llxorcipher.cpp

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#include "linden_common.h"

#include "llxorcipher.h"

#include "llerror.h"


LLXORCipher::LLXORCipher(const U8* pad, U32 pad_len) :
        mPad(NULL),
        mHead(NULL),
        mPadLen(0)
{
        init(pad, pad_len);
}

// Destroys the object
LLXORCipher::~LLXORCipher()
{
        init(NULL, 0);
}

LLXORCipher::LLXORCipher(const LLXORCipher& cipher) :
        mPad(NULL),
        mHead(NULL),
        mPadLen(0)
{
        init(cipher.mPad, cipher.mPadLen);
}

LLXORCipher& LLXORCipher::operator=(const LLXORCipher& cipher)
{
        if(this == &cipher) return *this;
        init(cipher.mPad, cipher.mPadLen);
        return *this;
}

U32 LLXORCipher::encrypt(const U8* src, U32 src_len, U8* dst, U32 dst_len)
{
        if(!src || !src_len || !dst || !dst_len || !mPad) return 0;
        U8* pad_end = mPad + mPadLen;
        U32 count = src_len;
        while(count--)
        {
                *dst++ = *src++ ^ *mHead++;
                if(mHead >= pad_end) mHead = mPad;
        }
        return src_len;
}

U32 LLXORCipher::decrypt(const U8* src, U32 src_len, U8* dst, U32 dst_len)
{
        // xor is a symetric cipher, thus, just call the other function.
        return encrypt(src, src_len, dst, dst_len);
}

U32 LLXORCipher::requiredEncryptionSpace(U32 len) const
{
        return len;
}

void LLXORCipher::init(const U8* pad, U32 pad_len)
{
        if(mPad)
        {
                delete [] mPad;
                mPad = NULL;
                mPadLen = 0;
        }
        if(pad && pad_len)
        {
                mPadLen = pad_len;
                mPad = new U8[mPadLen];
                if (mPad != NULL)
                {
                        memcpy(mPad, pad, mPadLen); /* Flawfinder : ignore */
                }
        }
        mHead = mPad;
}

#ifdef _DEBUG
// static
BOOL LLXORCipher::testHarness()
{
        const U32 PAD_LEN = 3;
        const U8 PAD[] = "abc";
        const S32 MSG_LENGTH = 12;
        const char MESSAGE[MSG_LENGTH+1] = "gesundheight";              /* Flawfinder : ignore */
        U8 encrypted[MSG_LENGTH];
        U8 decrypted[MSG_LENGTH];

        LLXORCipher cipher(PAD, PAD_LEN);
        cipher.encrypt((U8*)MESSAGE, MSG_LENGTH, encrypted, MSG_LENGTH);
        cipher.decrypt(encrypted, MSG_LENGTH, decrypted, MSG_LENGTH);

        if(0 != memcmp((void*)MESSAGE, decrypted, MSG_LENGTH)) return FALSE;
        return TRUE;
}
#endif

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