pyseto 1.1.0

A Python implementation of PASETO (Platfrom-Agnostic Security Tokens).

PySETO - A Python implementation of PASETO

PySETO is a PASETO (Platform-Agnostic SEcurity TOkens) implementation written in Python which supports all of the versions and purposes below and has passed all of the official tests.

• Version 4: Sodium Modern
  • ✅ Local: Symmetric Authenticated Encryption
    • XChaCha20 + BLAKE2b-MAC (Encrypt-then-MAC).
  • ✅ Public: Asymmetric Authentication (Public-Key Signatures)
    • EdDSA over Curve25519.
• Version 3: NIST Modern
  • ✅ Local: Symmetric Authenticated Encryption
    • AES-256-CTR + HMAC-SHA384 (Encrypt-then-MAC).
  • ✅ Public: Asymmetric Authentication (Public-Key Signatures)
    • ECDSA over NIST P-384, with SHA-384, using RFC 6979 deterministic k-values.
• Version 2: Sodium Original
  • ✅ Local: Symmetric Authenticated Encryption
    • XChaCha20-Poly1305 (192-bit nonce, 256-bit key, 128-bit authentication tag).
  • ✅ Public: Asymmetric Authentication (Public-Key Signatures)
    • EdDSA over Curve25519.
• Version 1: NIST Compatibility
  • ✅ Local: Symmetric Authenticated Encryption
    • AES-256-CTR + HMAC-SHA384 (Encrypt-then-MAC).
  • ✅ Public: Asymmetric Authentication (Public-Key Signatures)
    • RSASSA-PSS with 2048-bit key, SHA384 hashing and MGF1+SHA384.

In addition, PySETO also supports PASERK (Platform-Agnostic Serialized Keys).

See Document for details.

Installation

You can install PySETO with pip:

$ pip install pyseto

Usage

You can use it as follows:

v4.public

v4.public is one of current PASETO versions to be used for asymmetric authentication (public key signatures).

import pyseto
from pyseto import Key

private_key_pem = b"-----BEGIN PRIVATE KEY-----\nMC4CAQAwBQYDK2VwBCIEILTL+0PfTOIQcn2VPkpxMwf6Gbt9n4UEFDjZ4RuUKjd0\n-----END PRIVATE KEY-----"
public_key_pem = b"-----BEGIN PUBLIC KEY-----\nMCowBQYDK2VwAyEAHrnbu7wEfAP9cGBOAHHwmH4Wsot1ciXBHwBBXQ4gsaI=\n-----END PUBLIC KEY-----"

private_key = Key.new(version=4, purpose="public", key=private_key_pem)
token = pyseto.encode(private_key, b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}')

public_key = Key.new(version=4, purpose="public", key=public_key_pem)
decoded = pyseto.decode(public_key, token)

assert token == b'v4.public.eyJkYXRhIjogInRoaXMgaXMgYSBzaWduZWQgbWVzc2FnZSIsICJleHAiOiAiMjAyMi0wMS0wMVQwMDowMDowMCswMDowMCJ9l1YiKei2FESvHBSGPkn70eFO1hv3tXH0jph1IfZyEfgm3t1DjkYqD5r4aHWZm1eZs_3_bZ9pBQlZGp0DPSdzDg'
assert decoded.payload == b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}'

v4.local

v4.local is one of current PASETO versions to be used for symmetric authenticated encryption.

import pyseto
from pyseto import Key

key = Key.new(version=4, purpose="local", key=b"our-secret")
token = pyseto.encode(key, b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}')

decoded = pyseto.decode(key, token)
assert decoded.payload == b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}'

Usage with PASERK

PASERK (Platform-Agnostic Serialized Keys) is an extension to PASETO that provides key-wrapping and serialization.

Serializing/Deserializing PASERK

As shown in the examples above, the pyseto.Key used for encryption and signature can be generated from PASERK or converted to PASERK as follows:

import pyseto
from pyseto import Key

# pyseto.Key can be generated from PASERK.
symmetric_key = Key.new(version=4, purpose="local", key=b"our-secret")
private_key = Key.from_paserk("k4.secret.tMv7Q99M4hByfZU-SnEzB_oZu32fhQQUONnhG5QqN3Qeudu7vAR8A_1wYE4AcfCYfhayi3VyJcEfAEFdDiCxog")
public_key = Key.from_paserk("k4.public.Hrnbu7wEfAP9cGBOAHHwmH4Wsot1ciXBHwBBXQ4gsaI")

token = pyseto.encode(private_key, b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}')
decoded = pyseto.decode(public_key, token)

assert decoded.payload == b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}'

# PASERK can be derived from pyseto.Key.
assert symmetric_key.to_paserk() == "k4.local.b3VyLXNlY3JldA"
assert private_key.to_paserk() == "k4.secret.tMv7Q99M4hByfZU-SnEzB_oZu32fhQQUONnhG5QqN3Qeudu7vAR8A_1wYE4AcfCYfhayi3VyJcEfAEFdDiCxog"
assert public_key.to_paserk() == "k4.public.Hrnbu7wEfAP9cGBOAHHwmH4Wsot1ciXBHwBBXQ4gsaI"

Serializing PASERK ID

pyseto.Key can also be converted to PASERK ID as follows:

import pyseto
from pyseto import Key

# pyseto.Key can be generated from PASERK.
symmetric_key = Key.new(version=4, purpose="local", key=b"our-secret")
private_key = Key.from_paserk("k4.secret.tMv7Q99M4hByfZU-SnEzB_oZu32fhQQUONnhG5QqN3Qeudu7vAR8A_1wYE4AcfCYfhayi3VyJcEfAEFdDiCxog")
public_key = Key.from_paserk("k4.public.Hrnbu7wEfAP9cGBOAHHwmH4Wsot1ciXBHwBBXQ4gsaI")

# PASERK ID can be derived from pyseto.Key.
assert symmetric_key.to_paserk_id() == "k4.lid._D6kgTzxgiPGk35gMj9bukgj4En2H94u22wVX9zaoh05"
assert private_key.to_paserk() == "k4.secret.tMv7Q99M4hByfZU-SnEzB_oZu32fhQQUONnhG5QqN3Qeudu7vAR8A_1wYE4AcfCYfhayi3VyJcEfAEFdDiCxog"
assert public_key.to_paserk_id() == "k4.pid.yh4-bJYjOYAG6CWy0zsfPmpKylxS7uAWrxqVmBN2KAiJ"

Key Wrapping

If you call to_paserk with wrapping_key, you can get a wrapped (encrypted) PASERK with the wrapping key. The wrapped PASERK can be decrypted by calling from_paserk with wrapping key.

In case of local-wrap.pie:

import pyseto
from pyseto import Key

raw_key = Key.new(version=4, purpose="local", key=b"our-secret")
wrapping_key = token_bytes(32)
wpk = raw_key.to_paserk(wrapping_key=wrapping_key)

# assert wpk == "k4.local-wrap.pie.TNKEwC4K1xBcgJ_GiwWAoRlQFE33HJO3oN9DHEZ05pieSCd-W7bgAL64VG9TZ_pBkuNBFHNrfOGHtnfnhYGdbz5-x3CxShhPJxg"

unwrapped_key = Key.from_paserk(wpk, wrapping_key=wrapping_key)
token = pyseto.encode(raw_key, b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}')
decoded = pyseto.decode(unwrapped_key, token)
assert decoded.payload == b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}'

In case of secret-wrap.pie:

import pyseto
from pyseto import Key

raw_private_key = Key.from_paserk(
    "k4.secret.tMv7Q99M4hByfZU-SnEzB_oZu32fhQQUONnhG5QqN3Qeudu7vAR8A_1wYE4AcfCYfhayi3VyJcEfAEFdDiCxog"
)
public_key = Key.from_paserk(
    "k4.public.Hrnbu7wEfAP9cGBOAHHwmH4Wsot1ciXBHwBBXQ4gsaI"
)
wrapping_key = token_bytes(32)
wpk = raw_private_key.to_paserk(wrapping_key=wrapping_key)

# assert wpk == "k4.secret-wrap.pie.excv7V4-NaECy5hpji-tkSkMvyjsAgNxA-mGALgdjyvGNyDlTb89bJ35R1e3tILgbMpEW5WXMXzySe2T-sBz-ZAcs1j7rbD3ZWvsBTM6K5N9wWfAxbR4ppCXH_H5__9yY-kBaF2NimyAJyduhOhSmqLm6TTSucpAOakEJOXePW8"

unwrapped_private_key = Key.from_paserk(wpk, wrapping_key=wrapping_key)
token = pyseto.encode(unwrapped_private_key, b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}')
decoded = pyseto.decode(public_key, token)
assert decoded.payload == b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}'

Password-based Key Encryption

If you call to_paserk with password, you can get a wrapped (encrypted) PASERK with the password. The wrapped PASERK can be decrypted by calling from_paserk with passwrod.

In case of local-pw:

import pyseto
from pyseto import Key

raw_key = Key.new(version=4, purpose="local", key=b"our-secret")
wpk = raw_key.to_paserk(password="our-secret")

# assert wpk == "k4.local-pw.HrCs9Pu-2LB0l7jkHB-x2gAAAAAA8AAAAAAAAgAAAAGttW0IHZjQCHJdg-Vc3tqO_GSLR4vzLl-yrKk2I-l8YHj6jWpC0lQB2Z7uzTtVyV1rd_EZQPzHdw5VOtyucP0FkCU"

unwrapped_key = Key.from_paserk(wpk, password="our-secret")
token = pyseto.encode(raw_key, b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}')
decoded = pyseto.decode(unwrapped_key, token)
assert decoded.payload == b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}'

In case of secret-pw:

import pyseto
from pyseto import Key

raw_private_key = Key.from_paserk(
    "k4.secret.tMv7Q99M4hByfZU-SnEzB_oZu32fhQQUONnhG5QqN3Qeudu7vAR8A_1wYE4AcfCYfhayi3VyJcEfAEFdDiCxog"
)
public_key = Key.from_paserk(
    "k4.public.Hrnbu7wEfAP9cGBOAHHwmH4Wsot1ciXBHwBBXQ4gsaI"
)
wpk = raw_private_key.to_paserk(password="our-secret")

# assert wpk == "k4.secret-pw.MEMW4K1MaD5nWigCLyEyFAAAAAAA8AAAAAAAAgAAAAFU-tArtryNVjS2n2hCYiM11V6tOyuIog69Bjb0yNZanrLJ3afGclb3kPzQ6IhK8ob9E4QgRdEALGWCizZ0RCPFF_M95IQDfmdYKC0Er656UgKUK4UKG9JlxP4o81UwoJoZYz_D1zTlltipEa5RiNvUtNU8vLKoGSY"

unwrapped_private_key = Key.from_paserk(wpk, password="our-secret")
token = pyseto.encode(unwrapped_private_key, b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}')
decoded = pyseto.decode(public_key, token)
assert decoded.payload == b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}'

Asymmetric Encryption

At this time, PySETO supports asymmetric encryption (key sealing) for v2 and v4.

import pyseto
from pyseto import Key

private_key_pem = b"-----BEGIN PRIVATE KEY-----\nMC4CAQAwBQYDK2VuBCIEIFAF7jSCZHFgWvC8hUkXr55Az6Pot2g4zOAUxck0/6x8\n-----END PRIVATE KEY-----"
public_key_pem = b"-----BEGIN PUBLIC KEY-----\nMCowBQYDK2VuAyEAFv8IXsICYj0paznDK/99GyCsFOIGnfY87ayyNSIvSB4=\n-----END PUBLIC KEY-----"

raw_key = Key.new(version=4, purpose="local", key=b"our-secret")
token = pyseto.encode(
    raw_key,
    b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}',
)
sealed_key = raw_key.to_paserk(sealing_key=public_key_pem)

unsealed_key = Key.from_paserk(sealed_key, unsealing_key=private_key_pem)
decoded = pyseto.decode(unsealed_key, token)
assert (
    decoded.payload
    == b'{"data": "this is a signed message", "exp": "2022-01-01T00:00:00+00:00"}'
)

Key searing for v1 and v3 have not been supported yet.

API Reference

See Document.

Tests

You can run tests from the project root after cloning with:

$ tox