synta 0.1.9

ASN.1 parser, decoder, and encoder library with DER/BER support and C FFI
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# Error Handling


## Exception table

| Exception | When raised |
|---|---|
| `synta.SyntaError` | ASN.1 parse or encode failure (wraps the Rust `synta::Error`) |
| `synta.x509.X509VerificationError` | Certificate chain verification failure (see [`synta.x509`](../pki/x509-verification.md)) |
| `ValueError` | Invalid arguments (e.g. invalid OID string, bad charset for `PrintableString`, wrong password format) |
| `OverflowError` | `Integer.to_int()` / `to_i128()` when the value does not fit |
| `EOFError` | `Decoder.peek_tag()` / `decode_*` when no data remains |
| `ImportError` | `Certificate.to_pyca()` / `from_pyca()` when `cryptography` is not installed |

## Example

```python
import synta

try:
    # Invalid OID (first component must be 0, 1, or 2)
    oid = synta.ObjectIdentifier("5.2.840")
except ValueError as e:
    print(f"Error: {e}")

try:
    # Truncated data
    decoder = synta.Decoder(b'\x02\x05', synta.Encoding.DER)
    integer = decoder.decode_integer()
except EOFError as e:
    print(f"Unexpected end of data: {e}")

try:
    # Invalid DER
    decoder = synta.Decoder(b'\xff\xff', synta.Encoding.DER)
    obj = decoder.decode_any()
except synta.SyntaError as e:
    print(f"Parse error: {e}")
```

## Error mapping

`SyntaErr` (the internal Rust error type) is mapped to Python exceptions as
follows:

- EOF / truncated data → `EOFError`
- Integer overflow → `OverflowError`
- Any other ASN.1 parse error → `ValueError` or `synta.SyntaError`

The `SyntaError` exception class is a subclass of `Exception`.