Add did:ethr and EIP-712-based linked data proof type

Cargo.toml

@@ -45,12 +45,14 @@ blake2b_simd = "0.5"
 bs58 = { version = "0.4", features = ["check"] }
 libsecp256k1 = { version = "0.3", optional = true }
 thiserror = "1.0"
+keccak-hash = { version = "0.7", optional = true }
 
 [workspace]
 members = [
   "did-tezos",
   "did-key",
   "did-web",
+  "did-ethr",
   "vc-test",
 ]
 

contexts/eip712vm.jsonld

@@ -0,0 +1,52 @@
+{
+  "Eip712Method2021": "https://w3id.org/security#Eip712Method2021",
+  "Eip712Signature2021": {
+    "@id": "https://w3id.org/security#Eip712Signature2021",
+    "@context": {
+      "@version": 1.1,
+      "@protected": true,
+      "id": "@id",
+      "type": "@type",
+      "challenge": "https://w3id.org/security#challenge",
+      "created": {
+        "@id": "http://purl.org/dc/terms/created",
+        "@type": "http://www.w3.org/2001/XMLSchema#dateTime"
+      },
+      "domain": "https://w3id.org/security#domain",
+      "expires": {
+        "@id": "https://w3id.org/security#expiration",
+        "@type": "http://www.w3.org/2001/XMLSchema#dateTime"
+      },
+      "nonce": "https://w3id.org/security#nonce",
+      "proofPurpose": {
+        "@id": "https://w3id.org/security#proofPurpose",
+        "@type": "@vocab",
+        "@context": {
+          "@version": 1.1,
+          "@protected": true,
+          "id": "@id",
+          "type": "@type",
+          "assertionMethod": {
+            "@id": "https://w3id.org/security#assertionMethod",
+            "@type": "@id",
+            "@container": "@set"
+          },
+          "authentication": {
+            "@id": "https://w3id.org/security#authenticationMethod",
+            "@type": "@id",
+            "@container": "@set"
+          }
+        }
+      },
+      "proofValue": "https://w3id.org/security#proofValue",
+      "verificationMethod": {
+        "@id": "https://w3id.org/security#verificationMethod",
+        "@type": "@id"
+      },
+      "publicKeyJwk": {
+        "@id": "https://w3id.org/security#publicKeyJwk",
+        "@type": "@json"
+      }
+    }
+  }
+}

did-ethr/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "did-ethr"
+version = "0.0.1"
+authors = ["Spruce Systems, Inc."]
+edition = "2018"
+
+[dependencies]
+ssi = { path = "../", default-features = false, features = ["secp256k1", "keccak-hash"] }
+chrono = { version = "0.4", features = ["serde"] }
+tokio = { version = "1.0", features = ["macros", "rt"] }
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+async-trait = "0.1"
+libsecp256k1 = { version = "0.3" }
+keccak-hash = "0.7"