From 766068b5bc75f985f586c909bf6298941cccfd93 Mon Sep 17 00:00:00 2001
From: marisawoo <marisa.woo@hotmail.com>
Date: Wed, 1 Nov 2023 18:13:33 -0400
Subject: [PATCH] add support for decrypt RSA OAEP

---
 README.md                |  1 +
 commands/constructors.go | 18 ++++++++++++++++++
 commands/response.go     | 12 ++++++++++++
 3 files changed, 31 insertions(+)

diff --git a/README.md b/README.md
index 05aa9a2..a6cdeee 100644
--- a/README.md
+++ b/README.md
@@ -14,6 +14,7 @@ Currently the following commands are implemented:
  * PutAsymmetricKey
  * GetPubKey
  * DeriveEcdh
+ * DecryptOaep
  * Echo
  * ChangeAuthenticationKey
  * PutAuthenticationKey
diff --git a/commands/constructors.go b/commands/constructors.go
index 9b95a4f..33f03b3 100644
--- a/commands/constructors.go
+++ b/commands/constructors.go
@@ -264,6 +264,24 @@ func CreateDeriveEcdhCommand(objID uint16, pubkey []byte) (*CommandMessage, erro
 	return command, nil
 }
 
+func CreateDecryptOaepCommand(objID uint16, algorithm Algorithm, ciphertextFile []byte) (*CommandMessage, error) {
+	if algorithm < AlgorithmRSAOAEPSHA1 || algorithm > AlgorithmRSAOAEPSHA512 {
+        return nil, errors.New("invalid algorithm")
+    }
+
+	command := &CommandMessage{
+		CommandType: CommandTypeDecryptOaep,
+	}
+
+	payload := bytes.NewBuffer([]byte{})
+	binary.Write(payload, binary.BigEndian, objID)
+	binary.Write(payload, binary.BigEndian, algorithm)
+	payload.Write(ciphertextFile)
+	command.Data = payload.Bytes()
+
+	return command, nil
+}
+
 func CreateChangeAuthenticationKeyCommand(objID uint16, newPassword string) (*CommandMessage, error) {
 	command := &CommandMessage{
 		CommandType: CommandTypeChangeAuthenticationKey,
diff --git a/commands/response.go b/commands/response.go
index 87bcaee..453e4c0 100644
--- a/commands/response.go
+++ b/commands/response.go
@@ -94,6 +94,10 @@ type (
 		XCoordinate []byte
 	}
 
+    DecryptOaepResponse struct {
+		Plaintext []byte
+	}
+
 	ChangeAuthenticationKeyResponse struct {
 		ObjectID uint16
 	}
@@ -183,6 +187,8 @@ func ParseResponse(data []byte) (Response, error) {
 		return parseEchoResponse(payload)
 	case CommandTypeDeriveEcdh:
 		return parseDeriveEcdhResponse(payload)
+    case CommandTypeDecryptOaep:
+		return parseDecryptOaepResponse(payload)
 	case CommandTypeChangeAuthenticationKey:
 		return parseChangeAuthenticationKeyResponse(payload)
 	case CommandTypeGetPseudoRandom:
@@ -364,6 +370,12 @@ func parseDeriveEcdhResponse(payload []byte) (Response, error) {
 	}, nil
 }
 
+func parseDecryptOaepResponse(payload []byte) (Response, error) {
+	return &DecryptOaepResponse{
+		Plaintext: payload,
+	}, nil
+}
+
 func parseChangeAuthenticationKeyResponse(payload []byte) (Response, error) {
 	if len(payload) != 2 {
 		return nil, errors.New("invalid response payload length")