Add ADR-028 related functions

types/address/README.md

@@ -0,0 +1,7 @@
+# Account
+
+This package defines Cosmos SDK address related functions.
+
+## References
+
++ [ADR-028](../../docs/architecture/adr-028-public-key-addresses.md)

types/address/hash.go

@@ -0,0 +1,68 @@
+package address
+
+import (
+	"crypto/sha256"
+	"reflect"
+	"sort"
+	"unsafe"
+
+	"github.com/cosmos/cosmos-sdk/types/errors"
+)
+
+/*
+   TODO
+
+   I still need to think how to organize it.
+   Ideally, I wanted to Addressable Account abstraction
+   - so all kinds of accounts which could be addressable (base, multisig, module...)
+
+   Other idea is to leave away this abstraction, and only implement the related functions,
+   which would take more
+*/
+
+// BaseLen is the length of generated addresses constructed by BaseAddress.
+const BaseLen = sha256.Size
+
+type Addressable interface {
+	Address() []byte
+}
+
+func MkBase(typ string, key []byte) []byte {
+	hasher := sha256.New()
+	hasher.Write(unsafeStrToByteArray(typ))
+	th := hasher.Sum(nil)
+
+	hasher.Reset()
+	_, err := hasher.Write(th)
+	errors.Panic(err)
+	_, err = hasher.Write(key)
+	errors.Panic(err)
+	return hasher.Sum(nil)
+}
+
+func MkComposed(typ string, subAddresses []Addressable) []byte {
+	as := make([][]byte, len(subAddresses))
+	totalLen := 0
+	for i := range subAddresses {
+		as[i] = subAddresses[i].Address()
+		totalLen += len(as[i])
+	}
+
+	sort.Slice(as, func(i, j int) { byte.Compare(as[i], as[j]) <= 0 })
+	key := make(key, totalLen)
+	offset := 0
+	for i := range as {
+		key = copy(key[offset:], as[i])
+		offset += len(as[i])
+	}
+	return MkBase(typ, key)
+}
+
+// unsafeStrToByteArray uses unsafe to convert string into byte array. Returned array
+// cannot be altered after this functions is called
+func unsafeStrToByteArray(s string) []byte {
+	sh := *(*reflect.SliceHeader)(unsafe.Pointer(&s))
+	sh.Cap = sh.Len
+	bs := *(*[]byte)(unsafe.Pointer(&sh))
+	return bs
+}