Base58Check encoding

Base58Check encoding is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

The popular encoding of small and medium-sized checksums is base16, that is more compact than usual base10 and is human readable... For checksums resulting in hash digests bigger than ~100 bits, the base16 is too long: base58 is shorter and (when using good alphabet) preserves secure human readability. The most popular alphabet of base58 is the variant used in bitcoin address (see Bitcoin/address validation), so it is the "default base58 alphabet".

Write a program that takes a checksum (resultant hash digest) integer binary representation as argument, and converts (encode it) into base58 with the standard Bitcoin alphabet — which uses an alphabet of the characters 0 .. 9, A ..Z, a .. z, but without the four characters:

•   O   the uppercase letter "oh",
•   I    the uppercase letter "eye",
•   l    the lowercase letter "ell",   and
•   0   the digit zero.

The reference algorithm is at the Bitcoin's Base58Check page.

C#

Translation of: Java

<lang csharp>using System; using System.Collections.Generic; using System.Numerics; using System.Text;

namespace Base58CheckEncoding {

   class Program {
       const string ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";

       static BigInteger ToBigInteger(string value, int @base) {
           const string HEX = "0123456789ABCDEF";
           if (@base < 1 || @base > HEX.Length) {
               throw new ArgumentException("Base is out of range.");
           }

           BigInteger bi = BigInteger.Zero;
           foreach (char c in value) {
               char c2 = Char.ToUpper(c);
               int idx = HEX.IndexOf(c2);
               if (idx == -1 || idx >= @base) {
                   throw new ArgumentOutOfRangeException("Illegal character encountered.");
               }
               bi = bi * @base + idx;
           }

           return bi;
       }

       static string ConvertToBase58(string hash, int @base = 16) {
           BigInteger x;
           if (@base == 16 && hash.Substring(0, 2) == "0x") {
               x = ToBigInteger(hash.Substring(2), @base);
           } else {
               x = ToBigInteger(hash, @base);
           }

           StringBuilder sb = new StringBuilder();
           while (x > 0) {
               BigInteger r = x % 58;
               sb.Append(ALPHABET[(int)r]);
               x = x / 58;
           }

           char[] ca = sb.ToString().ToCharArray();
           Array.Reverse(ca);
           return new string(ca);
       }

       static void Main(string[] args) {
           string s = "25420294593250030202636073700053352635053786165627414518";
           string b = ConvertToBase58(s, 10);
           Console.WriteLine("{0} -> {1}", s, b);

           List<string> hashes = new List<string>() {
               "0x61",
               "0x626262",
               "0x636363",
               "0x73696d706c792061206c6f6e6720737472696e67",
               "0x516b6fcd0f",
               "0xbf4f89001e670274dd",
               "0x572e4794",
               "0xecac89cad93923c02321",
               "0x10c8511e",
           };
           foreach (string hash in hashes) {
               string b58 = ConvertToBase58(hash);
               Console.WriteLine("{0,-56} -> {1}", hash, b58);
           }
       }
   }

}</lang>

Output:

25420294593250030202636073700053352635053786165627414518 -> 6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM
0x61                                                     -> 2g
0x626262                                                 -> a3gV
0x636363                                                 -> aPEr
0x73696d706c792061206c6f6e6720737472696e67               -> 2cFupjhnEsSn59qHXstmK2ffpLv2
0x516b6fcd0f                                             -> ABnLTmg
0xbf4f89001e670274dd                                     -> 3SEo3LWLoPntC
0x572e4794                                               -> 3EFU7m
0xecac89cad93923c02321                                   -> EJDM8drfXA6uyA
0x10c8511e                                               -> Rt5zm

FreeBASIC

Library: GMP

<lang freebasic>' version 14-08-2017 ' compile with: fbc -s console ' uses GMP

1. Include Once "gmp.bi"

Data "25420294593250030202636073700053352635053786165627414518" ' 6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM Data "0x61" ' 2g Data "0x626262" ' a3gV Data "0x636363" ' aPEr Data "0x73696d706c792061206c6f6e6720737472696e67" ' 2cFupjhnEsSn59qHXstmK2ffpLv2 Data "0x516b6fcd0f" ' ABnLTmg Data "0xbf4f89001e670274dd" ' 3SEo3LWLoPntC Data "0x572e4794" ' 3EFU7m Data "0xecac89cad93923c02321" ' EJDM8drfXA6uyA Data "0x10c8511e" ' Rt5zm Data ""

Function conv2base58(decimal As String, _base_ As Integer = 0) As String

   Dim As String convert
   Dim As String base58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
   Dim As String norm58 = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuv"
   Dim As ZString Ptr gmp_str : gmp_str = Allocate(1000)
   Dim As Mpz_ptr tmp = Allocate(Len(__mpz_struct)) : Mpz_init(tmp)

   Mpz_set_str(tmp, decimal, _base_)
   Mpz_get_str(gmp_str, 58, tmp)

   convert = *gmp_str

   For i As uinteger = 0 To Len(convert) -1
       convert[i] = base58[InStr(norm58, Chr(convert[i])) -1]
   Next

   Mpz_clear(tmp) : DeAllocate(gmp_str)

   Return convert

End Function

' ------=< MAIN >=------ Dim As String str_in

Print "OkobppXBkab(58) --> "; conv2base58("OkobppXBkab", 58) ' 10687460092462769069(10) Print

Do

   Read str_in
   If str_in = "" Then Exit Do
   Print str_in;
   If Len(str_in) < 54 Then Print Tab(43);
   Print " --> "; conv2base58(str_in)

Loop

' empty keyboard buffer While Inkey <> "" : Wend Print : Print "hit any key to end program" Sleep End</lang>

Output:

OkobppXBkab(58) --> RosettaCode

25420294593250030202636073700053352635053786165627414518 --> 6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM
0x61                                       --> 2g
0x626262                                   --> a3gV
0x636363                                   --> aPEr
0x73696d706c792061206c6f6e6720737472696e67 --> 2cFupjhnEsSn59qHXstmK2ffpLv2
0x516b6fcd0f                               --> ABnLTmg
0xbf4f89001e670274dd                       --> 3SEo3LWLoPntC
0x572e4794                                 --> 3EFU7m
0xecac89cad93923c02321                     --> EJDM8drfXA6uyA
0x10c8511e                                 --> Rt5zm

D

<lang D>import std.bigint; import std.stdio;

void main() {

   report("25420294593250030202636073700053352635053786165627414518");
   report(0x61);
   report(0x626262);
   report(0x636363);
   report("0x73696d706c792061206c6f6e6720737472696e67");
   report(0x516b6fcd0f);
   report("0xbf4f89001e670274dd");
   report(0x572e4794);
   report("0xecac89cad93923c02321");
   report(0x10c8511e);

}

void report(T)(T v) {

   import std.traits;
   static if (isIntegral!T) {
       enum format = "%#56x -> %s";
   } else {
       enum format = "%56s -> %s";
   }
   writefln(format, v, v.toBase58);

}

string toBase58(T)(T input) {

   import std.traits;
   static if (isSomeString!T) {
       return toBase58(BigInt(input));
   } else {
       import std.algorithm.mutation : reverse;
       import std.array : appender;
       enum ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";

       auto sb = appender!(char[]);
       size_t mod;

       do {
           mod = cast(size_t) (input % ALPHABET.length);
           sb.put(ALPHABET[mod]);

           input /= ALPHABET.length;
       } while (input);

       sb.data.reverse;
       return sb.data.idup;
   }

}</lang>

Output:

25420294593250030202636073700053352635053786165627414518 -> 6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM
                                                    0x61 -> 2g
                                                0x626262 -> a3gV
                                                0x636363 -> aPEr
              0x73696d706c792061206c6f6e6720737472696e67 -> 2cFupjhnEsSn59qHXstmK2ffpLv2
                                            0x516b6fcd0f -> ABnLTmg
                                    0xbf4f89001e670274dd -> 3SEo3LWLoPntC
                                              0x572e4794 -> 3EFU7m
                                  0xecac89cad93923c02321 -> EJDM8drfXA6uyA
                                              0x10c8511e -> Rt5zm

Go

Translation of: Kotlin

<lang go>package main

import (

   "fmt"
   "log"
   "math/big"
   "strings"

)

const alphabet = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"

var big0 = new(big.Int) var big58 = big.NewInt(58)

func reverse(s string) string {

   r := []rune(s)
   for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {
       r[i], r[j] = r[j], r[i]
   }
   return string(r)

}

func convertToBase58(hash string, base int) (string, error) {

   var x, ok = new(big.Int).SetString(hash, base)
   if !ok {
       return "", fmt.Errorf("'%v' is not a valid integer in base '%d'", hash, base)
   }
   var sb strings.Builder
   var rem = new(big.Int)
   for x.Cmp(big0) == 1 {
       x.QuoRem(x, big58, rem)
       r := rem.Int64()
       sb.WriteByte(alphabet[r])
   }
   return reverse(sb.String()), nil

}

func main() {

   s := "25420294593250030202636073700053352635053786165627414518"
   b, err := convertToBase58(s, 10)
   if err != nil {
       log.Fatal(err)
   }
   fmt.Println(s, "->", b)
   hashes := [...]string{
       "0x61",
       "0x626262",
       "0x636363",
       "0x73696d706c792061206c6f6e6720737472696e67",
       "0x516b6fcd0f",
       "0xbf4f89001e670274dd",
       "0x572e4794",
       "0xecac89cad93923c02321",
       "0x10c8511e",
   }
   for _, hash := range hashes {
       b58, err := convertToBase58(hash, 0)
       if err != nil {
           log.Fatal(err)
       }
       fmt.Printf("%-56s -> %s\n", hash, b58)
   }

}</lang>

Output:

25420294593250030202636073700053352635053786165627414518 -> 6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM
0x61                                                     -> 2g
0x626262                                                 -> a3gV
0x636363                                                 -> aPEr
0x73696d706c792061206c6f6e6720737472696e67               -> 2cFupjhnEsSn59qHXstmK2ffpLv2
0x516b6fcd0f                                             -> ABnLTmg
0xbf4f89001e670274dd                                     -> 3SEo3LWLoPntC
0x572e4794                                               -> 3EFU7m
0xecac89cad93923c02321                                   -> EJDM8drfXA6uyA
0x10c8511e                                               -> Rt5zm

Haskell

<lang haskell>import Numeric (showIntAtBase)

chars = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"

base58Encode :: Integer -> String base58Encode n = showIntAtBase 58 (chars !!) n ""

main :: IO () main = mapM_ (putStrLn . base58Encode)

       [25420294593250030202636073700053352635053786165627414518,
        0x61,
        0x626262,
        0x636363,
        0x73696d706c792061206c6f6e6720737472696e67,
        0x516b6fcd0f,
        0xbf4f89001e670274dd,
        0x572e4794,
        0xecac89cad93923c02321,
        0x10c8511e]</lang>

Output:

6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM
2g
a3gV
aPEr
2cFupjhnEsSn59qHXstmK2ffpLv2
ABnLTmg
3SEo3LWLoPntC
3EFU7m
EJDM8drfXA6uyA
Rt5zm

and for bulk encoding, Array access would be one of various slightly faster alternatives to recursive subscripting of linked lists: <lang Haskell>import Numeric (showIntAtBase) import Data.Array

base58Codes :: (Num i, Ix i) => Array i Char base58Codes =

 listArray (0, 57) "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"

base58Encode :: (Show a, Integral a) => a -> String base58Encode n = showIntAtBase 58 (base58Codes !) n ""

main :: IO () main =

 mapM_
   (putStrLn . base58Encode)
   [ 25420294593250030202636073700053352635053786165627414518
   , 0x61
   , 0x626262
   , 0x636363
   , 0x73696d706c792061206c6f6e6720737472696e67
   , 0x516b6fcd0f
   , 0xbf4f89001e670274dd
   , 0x572e4794
   , 0xecac89cad93923c02321
   , 0x10c8511e
   ]</lang>

Output:

6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM
2g
a3gV
aPEr
2cFupjhnEsSn59qHXstmK2ffpLv2
ABnLTmg
3SEo3LWLoPntC
3EFU7m
EJDM8drfXA6uyA
Rt5zm

Java

Translation of: Kotlin

Works with: Java version 9

<lang Java>import java.math.BigInteger; import java.util.List;

public class Base58CheckEncoding {

   private static final String ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
   private static final BigInteger BIG0 = BigInteger.ZERO;
   private static final BigInteger BIG58 = BigInteger.valueOf(58);

   private static String convertToBase58(String hash) {
       return convertToBase58(hash, 16);
   }

   private static String convertToBase58(String hash, int base) {
       BigInteger x;
       if (base == 16 && hash.substring(0, 2).equals("0x")) {
           x = new BigInteger(hash.substring(2), 16);
       } else {
           x = new BigInteger(hash, base);
       }

       StringBuilder sb = new StringBuilder();
       while (x.compareTo(BIG0) > 0) {
           int r = x.mod(BIG58).intValue();
           sb.append(ALPHABET.charAt(r));
           x = x.divide(BIG58);
       }

       return sb.reverse().toString();
   }

   public static void main(String[] args) {
       String s = "25420294593250030202636073700053352635053786165627414518";
       String b = convertToBase58(s, 10);
       System.out.printf("%s -> %s\n", s, b);

       List<String> hashes = List.of(
           "0x61",
           "0x626262",
           "0x636363",
           "0x73696d706c792061206c6f6e6720737472696e67",
           "0x516b6fcd0f",
           "0xbf4f89001e670274dd",
           "0x572e4794",
           "0xecac89cad93923c02321",
           "0x10c8511e"
       );
       for (String hash : hashes) {
           String b58 = convertToBase58(hash);
           System.out.printf("%-56s -> %s\n", hash, b58);
       }
   }

}</lang>

Output:

25420294593250030202636073700053352635053786165627414518 -> 6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM
0x61                                                     -> 2g
0x626262                                                 -> a3gV
0x636363                                                 -> aPEr
0x73696d706c792061206c6f6e6720737472696e67               -> 2cFupjhnEsSn59qHXstmK2ffpLv2
0x516b6fcd0f                                             -> ABnLTmg
0xbf4f89001e670274dd                                     -> 3SEo3LWLoPntC
0x572e4794                                               -> 3EFU7m
0xecac89cad93923c02321                                   -> EJDM8drfXA6uyA
0x10c8511e                                               -> Rt5zm

Julia

Works with: Julia version 0.6

<lang julia>const alpha = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"

function encodebase58(hsh::AbstractString, base::Integer=16)

   x = if base == 16 && hsh[1:2] == "0x" parse(BigInt, hsh[3:end], 16)
       else parse(BigInt, hsh, base) end
   sb = IOBuffer()
   while x > 0
       x, r = divrem(x, 58)
       print(sb, alpha[r + 1])
   end
   return String(sb) |> reverse

end

s = "25420294593250030202636073700053352635053786165627414518" println("# $s\n -> ", encodebase58(s, 10)) for s in ["0x61", "0x626262", "0x636363", "0x73696d706c792061206c6f6e6720737472696e67",

         "0x516b6fcd0f", "0xbf4f89001e670274dd", "0x572e4794", "0xecac89cad93923c02321",
         "0x10c8511e"]
   println("# $s\n -> ", encodebase58(s))

end</lang>

Output:

# 25420294593250030202636073700053352635053786165627414518
 -> 6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM
# 0x61
 -> 2g
# 0x626262
 -> a3gV
# 0x636363
 -> aPEr
# 0x73696d706c792061206c6f6e6720737472696e67
 -> 2cFupjhnEsSn59qHXstmK2ffpLv2
# 0x516b6fcd0f
 -> ABnLTmg
# 0xbf4f89001e670274dd
 -> 3SEo3LWLoPntC
# 0x572e4794
 -> 3EFU7m
# 0xecac89cad93923c02321
 -> EJDM8drfXA6uyA
# 0x10c8511e
 -> Rt5zm

Kotlin

<lang scala>// version 1.1.51

import java.math.BigInteger

const val ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz" val big0 = BigInteger.ZERO val big58 = BigInteger.valueOf(58L)

fun convertToBase58(hash: String, base: Int = 16): String {

   var x = if (base == 16 && hash.take(2) == "0x") BigInteger(hash.drop(2), 16)
           else BigInteger(hash, base)
   val sb = StringBuilder()
   while (x > big0) {
       val r = (x % big58).toInt()
       sb.append(ALPHABET[r])
       x = x / big58  
   }
   return sb.toString().reversed()

}

fun main(args: Array<String>) {

   val s = "25420294593250030202636073700053352635053786165627414518"
   val b = convertToBase58(s, 10)
   println("$s -> $b")
   val hashes = listOf(
       "0x61",
       "0x626262",
       "0x636363",
       "0x73696d706c792061206c6f6e6720737472696e67",
       "0x516b6fcd0f",
       "0xbf4f89001e670274dd",
       "0x572e4794",
       "0xecac89cad93923c02321",
       "0x10c8511e"
   )
   for (hash in hashes) {
       val b58 = convertToBase58(hash)
       println("${hash.padEnd(56)} -> $b58")
   }

}</lang>

Output:

25420294593250030202636073700053352635053786165627414518 -> 6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM
0x61                                                     -> 2g
0x626262                                                 -> a3gV
0x636363                                                 -> aPEr
0x73696d706c792061206c6f6e6720737472696e67               -> 2cFupjhnEsSn59qHXstmK2ffpLv2
0x516b6fcd0f                                             -> ABnLTmg
0xbf4f89001e670274dd                                     -> 3SEo3LWLoPntC
0x572e4794                                               -> 3EFU7m
0xecac89cad93923c02321                                   -> EJDM8drfXA6uyA
0x10c8511e                                               -> Rt5zm

Perl 6

<lang perl6>sub encode_Base58 ( Int $x ) {

   constant @codes = <
         1 2 3 4 5 6 7 8 9
       A B C D E F G H   J K L M N   P Q R S T U V W X Y Z
       a b c d e f g h i j k   m n o p q r s t u v w x y z
   >;

   return @codes[ $x.polymod( 58 xx * ) ].join.flip;

}

my @tests =

   25420294593250030202636073700053352635053786165627414518 => '6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM',
   0x61                    => '2g',
   0x626262                => 'a3gV',
   0x636363                => 'aPEr',
   0x73696d706c792061206c6f6e6720737472696e67 => '2cFupjhnEsSn59qHXstmK2ffpLv2',
   0x516b6fcd0f            => 'ABnLTmg',
   0xbf4f89001e670274dd    => '3SEo3LWLoPntC',
   0x572e4794              => '3EFU7m',
   0xecac89cad93923c02321  => 'EJDM8drfXA6uyA',
   0x10c8511e              => 'Rt5zm',

use Test; for @tests {

   is encode_Base58(.key), .value, "{.key} encodes to {.value}";

} </lang>

Phix

Slight variation from Bitcoin/public_point_to_address#Phix in that it accepts any length string (which can be binary or text).
Includes leading zeroes, if you don't want that just comment out the three lines defining/using the integer lz. <lang Phix>constant b58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"

function base58(string s) string out = "" integer lz = length(s)

   while 1 do
       s = trim_head(s,'\0')
       if length(s)=0 then exit end if
       if out="" then lz -= length(s) end if
       integer c = 0
       for i=1 to length(s) do
           c = c*256+s[i]
           s[i] = floor(c/58)
           c = mod(c,58)
       end for
       out &= b58[c+1]
   end while
   out &= repeat('1',lz)
   return reverse(out)

end function

?base58(x"00010966776006953D5567439E5E39F86A0D273BEED61967F6") ?base58(x"61") ?base58(x"626262") ?base58(x"636363") ?base58(x"73696d706c792061206c6f6e6720737472696e67") ?base58(x"516b6fcd0f") ?base58(x"bf4f89001e670274dd") ?base58(x"572e4794") ?base58(x"ecac89cad93923c02321") ?base58(x"10c8511e")</lang>

Output:

"16UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM"
"2g"
"a3gV"
"aPEr"
"2cFupjhnEsSn59qHXstmK2ffpLv2"
"ABnLTmg"
"3SEo3LWLoPntC"
"3EFU7m"
"EJDM8drfXA6uyA"
"Rt5zm"

Racket

(Examples from some other task) <lang racket>#lang racket

(define ((base-n-alphabet-encode alphabet) hash-string (in-base 16))

 (define out-base (string-length alphabet))
 (let reduce-hash ((h (string->number (if (and (= in-base 16) (string-prefix? hash-string "0x"))
                                          (substring hash-string 2)
                                          hash-string)
                                      in-base))
                   (acc (list)))
   (if (zero? h)
       (list->string acc)
       (let-values (((q r) (quotient/remainder h out-base)))
         (reduce-hash q (cons (string-ref alphabet r) acc))))))

(define base58-check-encode (base-n-alphabet-encode "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"))

(module+ main

 (base58-check-encode "25420294593250030202636073700053352635053786165627414518" 10)
 (map base58-check-encode (list "0x61"
                                "0x626262"
                                "0x636363"
                                "0x73696d706c792061206c6f6e6720737472696e67"
                                "0x516b6fcd0f"
                                "0xbf4f89001e670274dd"
                                "0x572e4794"
                                "0xecac89cad93923c02321"
                                "0x10c8511e")))</lang>

Output:

"6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM"
'("2g" "a3gV" "aPEr" "2cFupjhnEsSn59qHXstmK2ffpLv2" "ABnLTmg" "3SEo3LWLoPntC" "3EFU7m" "EJDM8drfXA6uyA" "Rt5zm")

REXX

version 1

Following the description in https://www.anintegratedworld.com/how-to-manually-calculate-base58check-encoding/ I get the result expected there. Apart for the leading 1 the program works also for the inputs shown above. <lang rexx>/* REXX */ s="123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz" Numeric Digits 100 k='00010966776006953D5567439E5E39F86A0D273BEED61967F6'x n=c2d(k) o= Do Until n=0

 rem=n//58
 n=n%58
 o=o||substr(s,rem+1,1)
 End

o=o||substr(s,1,1) Say reverse(o)</lang>

Output:

16UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM

version 2

does what the others do <lang rexx>/* REXX */ s="123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz" Numeric Digits 1000 cnt_ok=0 Call test 'N',25420294593250030202636073700053352635053786165627414518,,

            '6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM'

Call test 'X','61'x ,'2g' Call test 'X','626262'x ,'a3gV' Call test 'X','636363'x ,'aPEr' Call test 'X','73696d706c792061206c6f6e6720737472696e67'x,,

             '2cFupjhnEsSn59qHXstmK2ffpLv2'

Call test 'X','516b6fcd0f'x ,'ABnLTmg' Call test 'X','bf4f89001e670274dd'x ,'3SEo3LWLoPntC' Call test 'X','572e4794'x ,'3EFU7m' Call test 'X','ecac89cad93923c02321'x ,'EJDM8drfXA6uyA' Call test 'X','10c8511e'x ,'Rt5zm' Call test 'X','10c8511e'x ,'check_error_handlimng' Say cnt_ok 'tests ok' Exit test:

 Parse Arg how,k,res
 If how='X' Then
   k=c2d(k)
 o=
 Do Until k=0
   rem=k//58
   k=k%58
   o=o||substr(s,rem+1,1)
   End
 o=reverse(o)
 If o=res Then cnt_ok+=1
 Else Do
   Say 'expected:' res
   Say 'found   :' o
   End
 Return</lang>

Output:

expected: check_error_handlimng
found   : Rt5zm
10 tests ok

version 3

This REXX version handles a null input.

It also handles the case of the hash digest that contain leading 1's (ones)   which are translated to leading 0's (zeros).

The algorithm used doesn't need to   reverse   the residual string   (it uses   prepend   instead of   append). <lang rexx>/*REXX pgm encodes a checksum (hash digest) into Base58 (the standard Bitcoin alphabet).*/ call B58 25420294593250030202636073700053352635053786165627414518 call B58 '61'x call B58 '626262'x call B58 '636363'x call B58 '73696d706c792061206c6f6e6720737472696e67'x call B58 '516b6fcd0f'x call B58 'bf4f89001e670274dd'x call B58 '572e4794'x call B58 'ecac89cad93923c02321'x call B58 '10c8511e'x exit /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ B58: parse arg z 1 oz; L1=0; hx=0; numeric digits 500 /*for huge nums.*/

    if z=  then return                                               /*Is Z missing? */
    if \datatype(z, 'W') | arg()>1  then hx=1;   if hx  then z=c2d(z)  /*is Z in hex ? */
    if left(z, 1)==1  then L1=verify(z ., 1) -1 /*count number of leading 1's  (ones). */
    /*       0─────────────────I─────O────────────────────l────────────────   ◄───omit.*/
    @=space(" 123456789ABCDEFGH JKLMN PQRSTUVWXYZabcdefghi jkmnopqrstuvwxyz",  0)
    $=
                                   do until z=0;   $=substr(@, z//58 +1, 1)$;    z=z % 58
                                   end  /*until*/
    if hx  then oz="'"c2x(oz)"'x"               /*Original arg in hex?  Then transform.*/
    say right(oz, 60) '───►'  left(, L1, 0)$  /*display given argument & the residual*/
    return                                      /* [↑]  also prepend residual with 1's.*/</lang>

output:

    25420294593250030202636073700053352635053786165627414518 ───► 6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM
                                                       '61'x ───► 2g
                                                   '626262'x ───► a3gV
                                                   '636363'x ───► aPEr
                 '73696D706C792061206C6F6E6720737472696E67'x ───► 2cFupjhnEsSn59qHXstmK2ffpLv2
                                               '516B6FCD0F'x ───► ABnLTmg
                                       'BF4F89001E670274DD'x ───► 3SEo3LWLoPntC
                                                 '572E4794'x ───► 03EFU7m
                                     'ECAC89CAD93923C02321'x ───► 000EJDM8drfXA6uyA
                                                 '10C8511E'x ───► Rt5zm

zkl

Uses libGMP <lang zkl>var [const] BN=Import.lib("zklBigNum"), // GNU Multiple Precision Arithmetic Library

  src="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuv",
  dst="123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";

println("OkobppXBkab(58)-->", # 10687460092462769069(10) "OkobppXBkab".translate(src,dst),"\n");

ns:=T(BN("25420294593250030202636073700053352635053786165627414518"),

     0x61, 0x626262, 0x636363, 
     "73696d706c792061206c6f6e6720737472696e67",
     0x516b6fcd0f, "bf4f89001e670274dd", 0x572e4794,
     "ecac89cad93923c02321", 0x10c8511e);

ns.pump(Console.println,'wrap(n){ BN(n,16).toString(58).translate(src,dst) });</lang>

Output:

OkobppXBkab(58)-->RosettaCode

6UwLL9Risc3QfPqBUvKofHmBQ7wMtjvM
2g
a3gV
aPEr
2cFupjhnEsSn59qHXstmK2ffpLv2
ABnLTmg
3SEo3LWLoPntC
3EFU7m
EJDM8drfXA6uyA
Rt5zm