nacl.bindings

The nacl.bindings module exposes the low-level APIs provided by libsodium.

AEAD constructions

crypto_aead_chacha20poly1305_decrypt(ciphertext, aad, nonce, key)

Decrypt the given ciphertext using the “legacy” construction described in draft-agl-tls-chacha20poly1305.

Parameters:

• ciphertext (bytes) – authenticated ciphertext
• aad (bytes) –
• nonce (bytes) –
• key (bytes) –

Returns:

message

Return type:

bytes

crypto_aead_chacha20poly1305_encrypt(message, aad, nonce, key)

Encrypt the given message using the “legacy” construction described in draft-agl-tls-chacha20poly1305.

Parameters:

• message (bytes) –
• aad (bytes) –
• nonce (bytes) –
• key (bytes) –

Returns:

authenticated ciphertext

Return type:

bytes

crypto_aead_chacha20poly1305_ietf_decrypt(ciphertext, aad, nonce, key)

Decrypt the given ciphertext using the IETF ratified chacha20poly1305 construction described in RFC7539.

Parameters:

• ciphertext (bytes) –
• aad (bytes) –
• nonce (bytes) –
• key (bytes) –

Returns:

message

Return type:

bytes

crypto_aead_chacha20poly1305_ietf_encrypt(message, aad, nonce, key)

Encrypt the given message using the IETF ratified chacha20poly1305 construction described in RFC7539.

Parameters:

• message (bytes) –
• aad (bytes) –
• nonce (bytes) –
• key (bytes) –

Returns:

authenticated ciphertext

Return type:

bytes

crypto_aead_xchacha20poly1305_ietf_decrypt(ciphertext, aad, nonce, key)

Decrypt the given ciphertext using the long-nonces xchacha20poly1305 construction.

Parameters:

• ciphertext (bytes) – authenticated ciphertext
• aad (bytes) –
• nonce (bytes) –
• key (bytes) –

Returns:

message

Return type:

bytes

crypto_aead_xchacha20poly1305_ietf_encrypt(message, aad, nonce, key)

Encrypt the given message using the long-nonces xchacha20poly1305 construction.

Parameters:

• message (bytes) –
• aad (bytes) –
• nonce (bytes) –
• key (bytes) –

Returns:

authenticated ciphertext

Return type:

bytes

Key exchange

crypto_kx_keypair()

Generate a keypair. This is a duplicate crypto_box_keypair, but is included for api consistency.

Returns:(public_key, secret_key) Return type:(bytes, bytes)

crypto_kx_client_session_keys(client_public_key, client_secret_key, server_public_key)

Generate session keys for the client.

Parameters:

• client_public_key (bytes) –
• client_secret_key (bytes) –
• server_public_key (bytes) –

Returns:

(rx_key, tx_key)

Return type:

(bytes, bytes)

crypto_kx_server_session_keys(server_public_key, server_secret_key, client_public_key)

Generate session keys for the server.

Parameters:

• server_public_key (bytes) –
• server_secret_key (bytes) –
• client_public_key (bytes) –

Returns:

(rx_key, tx_key)

Return type:

(bytes, bytes)

Utilities

sodium_add(a, b)

Given a couple of same-sized byte sequences, interpreted as the little-endian representation of two unsigned integers, compute the modular addition of the represented values, in constant time for a given common length of the byte sequences.

Parameters:

• a (bytes) – input bytes buffer
• b (bytes) – input bytes buffer

Returns:

a byte-sequence representing, as a little-endian big integer, the integer value of (to_int(a) + to_int(b)) mod 2^(8*len(a))

Return type:

bytes

sodium_increment(inp)

Increment the value of a byte-sequence interpreted as the little-endian representation of a unsigned big integer.

Parameters:inp (bytes) – input bytes buffer Returns:a byte-sequence representing, as a little-endian unsigned big integer, the value to_int(inp) incremented by one. Return type:bytes

sodium_memcmp(inp1, inp2)

Compare contents of two memory regions in constant time

sodium_pad(s, blocksize)

Pad the input bytearray s to a multiple of blocksize using the ISO/IEC 7816-4 algorithm

Parameters:

• s (bytes) – input bytes string
• blocksize (int) –

Returns:

padded string

Return type:

bytes

sodium_unpad(s, blocksize)

Remove ISO/IEC 7816-4 padding from the input byte array s

Parameters:

• s (bytes) – input bytes string
• blocksize (int) –

Returns:

unpadded string

Return type:

bytes