Refactor BinaryParser and tests, update key representation

This commit includes modifications to handling of key access in BinaryParser and changes the way the ephemeral public key data is represented in NanoTDF. Removed redundant code in BinaryParser by eliminating unnecessary if-else checks and updated how bindingSize is calculated. Some previously commented code in the test suite has been uncommented and refined, ensuring a more accurate validation of our tests. Now, the test suite also checks the existence of the ephemeral public key.

NanoTDF/BinaryParser.swift

@@ -87,7 +87,7 @@ class BinaryParser {
             print("Failed to read Embedded Policy plaintext / ciphertext")
             return nil
         }
-        let keyAccess = policyType == .embeddedEncryptedWithPolicyKeyAccess ? readPolicyKeyAccess(bindingMode: bindingMode) : nil
+//        let keyAccess = policyType == .embeddedEncryptedWithPolicyKeyAccess ? readPolicyKeyAccess(bindingMode: bindingMode) : nil
 
         return EmbeddedPolicyBody(length: plaintextCiphertext.count, body: plaintextCiphertext, keyAccess: nil)
     }
@@ -138,8 +138,6 @@ class BinaryParser {
         var bindingSize: Int
         print("bindingMode", bindingMode)
         if bindingMode.ecdsaBinding {
-            bindingSize = 64
-        } else {
             switch bindingMode.curve {
             case .secp256r1, .xsecp256k1:
                 bindingSize = 64
@@ -148,11 +146,11 @@ class BinaryParser {
             case .secp521r1:
                 bindingSize = 132
             }
+        } else {
+            // GMAC Tag Binding
+            bindingSize = 16
         }
         print("bindingSize", bindingSize)
-        if bindingMode.ecdsaBinding {
-            bindingSize = 64
-        }
         return read(length: bindingSize)
     }
 

NanoTDF/NanoTDF.swift

@@ -373,7 +373,7 @@ func createNanoTDF(kas: KasMetadata, policy: inout Policy, plaintext: Data) thro
     let curve: Curve = .secp256r1
     var ephemeralPublicKeyData: Data = Data()
     if let ephemeralPublicKey = ephemeralPublicKey as? P256.KeyAgreement.PublicKey {
-        ephemeralPublicKeyData = ephemeralPublicKey.x963Representation
+        ephemeralPublicKeyData = ephemeralPublicKey.compressedRepresentation
     }
     print("ephemeralPublicKeyData.count", ephemeralPublicKeyData.count)
     let header = Header(magicNumber: magicNumber,

Tests/NanoTDFCreationTests.swift

@@ -22,6 +22,7 @@ class NanoTDFCreationTests: XCTestCase {
         XCTAssertNotNil(nanoTDF, "NanoTDF should not be nil")
         XCTAssertNotNil(nanoTDF.header, "Header should not be nil")
         XCTAssertNotNil(nanoTDF.header.policy.remote, "Policy body should not be nil")
+        XCTAssertNotNil(nanoTDF.header.ephemeralPublicKey, "Ephemeral PublicKey should not be nil")
         XCTAssertNotNil(nanoTDF.payload, "Payload should not be nil")
         XCTAssertNotNil(nanoTDF.payload.iv, "Payload nonce should not be nil")
         XCTAssertNotNil(nanoTDF.payload.ciphertext, "Payload ciphertext should not be nil")
@@ -56,11 +57,11 @@ class NanoTDFCreationTests: XCTestCase {
         // Ephemeral Key
         let ephemeralKeyHexString = header.ephemeralPublicKey.map { String(format: "%02x", $0) }.joined(separator: " ")
         print("Ephemeral Key:", ephemeralKeyHexString)
-        // FIXME payload length is incorrect
-//        let payload = try parser.parsePayload(config: header.payloadSignatureConfig)
-//        let snanoTDF = NanoTDF(header: header, payload: payload, signature: nil)
-//        // Print final the signature NanoTDF
-//        print(snanoTDF)
+        let payload = try parser.parsePayload(config: header.payloadSignatureConfig)
+        let snanoTDF = NanoTDF(header: header, payload: payload, signature: nil)
+        // Print final the signature NanoTDF
+        print(snanoTDF)
+        XCTAssertEqual(payload.length, 43)
     }
 
     func testCreateNanoTDFWithInvalidKasMetadata() {