EncryptedFile

class EncryptedFile

Class used to create and read encrypted files. WARNING: The encrypted file should not be backed up with Auto Backup. When restoring the file it is likely the key used to encrypt it will no longer be present. You should exclude all EncryptedFiles from backup using backup rules. Be aware that if you are not explicitly calling setKeysetPrefName() there is also a silently-created default preferences file created at 

    ApplicationProvider
         .getApplicationContext()
         .getFilesDir()
         .getParent() + "/shared_prefs/__androidx_security_crypto_encrypted_file_pref__"
 This preferences file (or any others created with a custom specified location) also should be excluded from backups. Basic use of the class: 
 MasterKey masterKey = new MasterKey.Builder(context)
     .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
     .build();

 File file = new File(context.getFilesDir(), "secret_data");
 EncryptedFile encryptedFile = EncryptedFile.Builder(
     context,
     file,
     masterKey,
     EncryptedFile.FileEncryptionScheme.AES256_GCM_HKDF_4KB
 ).build();

 // write to the encrypted file
 FileOutputStream encryptedOutputStream = encryptedFile.openFileOutput();

 // read the encrypted file
 FileInputStream encryptedInputStream = encryptedFile.openFileInput();

Summary

Nested types

Builder class to configure EncryptedFile

The encryption scheme to encrypt files.

Public functions
FileInputStream

Opens a FileInputStream that reads encrypted files based on the previous settings.
FileOutputStream

Opens a FileOutputStream for writing that automatically encrypts the data based on the provided settings.

Public functions

openFileInput

Added in 1.0.0
fun openFileInput(): FileInputStream

Opens a FileInputStream that reads encrypted files based on the previous settings.

Please ensure that the same master key and keyset are used to decrypt or it will cause failures.

Returns
FileInputStream

The input stream to read previously encrypted data.
Throws
java.security.GeneralSecurityException

when a bad master key or keyset has been used
java.io.FileNotFoundException

when the file was not found
java.io.IOException

when other I/O errors occur

openFileOutput

Added in 1.0.0
fun openFileOutput(): FileOutputStream

Opens a FileOutputStream for writing that automatically encrypts the data based on the provided settings.

Please ensure that the same master key and keyset are used to decrypt or it will cause failures.

Returns
FileOutputStream

The FileOutputStream that encrypts all data.
Throws
java.security.GeneralSecurityException

when a bad master key or keyset has been used
java.io.IOException

when the file already exists or is not available for writing