Addresses & Checksums

From pubkey to address—and how a single bit breaks the checksum.

Encode and decode Base58Check, see the checksum bytes, then flip a bit to watch verification fail. This is the safety net behind “copy-paste your address carefully.”

Base58Check Checksums Typos & bit flips Address safety

Quick guide

Pick version + payload and Encode to Base58Check; Decode to inspect version/payload/checksum.
Derive a toy address from a pubkey hash; see every intermediate hash plus the checksum.
Flip a bit in the payload and watch the recomputed checksum fail—typos get caught.

Base58Check sandbox

Encode & decode with checksum

Encode (HEX → Base58Check)

Network & type (version byte) Payload (HEX, typically 20 bytes = HASH160 of pubkey)

Tip: Use Random to generate a valid 20-byte HEX.

Generates Base58Check with checksum

Address:

Decode (Base58Check → fields)

Address (Base58Check)

Tip: Use Random to try a known valid address.

Parses version, payload, and verifies checksum

Version:

Payload (HEX):

Checksum OK:

Toy pipeline: pubkey → address → checksum

Compressed pubkey, SHA-256 only (teaching)

Step 1 — SHA-256(pubkey) (hex)

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Step 2 — Address = first 20 bytes

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Step 3 — Checksum = first 4 bytes of SHA-256(address)

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Step 4 — Base58Check(version 0x00 | addr | checksum)

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Flip a bit (see checksum fail)

Address payload = 20 bytes (160 bits)

Bit index (0 = MSB of byte 0)

(status: —)

Mutated address (hex) + recomputed checksum

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Checksums, typos, and why Base58Check sticks

Encode: pick version and payload, click Encode to see Base58Check.
Decode: paste an address and Decode to inspect version/payload/checksum validity.
Derive: use Randomize then Derive address to view every intermediate hash.
Flip: choose a bit index, flip, and compare the new checksum to the original.