Crate didcomm_rs

source · [−]
Expand description

Rust implementation of DIDComm v2 spec

tests

License

Apache-2.0

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);

// 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)
    // 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) // 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.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 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"}"#)
    // 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) // 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
// Creating message with multiple recipients.
let m = Message::new()
    .from("did:key:z6MkiTBz1ymuepAQ4HEHYSF1H8quG5GLVVQR3djdX3mDooWp")
    .to(&[
        "did:key:z6MkjchhfUsD6mmvni8mCdXHw216Xrm9bQe2mBH1P5RDjVJG",
        "did:key:z6MknGc3ocHs3zdPiJbnaaqDi58NGb4pk1Sp9WxWufuXSdxf",
    ])
    .as_jwe(&CryptoAlgorithm::XC20P, None);

let jwe = m.seal(&alice_private, None);
// Packing was ok?
assert!(jwe.is_ok());

let jwe = jwe.unwrap();

// Each of the recipients receive it in same way as before (direct with single recipient)
let received_first = Message::receive(&jwe, Some(&bobs_private), None, None);
let received_second = Message::receive(&jwe, Some(&carol_private), None, None);

// All good without any extra inputs
assert!(received_first.is_ok());
assert!(received_second.is_ok());

Pluggable cryptography

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

didcomm_rs::crypto::Cypher

didcomm_rs::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); // 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