Bitcoin source code Research (1)-BASE58 code

BASE58 encoding consists of 58 numbers and uppercase and lowercase letters, the bitcoin source code is defined and annotated as follows:

/** all alphanumeric characters except for "0", "I", "O", and "L " */

static const char* PSZBASE58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZABCDEFGHIJKMNOPQRSTUVWXYZ";

such as unsigned char ucdata[4] = {0x39, 0x3a, 0x3b, 0x3c}, the BASE58 encoding process is as follows:

1, first calculate ucdata start for 0x00 number zeros, here zeros = 0;

while (pbegin! = Pend && *pbegin = = 0) {

pbegin++;

zeroes++;

    }

2, skip the beginning of zeros 0x00, calculate the required cache

int size = (pend-pbegin) * 138/100 + 1; Log (+)/log (rounded), up.

3, 256 The calculation of the binary turn 58 binary

std::vector<unsigned char> b58 (size);

Process the bytes.

while (pbegin! = pend) {

int carry = *pbegin;

int i = 0;

Apply "b58 = b58 * + ch".

For (std::vector<unsigned char>::reverse_iterator it = B58.rbegin ();

(Carry! = 0 | | I < length) && (It! = B58.rend ()); it++, i++) {

Carry + = * (*it);

*it = carry% 58;

Carry/= 58;

}

ASSERT (Carry = = 0);

length = i;

pbegin++;

}

4. Output encoding Result

Precede the string with zeros 1, followed by the prefix plus dstbyte corresponding pszBase58 character

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Bitcoin source code Research (1)-BASE58 code