From 40a5b80a4522a9b3ad3820b5a953bb4f3611e009 Mon Sep 17 00:00:00 2001
From: weidai <weidai11@users.noreply.github.com>
Date: Sat, 19 Jun 2004 08:26:29 +0000
Subject: [PATCH] fix encoding/decoding of optional attributes

---
 asn.cpp | 43 ++++++++++++++++++++++++++++++++++++-------
 asn.h   | 20 ++++++++++++++------
 2 files changed, 50 insertions(+), 13 deletions(-)

diff --git a/asn.cpp b/asn.cpp
index 41211ce2..272cec37 100644
--- a/asn.cpp
+++ b/asn.cpp
@@ -195,6 +195,23 @@ unsigned int BERDecodeBitString(BufferedTransformation &bt, SecByteBlock &str, u
 	return bc-1;
 }
 
+void DERReencode(BufferedTransformation &source, BufferedTransformation &dest)
+{
+	byte tag;
+	source.Peek(tag);
+	BERGeneralDecoder decoder(source, tag);
+	DERGeneralEncoder encoder(dest, tag);
+	if (decoder.IsDefiniteLength())
+		decoder.TransferTo(encoder, decoder.RemainingLength());
+	else
+	{
+		while (!decoder.EndReached())
+			DERReencode(decoder, encoder);
+	}
+	decoder.MessageEnd();
+	encoder.MessageEnd();
+}
+
 void OID::EncodeValue(BufferedTransformation &bt, unsigned long v)
 {
 	for (unsigned int i=RoundUpToMultipleOf(STDMAX(7U,BitPrecision(v)), 7U)-7; i != 0; i-=7)
@@ -354,15 +371,16 @@ void EncodedObjectFilter::Put(const byte *inString, unsigned int length)
 BERGeneralDecoder::BERGeneralDecoder(BufferedTransformation &inQueue, byte asnTag)
 	: m_inQueue(inQueue), m_finished(false)
 {
-	byte b;
-	if (!m_inQueue.Get(b) || b != asnTag)
-		BERDecodeError();
-
-	m_definiteLength = BERLengthDecode(m_inQueue, m_length);
+	Init(asnTag);
 }
 
 BERGeneralDecoder::BERGeneralDecoder(BERGeneralDecoder &inQueue, byte asnTag)
 	: m_inQueue(inQueue), m_finished(false)
+{
+	Init(asnTag);
+}
+
+void BERGeneralDecoder::Init(byte asnTag)
 {
 	byte b;
 	if (!m_inQueue.Get(b) || b != asnTag)
@@ -370,7 +388,7 @@ BERGeneralDecoder::BERGeneralDecoder(BERGeneralDecoder &inQueue, byte asnTag)
 
 	m_definiteLength = BERLengthDecode(m_inQueue, m_length);
 	if (!m_definiteLength && !(asnTag & CONSTRUCTED))
-		BERDecodeError();	// cannot be primitive have indefinite length
+		BERDecodeError();	// cannot be primitive and have indefinite length
 }
 
 BERGeneralDecoder::~BERGeneralDecoder()
@@ -534,7 +552,8 @@ void PKCS8PrivateKey::BERDecode(BufferedTransformation &bt)
 			BERDecodeKey2(octetString, parametersPresent, privateKeyInfo.RemainingLength());
 		octetString.MessageEnd();
 
-		BERDecodeOptionalAttributes(privateKeyInfo);
+		if (!privateKeyInfo.EndReached())
+			BERDecodeOptionalAttributes(privateKeyInfo);
 	privateKeyInfo.MessageEnd();
 }
 
@@ -556,6 +575,16 @@ void PKCS8PrivateKey::DEREncode(BufferedTransformation &bt) const
 	privateKeyInfo.MessageEnd();
 }
 
+void PKCS8PrivateKey::BERDecodeOptionalAttributes(BufferedTransformation &bt)
+{
+	DERReencode(bt, m_optionalAttributes);
+}
+
+void PKCS8PrivateKey::DEREncodeOptionalAttributes(BufferedTransformation &bt) const
+{
+	m_optionalAttributes.CopyTo(bt);
+}
+
 NAMESPACE_END
 
 #endif
diff --git a/asn.h b/asn.h
index ff91f86e..b833d248 100644
--- a/asn.h
+++ b/asn.h
@@ -75,6 +75,9 @@ CRYPTOPP_DLL unsigned int BERDecodeTextString(BufferedTransformation &in, std::s
 CRYPTOPP_DLL unsigned int DEREncodeBitString(BufferedTransformation &out, const byte *str, unsigned int strLen, unsigned int unusedBits=0);
 CRYPTOPP_DLL unsigned int BERDecodeBitString(BufferedTransformation &in, SecByteBlock &str, unsigned int &unusedBits);
 
+// BER decode from source and DER reencode into dest
+CRYPTOPP_DLL void DERReencode(BufferedTransformation &source, BufferedTransformation &dest);
+
 //! Object Identifier
 class CRYPTOPP_DLL OID
 {
@@ -147,6 +150,7 @@ protected:
 	unsigned int m_length;
 
 private:
+	void Init(byte asnTag);
 	void StoreInitialize(const NameValuePairs &parameters) {assert(false);}
 	unsigned int ReduceLength(unsigned int delta);
 };
@@ -221,8 +225,8 @@ public:
 	}
 	void DEREncode(BufferedTransformation &out)
 	{
-		if (get() != NULL)
-			get()->DEREncode(out);
+		if (this->get() != NULL)
+			this->get()->DEREncode(out);
 	}
 };
 
@@ -259,10 +263,14 @@ public:
 	void BERDecode(BufferedTransformation &bt);
 	void DEREncode(BufferedTransformation &bt) const;
 
-	virtual void BERDecodeOptionalAttributes(BufferedTransformation &bt)
-		{}	// TODO: skip optional attributes if present
-	virtual void DEREncodeOptionalAttributes(BufferedTransformation &bt) const
-		{}
+	//! decode optional attributes including context-specific tag
+	/*! /note default implementation stores attributes to be output in DEREncodeOptionalAttributes */
+	virtual void BERDecodeOptionalAttributes(BufferedTransformation &bt);
+	//! encode optional attributes including context-specific tag
+	virtual void DEREncodeOptionalAttributes(BufferedTransformation &bt) const;
+
+private:
+	ByteQueue m_optionalAttributes;
 };
 
 // ********************************************************