From b5b005ad6363e110acc130765cc22ec47a74df60 Mon Sep 17 00:00:00 2001
From: Kirk Haines <wyhaines@gmail.com>
Date: Tue, 14 Mar 2023 17:55:40 -0600
Subject: [PATCH] Commit the changes that let SS58 work with any arbitrary
 length payload. Substrates SS58 address format doc prescribes checksum
 lengths only for payloads of 1, 2, 4, 8, or 32 bytes. For any other payload,
 the behaviour is undefined. For lack of any other clear guidance beyond the
 abundance of 2 byte checksums in the actual live use of SS58, this library is
 implementing a default checksum of 2 bytes for otherwise undefined payload
 lengths. This change adds a `Base58::SS58.encode` and a `Base58::SS58.decode`
 method for dealing with arbitrary data, of arbitrary sizes.

---
 VERSION            |  2 +-
 shard.yml          |  2 +-
 src/base58/ss58.cr | 43 ++++++++++++++++++++++++++++++-------------
 3 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/VERSION b/VERSION
index 0ea3a94..0c62199 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.2.0
+0.2.1
diff --git a/shard.yml b/shard.yml
index 32f70c3..274b0e9 100644
--- a/shard.yml
+++ b/shard.yml
@@ -1,5 +1,5 @@
 name: base58
-version: 0.2.0
+version: 0.2.1
 
 authors:
   - Kirk Haines <wyhaines@gmail.com>
diff --git a/src/base58/ss58.cr b/src/base58/ss58.cr
index f7b7e52..9a70b62 100644
--- a/src/base58/ss58.cr
+++ b/src/base58/ss58.cr
@@ -62,10 +62,6 @@ module Base58
 
     # :nodoc:
     def self.check_args(address, format)
-      if format < 0 || format > 16383 || format == 46 || format == 47
-        raise ArgumentError.new("Invalid address format: #{format}")
-      end
-
       address_size = address.size
       if TwoByteChecksumAddresses.includes?(address_size)
         checksum_length = 2
@@ -75,20 +71,36 @@ module Base58
         raise ArgumentError.new("Invalid address size: #{address_size}; Substrate addresses can only be 1, 2, 4, 8, 32, or 33 bytes long")
       end
 
+      {
+        type:            Base58::Checksum::SS58,
+        prefix:          String.new(derive_format(format)),
+        checksum_length: checksum_length,
+        checksum_prefix: ChecksumPrefix,
+      }
+    end
+
+    # :nodoc:
+    def self.derive_format(format)
+      if format < 0 || format > 16383 || format == 46 || format == 47
+        raise ArgumentError.new("Invalid address format: #{format}")
+      end
+
       if format < 64
-        format_bytes = Slice[format.to_u8]
+        Slice[format.to_u8]
       else
-        format_bytes = Slice[
+        Slice[
           (((format & 0b0000_000011111100) >> 2) | 0b01000000).to_u8,
           ((format >> 8) | ((format & 0b0000000000000011) << 6)).to_u8,
         ]
       end
-      {
-        type:            Base58::Checksum::SS58,
-        prefix:          String.new(format_bytes),
-        checksum_length: checksum_length,
-        checksum_prefix: ChecksumPrefix,
-      }
+    end
+
+    # To encode content with an arbitrary length payload, use the `encode` method instead
+    # of `encode_address`. The Substrate SS58 spec only prescribes checksum lengths for
+    # payloads which are 1, 2, 4, 8, or 32 bytes long. So, for other payloads, this library
+    # is defaulting to a 2 byte checksum.
+    def self.encode(payload, into, format : Int = 42)
+      Base58.encode(payload, into: into, check: Check.new(type: Base58::Checksum::SS58, prefix: String.new(derive_format(format)), checksum_length: checksum_length(payload), checksum_prefix: ChecksumPrefix))
     end
 
     def self.encode_address(address, into : String.class = String, format : Int = 42)
@@ -147,6 +159,11 @@ module Base58
       Base58.encode(address, into: into, check: Check.new(**check_args(address, format)))
     end
 
+    # To decode content with an arbitrary length payload, use `decode` instead of `decode_address`.
+    def self.decode(payload, into, format = 42)
+      decode_address(payload, into: into, format: format)
+    end
+
     def self.decode_address(address, into : String.class = String, format : Int? = nil)
       String.new(decode_address(address, Slice(UInt8), format))
     end
@@ -278,7 +295,7 @@ module Base58
       when 17
         8
       else
-        0
+        2
       end
     end