How do you create an altcoin?

[chris200x9]

Didn't read all through it yet but maybe this helps? https://bitcointalk.org/index.php?topic=171355.0

[Remember remember the 5th of November]

Ok, so we basically have this

Code:

        const char* pszTimestamp = "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks";
        CTransaction txNew;
        txNew.vin.resize(1);
        txNew.vout.resize(1);
        txNew.vin[0].scriptSig = CScript() << 486604799 << CBigNum(4) << vector<unsigned char>((const unsigned char*)pszTimestamp, (const unsigned char*)pszTimestamp + strlen(pszTimestamp));
        txNew.vout[0].nValue = 50 * COIN;
        txNew.vout[0].scriptPubKey = CScript() << ParseHex("04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5f") << OP_CHECKSIG;
        CBlock block;
        block.vtx.push_back(txNew);
        block.hashPrevBlock = 0;
        block.hashMerkleRoot = block.BuildMerkleTree();

What we are interested in is, BuildMerkleTree which is found in main.h

Code:

    uint256 BuildMerkleTree() const
    {
        vMerkleTree.clear();
        BOOST_FOREACH(const CTransaction& tx, vtx)
            vMerkleTree.push_back(tx.GetHash());
        int j = 0;
        for (int nSize = vtx.size(); nSize > 1; nSize = (nSize + 1) / 2)
        {
            for (int i = 0; i < nSize; i += 2)
            {
                int i2 = std::min(i+1, nSize-1);
                vMerkleTree.push_back(Hash(BEGIN(vMerkleTree[j+i]),  END(vMerkleTree[j+i]),
                                           BEGIN(vMerkleTree[j+i2]), END(vMerkleTree[j+i2])));
            }
            j += nSize;
        }
        return (vMerkleTree.empty() ? 0 : vMerkleTree.back());
    }

Next we are interested in this, I believe.

Code:

vMerkleTree.push_back(tx.GetHash());

since we have only one transaction, this will return as soon as it computes the has. So we see tx.GetHash, and that tx is of type CTransaction, so we head in that class, which is in main.h again

and see this coide

Code:

    uint256 GetHash() const
    {
        return SerializeHash(*this);
    }

which passes the instance of the object to SerializeHash. SerializeHash is located in hash.h

Code:

template<typename T>
uint256 SerializeHash(const T& obj, int nType=SER_GETHASH, int nVersion=PROTOCOL_VERSION)
{
    CHashWriter ss(nType, nVersion);
    ss << obj;
    return ss.GetHash();
}

Here we see that the object is written(I think, not sure) to ss which is an instance of CHashWriter which is also in main.h and that is where the funky business happens that is uber hard to understand.

But here we go,

Code:

class CHashWriter
{
private:
    SHA256_CTX ctx;

public:
    int nType;
    int nVersion;

    void Init() {
        SHA256_Init(&ctx);
    }

    CHashWriter(int nTypeIn, int nVersionIn) : nType(nTypeIn), nVersion(nVersionIn) {
        Init();
    }

    CHashWriter& write(const char *pch, size_t size) {
        SHA256_Update(&ctx, pch, size);
        return (*this);
    }

    // invalidates the object
    uint256 GetHash() {
        uint256 hash1;
        SHA256_Final((unsigned char*)&hash1, &ctx);
        uint256 hash2;
        SHA256((unsigned char*)&hash1, sizeof(hash1), (unsigned char*)&hash2);
        return hash2;
    }

    template<typename T>
    CHashWriter& operator<<(const T& obj) {
        // Serialize to this stream
        ::Serialize(*this, obj, nType, nVersion);
        return (*this);
    }
};

CHashWriter, small, but deadly. I guess what we are further interested in, is

Code:

    template<typename T>
    CHashWriter& operator<<(const T& obj) {
        // Serialize to this stream
        ::Serialize(*this, obj, nType, nVersion);
        return (*this);
    }

which as you calls some global function Serialize that may or may not be located in serialize.h

[pixel]

Ok, so we basically have this

Code:

        const char* pszTimestamp = "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks";
        CTransaction txNew;
        txNew.vin.resize(1);
        txNew.vout.resize(1);
        txNew.vin[0].scriptSig = CScript() << 486604799 << CBigNum(4) << vector<unsigned char>((const unsigned char*)pszTimestamp, (const unsigned char*)pszTimestamp + strlen(pszTimestamp));
        txNew.vout[0].nValue = 50 * COIN;
        txNew.vout[0].scriptPubKey = CScript() << ParseHex("04678afdb0fe5548271967f1a67130b7105cd6a828e03909a67962e0ea1f61deb649f6bc3f4cef38c4f35504e51ec112de5c384df7ba0b8d578a4c702b6bf11d5f") << OP_CHECKSIG;
        CBlock block;
        block.vtx.push_back(txNew);
        block.hashPrevBlock = 0;
        block.hashMerkleRoot = block.BuildMerkleTree();

What we are interested in is, BuildMerkleTree which is found in main.h

Code:

    uint256 BuildMerkleTree() const
    {
        vMerkleTree.clear();
        BOOST_FOREACH(const CTransaction& tx, vtx)
            vMerkleTree.push_back(tx.GetHash());
        int j = 0;
        for (int nSize = vtx.size(); nSize > 1; nSize = (nSize + 1) / 2)
        {
            for (int i = 0; i < nSize; i += 2)
            {
                int i2 = std::min(i+1, nSize-1);
                vMerkleTree.push_back(Hash(BEGIN(vMerkleTree[j+i]),  END(vMerkleTree[j+i]),
                                           BEGIN(vMerkleTree[j+i2]), END(vMerkleTree[j+i2])));
            }
            j += nSize;
        }
        return (vMerkleTree.empty() ? 0 : vMerkleTree.back());
    }

Next we are interested in this, I believe.

Code:

vMerkleTree.push_back(tx.GetHash());

since we have only one transaction, this will return as soon as it computes the has. So we see tx.GetHash, and that tx is of type CTransaction, so we head in that class, which is in main.h again

and see this coide

Code:

    uint256 GetHash() const
    {
        return SerializeHash(*this);
    }

which passes the instance of the object to SerializeHash. SerializeHash is located in hash.h

Code:

template<typename T>
uint256 SerializeHash(const T& obj, int nType=SER_GETHASH, int nVersion=PROTOCOL_VERSION)
{
    CHashWriter ss(nType, nVersion);
    ss << obj;
    return ss.GetHash();
}

Here we see that the object is written(I think, not sure) to ss which is an instance of CHashWriter which is also in main.h and that is where the funky business happens that is uber hard to understand.

But here we go,

Code:

class CHashWriter
{
private:
    SHA256_CTX ctx;

public:
    int nType;
    int nVersion;

    void Init() {
        SHA256_Init(&ctx);
    }

    CHashWriter(int nTypeIn, int nVersionIn) : nType(nTypeIn), nVersion(nVersionIn) {
        Init();
    }

    CHashWriter& write(const char *pch, size_t size) {
        SHA256_Update(&ctx, pch, size);
        return (*this);
    }

    // invalidates the object
    uint256 GetHash() {
        uint256 hash1;
        SHA256_Final((unsigned char*)&hash1, &ctx);
        uint256 hash2;
        SHA256((unsigned char*)&hash1, sizeof(hash1), (unsigned char*)&hash2);
        return hash2;
    }

    template<typename T>
    CHashWriter& operator<<(const T& obj) {
        // Serialize to this stream
        ::Serialize(*this, obj, nType, nVersion);
        return (*this);
    }
};

CHashWriter, small, but deadly. I guess what we are further interested in, is

Code:

    template<typename T>
    CHashWriter& operator<<(const T& obj) {
        // Serialize to this stream
        ::Serialize(*this, obj, nType, nVersion);
        return (*this);
    }

which as you calls some global function Serialize that may or may not be located in serialize.h

We really need an altcoin dev in here

[Remember remember the 5th of November]

If Sunny King can help us, it'd be nice. But I guess the reason the genesis block creation information is not found easily is because every noob(me included) on the block will have an alt-currency out by the end of the day.

[pixel]

Ive made a discovery... i think??

Starting on line 1,985 of main.cpp

Code:

    //
    // Init with genesis block
    //
    if (mapBlockIndex.empty())
    {
        if (!fAllowNew)
            return false;

        // Genesis Block:
        // CBlock(hash=12a765e31ffd4059bada, PoW=0000050c34a64b415b6b, ver=1, hashPrevBlock=00000000000000000000, hashMerkleRoot=97ddfbbae6, nTime=1317972665, nBits=1e0ffff0, nNonce=2084524493, vtx=1)
        //   CTransaction(hash=97ddfbbae6, ver=1, vin.size=1, vout.size=1, nLockTime=0)
        //     CTxIn(COutPoint(0000000000, -1), coinbase 04ffff001d0104404e592054696d65732030352f4f63742f32303131205374657665204a6f62732c204170706c65e280997320566973696f6e6172792c2044696573206174203536)
        //     CTxOut(nValue=50.00000000, scriptPubKey=040184710fa689ad5023690c80f3a4)
        //   vMerkleTree: 97ddfbbae6

        // Genesis block
        const char* pszTimestamp = "NY Times 05/Oct/2011 Steve Jobs, Apple’s Visionary, Dies at 56";
        CTransaction txNew;
        txNew.vin.resize(1);
        txNew.vout.resize(1);
        txNew.vin[0].scriptSig = CScript() << 486604799 << CBigNum(4) << vector<unsigned char>((const unsigned char*)pszTimestamp, (const unsigned char*)pszTimestamp + strlen(pszTimestamp));
        txNew.vout[0].nValue = 50 * COIN;
        txNew.vout[0].scriptPubKey = CScript() << ParseHex("040184710fa689ad5023690c80f3a49c8f13f8d45b8c857fbcbc8bc4a8e4d3eb4b10f4d4604fa08dce601aaf0f470216fe1b51850b4acf21b179c45070ac7b03a9") << OP_CHECKSIG;
        CBlock block;
        block.vtx.push_back(txNew);
        block.hashPrevBlock = 0;
        block.hashMerkleRoot = block.BuildMerkleTree();
        block.nVersion = 1;
        block.nTime    = 1317972665;
        block.nBits    = 0x1e0ffff0;
        block.nNonce   = 2084524493;

        if (fTestNet)
        {
            block.nTime    = 1317798646;
            block.nNonce   = 385270584;
        }

[pixel]

If Sunny King can help us, it'd be nice. But I guess the reason the genesis block creation information is not found easily is because every noob(me included) on the block will have an alt-currency out by the end of the day.

But then how did altcoin authors create theirs? 

[achillez]

Perhaps, but a q on this. Do you really want to create a sha256 alt, or LiteCoin (or better yet PPCoin) type chain instead?  

[Remember remember the 5th of November]

Ive made a discovery... i think??

That's where I derived my information from, by following the functions.

[pixel]

Perhaps, but a q on this. Do you really want to create a sha256 alt, or LiteCoin (or better yet PPCoin) type chain instead?  

Really either is fine at this point im just trying to get somthing running

[Remember remember the 5th of November]

If Sunny King can help us, it'd be nice. But I guess the reason the genesis block creation information is not found easily is because every noob(me included) on the block will have an alt-currency out by the end of the day.

But then how did altcoin authors create theirs? 

They've learned C++ and have no issue with the C++ semantics? Understand Cryptography more than we do?

[pixel]

If Sunny King can help us, it'd be nice. But I guess the reason the genesis block creation information is not found easily is because every noob(me included) on the block will have an alt-currency out by the end of the day.

But then how did altcoin authors create theirs? 

They've learned C++ and have no issue with the C++ semantics? Understand Cryptography more than we do?

True, true 

[wmikrut]

If Sunny King can help us, it'd be nice. But I guess the reason the genesis block creation information is not found easily is because every noob(me included) on the block will have an alt-currency out by the end of the day.

It's open source... it may be obscure... but that doesn't mean people don't have a right to know how to do it.
By the end of this thread hopefully we'll all know how it works!  

[Remember remember the 5th of November]

If Sunny King can help us, it'd be nice. But I guess the reason the genesis block creation information is not found easily is because every noob(me included) on the block will have an alt-currency out by the end of the day.

It's open source... it may be obscure... but that doesn't mean people don't have a right to know how to do it.
By the end of this thread hopefully we'll all know how it works!  

Yeah, but we likely won't understand the process itself.

[pixel]

If Sunny King can help us, it'd be nice. But I guess the reason the genesis block creation information is not found easily is because every noob(me included) on the block will have an alt-currency out by the end of the day.

It's open source... it may be obscure... but that doesn't mean people don't have a right to know how to do it.
By the end of this thread hopefully we'll all know how it works!  

This, I was not expecting this much interest when I started this thread but now myself and im sure a bunch of others really want to know what goes into this

[wmikrut]

If Sunny King can help us, it'd be nice. But I guess the reason the genesis block creation information is not found easily is because every noob(me included) on the block will have an alt-currency out by the end of the day.

It's open source... it may be obscure... but that doesn't mean people don't have a right to know how to do it.
By the end of this thread hopefully we'll all know how it works!  

Yeah, but we likely won't understand the process itself.

We'll figure it out  

[pixel]

If Sunny King can help us, it'd be nice. But I guess the reason the genesis block creation information is not found easily is because every noob(me included) on the block will have an alt-currency out by the end of the day.

It's open source... it may be obscure... but that doesn't mean people don't have a right to know how to do it.
By the end of this thread hopefully we'll all know how it works!  

Yeah, but we likely won't understand the process itself.

We'll figure it out  

I like your positive attitude

[pixel]

Is this whole thing on hold till we can get someone to help with the genesis block?

[Remember remember the 5th of November]

More like till an alt-coin dev sees the thread.

[pixel]

More like till an alt-coin dev sees the thread.

I got my fingers crossed a dev runs across it, ill keep checking in

[wmikrut]

Not that it's completely relevant... but I have been in programming for over 20 years.
I'll keep researching and reading code... if nothing else, I will try to decode the process as much as I can and relay all the information back here.... unless a dev comes in and goes "Oh.. 1, 2, 3... Done!".