cryptio package

Submodules

cryptio.header module

class cryptio.header.CryptHeader(_file)

Bases: object

initialize()

read()

write(tag=None)

cryptio.io module

class cryptio.io.CryptIO(_file, key)

Bases: io.RawIOBase

CryptIO is a minimal file-like object wrapper that only specifically implements read(), write(), and close().

Example:

chunk = f.read(1024)
f.write(b'bytes')
f.close()

CryptIO is also a context manager, and can be used with the with statement like a normal FileIO object.

The difference between FileIO and CryptIO:

• read() and write() transparently handle aes-gcm decryption and encryption, respectively.
• close() transparently handles message validation and file header updates
• initialization vectors and gcm authentication tags are handled automatically

close()

In addition to closing the underlying file object, also handle any outstanding encryptor or decryptor finalization as necessary.

Raises:InvalidTag – if the GCM tag does not match the ciphertext

read(size=-1)

Read a ciphertext chunk from the underlying file object, and decrypt the result.

Parameters:size (int) – number of bytes to be read Returns:plaintext chunk Return type:bytes

write(chunk)

Encrypts chunk, and writes the ciphertext to the underlying file object.

Parameters:chunk (bytes) – bytes or similar Returns:number of ciphertext bytes written Return type:int

class cryptio.io.CryptReader(header, key)

Bases: object

decryptor

finalize()

class cryptio.io.CryptWriter(header, key)

Bases: object

encryptor

finalize()

cryptio.io.default_cipher(key, iv, tag=None)

cryptio.io.open(file, mode='rb', *, key, _open=None, **kwargs)

open() is a wrapper around io.open(), with a few differences:

• instead of some variant of an io.FileIO object, a CryptIO wrapper is returned
• only binary modes are supported

Example:

key = os.urandom(32)  # 16 and 24-byte keys are also valid
f = open('filename', 'rb', key=key)

For more information on how to manipulate the object returned by open(), see CryptIO

Parameters:

• file – path-like object; see open
• mode – mode string
• key – aes symmetric key

Returns:

encrypted file object wrapper

Return type:

CryptIO

Module contents

cryptio.open(file, mode='rb', *, key, _open=None, **kwargs)

open() is a wrapper around io.open(), with a few differences:

• instead of some variant of an io.FileIO object, a CryptIO wrapper is returned
• only binary modes are supported

Example:

key = os.urandom(32)  # 16 and 24-byte keys are also valid
f = open('filename', 'rb', key=key)

For more information on how to manipulate the object returned by open(), see CryptIO

Parameters:

• file –

  path-like object; see open

• mode – mode string
• key – aes symmetric key

Returns:

encrypted file object wrapper

Return type:

CryptIO