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.

Author: wyhaines

VERSION

@@ -1 +1 @@
-0.2.0
+0.2.1

shard.yml

@@ -1,5 +1,5 @@
 name: base58
-version: 0.2.0
+version: 0.2.1
 
 authors:
   - Kirk Haines <[email protected]>

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