feat: add input doc generation helper

This adds an optional helper for generating an input document from a set of keys and services. This helper is intentionally simple; it won't cover all use cases. But when all you need is a basic document, it will get you there without having to worry about contexts and such. Additionally, those familiar with the did-peer-2 library will see similarities between the helper added here and the `generate` method in the did-peer-2 library. This is deliberate and should hopefully help ease the transition for those adopting did:peer:4 after did:peer:2. I accidentally made the generation of did:peer:2 actually pretty okay, interface wise. This addition seeks to prevent that from becoming a barrier to adoption. Signed-off-by: Daniel Bluhm <[email protected]>
decentralized-identity · Nov 8, 2023 · 571d699 · 571d699
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diff --git a/did_peer_4/input_doc.py b/did_peer_4/input_doc.py
@@ -0,0 +1,58 @@
+"""Helpers for creating input documents for the DID method."""
+from dataclasses import dataclass
+from typing import Any, Dict, Literal, Optional, Sequence
+
+RELATIONSHIPS = (
+    "authentication",
+    "assertionMethod",
+    "keyAgreement",
+    "capabilityDelegation",
+    "capabilityInvocation",
+)
+
+Relationship = Literal[
+    "authentication",
+    "assertionMethod",
+    "keyAgreement",
+    "capabilityDelegation",
+    "capabilityInvocation",
+]
+
+
+@dataclass
+class KeySpec:
+    """Key specification."""
+
+    multikey: str
+    relationships: Sequence[Relationship]
+
+
+def input_doc_from_keys_and_services(
+    keys: Sequence[KeySpec], services: Optional[Sequence[dict]] = None
+) -> dict:
+    """Create an input document for a set of keys and services."""
+    input_doc: Dict[str, Any] = {
+        "@context": [
+            "https://www.w3.org/ns/did/v1",
+            "https://w3id.org/security/multikey/v1",
+        ]
+    }
+    for index, key in enumerate(keys):
+        ident = f"#key-{index}"
+        input_doc.setdefault("verificationMethod", []).append(
+            {
+                "id": ident,
+                "type": "Multikey",
+                "publicKeyMultibase": key.multikey,
+            }
+        )
+        for relationship in key.relationships:
+            if relationship not in RELATIONSHIPS:
+                raise ValueError(f"Invalid relationship: {relationship}")
+
+            input_doc.setdefault(relationship, []).append(ident)
+
+        if services:
+            input_doc["service"] = services
+
+    return input_doc
diff --git a/tests/test_input_doc.py b/tests/test_input_doc.py
@@ -0,0 +1,64 @@
+from did_peer_4 import encode
+from did_peer_4.input_doc import input_doc_from_keys_and_services, KeySpec
+from did_peer_4.valid import validate_input_document
+
+ED25519_MULTIKEY = "z6MkrCD1csqtgdj8sjrsu8jxcbeyP6m7LiK87NzhfWqio5yr"
+X25519_MULTIKEY = "z6LSqPZfn9krvgXma2icTMKf2uVcYhKXsudCmPoUzqGYW24U"
+
+
+def test_input_doc_generation():
+    input_doc = input_doc_from_keys_and_services(
+        [
+            KeySpec(
+                multikey=ED25519_MULTIKEY,
+                relationships=["authentication"],
+            ),
+            KeySpec(
+                multikey=X25519_MULTIKEY,
+                relationships=["keyAgreement"],
+            ),
+        ],
+        [
+            {
+                "id": "#didcommmessaging-0",
+                "type": "DIDCommMessaging",
+                "serviceEndpoint": {
+                    "uri": "didcomm:transport/queue",
+                    "accept": ["didcomm/v2"],
+                },
+            }
+        ],
+    )
+
+    assert input_doc == {
+        "@context": [
+            "https://www.w3.org/ns/did/v1",
+            "https://w3id.org/security/multikey/v1",
+        ],
+        "verificationMethod": [
+            {
+                "id": "#key-0",
+                "type": "Multikey",
+                "publicKeyMultibase": ED25519_MULTIKEY,
+            },
+            {
+                "id": "#key-1",
+                "type": "Multikey",
+                "publicKeyMultibase": X25519_MULTIKEY,
+            },
+        ],
+        "authentication": ["#key-0"],
+        "keyAgreement": ["#key-1"],
+        "service": [
+            {
+                "id": "#didcommmessaging-0",
+                "type": "DIDCommMessaging",
+                "serviceEndpoint": {
+                    "uri": "didcomm:transport/queue",
+                    "accept": ["didcomm/v2"],
+                },
+            }
+        ],
+    }
+    assert validate_input_document(input_doc)
+    assert encode(input_doc)