| CE_TPM_CRYPTO, |
| CE_TPM_REBOOT, |
| CE_SCRYPT_CRYPTO, |
| CE_OTHER_FATAL, |
| CE_OTHER_CRYPTO, |
| CE_NO_PUBLIC_KEY_HASH, |
| // Low Entropy(LE) credential protection is not supported on this device. |
| CE_LE_NOT_SUPPORTED, |
| // The LE secret provided during decryption is invalid. |
| CE_LE_INVALID_SECRET, |
| }; |
| |
| // Default constructor |
| explicit Crypto(Platform* platform); |
| |
| virtual ~Crypto(); |
| |
| // Initializes Crypto |
| virtual bool Init(TpmInit* tpm_init); |
| |
| // Decrypts an encrypted vault keyset. The vault keyset should be the output |
| // of EncryptVaultKeyset(). |
| // |
| // Parameters |
| // encrypted_keyset - The blob containing the encrypted keyset |
| // vault_key - The passkey used to decrypt the keyset |
| // crypt_flags (OUT) - Whether the keyset was wrapped by the TPM or scrypt |
| // error (OUT) - The specific error code on failure |
| // vault_keyset (OUT) - The decrypted vault keyset on success |
| virtual bool DecryptVaultKeyset(const SerializedVaultKeyset& serialized, |
| const brillo::SecureBlob& vault_key, |
| unsigned int* crypt_flags, CryptoError* error, |
| VaultKeyset* vault_keyset) const; |
| |
| // Encrypts the vault keyset with the given passkey |
| // |
| // Parameters |
| // vault_keyset - The VaultKeyset to encrypt |
| // vault_key - The passkey used to encrypt the keyset |
| // vault_key_salt - The salt to use for the vault passkey to key conversion |
| // when encrypting the keyset |
| // obfuscated_username - The value of username obfuscated. It's the same |
| // value used as the folder name where the user data |
| // is stored. |
| // encrypted_keyset - On success, the encrypted vault keyset |
| virtual bool EncryptVaultKeyset(const VaultKeyset& vault_keyset, |
| const brillo::SecureBlob& vault_key, |
| const brillo::SecureBlob& vault_key_salt, |
| const std::string& obfuscated_username, |
| SerializedVaultKeyset* serialized) const; |
| |
| // Derives secrets and other values from User Passkey. |
| // |
| // Parameters |
| // passkey - The User Passkey, from which to derive the secrets. |
| // salt - The salt used when deriving the secrests. |
| // gen_secrets (OUT) - Vector containing resulting secrets. |
| // |
| // The blob in |gen_secrets| should be allocated by the caller. |
| bool DeriveSecretsSCrypt(const brillo::Blob& passkey, |
| const brillo::Blob& salt, |
| std::vector<brillo::SecureBlob*> gen_secrets) const; |
| |
| // Converts the passkey to authorization data for a TPM-backed crypto token. |
| // |
| // Parameters |
| // passkey - The passkey from which to derive the authorization data. |
| // salt - The salt file used in deriving the authorization data. |
| // auth_data (OUT) - The token authorization data. |
| virtual bool PasskeyToTokenAuthData(const brillo::Blob& passkey, |
| const base::FilePath& salt_file, |
| brillo::SecureBlob* auth_data) const; |
| |
| // Gets an existing salt, or creates one if it doesn't exist |
| // |
| // Parameters |
| // path - The path to the salt file |
| // length - The length of the new salt if it needs to be created |
| // force - If true, forces creation of a new salt even if the file exists |
| // salt (OUT) - The salt |
| virtual bool GetOrCreateSalt(const base::FilePath& path, |
| size_t length, |
| bool force, |
| brillo::SecureBlob* salt) const; |
| |
| // Converts a null-terminated password to a passkey (ascii-encoded first half |
| // of the salted SHA1 hash of the password). |
| // |
| // Parameters |
| // password - The password to convert |
| // salt - The salt used during hashing |
| // passkey (OUT) - The passkey |
| static void PasswordToPasskey(const char* password, |
| const brillo::Blob& salt, |
| brillo::SecureBlob* passkey); |
| |
| // Ensures that the TPM is connected |
| CryptoError EnsureTpm(bool reload_key) const; |
| |
| // Seals arbitrary-length data to the TPM's PCR0. |
| // Parameters |
| // data - Data to encrypt with tpm. |
| // encrypted_data (OUT) - Encrypted data as a string. |
| // Returns true if we succeeded in creating the encrypted data blob. |
| virtual bool EncryptWithTpm(const brillo::SecureBlob& data, |
| std::string* encrypted_data) const; |
| |
| // Decrypts data previously sealed to the TPM's PCR0. |
| // Parameters |
| // encrypted_data - Encrypted data previously sealed with EncryptWithTPM. |
| // data (OUT) - Decrypted data as a blob. |
| // Returns true if we succeeded to decrypt the data blob. |
| virtual bool DecryptWithTpm(const std::string& encrypted_data, |
| brillo::SecureBlob* data) const; |
| |
| // Note the following 4 methods are only to be used if there is a strong |
| // reason to avoid talking to the TPM e.g. needing to flush some encrypted |
| // data periodically to disk and you don't want to seal a key each time. |
| // Otherwise, a user should use Encrypt/DecryptWithTpm. |
| |
| // Creates a randomly generated aes key and seals it to the TPM's PCR0. |
| virtual bool CreateSealedKey(brillo::SecureBlob* aes_key, |
| brillo::SecureBlob* sealed_key) const; |
| |
| // Encrypts the given data using the aes_key. Sealed key is necessary to |
| // wrap into the returned data to allow for decryption. |
| virtual bool EncryptData(const brillo::SecureBlob& data, |
| const brillo::SecureBlob& aes_key, |
| const brillo::SecureBlob& sealed_key, |
| std::string* encrypted_data) const; |
| |
| // Returns the sealed and unsealed aes_key wrapped in the encrypted_data. |
| virtual bool UnsealKey(const std::string& encrypted_data, |
| brillo::SecureBlob* aes_key, |
| brillo::SecureBlob* sealed_key) const; |
| |
| // Decrypts encrypted_data using the aes_key. |
| virtual bool DecryptData(const std::string& encrypted_data, |
| const brillo::SecureBlob& aes_key, |
| brillo::SecureBlob* data) const; |
| |
| // Attempts to reset an LE credential, specified by |serialized_reset| |
| // with an unencrypted key represented by |vk|. |
| // Returns true on success. |
| // On failure, false is returned and |error| is set with the appropriate |
| // error. |
| bool ResetLECredential(const SerializedVaultKeyset& serialized_reset, |
| CryptoError* error, |
| const VaultKeyset& vk) const; |
| |
| // Removes an LE credential specified by |label|. |
| // Returns true on success, false otherwise. |
| bool RemoveLECredential(uint64_t label) const; |
| |
| // Returns whether the provided label needs valid PCR criteria attached. |
| bool NeedsPcrBinding(const uint64_t& label) const; |
| |
| // Sets whether or not to use the TPM (must be called before init, depends |
| // on the presence of a functioning, initialized TPM). The TPM is merely used |
| // to add a layer of difficulty in a brute-force attack against the user's |
| // credentials. |
| void set_use_tpm(bool value) { |
| use_tpm_ = value; |
| } |
| |
| // Sets the TPM implementation |
| void set_tpm(Tpm* value) { |
| tpm_ = value; |
| } |
| |
| // Gets whether the TPM is set |
| bool has_tpm() { |
| return (tpm_ != NULL); |
| } |
| |
| // Gets the TPM implementation |
| Tpm* get_tpm() { |
| return tpm_; |
| } |
| |
| // Checks if the cryptohome key is loaded in TPM |
| bool is_cryptohome_key_loaded() const; |
| |
| // Sets the Platform implementation |
| // Does NOT take ownership of the pointer. |
| void set_platform(Platform* value) { |
| platform_ = value; |
| } |
| |
| Platform* platform() { |
| return platform_; |
| } |
| |
| void set_scrypt_max_encrypt_time(double max_time) { |
| scrypt_max_encrypt_time_ = max_time; |
| } |
| |
| void set_le_manager_for_testing( |
| std::unique_ptr<LECredentialManager> le_manager) { |
| le_manager_ = std::move(le_manager); |
| } |
| |
| static const int64_t kSaltMax; |
| |
| private: |
| // Converts a TPM error to a Crypto error |
| CryptoError TpmErrorToCrypto(Tpm::TpmRetryAction retry_action) const; |
| |
| bool GenerateEncryptedRawKeyset(const VaultKeyset& vault_keyset, |
| const brillo::SecureBlob& kdf_skey, |
| const brillo::SecureBlob& vkk_seed, |
| const brillo::SecureBlob& fek_iv, |
| const brillo::SecureBlob& chaps_iv, |
| brillo::SecureBlob* cipher_text, |
| brillo::SecureBlob* wrapped_chaps_key, |
| brillo::SecureBlob* vkk_key) const; |
| |
| bool EncryptTPM(const VaultKeyset& vault_keyset, |
| const brillo::SecureBlob& key, |
| const brillo::SecureBlob& salt, |
| SerializedVaultKeyset* serialized) const; |
| |
| // Encrypt a provided blob using Scrypt encryption. |
| // |
| // This is a helper function used by EncryptScrypt() to encrypt various |
| // data blobs. The parameters are as follows: |
| // - blob: Data blob to be encrypted. |
| // - key_source: User passphrase key used for encryption. |
| // - wrapped_blob: Pointer to blob where encrypted data is stored. |
| // |
| // Returns true on success, and false on failure. |
| bool EncryptScryptBlob(const brillo::SecureBlob& blob, |
| const brillo::SecureBlob& key_source, |
| brillo::SecureBlob* wrapped_blob) const; |
| |
| bool EncryptScrypt(const VaultKeyset& vault_keyset, |
| const brillo::SecureBlob& key, |
| SerializedVaultKeyset* serialized) const; |
| |
| bool EncryptLECredential(const VaultKeyset& vault_keyset, |
| const brillo::SecureBlob& key, |
| const brillo::SecureBlob& salt, |
| const std::string& obfuscated_username, |
| SerializedVaultKeyset* serialized) const; |
| |
| bool DecryptTPM(const SerializedVaultKeyset& serialized, |
| const brillo::SecureBlob& key, |
| CryptoError* error, |
| VaultKeyset* vault_keyset) const; |
| |
| // Companion decryption function for Crypto::EncryptScryptBlob() |
| // This is a helper function used by DecryptScrypt() to decrypt |
| // the data blobs which were encrypted using EncryptScryptBlob(). |
| // |
| // Returns true on success. On failure, false is returned, and |
| // |error| is set with the appropriate error code. |
| bool DecryptScryptBlob(const brillo::SecureBlob& wrapped_blob, |
| const brillo::SecureBlob& key, |
| brillo::SecureBlob* blob, |
| CryptoError* error) const; |
| |
| bool DecryptScrypt(const SerializedVaultKeyset& serialized, |
| const brillo::SecureBlob& key, |
| CryptoError* error, |
| VaultKeyset* keyset) const; |
| |
| bool DecryptLECredential(const SerializedVaultKeyset& serialized, |
| const brillo::SecureBlob& key, |
| CryptoError* error, |
| VaultKeyset* vault_keyset) const; |
| |
| bool EncryptAuthorizationData(SerializedVaultKeyset* serialized, |
| const brillo::SecureBlob& vkk_key, |
| const brillo::SecureBlob& vkk_iv) const; |
| |
| void DecryptAuthorizationData(const SerializedVaultKeyset& serialized, |
| VaultKeyset* keyset, |
| const brillo::SecureBlob& vkk_key, |
| const brillo::SecureBlob& vkk_iv) const; |
| |
| bool IsTPMPubkeyHash(const std::string& hash, CryptoError* error) const; |
| |
| // Computes the PCR digest for default state as well as the future digest |
| // obtained if PCR for ARC++ would be extended with |obfuscated_username| |
| // value. Populates the results in |valid_pcr_criteria| where each pair |
| // represents the bitmask of used PCR indexes and the expected digest. |
| bool GetValidPCRValues(const std::string& obfuscated_username, |
| ValidPcrCriteria* valid_pcr_criteria) const; |
| |
| // If set, the TPM will be used during the encryption of the vault keyset |
| bool use_tpm_; |
| |
| // The TPM implementation |
| Tpm* tpm_; |
| |
| // Platform abstraction |
| Platform* platform_; |
| |
| // The TpmInit object used to reload Cryptohome key |
| TpmInit* tpm_init_; |
| |
| double scrypt_max_encrypt_time_; |
| |
| // Handler for Low Entropy credentials. |
| std::unique_ptr<LECredentialManager> le_manager_; |
| |
| DISALLOW_COPY_AND_ASSIGN(Crypto); |
| }; |
| |
| } // namespace cryptohome |
| |
| #endif // CRYPTOHOME_CRYPTO_H_ |