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genesisblock.c
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genesisblock.c
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#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>
#include <inttypes.h>
#include <ctype.h>
#include <string.h>
#include <time.h>
#include <openssl/sha.h>
//Copied from Bitcoin source
const uint64_t COIN = 100000000;
const uint64_t CENT = 1000000;
uint32_t OP_CHECKSIG = 172; // This is expressed as 0xAC
bool generateBlock = false;
uint32_t startNonce = 0;
uint32_t unixtime = 0;
typedef struct {
/* Hash of Tx */
uint8_t merkleHash[32];
/* Tx serialization before hashing */
uint8_t *serializedData;
/* Tx version */
uint32_t version;
/* Input */
uint8_t numInputs; // Program assumes one input
uint8_t prevOutput[32];
uint32_t prevoutIndex;
uint8_t *scriptSig;
uint32_t sequence;
/* Output */
uint8_t numOutputs; // Program assumes one output
uint64_t outValue;
uint8_t *pubkeyScript;
/* Final */
uint32_t locktime;
} Transaction;
// Got this off the internet. Am not sure if it can fail in some circumstances
void byteswap(uint8_t *buf, int length)
{
int i;
uint8_t temp;
for(i = 0; i < length / 2; i++)
{
temp = buf[i];
buf[i] = buf[length - i - 1];
buf[length - i - 1] = temp;
}
}
// Following two functions are borrowed from cgminer.
char *bin2hex(const unsigned char *p, size_t len)
{
char *s = malloc((len * 2) + 1);
unsigned int i;
if (!s)
return NULL;
for (i = 0; i < len; i++)
sprintf(s + (i * 2), "%02x", (unsigned int) p[i]);
return s;
}
size_t hex2bin(unsigned char *p, const char *hexstr, size_t len)
{
int ret = 0;
size_t retlen = len;
while (*hexstr && len) {
char hex_byte[4];
unsigned int v;
if (!hexstr[1]) {
return ret;
}
memset(hex_byte, 0, 4);
hex_byte[0] = hexstr[0];
hex_byte[1] = hexstr[1];
if (sscanf(hex_byte, "%x", &v) != 1) {
return ret;
}
*p = (unsigned char) v;
p++;
hexstr += 2;
len--;
}
if (len == 0 && *hexstr == 0)
ret = retlen;
return ret;
}
Transaction *InitTransaction()
{
Transaction *transaction;
transaction = calloc(1, sizeof(*transaction));
if(!transaction)
{
return NULL;
}
// Set some initial data that will remain constant throughout the program
transaction->version = 1;
transaction->numInputs = 1;
transaction->numOutputs = 1;
transaction->locktime = 0;
transaction->prevoutIndex = 0xFFFFFFFF;
transaction->sequence = 0xFFFFFFFF;
transaction->outValue = 50*COIN;
// We initialize the previous output to 0 as there is none
memset(transaction->prevOutput, 0, 32);
return transaction;
}
int main(int argc, char *argv[])
{
Transaction *transaction;
unsigned char hash1[32], hash2[32];
char timestamp[255], pubkey[132];
uint32_t timestamp_len = 0, scriptSig_len = 0, pubkey_len = 0, pubkeyScript_len = 0;
uint32_t nBits = 0;
if((argc-1) < 3)
{
fprintf(stderr, "Usage: genesisgen [options] <pubkey> \"<timestamp>\" <nBits>\n");
return 0;
}
pubkey_len = strlen(argv[1]) / 2; // One byte is represented as two hex characters, thus we divide by two to get real length.
timestamp_len = strlen(argv[2]);
if(pubkey_len != 65)
{
fprintf(stderr, "Invalid public key length! %s\n", argv[1]);
return 0;
}
if(timestamp_len > 254 || timestamp_len <= 0)
{
fprintf(stderr, "Size of timestamp is 0 or exceeds maximum length of 254 characters!\n");
return 0;
}
transaction = InitTransaction();
if(!transaction)
{
fprintf(stderr, "Could not allocate memory! Exiting...\n");
return 0;
}
strncpy(pubkey, argv[1], sizeof(pubkey));
strncpy(timestamp, argv[2], sizeof(timestamp));
sscanf(argv[3], "%lu", (long unsigned int *)&nBits);
pubkey_len = strlen(pubkey) >> 1;
scriptSig_len = timestamp_len;
// Encode pubkey to binary and prepend pubkey size, then append the OP_CHECKSIG byte
transaction->pubkeyScript = malloc((pubkey_len+2)*sizeof(uint8_t));
pubkeyScript_len = hex2bin(transaction->pubkeyScript+1, pubkey, pubkey_len); // No error checking, yeah.
transaction->pubkeyScript[0] = 0x41; // A public key is 32 bytes X coordinate, 32 bytes Y coordinate and one byte 0x04, so 65 bytes i.e 0x41 in Hex.
pubkeyScript_len+=1;
transaction->pubkeyScript[pubkeyScript_len++] = OP_CHECKSIG;
// Encode timestamp to binary
transaction->scriptSig = malloc(scriptSig_len*sizeof(uint8_t));
uint32_t scriptSig_pos = 0;
// This is basically how I believe the size of the nBits is calculated
if(nBits <= 255)
{
transaction->scriptSig[scriptSig_pos++] = 0x01;
transaction->scriptSig[scriptSig_pos++] = (uint8_t)nBits;
}
else if(nBits <= 65535)
{
transaction->scriptSig[scriptSig_pos++] = 0x02;
memcpy(transaction->scriptSig+scriptSig_pos, &nBits, 2);
scriptSig_pos+=2;
}
else if(nBits <= 16777215)
{
transaction->scriptSig[scriptSig_pos++] = 0x03;
memcpy(transaction->scriptSig+scriptSig_pos, &nBits, 3);
scriptSig_pos+=3;
}
else //else if(nBits <= 4294967296LL)
{
transaction->scriptSig[scriptSig_pos++] = 0x04;
memcpy(transaction->scriptSig+scriptSig_pos, &nBits, 4);
scriptSig_pos+=4;
}
// Important! In the Bitcoin code there is a statement 'CBigNum(4)'
// i've been wondering for a while what it is but
// seeing as alt-coins keep it the same, we'll do it here as well
// It should essentially mean PUSH 1 byte on the stack which in this case is 0x04 or just 4
transaction->scriptSig[scriptSig_pos++] = 0x01;
transaction->scriptSig[scriptSig_pos++] = 0x04;
transaction->scriptSig[scriptSig_pos++] = (uint8_t)scriptSig_len;
scriptSig_len += scriptSig_pos;
transaction->scriptSig = realloc(transaction->scriptSig, scriptSig_len*sizeof(uint8_t));
memcpy(transaction->scriptSig+scriptSig_pos, (const unsigned char *)timestamp, timestamp_len);
// Here we are asuming some values will have the same size
uint32_t serializedLen =
4 // tx version
+1 // number of inputs
+32 // hash of previous output
+4 // previous output's index
+1 // 1 byte for the size of scriptSig
+scriptSig_len
+4 // size of sequence
+1 // number of outputs
+8 // 8 bytes for coin value
+1 // 1 byte to represent size of the pubkey Script
+pubkeyScript_len
+4; // 4 bytes for lock time
// Now let's serialize the data
uint32_t serializedData_pos = 0;
transaction->serializedData = malloc(serializedLen*sizeof(uint8_t));
memcpy(transaction->serializedData+serializedData_pos, &transaction->version, 4);
serializedData_pos += 4;
memcpy(transaction->serializedData+serializedData_pos, &transaction->numInputs, 1);
serializedData_pos += 1;
memcpy(transaction->serializedData+serializedData_pos, transaction->prevOutput, 32);
serializedData_pos += 32;
memcpy(transaction->serializedData+serializedData_pos, &transaction->prevoutIndex, 4);
serializedData_pos += 4;
memcpy(transaction->serializedData+serializedData_pos, &scriptSig_len, 1);
serializedData_pos += 1;
memcpy(transaction->serializedData+serializedData_pos, transaction->scriptSig, scriptSig_len);
serializedData_pos += scriptSig_len;
memcpy(transaction->serializedData+serializedData_pos, &transaction->sequence, 4);
serializedData_pos += 4;
memcpy(transaction->serializedData+serializedData_pos, &transaction->numOutputs, 1);
serializedData_pos += 1;
memcpy(transaction->serializedData+serializedData_pos, &transaction->outValue, 8);
serializedData_pos += 8;
memcpy(transaction->serializedData+serializedData_pos, &pubkeyScript_len, 1);
serializedData_pos += 1;
memcpy(transaction->serializedData+serializedData_pos, transaction->pubkeyScript, pubkeyScript_len);
serializedData_pos += pubkeyScript_len;
memcpy(transaction->serializedData+serializedData_pos, &transaction->locktime, 4);
serializedData_pos += 4;
// Now that the data is serialized
// we hash it with SHA256 and then hash that result to get merkle hash
SHA256(transaction->serializedData, serializedLen, hash1);
SHA256(hash1, 32, hash2);
// This copy isn't necessary imo, but here for clarity
memcpy(transaction->merkleHash, hash2, 32);
char *merkleHash = bin2hex(transaction->merkleHash, 32);
byteswap(transaction->merkleHash, 32);
char *merkleHashSwapped = bin2hex(transaction->merkleHash, 32);
char *txScriptSig = bin2hex(transaction->scriptSig, scriptSig_len);
char *pubScriptSig = bin2hex(transaction->pubkeyScript, pubkeyScript_len);
printf("\nCoinbase: %s\n\nPubkeyScript: %s\n\nMerkle Hash: %s\nByteswapped: %s\n",txScriptSig, pubScriptSig, merkleHash, merkleHashSwapped);
//if(generateBlock)
{
printf("Generating block...\n");
if(!unixtime)
{
unixtime = time(NULL);
}
unsigned char block_header[80], block_hash1[32], block_hash2[32];
uint32_t blockversion = 1;
memcpy(block_header, &blockversion, 4);
memset(block_header+4, 0, 32);
byteswap(transaction->merkleHash, 32); // We swapped it before, so do it again now.
memcpy(block_header+36, transaction->merkleHash, 32);
memcpy(block_header+68, &unixtime, 4);
memcpy(block_header+72, &nBits, 4);
memcpy(block_header+76, &startNonce, 4);
uint32_t *pNonce = (uint32_t *)(block_header + 76);
uint32_t *pUnixtime = (uint32_t *)(block_header + 68);
unsigned int counter, start = time(NULL);
while(1)
{
SHA256(block_header, 80, block_hash1);
SHA256(block_hash1, 32, block_hash2);
unsigned int check = *((uint32_t *)(block_hash2 + 28)); // The hash is in little-endian, so we check the last 4 bytes.
if(check == 0) // \x00\x00\x00\x00
{
byteswap(block_hash2, 32);
char *blockHash = bin2hex(block_hash2, 32);
printf("\nBlock found!\nHash: %s\nNonce: %u\nUnix time: %u", blockHash, startNonce, unixtime);
free(blockHash);
break;
}
startNonce++;
counter+=1;
if(time(NULL)-start >= 1)
{
printf("\r%d Hashes/s, Nonce %u\r", counter, startNonce);
counter = 0;
start = time(NULL);
}
*pNonce = startNonce;
if(startNonce > 4294967294LL)
{
//printf("\nBlock found!\nHash: %s\nNonce: %u\nUnix time: %u", blockHash, startNonce, unixtime);
unixtime++;
*pUnixtime = unixtime;
startNonce = 0;
}
}
}
// Lots of cleanup
free(merkleHash);
free(merkleHashSwapped);
free(txScriptSig);
free(pubScriptSig);
free(transaction->serializedData);
free(transaction->scriptSig);
free(transaction->pubkeyScript);
free(transaction);
return 0;
}