Method base58Decode

java/lib/src/main/java/io/github/ccxt/base/Encode.java:118–154

(String input)

        }
    }
    private static byte[] base58Decode(String input) {
        if (input == null || input.isEmpty()) return new byte[0];

        // Count leading zeros
        int zeros = 0;
        while (zeros < input.length() && input.charAt(zeros) == '1') zeros++;

        // Base58 -> base256
        byte[] b256 = new byte[input.length() * 733 / 1000 + 1];
        int length = 0;
        for (int i = zeros; i < input.length(); i++) {
            int ch = input.charAt(i);
            if (ch >= 128 || B58_INDEX[ch] == -1) throw new IllegalArgumentException("Invalid Base58 char: " + (char) ch);
            int carry = B58_INDEX[ch];
            int j = b256.length - 1;
            for (int k = b256.length - 1; k >= b256.length - length; k--, j--) {
                carry += (b256[k] & 0xFF) * 58;
                b256[k] = (byte) (carry & 0xFF);
                carry >>= 8;
            }
            while (carry > 0) {
                b256[j--] = (byte) (carry & 0xFF);
                carry >>= 8;
                length++;
            }
        }

        // Skip leading zeros in b256
        int idx = b256.length - length;
        while (idx < b256.length && b256[idx] == 0) { idx++; }

        // Result = zeros + the rest
        byte[] res = new byte[zeros + (b256.length - idx)];
        Arrays.fill(res, 0, zeros, (byte) 0);
        System.arraycopy(b256, idx, res, zeros, res.length - zeros);
        return res;
    }

    // ----------------------------
    // binary concat