How would I generate a valid vanity address for destroying coins? I want to generate very long vanity addresses, with the relaxed constraint that I don't need the corresponding private key, they only need to be valid Bitcoin addresses. How would I do this?

Example:

Input Prefix: 1XXXXXXXXXXXXXXXXXXXX
Output: 1XXXXXXXXXXXXXXXXXXXXUW9j3f3
You can do this manually using the hex/base58check converter (such as the converter on brainwallet.org)


Remove the starting 1 and convert from base58 XXXXXXXXXXXXXXXXXXXXXXXXXXX to hex: 25c7415deb828c49ccb799c452ae17589bca1af2 (make sure result is 24 bytes)
Remove last 4 bytes to get a 20-byte hash:
25c7415deb828c49ccb799c452ae17589bca1af2 -> 25c7415deb828c49ccb799c452ae1758
Convert from hex 25c7415deb828c49ccb799c452ae1758 to base58check: 1XXXXXXXXXXXXXXXXXXXXXYDgWVE


Final result is valid 1XXXXXXXXXXXXXXXXXXXXXYDgWVE