basecode.cpp

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

#include "pch.h"

#ifndef CRYPTOPP_IMPORTS

#include "basecode.h"
#include "fltrimpl.h"
#include <ctype.h>

NAMESPACE_BEGIN(CryptoPP)

void BaseN_Encoder::IsolatedInitialize(const NameValuePairs &parameters)
{
        parameters.GetRequiredParameter("BaseN_Encoder", Name::EncodingLookupArray(), m_alphabet);

        parameters.GetRequiredIntParameter("BaseN_Encoder", Name::Log2Base(), m_bitsPerChar);
        if (m_bitsPerChar <= 0 || m_bitsPerChar >= 8)
                throw InvalidArgument("BaseN_Encoder: Log2Base must be between 1 and 7 inclusive");

        byte padding;
        bool pad;
        if (parameters.GetValue(Name::PaddingByte(), padding))
                pad = parameters.GetValueWithDefault(Name::Pad(), true);
        else
                pad = false;
        m_padding = pad ? padding : -1;

        m_bytePos = m_bitPos = 0;

        int i = 8;
        while (i%m_bitsPerChar != 0)
                i += 8;
        m_outputBlockSize = i/m_bitsPerChar;

        m_outBuf.New(m_outputBlockSize);
}

size_t BaseN_Encoder::Put2(const byte *begin, size_t length, int messageEnd, bool blocking)
{
        FILTER_BEGIN;
        while (m_inputPosition < length)
        {
                if (m_bytePos == 0)
                        memset(m_outBuf, 0, m_outputBlockSize);

                {
                unsigned int b = begin[m_inputPosition++], bitsLeftInSource = 8;
                while (true)
                {
                        assert(m_bitPos < m_bitsPerChar);
                        unsigned int bitsLeftInTarget = m_bitsPerChar-m_bitPos;
                        m_outBuf[m_bytePos] |= b >> (8-bitsLeftInTarget);
                        if (bitsLeftInSource >= bitsLeftInTarget)
                        {
                                m_bitPos = 0;
                                ++m_bytePos;
                                bitsLeftInSource -= bitsLeftInTarget;
                                if (bitsLeftInSource == 0)
                                        break;
                                b <<= bitsLeftInTarget;
                                b &= 0xff;
                        }
                        else
                        {
                                m_bitPos += bitsLeftInSource;
                                break;
                        }
                }
                }

                assert(m_bytePos <= m_outputBlockSize);
                if (m_bytePos == m_outputBlockSize)
                {
                        int i;
                        for (i=0; i<m_bytePos; i++)
                        {
                                assert(m_outBuf[i] < (1 << m_bitsPerChar));
                                m_outBuf[i] = m_alphabet[m_outBuf[i]];
                        }
                        FILTER_OUTPUT(1, m_outBuf, m_outputBlockSize, 0);
                        
                        m_bytePos = m_bitPos = 0;
                }
        }
        if (messageEnd)
        {
                if (m_bitPos > 0)
                        ++m_bytePos;

                int i;
                for (i=0; i<m_bytePos; i++)
                        m_outBuf[i] = m_alphabet[m_outBuf[i]];

                if (m_padding != -1 && m_bytePos > 0)
                {
                        memset(m_outBuf+m_bytePos, m_padding, m_outputBlockSize-m_bytePos);
                        m_bytePos = m_outputBlockSize;
                }
                FILTER_OUTPUT(2, m_outBuf, m_bytePos, messageEnd);
                m_bytePos = m_bitPos = 0;
        }
        FILTER_END_NO_MESSAGE_END;
}

void BaseN_Decoder::IsolatedInitialize(const NameValuePairs &parameters)
{
        parameters.GetRequiredParameter("BaseN_Decoder", Name::DecodingLookupArray(), m_lookup);

        parameters.GetRequiredIntParameter("BaseN_Decoder", Name::Log2Base(), m_bitsPerChar);
        if (m_bitsPerChar <= 0 || m_bitsPerChar >= 8)
                throw InvalidArgument("BaseN_Decoder: Log2Base must be between 1 and 7 inclusive");

        m_bytePos = m_bitPos = 0;

        int i = m_bitsPerChar;
        while (i%8 != 0)
                i += m_bitsPerChar;
        m_outputBlockSize = i/8;

        m_outBuf.New(m_outputBlockSize);
}

size_t BaseN_Decoder::Put2(const byte *begin, size_t length, int messageEnd, bool blocking)
{
        FILTER_BEGIN;
        while (m_inputPosition < length)
        {
                unsigned int value;
                value = m_lookup[begin[m_inputPosition++]];
                if (value >= 256)
                        continue;

                if (m_bytePos == 0 && m_bitPos == 0)
                        memset(m_outBuf, 0, m_outputBlockSize);

                {
                        int newBitPos = m_bitPos + m_bitsPerChar;
                        if (newBitPos <= 8)
                                m_outBuf[m_bytePos] |= value << (8-newBitPos);
                        else
                        {
                                m_outBuf[m_bytePos] |= value >> (newBitPos-8);
                                m_outBuf[m_bytePos+1] |= value << (16-newBitPos);
                        }

                        m_bitPos = newBitPos;
                        while (m_bitPos >= 8)
                        {
                                m_bitPos -= 8;
                                ++m_bytePos;
                        }
                }

                if (m_bytePos == m_outputBlockSize)
                {
                        FILTER_OUTPUT(1, m_outBuf, m_outputBlockSize, 0);
                        m_bytePos = m_bitPos = 0;
                }
        }
        if (messageEnd)
        {
                FILTER_OUTPUT(2, m_outBuf, m_bytePos, messageEnd);
                m_bytePos = m_bitPos = 0;
        }
        FILTER_END_NO_MESSAGE_END;
}

void BaseN_Decoder::InitializeDecodingLookupArray(int *lookup, const byte *alphabet, unsigned int base, bool caseInsensitive)
{
        std::fill(lookup, lookup+256, -1);

        for (unsigned int i=0; i<base; i++)
        {
                if (caseInsensitive && isalpha(alphabet[i]))
                {
                        assert(lookup[toupper(alphabet[i])] == -1);
                        lookup[toupper(alphabet[i])] = i;
                        assert(lookup[tolower(alphabet[i])] == -1);
                        lookup[tolower(alphabet[i])] = i;
                }
                else
                {
                        assert(lookup[alphabet[i]] == -1);
                        lookup[alphabet[i]] = i;
                }
        }
}

void Grouper::IsolatedInitialize(const NameValuePairs &parameters)
{
        m_groupSize = parameters.GetIntValueWithDefault(Name::GroupSize(), 0);
        ConstByteArrayParameter separator, terminator;
        if (m_groupSize)
                parameters.GetRequiredParameter("Grouper", Name::Separator(), separator);
        else
                parameters.GetValue(Name::Separator(), separator);
        parameters.GetValue(Name::Terminator(), terminator);

        m_separator.Assign(separator.begin(), separator.size());
        m_terminator.Assign(terminator.begin(), terminator.size());
        m_counter = 0;
}

size_t Grouper::Put2(const byte *begin, size_t length, int messageEnd, bool blocking)
{
        FILTER_BEGIN;
        if (m_groupSize)
        {
                while (m_inputPosition < length)
                {
                        if (m_counter == m_groupSize)
                        {
                                FILTER_OUTPUT(1, m_separator, m_separator.size(), 0);
                                m_counter = 0;
                        }

                        size_t len;
                        FILTER_OUTPUT2(2, len = STDMIN(length-m_inputPosition, m_groupSize-m_counter),
                                begin+m_inputPosition, len, 0);
                        m_inputPosition += len;
                        m_counter += len;
                }
        }
        else
                FILTER_OUTPUT(3, begin, length, 0);

        if (messageEnd)
        {
                FILTER_OUTPUT(4, m_terminator, m_terminator.size(), messageEnd);
                m_counter = 0;
        }
        FILTER_END_NO_MESSAGE_END
}

NAMESPACE_END

#endif

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