didcomm-rs

Rust implementation of DIDComm v2 spec

License

Apache-2.0

Examples of usage

1. Prepare raw message for send and receive

GoTo: full test

``rust // Message construction let m = Message::new() // settingfromheader (sender) - Optional .from("did:xyz:ulapcuhsatnpuhza930hpu34n_") // settingtoheader (recepients) - Optional .to(&["did::xyz:34r3cu403hnth03r49g03", "did:xyz:30489jnutnjqhiu0uh540u8hunoe"]) // populating body with some data -Vec` .setbody(somepayload.as_bytes());

// Serialize message into JWM json (SENDER action)
let ready_to_send = m.as_raw_json().unwrap();

//... transport is happening here ...

// On receival deserialize from json into Message (RECEIVER action)
// Error handling recommended here
let received = Message::receive(&ready_to_send, None).unwrap();

```

2. Prepare JWE message for direct send

GoTo: full test

``rust // decide which [Algorithm](crypto::encryptor::CryptoAlgorithm) is used (based on key) let alg = CryptoAlgorithm::XC20P; // key as bytes let ek = [130, 110, 93, 113, 105, 127, 4, 210, 65, 234, 112, 90, 150, 120, 189, 252, 212, 165, 30, 209, 194, 213, 81, 38, 250, 187, 216, 14, 246, 250, 166, 92] // creating message let mut message = Message::new() // packing in some payload (can be anything really) .set_body(br#"{'key':'value','key2':'value2'}"#) // set JOSE header for XC20P algorithm .as_jwe(alg) // add some custom app/protocol related headers to didcomm header portion // these are not included into JOSE header .add_header_field("my_custom_key".into(), "my_custom_value".into()) .add_header_field("another_key".into(), "another_value".into()); // setkidproperty message.jwm_header.kid = Some(String::from(r#"Ef1sFuyOozYm3CEY4iCdwqxiSyXZ5Br-eUDdQXk6jaQ"#)); // encrypt and serialize message with JOSE header included let ready_to_send = message.seal(ek.as_bytes())?; // use transport of choice to sendreadytosend` data to the receiver!

//... transport is happening here ...

```

3. Prepare JWS message -> send -> receive

• Here Message is signed but not encrypted.
• In such scenarios explicit use of .sign(...) and Message::verify(...) required.

```rust // Message construction an JWS wrapping let message = Message::new() // creating message .from("did:xyz:ulapcuhsatnpuhza930hpu34n") // setting from .to(&["did::xyz:34r3cu403hnth03r49g03", "did:xyz:30489jnutnjqhiu0uh540u8hunoe"]) // setting to .setbody(sampledids::TESTDIDSIGN1.asbytes()) // packing in some payload .asjws(&SignatureAlgorithm::EdDsa) .sign(SignatureAlgorithm::EdDsa.signer(), &signkeypair.tobytes()).unwrap();

//... transport is happening here ...

// Receiving JWS
let received = Message::verify(&message.unwrap().as_bytes(), &sign_keypair.public.to_bytes());

```

4. Prepare JWE message to be mediated -> mediate -> receive

• Message should be encrypted by destination key first in .routed_by() method call using key for the recepient.
• Next it should be encrypted by mediator key in .seal() method call - this can be done multiple times - once for each mediator in chain but should be strictly sequentual to match mediators sequence in the chain.
• Method call .seal() MUST be preceeded by .as_jwe(CryptoAlgorithm) as mediators may use different algorithms and key types than destination and this is not automatically predicted or populated.
• Keys used for encryption should be used in reverse order - final destination - last mediator - second to last mediator - etc. Onion style.

GoTo: full test

``rust // Message construction let message = Message::new() // setting from .from("did:xyz:ulapcuhsatnpuhza930hpu34n_") // setting to .to(&["did:xyz:34r3cu403hnth03r49g03", "did:xyz:30489jnutnjqhiu0uh540u8hunoe"]) // packing in some payload .set_body(some_payload.as_bytes()) // set JOSE header for XC20P algorithm .as_jwe(CryptoAlgorithm::XC20P) // custom header .add_header_field("my_custom_key".into(), "my_custom_value".into()) // another coustom header .add_header_field("another_key".into(), "another_value".into()) // set kid header .kid(String::from(r#"Ef1sFuyOozYm3CEY4iCdwqxiSyXZ5Br-eUDdQXk6jaQ"#)) // here we use destination key to bob andtoheader of mediator - //**THISH MUST BE LAST IN THE CHAIN** - after this call you'll get new instance of envelopeMessagedestined to the mediator. //ektobob` - destination targeted encryption key .routedby(ektobob.asbytes(), vec!("did:mediator:suetcpl23pt23rp2teu995t98u"));

// Message envelope to mediator
let ready_to_send = message
    .unwrap() // **ERROR HANDLE** here is recommended
    .as_jwe(CryptoAlgorithm::XC20P) // here this method call is crucial as mediator and end receiver may use different algorithms.
    // `ek_to_mediator` - mediator targeted encryption key
    .seal(ek_to_mediator.as_bytes()); // this would've failed without previous method call.

//... transport to mediator is happening here ...

// Received by mediator
// `rk_mediator` - key to decrypt mediated message
let received_mediated = Message::receive(&ready_to_send.unwrap(), Some(rk_mediator.as_bytes()));

//... transport to destination is happening here ...

// Received by Bob
// `rk_bob` - key to decrypt final message
let received_bob = Message::receive(&String::from_utf8_lossy(&received_mediated.unwrap().get_body()?.as_ref()), Some(rk_bob.as_bytes()));

```

5. Prepare JWS envelope wrapped into JWE -> sign -> pack -> receive

• JWS header is set automatically based on signing algorythm type.
• Message forming and encryption happens in same way as in other JWE examples.
• ED25519-dalek signature is used in this example with keypair for signing and public key for verification.

GoTo: full test

```rust // Message construction let message = Message::new() // creating message .from("did:xyz:ulapcuhsatnpuhza930hpu34n") // setting from .to(&["did::xyz:34r3cu403hnth03r49g03"]) // setting to .setbody(sampledids::TESTDIDSIGN1.asbytes()) // packing in some payload .asjwe(CryptoAlgorithm::XC20P) // set JOSE header for XC20P algorithm .addheaderfield("mycustomkey".into(), "mycustomvalue".into()) // custom header .addheaderfield("anotherkey".into(), "anothervalue".into()) // another coustom header .kid(String::from(r#"Ef1sFuyOozYm3CEY4iCdwqxiSyXZ5Br-eUDdQXk6jaQ"#)); // set kid header

// Send as signed and encrypted JWS wrapped into JWE
let ready_to_send = message.seal_signed(
    encryption_key.as_bytes(),
    &sign_keypair.to_bytes(),
    SignatureAlgorithm::EdDsa)
    .unwrap();

//... transport to destination is happening here ...

//Receive - same method to receive for JWE or JWS wrapped into JWE but with pub verifying key
let received = Message::receive(
    &ready_to_send,
    Some(decryption_key.as_bytes()),
    Some(&pub_sign_verify_key.to_bytes())); // and now we parse received

```

6. Multiple receivers static key wrap per recepient with shared secret

• ! Works with resolve feature only - requires resolution of public keys for each recepient for shared secret generation.
• Static key generated randomly in the background (to field has >1 recepient).

GoTo: full test

```rust // Creating message with multiple recepients. let m = Message::new() .from("did:key:z6MkiTBz1ymuepAQ4HEHYSF1H8quG5GLVVQR3djdX3mDooWp") .to(&["did:key:z6MkjchhfUsD6mmvni8mCdXHw216Xrm9bQe2mBH1P5RDjVJG", "did:key:z6MknGc3ocHs3zdPiJbnaaqDi58NGb4pk1Sp9WxWufuXSdxf"]) .as_jwe(&CryptoAlgorithm::XC20P);

let jwe = m.seal(&senderprivate); // Packing was ok? assert!(jwe.isok());

let jwe = jwe.unwrap();

// Each of the recepients receive it in same way as before (direct with single receiver) let receivedfirst = Message::receive(&jwe, &firstprivate); let receivedsecond = Message::receive(&jwe, &secondprivate);

// All good without any extra inputs assert!(receivedfirst.isok()); assert!(receivedsecond.isok()); ```

7. Working with attachments

7.1 Adding Attachment

```rust use didcomm_rs::{Message, AttachmentBuilder, AttachmentDataBuilder};

let payload = b"some usefull data"; let mut m = Message:new(); m.appendattachment( AttachmentBuilder::new(true) .withid("best attachment") .withdata( AttachmentDataBuilder::new() .withraw_payload(payload) ) ); ```

or

```rust use didcomm_rs::{Message, AttachmentBuilder, AttachmentDataBuilder};

let attachments: Vec; // instantiate properly

let mut m = Message:new();

for attachment in attachments { m.append_attachment(attachment); } ```

7.2 Parsing Attachment's

``rust //misreceive()'d instance of aMessage`

let somethingimlookingfor = m.getattachments().filter(|single| single.id == "id I'm looking for"); assert!(somethingimlookingfor.next().issome());

for found in somethingimlooking_for { // process attachments }

```

8. Threading

By default all new messages are created with random UUID as thid header value and with empty pthid value.

To reply to a message in thread with both thid and pthid copied use reply_to method:

```rust

let m = Message::new() .reply_to(&received) // - other methods to form a message ; ```

To set parent thread id (or pthid header), use with_parent method:

```rust

let m = Message::new() .with_parent(&receievd) // - other methods to form a message ; ```

9. Other application-level headers and decorators

In order to satisfy any other header values universal method is present: Message::add_header_field' This method is backed up by aHashMap` of . If the key was present - it's value will be updated.

```rust

let m = Message::new() .addheaderfield("key", "value") .addheaderfield("~decorator", "value") // - other methods to form a message ; ```

To find if specific application level header is present and get it's value get_application_params method should be used.

```rust

let m: Message; // proprely instantiated received message

if let Some((mykey, myvalue)) = m.getapplicationparams().filter(|(key, )| key == "mykey").first(); ```

Plugable cryptography

In order to use your own implementation[s] of message crypto and/or signature algorythms implement these trait[s]:

didcomm_rs::crypto::Cypher

didcomm_rs::crypto::Signer

Dont use default feature - might change in future.

When implemented - use them instead of CrptoAlgorithm and SignatureAlgorithm from examples above.

Strongly typed Message payload (body)

GoTo: full test

In most cases apllication implementation would prefer to have strongly typed body of the message instead of raw Vec<u8>. For this scenario Shape trait should be implemented for target type.

• First, let's define our target type. JSON in this example. ```rust

  [derive(Serialize, Deserialize, PartialEq, Debug)]

struct DesiredShape { numfield: usize, stringfield: String, } ```

• Next, implement Shape trait for it rust impl Shape for DesiredShape { type Err = Error; fn shape(m: &Message) -> Result<DesiredShape, Error> { serde_json::from_slice(&m.body) .map_err(|e| Error::SerdeError(e)) } }

• Now we can call shape() on our Message and shape in in.

• In this example we expect JSON payload and use it's Deserializer to get our data, but your implementation can work with any serialization. rust let received_typed_body = DesiredShape::shape(&m).unwrap(); // Where m = Message

Disclaimer

This is a sample implementation of the DIDComm V2 spec. The DIDComm V2 spec is still actively being developed by the DIDComm WG in the DIF and therefore subject to change.