| API changes | |
| * Modify semantics of `mbedtls_ssl_conf_[opaque_]psk()`: | |
| In Mbed TLS 2.X, the API prescribes that later calls overwrite | |
| the effect of earlier calls. In Mbed TLS 3.0, calling | |
| `mbedtls_ssl_conf_[opaque_]psk()` more than once will fail, | |
| leaving the PSK that was configured first intact. | |
| Support for more than one PSK may be added in 3.X. |