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Title: bitcoin address calculation deep dive, does not add up Post by: ggbtctalk000 on September 06, 2017, 06:44:07 AM Looking through mastering bitcoin book's chapters, I get the following formula for bitcoin address generation:
BitcoinAddress=base58encode( 2 bytes version + 20 bytes output from RIPEMD160(SHA256(pubkey)) + 4 bytes checksum) = base58encode(26 bytes)=base58encode(104 bits) however this is generating base58 digit size of 104bits / ((log(58)/log(2)) = 104bits/5.8579...=17.75 base58 digits. Why 104bits / (log(58)/log(2))? Suppose 256-bits address and how many hexes are there if represented by hex? 256 / ((log 16) / log(2)) = 256/4 = 64 hex digits. But when I check several bitcoin wallet address the base58encoded address they are showing is 34 base58 digits. Definitely not adding up or I am missing something here. Title: Re: bitcoin address calculation deep dive, does not add up Post by: Foxpup on September 06, 2017, 07:58:51 AM base58encode(26 bytes)=base58encode(104 bits) I think you'll find 26 bytes is actually 208 bits. ;)Title: Re: bitcoin address calculation deep dive, does not add up Post by: DannyHamilton on September 06, 2017, 08:54:34 AM BitcoinAddress=base58encode( 2 bytes version + 20 bytes output from RIPEMD160(SHA256(pubkey)) + 4 bytes checksum) Are you sure about that? I thought: BitcoinAddress=base58encode( 1 bytes version + 20 bytes output from RIPEMD160(SHA256(pubkey)) + 4 bytes checksum) 1 + 20 + 4 = 25 bytes Since 1 byte = 8 bits... 25 * 8 = 200 bits base58encode(25 bytes) = base58encode(200 bits) 200 bits / [ log(58) / log(2) ] = 200 bits / 5.85798... = 34.14 base58 digits Title: Re: bitcoin address calculation deep dive, does not add up Post by: ggbtctalk000 on September 06, 2017, 03:02:50 PM THANKS for both of you guys :) !! now it adds up! why do i always mess up between nibbles and bytes!! ;D
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