asn.cpp

// asn.cpp - written and placed in the public domain by Wei Dai

#include "pch.h"

#ifndef CRYPTOPP_IMPORTS

#include "asn.h"

#include <iomanip>
#include <time.h>

NAMESPACE_BEGIN(CryptoPP)
USING_NAMESPACE(std)

/// DER Length
unsigned int DERLengthEncode(BufferedTransformation &bt, unsigned int length)
{
        unsigned int i=0;
        if (length <= 0x7f)
        {
                bt.Put(byte(length));
                i++;
        }
        else
        {
                bt.Put(byte(BytePrecision(length) | 0x80));
                i++;
                for (int j=BytePrecision(length); j; --j)
                {
                        bt.Put(byte(length >> (j-1)*8));
                        i++;
                }
        }
        return i;
}

bool BERLengthDecode(BufferedTransformation &bt, unsigned int &length, bool &definiteLength)
{
        byte b;

        if (!bt.Get(b))
                return false;

        if (!(b & 0x80))
        {
                definiteLength = true;
                length = b;
        }
        else
        {
                unsigned int lengthBytes = b & 0x7f;

                if (lengthBytes == 0)
                {
                        definiteLength = false;
                        return true;
                }

                definiteLength = true;
                length = 0;
                while (lengthBytes--)
                {
                        if (length >> (8*(sizeof(length)-1)))
                                BERDecodeError();       // length about to overflow

                        if (!bt.Get(b))
                                return false;

                        length = (length << 8) | b;
                }
        }
        return true;
}

bool BERLengthDecode(BufferedTransformation &bt, unsigned int &length)
{
        bool definiteLength;
        if (!BERLengthDecode(bt, length, definiteLength))
                BERDecodeError();
        return definiteLength;
}

void DEREncodeNull(BufferedTransformation &out)
{
        out.Put(TAG_NULL);
        out.Put(0);
}

void BERDecodeNull(BufferedTransformation &in)
{
        byte b;
        if (!in.Get(b) || b != TAG_NULL)
                BERDecodeError();
        unsigned int length;
        if (!BERLengthDecode(in, length) || length != 0)
                BERDecodeError();
}

/// ASN Strings
unsigned int DEREncodeOctetString(BufferedTransformation &bt, const byte *str, unsigned int strLen)
{
        bt.Put(OCTET_STRING);
        unsigned int lengthBytes = DERLengthEncode(bt, strLen);
        bt.Put(str, strLen);
        return 1+lengthBytes+strLen;
}

unsigned int DEREncodeOctetString(BufferedTransformation &bt, const SecByteBlock &str)
{
        return DEREncodeOctetString(bt, str.begin(), str.size());
}

unsigned int BERDecodeOctetString(BufferedTransformation &bt, SecByteBlock &str)
{
        byte b;
        if (!bt.Get(b) || b != OCTET_STRING)
                BERDecodeError();

        unsigned int bc;
        if (!BERLengthDecode(bt, bc))
                BERDecodeError();

        str.resize(bc);
        if (bc != bt.Get(str, bc))
                BERDecodeError();
        return bc;
}

unsigned int BERDecodeOctetString(BufferedTransformation &bt, BufferedTransformation &str)
{
        byte b;
        if (!bt.Get(b) || b != OCTET_STRING)
                BERDecodeError();

        unsigned int bc;
        if (!BERLengthDecode(bt, bc))
                BERDecodeError();

        bt.TransferTo(str, bc);
        return bc;
}

unsigned int DEREncodeTextString(BufferedTransformation &bt, const std::string &str, byte asnTag)
{
        bt.Put(asnTag);
        unsigned int lengthBytes = DERLengthEncode(bt, str.size());
        bt.Put((const byte *)str.data(), str.size());
        return 1+lengthBytes+str.size();
}

unsigned int BERDecodeTextString(BufferedTransformation &bt, std::string &str, byte asnTag)
{
        byte b;
        if (!bt.Get(b) || b != asnTag)
                BERDecodeError();

        unsigned int bc;
        if (!BERLengthDecode(bt, bc))
                BERDecodeError();

        SecByteBlock temp(bc);
        if (bc != bt.Get(temp, bc))
                BERDecodeError();
        str.assign((char *)temp.begin(), bc);
        return bc;
}

/// ASN BitString
unsigned int DEREncodeBitString(BufferedTransformation &bt, const byte *str, unsigned int strLen, unsigned int unusedBits)
{
        bt.Put(BIT_STRING);
        unsigned int lengthBytes = DERLengthEncode(bt, strLen+1);
        bt.Put((byte)unusedBits);
        bt.Put(str, strLen);
        return 2+lengthBytes+strLen;
}

unsigned int BERDecodeBitString(BufferedTransformation &bt, SecByteBlock &str, unsigned int &unusedBits)
{
        byte b;
        if (!bt.Get(b) || b != BIT_STRING)
                BERDecodeError();

        unsigned int bc;
        if (!BERLengthDecode(bt, bc))
                BERDecodeError();

        byte unused;
        if (!bt.Get(unused))
                BERDecodeError();
        unusedBits = unused;
        str.resize(bc-1);
        if ((bc-1) != bt.Get(str, bc-1))
                BERDecodeError();
        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)
                bt.Put((byte)(0x80 | ((v >> i) & 0x7f)));
        bt.Put((byte)(v & 0x7f));
}

unsigned int OID::DecodeValue(BufferedTransformation &bt, unsigned long &v)
{
        byte b;
        unsigned int i=0;
        v = 0;
        while (true)
        {
                if (!bt.Get(b))
                        BERDecodeError();
                i++;
                v <<= 7;
                v += b & 0x7f;
                if (!(b & 0x80))
                        return i;
        }
}

void OID::DEREncode(BufferedTransformation &bt) const
{
        assert(m_values.size() >= 2);
        ByteQueue temp;
        temp.Put(byte(m_values[0] * 40 + m_values[1]));
        for (unsigned int i=2; i<m_values.size(); i++)
                EncodeValue(temp, m_values[i]);
        bt.Put(OBJECT_IDENTIFIER);
        DERLengthEncode(bt, temp.CurrentSize());
        temp.TransferTo(bt);
}

void OID::BERDecode(BufferedTransformation &bt)
{
        byte b;
        if (!bt.Get(b) || b != OBJECT_IDENTIFIER)
                BERDecodeError();

        unsigned int length;
        if (!BERLengthDecode(bt, length) || length < 1)
                BERDecodeError();

        if (!bt.Get(b))
                BERDecodeError();
        
        length--;
        m_values.resize(2);
        m_values[0] = b / 40;
        m_values[1] = b % 40;

        while (length > 0)
        {
                unsigned long v;
                unsigned int valueLen = DecodeValue(bt, v);
                if (valueLen > length)
                        BERDecodeError();
                m_values.push_back(v);
                length -= valueLen;
        }
}

void OID::BERDecodeAndCheck(BufferedTransformation &bt) const
{
        OID oid(bt);
        if (*this != oid)
                BERDecodeError();
}

inline BufferedTransformation & EncodedObjectFilter::CurrentTarget()
{
        if (m_flags & PUT_OBJECTS) 
                return *AttachedTransformation();
        else
                return TheBitBucket();
}

void EncodedObjectFilter::Put(const byte *inString, unsigned int length)
{
        if (m_nCurrentObject == m_nObjects)
        {
                AttachedTransformation()->Put(inString, length);
                return;
        }

        LazyPutter lazyPutter(m_queue, inString, length);

        while (m_queue.AnyRetrievable())
        {
                switch (m_state)
                {
                case IDENTIFIER:
                        if (!m_queue.Get(m_id))
                                return;
                        m_queue.TransferTo(CurrentTarget(), 1);
                        m_state = LENGTH;       // fall through
                case LENGTH:
                {
                        byte b;
                        if (m_level > 0 && m_id == 0 && m_queue.Peek(b) && b == 0)
                        {
                                m_queue.TransferTo(CurrentTarget(), 1);
                                m_level--;
                                m_state = IDENTIFIER;
                                break;
                        }
                        ByteQueue::Walker walker(m_queue);
                        bool definiteLength;
                        if (!BERLengthDecode(walker, m_lengthRemaining, definiteLength))
                                return;
                        m_queue.TransferTo(CurrentTarget(), walker.GetCurrentPosition());
                        if (!((m_id & CONSTRUCTED) || definiteLength))
                                BERDecodeError();
                        if (!definiteLength)
                        {
                                if (!(m_id & CONSTRUCTED))
                                        BERDecodeError();
                                m_level++;
                                m_state = IDENTIFIER;
                                break;
                        }
                        m_state = BODY;         // fall through
                }
                case BODY:
                        m_lengthRemaining -= m_queue.TransferTo(CurrentTarget(), m_lengthRemaining);

                        if (m_lengthRemaining == 0)
                                m_state = IDENTIFIER;
                }

                if (m_state == IDENTIFIER && m_level == 0)
                {
                        // just finished processing a level 0 object
                        ++m_nCurrentObject;

                        if (m_flags & PUT_MESSANGE_END_AFTER_EACH_OBJECT)
                                AttachedTransformation()->MessageEnd();

                        if (m_nCurrentObject == m_nObjects)
                        {
                                if (m_flags & PUT_MESSANGE_END_AFTER_ALL_OBJECTS)
                                        AttachedTransformation()->MessageEnd();

                                if (m_flags & PUT_MESSANGE_SERIES_END_AFTER_ALL_OBJECTS)
                                        AttachedTransformation()->MessageSeriesEnd();

                                m_queue.TransferAllTo(*AttachedTransformation());
                                return;
                        }
                }
        }
}

BERGeneralDecoder::BERGeneralDecoder(BufferedTransformation &inQueue, byte asnTag)
        : m_inQueue(inQueue), m_finished(false)
{
        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)
                BERDecodeError();

        m_definiteLength = BERLengthDecode(m_inQueue, m_length);
        if (!m_definiteLength && !(asnTag & CONSTRUCTED))
                BERDecodeError();       // cannot be primitive and have indefinite length
}

BERGeneralDecoder::~BERGeneralDecoder()
{
        try     // avoid throwing in constructor
        {
                if (!m_finished)
                        MessageEnd();
        }
        catch (...)
        {
        }
}

bool BERGeneralDecoder::EndReached() const
{
        if (m_definiteLength)
                return m_length == 0;
        else
        {       // check end-of-content octets
                word16 i;
                return (m_inQueue.PeekWord16(i)==2 && i==0);
        }
}

byte BERGeneralDecoder::PeekByte() const
{
        byte b;
        if (!Peek(b))
                BERDecodeError();
        return b;
}

void BERGeneralDecoder::CheckByte(byte check)
{
        byte b;
        if (!Get(b) || b != check)
                BERDecodeError();
}

void BERGeneralDecoder::MessageEnd()
{
        m_finished = true;
        if (m_definiteLength)
        {
                if (m_length != 0)
                        BERDecodeError();
        }
        else
        {       // remove end-of-content octets
                word16 i;
                if (m_inQueue.GetWord16(i) != 2 || i != 0)
                        BERDecodeError();
        }
}

unsigned int BERGeneralDecoder::TransferTo2(BufferedTransformation &target, unsigned long &transferBytes, const std::string &channel, bool blocking)
{
        if (m_definiteLength && transferBytes > m_length)
                transferBytes = m_length;
        unsigned int blockedBytes = m_inQueue.TransferTo2(target, transferBytes, channel, blocking);
        ReduceLength(transferBytes);
        return blockedBytes;
}

unsigned int BERGeneralDecoder::CopyRangeTo2(BufferedTransformation &target, unsigned long &begin, unsigned long end, const std::string &channel, bool blocking) const
{
        if (m_definiteLength)
                end = STDMIN((unsigned long)m_length, end);
        return m_inQueue.CopyRangeTo2(target, begin, end, channel, blocking);
}

unsigned int BERGeneralDecoder::ReduceLength(unsigned int delta)
{
        if (m_definiteLength)
        {
                if (m_length < delta)
                        BERDecodeError();
                m_length -= delta;
        }
        return delta;
}

DERGeneralEncoder::DERGeneralEncoder(BufferedTransformation &outQueue, byte asnTag)
        : m_outQueue(outQueue), m_finished(false), m_asnTag(asnTag)
{
}

DERGeneralEncoder::DERGeneralEncoder(DERGeneralEncoder &outQueue, byte asnTag)
        : m_outQueue(outQueue), m_finished(false), m_asnTag(asnTag)
{
}

DERGeneralEncoder::~DERGeneralEncoder()
{
        try     // avoid throwing in constructor
        {
                if (!m_finished)
                        MessageEnd();
        }
        catch (...)
        {
        }
}

void DERGeneralEncoder::MessageEnd()
{
        m_finished = true;
        unsigned int length = (unsigned int)CurrentSize();
        m_outQueue.Put(m_asnTag);
        DERLengthEncode(m_outQueue, length);
        TransferTo(m_outQueue);
}

// *************************************************************

void X509PublicKey::BERDecode(BufferedTransformation &bt)
{
        BERSequenceDecoder subjectPublicKeyInfo(bt);
                BERSequenceDecoder algorithm(subjectPublicKeyInfo);
                        GetAlgorithmID().BERDecodeAndCheck(algorithm);
                        bool parametersPresent = algorithm.EndReached() ? false : BERDecodeAlgorithmParameters(algorithm);
                algorithm.MessageEnd();

                BERGeneralDecoder subjectPublicKey(subjectPublicKeyInfo, BIT_STRING);
                        subjectPublicKey.CheckByte(0);  // unused bits
                        BERDecodeKey2(subjectPublicKey, parametersPresent, subjectPublicKey.RemainingLength());
                subjectPublicKey.MessageEnd();
        subjectPublicKeyInfo.MessageEnd();
}

void X509PublicKey::DEREncode(BufferedTransformation &bt) const
{
        DERSequenceEncoder subjectPublicKeyInfo(bt);

                DERSequenceEncoder algorithm(subjectPublicKeyInfo);
                        GetAlgorithmID().DEREncode(algorithm);
                        DEREncodeAlgorithmParameters(algorithm);
                algorithm.MessageEnd();

                DERGeneralEncoder subjectPublicKey(subjectPublicKeyInfo, BIT_STRING);
                        subjectPublicKey.Put(0);        // unused bits
                        DEREncodeKey(subjectPublicKey);
                subjectPublicKey.MessageEnd();

        subjectPublicKeyInfo.MessageEnd();
}

void PKCS8PrivateKey::BERDecode(BufferedTransformation &bt)
{
        BERSequenceDecoder privateKeyInfo(bt);
                word32 version;
                BERDecodeUnsigned<word32>(privateKeyInfo, version, INTEGER, 0, 0);      // check version

                BERSequenceDecoder algorithm(privateKeyInfo);
                        GetAlgorithmID().BERDecodeAndCheck(algorithm);
                        bool parametersPresent = BERDecodeAlgorithmParameters(algorithm);
                algorithm.MessageEnd();

                BERGeneralDecoder octetString(privateKeyInfo, OCTET_STRING);
                        BERDecodeKey2(octetString, parametersPresent, privateKeyInfo.RemainingLength());
                octetString.MessageEnd();

                if (!privateKeyInfo.EndReached())
                        BERDecodeOptionalAttributes(privateKeyInfo);
        privateKeyInfo.MessageEnd();
}

void PKCS8PrivateKey::DEREncode(BufferedTransformation &bt) const
{
        DERSequenceEncoder privateKeyInfo(bt);
                DEREncodeUnsigned<word32>(privateKeyInfo, 0);   // version

                DERSequenceEncoder algorithm(privateKeyInfo);
                        GetAlgorithmID().DEREncode(algorithm);
                        DEREncodeAlgorithmParameters(algorithm);
                algorithm.MessageEnd();

                DERGeneralEncoder octetString(privateKeyInfo, OCTET_STRING);
                        DEREncodeKey(octetString);
                octetString.MessageEnd();

                DEREncodeOptionalAttributes(privateKeyInfo);
        privateKeyInfo.MessageEnd();
}

void PKCS8PrivateKey::BERDecodeOptionalAttributes(BufferedTransformation &bt)
{
        DERReencode(bt, m_optionalAttributes);
}

void PKCS8PrivateKey::DEREncodeOptionalAttributes(BufferedTransformation &bt) const
{
        m_optionalAttributes.CopyTo(bt);
}

NAMESPACE_END

#endif

---