Function sign_event 

pub fn sign_event<K>(
    entity_id: &str,
    key_pair: &K,
    object: &mut CanonicalJsonObject,
    redaction_rules: &RedactionRules,
) -> Result<(), JsonError>
where
    K: KeyPair,

Compute and add the signature of the given event.

This adds or overwrites the signature for the given entity and key in the signatures object of the event.

When creating a new event, add_content_hash_to_event() should be called first.

Parameters

• entity_id: The identifier of the entity creating the signature. Generally this means a homeserver, e.g. “example.com”.
• key_pair: The cryptographic key pair used to sign the event.
• object: The event to be signed according to the Matrix specification.
• redaction_rules: The redaction rules for the version of the event’s room.

Errors

Returns an error if:

• object contains a field called content that is not a JSON object.
• object contains a field called signatures that is not a JSON object.
• object is missing the type field or the field is not a JSON string.

Examples

use ruma_common::CanonicalJsonObject;
use ruma_signatures::sign_event;

// Deserialize an event from JSON.
let mut event = serde_json::from_str(
    r#"{
        "room_id": "!x:domain",
        "sender": "@a:domain",
        "origin": "domain",
        "origin_server_ts": 1000000,
        "type": "X",
        "content": {},
        "prev_events": [],
        "auth_events": [],
        "depth": 3,
        "hashes": {
            "sha256": "5jM4wQpv6lnBo7CLIghJuHdW+s2CMBJPUOGOC89ncos"
        }
    }"#,
)?;

// Get the rules for the version of the current room.
let rules = room_version_rules();

// Sign the event with the key pair.
sign_event("domain", &key_pair, &mut event, &rules.redaction)?;

// The signature was added.
assert_eq!(
    event,
    serde_json::from_str::<CanonicalJsonObject>(
        r#"{
            "room_id": "!x:domain",
            "sender": "@a:domain",
            "origin": "domain",
            "origin_server_ts": 1000000,
            "type": "X",
            "content": {},
            "prev_events": [],
            "auth_events": [],
            "depth": 3,
            "hashes": {
                "sha256": "5jM4wQpv6lnBo7CLIghJuHdW+s2CMBJPUOGOC89ncos"
            },
            "signatures": {
                "domain": {
                    "ed25519:1": "PxOFMn6ORll8PFSQp0IRF6037MEZt3Mfzu/ROiT/gb/ccs1G+f6Ddoswez4KntLPBI3GKCGIkhctiK37JOy2Aw"
                }
            }
        }"#,
    )?
);