Metadata-Version: 2.4
Name: pysapsso2
Version: 1.0.0
Summary: A pure python library for generating SAP Assertion/Logon tickets.
Author: BougeBouge Consulting
License: MIT License
        
        Copyright (c) 2019 BougeBouge Consulting
        
        Permission is hereby granted, free of charge, to any person obtaining a copy
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Project-URL: Homepage, https://github.com/bougebouge/pysapsso2
Project-URL: Repository, https://github.com/bougebouge/pysapsso2
Project-URL: Issues, https://github.com/bougebouge/pysapsso2/issues
Keywords: sap,sso,logon-ticket,assertion-ticket,netweaver
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.10
Classifier: Programming Language :: Python :: 3.11
Classifier: Programming Language :: Python :: 3.12
Classifier: Programming Language :: Python :: 3.13
Classifier: Topic :: Security :: Cryptography
Classifier: Topic :: System :: Systems Administration :: Authentication/Directory
Requires-Python: >=3.10
Description-Content-Type: text/markdown
License-File: LICENSE
Requires-Dist: asn1crypto>=1.5.1
Requires-Dist: pycryptodome>=3.19.0
Dynamic: license-file

# pysapsso2
A pure python library for generating SAP Assertion/Logon tickets.

SAP Logon Tickets are authentication tokens accepted by :
 - SAP NetWeaver ABAP (SAP GUI, Webdynpro/Fiori, Web Services)
 - SAP NetWeaver Java (Web)


This library is an opensource alternative to SAPSSOEXT ([304450 - Single-Sign-On with SAP logon tickets in non-SAP systems](https://me.sap.com/notes/304450))

## Installation

```
pip install pysapsso2
```

## How to generate an SAP shortcut
cf. [examples/generate_shortcut.py](examples/generate_shortcut.py)

## How to parse an SAP Logon Ticket

```python
from pysapsso2 import SapTicket

ticket = SapTicket.from_b64(cookie_value)
print(ticket.user, ticket.source_sid, ticket.source_client, ticket.expires_at)
```

## How to verify an SAP Logon Ticket

```python
from pysapsso2 import SapTicket, SapTicketHandler

ticket = SapTicket.from_b64(cookie_value)
handler = SapTicketHandler("SSO", "000", certificate=trusted_cert_pem)
handler.verify(ticket)  # raises SignatureError / CertificateError
```

`verify()` checks, in order:

1. the payload digest against the `message_digest` signed attribute,
2. that the ticket names the supplied certificate as its signer,
3. that the certificate is within its validity period (`check_certificate_validity=False` to skip, `at_time=` to pin the moment),
4. the signature over the signed attributes.

**The certificate must come from the caller.** A ticket may embed a certificate,
but anybody can embed one they hold the key for, so it is never used as a trust
anchor. `pysapsso2.crypto.get_dsa_key()` exposes the embedded key for inspection
only.

## Signing algorithms

| Key | Key sizes | Digest |
|---|---|---|
| DSA | 1024 – 4096 | `sha1`, `sha256` |
| RSA (PKCS#1 v1.5) | 1024 – 4096 | `sha1`, `sha256` |
| ECDSA | P-256, P-384, P-521 | `sha1`, `sha256` |

Every combination in the table was accepted by a live SAP NetWeaver ABAP system.

DSA with `sha1` is the default, because that is what SAPSSOEXT emits. Use it if
you need a ticket that SAPSSOEXT can also read. Otherwise prefer RSA or ECDSA
with `sha256`.

Pick the algorithm on the handler:

```python
from Crypto.PublicKey import RSA
from pysapsso2 import SapTicketHandler

handler = SapTicketHandler(
    "SSO",
    "000",
    private_key=RSA.import_key(key_pem),
    certificate=cert_pem,
    digest_algorithm="sha256",
)
ticket = handler.new("DEMOUSER")
```

`digest_algorithm` defaults to `"sha1"`. The handler picks the signer from the
key type. You can also build the signer yourself with
`pysapsso2.DsaSigner`, `pysapsso2.RsaSigner` or `pysapsso2.signer_for_key()` and
pass it as `private_key`; the handler's `digest_algorithm` is then ignored,
because the signer carries its own.

Verification needs no configuration. `verify()` reads the digest algorithm from
the ticket and the key algorithm from the certificate.

## How to generate an SAP Logon Ticket with SAPSSOEXT
For reference here are commands to generate a new key and self-signed certificate for testing SAPSSOEXT:

```
# Generate a DSA key
openssl dsaparam -out sapsso2.key -genkey 1024

# Generate a certificate
openssl req -x509 -new -sha1 -subj "/CN=pysapsso2" -key sapsso2.key -out sapsso2.crt

# Bundle it in a P12 and convert it to SAP PSE
openssl pkcs12 -export -in sapsso2.crt -inkey sapsso2.key -out sapsso2.p12
sapgenpse import_p12 -p sapsso2.pse sapsso2.p12

# Create an SAP Assertion Ticket using SAPSSOEXT
java -cp .\sapssoext.jar com.mysap.sso.SSO2Ticket -i ticket.txt -c -mysid SSO -mycli 000 -exsid ERP -excli 100 -p sapsso2.pse
```

**Notes:**
- SAPSSOEXT signs with a DSA key only when the key's subgroup `q` is 160 bits. The key size itself does not matter — 1024, 2048, 3072 and 4096 all sign with `q` = 160, while `q` = 224 and `q` = 256 fail at every size with "MySapCreateAssertionTicket failed: standard error= 9, ssf error= 27". `openssl dsaparam` picks `q` = 224 above 1024 bits, so ask for `q` = 160 explicitly when you build a larger key for SAPSSOEXT. RSA has no such limit: 1024 through 4096 all sign.
- SAPSSOEXT also signs RSA keys, 1024 to 4096 bit, with a SHA-1 digest. It cannot sign with an EC key on any curve — that gives `standard error= 9, ssf error= 10`.
- NetWeaver ABAP accepts DSA, RSA and ECDSA up to 4096 bits, with SHA-1 and SHA-256. See the matrix under "Signing algorithms" for exactly what was tested. NetWeaver Java was not tested.

## Development
This project uses [uv](https://docs.astral.sh/uv/).

```
# Create the virtualenv and install the project with its dev dependencies
uv sync

# Run the tests / linter
uv run pytest
uv run ruff check

# Run an example
uv run examples/generate_shortcut.py

# Build the sdist and wheel
uv build
```

`tests/keys/` holds throwaway self-signed keys, one pair per row of the
algorithm matrix. They are committed, so a clone runs the suite straight away.
To replace them, or to add a key size or curve, run
`pwsh tools/make_test_keys.ps1 -Force`. It needs `openssl`; on Windows it falls
back to the one shipped with Git.

`sapsso2.key` and `sapsso2.crt` are the exception: the script never touches
them. That key signed the SAPSSOEXT reference ticket pinned in
`tests/test_sapticket.py`, so a regenerated key would not verify that
signature.

## Testing against SAPSSOEXT

`uv run pytest` checks this library against itself. The suite in
`tests/test_oracle.py` checks it against **SAPSSOEXT**, SAP's closed-source
reference implementation. That is the only way to catch a disagreement with SAP,
so run it after any change to the wire format, the signature, or the validity
fields. When the two disagree, SAPSSOEXT is right.

These tests are skipped by default, because SAPSSOEXT is not redistributable and
its native libraries are Windows amd64 only.

The pytest oracle suite pins DSA/SHA-1 only, because that is what this library
emits by default. The other combinations are covered by the offline round-trip
tests and by live NetWeaver runs. See [docs/interop.md](docs/interop.md) for
what SAPSSOEXT and NetWeaver each accept.

### Setup

Put these two files in `internal/` (gitignored — do not commit them):

| File | Where it comes from |
|---|---|
| `sapssoext.jar` | SAP note 304450 |
| `SAPCRYPTOLIB*.SAR` | SAP Software Center, **Windows x86_64** build |
| `SAPCAR*.EXE` | SAP Software Center, **Windows x86_64** build |

The SAR and SAPCAR must be the Windows builds. The Linux ones are ELF binaries
and will not run; `bootstrap.py` checks this and says so.

You also need a JDK (`javac`, not just `java`) and `openssl` on `PATH`.

```
# One-off: extract SAPCRYPTOLIB, generate a test key, certificate and PSE,
# and compile the Java helper. Everything lands in internal/oracle/.
uv run tools/oracle/bootstrap.py

# Run the interop suite
uv run pytest -m oracle

# Run everything
uv run pytest -m "oracle or not oracle"
```

`bootstrap.py` is idempotent — re-running skips work already done. Pass
`--force` to rebuild. The key it generates is 1024-bit DSA, which matches the
reference fixture. A larger DSA key also works, as long as its subgroup `q` is
160 bits; `q` = 224 and `q` = 256 give `standard error=9, ssf error=27` at every
key size.

### What the oracle records

`tools/oracle/oracle.py` maps SAPSSOEXT's `(standard, ssf)` error pairs to
meanings, so a failing test says *why* rather than just failing. SAP documents
none of them. The table is in
[docs/interop.md](docs/interop.md#sapssoext-error-pairs).

## Further reading

[docs/interop.md](docs/interop.md) records what SAP actually does with a ticket,
measured rather than quoted: which keys and digests each consumer signs and
validates, the DSA subgroup rule, the error pairs, and the validity and base64
behaviour.

## TODO
- Add pyright type checking and a CI workflow
