Crate co_didcomm

Expand description

Rust implementation of DIDComm v2 spec

§License

§Examples of usage

§1. Prepare raw message for send and receive

§GoTo: full test

// Message construction
let m = Message::new()
    // setting `from` header (sender) - Optional
    .from("did:xyz:ulapcuhsatnpuhza930hpu34n_")
    // setting `to` header (recipients) - Optional
    .to(&[
        "did::xyz:34r3cu403hnth03r49g03",
        "did:xyz:30489jnutnjqhiu0uh540u8hunoe",
    ])
    // populating body with some data - `Vec<bytes>`
    .body(TEST_DID).unwrap();

// Serialize message into JWM json (SENDER action)
let ready_to_send = m.clone().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, None, None);

§2. Prepare JWE message for direct send

§GoTo: full test

// sender 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];

// Message construction
let message = Message::new()
    .from("did:key:z6MkiTBz1ymuepAQ4HEHYSF1H8quG5GLVVQR3djdX3mDooWp")
    .to(&[
        "did:key:z6MkiTBz1ymuepAQ4HEHYSF1H8quG5GLVVQR3djdX3mDooWp",
        "did:key:z6MkjchhfUsD6mmvni8mCdXHw216Xrm9bQe2mBH1P5RDjVJG",
    ])
    // packing in some payload (can be anything really)
    .body(TEST_DID).unwrap()
    // decide which [Algorithm](crypto::encryptor::CryptoAlgorithm) is used (based on key)
    .as_jwe(
        &CryptoAlgorithm::XC20P,
        Some(bobs_public.to_vec()),
    )
    // 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())
    // set `kid` property
    .kid(r#"#z6LShs9GGnqk85isEBzzshkuVWrVKsRp24GnDuHk8QWkARMW"#);

// recipient public key is automatically resolved
let ready_to_send = message.seal(
    &ek,
    Some(vec![Some(bobs_public.to_vec()), Some(carol_public.to_vec())]),
).unwrap();

//... 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.

// 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
    .body(TEST_DID).unwrap() // packing in some payload
    .as_jws(&SignatureAlgorithm::EdDsa)
    .sign(SignatureAlgorithm::EdDsa.signer(), &sign_keypair.to_bytes()).unwrap();

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

// Receiving JWS
let received = Message::verify(&message.as_bytes(), &sign_keypair.verifying_key().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 recipient.
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 sequential to match mediators sequence in the chain.
Method call .seal() MUST be preceded 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

let mediated = Message::new()
    // setting from
    .from("did:key:z6MkiTBz1ymuepAQ4HEHYSF1H8quG5GLVVQR3djdX3mDooWp")
    // setting to
    .to(&["did:key:z6MkjchhfUsD6mmvni8mCdXHw216Xrm9bQe2mBH1P5RDjVJG"])
    // packing in some payload
    .body(r#"{"foo":"bar"}"#).unwrap()
    // set JOSE header for XC20P algorithm
    .as_jwe(&CryptoAlgorithm::XC20P, Some(bobs_public.to_vec()))
    // custom header
    .add_header_field("my_custom_key".into(), "my_custom_value".into())
    // another custom header
    .add_header_field("another_key".into(), "another_value".into())
    // set kid header
    .kid(&"Ef1sFuyOozYm3CEY4iCdwqxiSyXZ5Br-eUDdQXk6jaQ")
    // here we use destination key to bob and `to` header of mediator -
    //**THIS MUST BE LAST IN THE CHAIN** - after this call you'll get new instance of envelope `Message` destined to the mediator.
    .routed_by(
        &alice_private,
        Some(vec![Some(bobs_public.to_vec())]),
        "did:key:z6MknGc3ocHs3zdPiJbnaaqDi58NGb4pk1Sp9WxWufuXSdxf",
        Some(mediators_public.to_vec()),
    );
assert!(mediated.is_ok());

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

// Received by mediator
let mediator_received = Message::receive(
    &mediated.unwrap(),
    Some(&mediators_private),
    Some(alice_public.to_vec()),
    None,
);
assert!(mediator_received.is_ok());

// Get inner JWE as string from message
let mediator_received_unwrapped = mediator_received.unwrap().get_body().unwrap();
let pl_string = String::from_utf8_lossy(mediator_received_unwrapped.as_ref());
let message_to_forward: Mediated = serde_json::from_str(&pl_string).unwrap();
let attached_jwe = serde_json::from_slice::<Jwe>(&message_to_forward.payload);
assert!(attached_jwe.is_ok());
let str_jwe = serde_json::to_string(&attached_jwe.unwrap());
assert!(str_jwe.is_ok());

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

// Received by Bob
let bob_received = Message::receive(
    &String::from_utf8_lossy(&message_to_forward.payload),
    Some(&bobs_private),
    Some(alice_public.to_vec()),
    None,
);
assert!(bob_received.is_ok());

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

JWS header is set automatically based on signing algorithm 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

let KeyPairSet {
    alice_public,
    alice_private,
    bobs_private,
    bobs_public,
    ..
} = get_keypair_set();
// Message construction
let message = Message::new() // creating message
    .from("did:xyz:ulapcuhsatnpuhza930hpu34n_") // setting from
    .to(&["did::xyz:34r3cu403hnth03r49g03"]) // setting to
    .body(TEST_DID).unwrap() // packing in some payload
    .as_jwe(&CryptoAlgorithm::XC20P, Some(bobs_public.to_vec())) // set JOSE header for XC20P algorithm
    .add_header_field("my_custom_key".into(), "my_custom_value".into()) // custom header
    .add_header_field("another_key".into(), "another_value".into()) // another custom header
    .kid(r#"Ef1sFuyOozYm3CEY4iCdwqxiSyXZ5Br-eUDdQXk6jaQ"#); // set kid header

// Send as signed and encrypted JWS wrapped into JWE
let ready_to_send = message.seal_signed(
    &alice_private,
    Some(vec![Some(bobs_public.to_vec())]),
    SignatureAlgorithm::EdDsa,
    &sign_keypair.to_bytes(),
).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(&bobs_private),
    Some(alice_public.to_vec()),
    None,
); // and now we parse received

§6. Multiple recipients static key wrap per recipient with shared secret

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

§GoTo: full test

§Pluggable cryptography

In order to use your own implementation(s) of message crypto and/or signature algorithms implement these trait(s):

co_didcomm::crypto::Cypher

co_didcomm::crypto::Signer

Don’t use default feature - might change in future.

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

§Strongly typed Message payload (body)

§GoTo: full test

In most cases application 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.

#[derive(Serialize, Deserialize, PartialEq, Debug)]
struct DesiredShape {
    num_field: usize,
    string_field: String,
}

Next, implement Shape trait for it

impl Shape for DesiredShape {
    type Err = Error;
    fn shape(m: &Message) -> Result<DesiredShape, Error> {
        serde_json::from_str(&m.get_body().unwrap())
            .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.

let body = r#"{"num_field":123,"string_field":"foobar"}"#.to_string();
let message = Message::new() // creating message
    .from("did:xyz:ulapcuhsatnpuhza930hpu34n_") // setting from
    .to(&["did::xyz:34r3cu403hnth03r49g03"]) // setting to
    .body(&body).unwrap(); // packing in some payload
let received_typed_body = DesiredShape::shape(&message).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.

Modules§

crypto: Collection of utilities for cryptography related components.
decorators: Decorator Types.
out_of_band

Structs§

Attachment: Attachment holding structure
AttachmentBuilder: Builder of attachment metadata and payload. Used to construct and inject Attachment into Message
AttachmentData: Attachment Data holding structure
AttachmentDataBuilder: Builder for AttachmentData
DidCommHeader: Collection of DIDComm message specific headers, will be flattened into DIDComm plain message according to spec.
Epk: Encryption public key
Jwe: JWE representation of Message with public header. Can be serialized to JSON or Compact representations and from same.
Jwk: Json Web Keys structure defined by RFC
JwmHeader: JWM Header as specified in RFC With single deviation - allows raw text JWM to support DIDComm spec
Jws: A struct to generate and serialize JWS envelopes for DIDComm messages.
Mediated: Mediated Message value
Message: DIDComm message structure.
PriorClaims: header used for DID rotation
Problem
Recipient: This struct presents single recipient of JWE recipients collection. Each recipient should have same body cypher key encrypted with shared secret. Spec
Signature: Signature data for JWS envelopes. They can be used per recipient in General JWS JSON, triggered by using .as_jws or as a single signature for the entire JWS in Flattened JWS JSON, triggered by .as_flat_jws.
Thread: A ~thread message decorator that provides request/reply and threading semantics according to Aries RFC 0008.

Enums§

ContentType: Enum that represents DIDComm message payload type
Error: Error type used througout crate
KeyAlgorithm: alg field values provided by RFC
KeyOps
KnownProblems: Values defined in spec: https://identity.foundation/didcomm-messaging/spec/#problem-codes Except KnownProblems::Unknow, which is default and should be used as little as possible
MessageType: Enum that represents DIDComm envelope type

Traits§

Shape: trait that can be used to verify body, see example here

Type Aliases§

Result: Result type. See module level documentation.

Crate co_didcomm

Crate co_didcomm Copy item path

§License

§Examples of usage

§1. Prepare raw message for send and receive

§GoTo: full test

§2. Prepare JWE message for direct send

§GoTo: full test

§3. Prepare JWS message -> send -> receive

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

§GoTo: full test

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

§GoTo: full test

§6. Multiple recipients static key wrap per recipient with shared secret

§GoTo: full test

§Pluggable cryptography

§Strongly typed Message payload (body)

§GoTo: full test

§Disclaimer

Modules§

Structs§

Enums§

Traits§

Type Aliases§

Crate co_didcomm