PKIFCryptoPPExternalDigest.cpp

Go to the documentation of this file.

#include "PKIFCryptoPPExternalDigest.h"

using namespace CryptoPP;

PKIFCryptoPPExternalDigest::~PKIFCryptoPPExternalDigest()
{
    if(m_digestBuf) {
        delete[] m_digestBuf;
        m_digestBuf = 0;
    }
}

void PKIFCryptoPPExternalDigest::SetDigest(const unsigned char * buf, unsigned int length)
{
    if(m_digestBuf) {
        delete[] m_digestBuf;
        m_digestSize = length;
        m_digestBuf = new unsigned char[m_digestSize];
    } else {
        m_digestSize = length;
        m_digestBuf = new unsigned char[m_digestSize];
    }
    memcpy(m_digestBuf,buf,m_digestSize);
}

unsigned int PKIFCryptoPPExternalDigest::DigestSize() const {
    return m_digestSize;
}

void PKIFCryptoPPExternalDigest::TruncatedFinal( 
                                    byte * digest, 
                                    size_t digestSize)
{
    // I'd *really* like this to throw if digestSize and m_digestSize don't match, but
    // there's no documentation in crypto++ around where this could be called. Since the
    // name strongly implies that truncation should be OK, that's what we'll do. XXX Revisit
    if(digestSize > 0) {
        memcpy(digest,m_digestBuf,digestSize > m_digestSize ? m_digestSize : digestSize);
    }
}

bool PKIFCryptoPPExternalDigest::TruncatedVerify(
                                     const byte * digest,
                                     size_t digestLength)
{
    if(digestLength != m_digestSize) return false;
    return (0 == memcmp(m_digestBuf,digest, digestLength));
}


PKIFCryptoPPExternalDigestAccumulator * NewEDAccumulator(
    unsigned char * digest,
    size_t len)
{
    // this is ugly but it's the only way to let the caller calculate a hash
    // without subclassing every digest algorithm we'd like this to work with.
    // Since doing that would mean the same code copied and pasted at least for
    // MD5, SHA-1, SHA-256, SHA-384 and SHA-512, this is reluctantly preferred.
    // This is not generally a great way to use crypto++, as it removes most of
    // the power of the filter pattern they use, but that's unneeded inside PKIF
    // for the most part. Do not emulate this outside PKIF.
    PKIFCryptoPPExternalDigestAccumulator * acc = new PKIFCryptoPPExternalDigestAccumulator();
    HashTransformation & h = acc->AccessHash();
    PKIFCryptoPPExternalDigest * ed = dynamic_cast<PKIFCryptoPPExternalDigest *>(&h);
    ed->SetDigest(digest,(unsigned int)len);
    return acc;
}