Function EncodeBase58

libraries/fc/src/crypto/base58.cpp:505–550

Encode a byte sequence as a base58-encoded string

// Encode a byte sequence as a base58-encoded string
inline std::string EncodeBase58(const unsigned char* pbegin, const unsigned char* pend, const fc::yield_function_t& yield)
{
    CAutoBN_CTX pctx;
    CBigNum bn58 = 58;
    CBigNum bn0 = 0;

    // Convert big endian data to little endian
    // Extra zero at the end make sure bignum will interpret as a positive number
    std::vector<unsigned char> vchTmp(pend-pbegin+1, 0);
    yield();
    reverse_copy(pbegin, pend, vchTmp.begin());
    yield();

    // Convert little endian data to bignum
    CBigNum bn;
    bn.setvch(vchTmp);

    // Convert bignum to std::string
    std::string str;
    // Expected size increase from base58 conversion is approximately 137%
    // use 138% to be safe
    str.reserve((pend - pbegin) * 138 / 100 + 1);
    CBigNum dv;
    CBigNum rem;
    while (bn > bn0)
    {
        yield();
        if (!BN_div(dv.to_bignum(), rem.to_bignum(), bn.to_bignum(), bn58.to_bignum(), pctx))
            throw bignum_error("EncodeBase58 : BN_div failed");
        bn = dv;
        unsigned int c = rem.getulong();
        str += pszBase58[c];
    }

    // Leading zeroes encoded as base58 zeros
    for (const unsigned char* p = pbegin; p < pend && *p == 0; p++)
        str += pszBase58[0];

    yield();
    // Convert little endian std::string to big endian
    reverse(str.begin(), str.end());
//    slog( "Encode '%s'", str.c_str() );
    yield();

    return str;
}

// Encode a byte vector as a base58-encoded string
inline std::string EncodeBase58(const std::vector<unsigned char>& vch, const fc::yield_function_t& yield)