diff --git a/_rsrch/cidiface/cid.go b/_rsrch/cidiface/cid.go
new file mode 100644
index 0000000..8a888e1
--- /dev/null
+++ b/_rsrch/cidiface/cid.go
@@ -0,0 +1,46 @@
+package cid
+
+import (
+	mh "github.com/multiformats/go-multihash"
+)
+
+// Cid represents a self-describing content adressed identifier.
+//
+// A CID is composed of:
+//
+//   - a Version of the CID itself,
+//   - a Multicodec (indicates the encoding of the referenced content),
+//   - and a Multihash (which identifies the referenced content).
+//
+// (Note that the Multihash further contains its own version and hash type
+// indicators.)
+type Cid interface {
+	// n.b. 'yields' means "without copy", 'produces' means a malloc.
+
+	Version() uint64         // Yields the version prefix as a uint.
+	Multicodec() uint64      // Yields the multicodec as a uint.
+	Multihash() mh.Multihash // Yields the multihash segment.
+
+	String() string // Produces the CID formatted as b58 string.
+
+	Prefix() Prefix // Produces a tuple of non-content metadata.
+
+	// some change notes:
+	// - `KeyString() CidString` is gone because we're natively a map key now, you're welcome.
+	// - `StringOfBase(mbase.Encoding) (string, error)` is skipped, maybe it can come back but maybe it should be a formatter's job.
+	// - `Equals(o Cid) bool` is gone because it's now `==`, you're welcome.
+	// - `Bytes() []byte` is gone because I can't imagine where that should be used except again where a formatter should be involved.
+}
+
+// Prefix represents all the metadata of a Cid,
+// that is, the Version, the Codec, the Multihash type
+// and the Multihash length. It does not contains
+// any actual content information.
+// NOTE: The use -1 in MhLength to mean default length is deprecated,
+//   use the V0Builder or V1Builder structures instead
+type Prefix struct {
+	Version  uint64
+	Codec    uint64
+	MhType   uint64
+	MhLength int
+}
diff --git a/_rsrch/cidiface/cidString.go b/_rsrch/cidiface/cidString.go
new file mode 100644
index 0000000..c0deb9b
--- /dev/null
+++ b/_rsrch/cidiface/cidString.go
@@ -0,0 +1,69 @@
+package cid
+
+import (
+	"encoding/binary"
+
+	mbase "github.com/multiformats/go-multibase"
+	mh "github.com/multiformats/go-multihash"
+)
+
+var _ Cid = CidStr("")
+
+// CidStr is a representation of a Cid as a string type containing binary.
+//
+// Using golang's string type is preferable over byte slices even for binary
+// data because golang strings are immutable, usable as map keys,
+// trivially comparable with built-in equals operators, etc.
+type CidStr string
+
+// EmptyCid is a constant for a zero/uninitialized/sentinelvalue cid;
+// it is declared mainly for readability in checks for sentinel values.
+const EmptyCid = CidStr("")
+
+func (c CidStr) Version() uint64 {
+	bytes := []byte(c)
+	v, _ := binary.Uvarint(bytes)
+	return v
+}
+
+func (c CidStr) Multicodec() uint64 {
+	bytes := []byte(c)
+	_, n := binary.Uvarint(bytes) // skip version length
+	codec, _ := binary.Uvarint(bytes[n:])
+	return codec
+}
+
+func (c CidStr) Multihash() mh.Multihash {
+	bytes := []byte(c)
+	_, n1 := binary.Uvarint(bytes)      // skip version length
+	_, n2 := binary.Uvarint(bytes[n1:]) // skip codec length
+	return mh.Multihash(bytes[n1+n2:])  // return slice of remainder
+}
+
+// String returns the default string representation of a Cid.
+// Currently, Base58 is used as the encoding for the multibase string.
+func (c CidStr) String() string {
+	switch c.Version() {
+	case 0:
+		return c.Multihash().B58String()
+	case 1:
+		mbstr, err := mbase.Encode(mbase.Base58BTC, []byte(c))
+		if err != nil {
+			panic("should not error with hardcoded mbase: " + err.Error())
+		}
+		return mbstr
+	default:
+		panic("not possible to reach this point")
+	}
+}
+
+// Prefix builds and returns a Prefix out of a Cid.
+func (c CidStr) Prefix() Prefix {
+	dec, _ := mh.Decode(c.Multihash()) // assuming we got a valid multiaddr, this will not error
+	return Prefix{
+		MhType:   dec.Code,
+		MhLength: dec.Length,
+		Version:  c.Version(),
+		Codec:    c.Multicodec(),
+	}
+}