dsa.cpp

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

#include "pch.h"

#ifndef CRYPTOPP_IMPORTS

#include "dsa.h"
#include "asn.h"
#include "integer.h"
#include "filters.h"
#include "nbtheory.h"

NAMESPACE_BEGIN(CryptoPP)

size_t DSAConvertSignatureFormat(byte *buffer, size_t bufferSize, DSASignatureFormat toFormat, const byte *signature, size_t signatureLen, DSASignatureFormat fromFormat)
{
    Integer r, s;
    StringStore store(signature, signatureLen);
    ArraySink sink(buffer, bufferSize);

    switch (fromFormat)
    {
    case DSA_P1363:
        r.Decode(store, signatureLen/2);
        s.Decode(store, signatureLen/2);
        break;
    case DSA_DER:
    {
        BERSequenceDecoder seq(store);
        r.BERDecode(seq);
        s.BERDecode(seq);
        seq.MessageEnd();
        break;
    }
    case DSA_OPENPGP:
        r.OpenPGPDecode(store);
        s.OpenPGPDecode(store);
        break;
    }

    switch (toFormat)
    {
    case DSA_P1363:
        r.Encode(sink, bufferSize/2);
        s.Encode(sink, bufferSize/2);
        break;
    case DSA_DER:
    {
        DERSequenceEncoder seq(sink);
        r.DEREncode(seq);
        s.DEREncode(seq);
        seq.MessageEnd();
        break;
    }
    case DSA_OPENPGP:
        r.OpenPGPEncode(sink);
        s.OpenPGPEncode(sink);
        break;
    }

    return (size_t)sink.TotalPutLength();
}

NAMESPACE_END

#endif