IN PROGRESS: did helpers: ecdsa p-384 key loading

Signed-off-by: John Andersen <[email protected]>

pytest.ini

@@ -1,2 +1,8 @@
 [pytest]
+# https://docs.pytest.org/en/7.1.x/how-to/doctest.html#using-doctest-options
+doctest_optionflags = NORMALIZE_WHITESPACE IGNORE_EXCEPTION_DETAIL
+# Alternatively, options can be enabled by an inline comment in the doc test itself:
+# >>> something_that_raises()  # doctest: +IGNORE_EXCEPTION_DETAIL
+# Traceback (most recent call last):
+# ValueError: ...
 addopts = --doctest-modules

scitt_emulator/did_helpers.py

@@ -4,6 +4,8 @@
 import urllib.parse
 from typing import Optional, Callable
 
+import multiformats
+
 
 def did_web_to_url(
     did_web_string: str,
@@ -27,8 +29,42 @@ class DIDKeyDecoderNotFoundError(NotImplementedError):
 DID_KEY_METHOD = "did:key:"
 
 
-def did_key_to_jwk_dict_is_p_384_startswith_z82(did_key: str) -> dict[str, str]:
-    did_key = did_key.replace(DID_KEY_METHOD, "", 1)
+def did_key_decode(
+    did_key_without_method_or_key_type_prefix: str,
+) -> tuple[str, bytes]:
+    return
+
+
+import snoop
+
+
+@snoop
+def did_key_decode_public_key(did_key: str) -> dict[str, str]:
+    """
+    3.1.3 Decode Public Key Algorithm
+    The following algorithm can be used for expanding a multibase-encoded
+    multicodec value to decoded public key components. A multibaseValue and
+    options are the required inputs. A decodedPublicKey is the output.
+    """
+
+    # Set decodedPublicKey to an empty object.
+    decoded_public_key = None
+
+    # Decode multibaseValue using the base58-btc multibase alphabet and set multicodecValue to the multicodec header for the decoded value. Implementers are cautioned to ensure that the multicodecValue is set to the result after performing varint decoding.
+    base58btc_decoded = multiformats.multibase.get("base58btc").decode(did_key)
+    # 3.1.2.3
+    multibase_value = base58btc_decoded[:2]
+    if multibase_value[0] != 0x12:
+        multibase_value = base58btc_decoded[:1]
+
+    # Set the rawPublicKeyBytes to the bytes remaining after the multicodec header.
+    raw_public_key_bytes = base58btc_decoded[len(multibase_value) :]
+
+    # Return multicodecValue and rawPublicKeyBytes as the decodedPublicKey.
+    return multibase_value, raw_public_key_bytes
+
+
+def did_key_to_jwk_dict_is_p_384_startswith_z82(multibase_value, raw_public_key_bytes) -> dict[str, str]:
     return
 
 
@@ -49,7 +85,7 @@ def did_key_to_jwk_dict(
     >>> did_key_to_jwk_dict("did:key:invalid")
     Traceback (most recent call last):
     DIDKeyDecoderNotFoundError: ...
-    >>> did_key_to_jwk_dict("did:key:z82LkvCwHNreneWpsgPEbV3gu1C6NFJEBg4srfJ5gdxEsMGRJUz2sG9FE42shbn2xkZJh54")
+    >>> did_key_to_jwk_dict("did:key:z6MkhaXgBZDvotDkL5257faiztiGiC2QtKLGpbnnEGta2doK")
     """
     if decoders_by_prefix is None:
         decoders_by_prefix = {
@@ -61,8 +97,15 @@ def did_key_to_jwk_dict(
             )
         }
 
+    try:
+        multibase_value, raw_public_key_bytes = did_key_decode_public_key(
+            did_key.replace(DID_KEY_METHOD, "", 1)
+        )
+    except multiformats.multibase.err.MultibaseKeyError as e:
+        raise DIDKeyDecoderNotFoundError(did_key) from e
+
     for prefix, decoder in decoders_by_prefix.items():
         if did_key.startswith(DID_KEY_METHOD + prefix):
-            return decoder(did_key)
+            return decoder(multibase_value, raw_public_key_bytes)
 
     raise DIDKeyDecoderNotFoundError(did_key)