From 576161fbf885fc10137ed3c289d31e5cff8c5291 Mon Sep 17 00:00:00 2001
From: Derrick Hammer <derrick@derrickhammer.com>
Date: Wed, 3 Jan 2024 08:46:30 -0500
Subject: [PATCH] feat: add EncryptedCID

---
 encoding/encrypted_cid.go | 77 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 encoding/encrypted_cid.go

diff --git a/encoding/encrypted_cid.go b/encoding/encrypted_cid.go
new file mode 100644
index 0000000..673912e
--- /dev/null
+++ b/encoding/encrypted_cid.go
@@ -0,0 +1,77 @@
+package encoding
+
+import (
+	"errors"
+	"git.lumeweb.com/LumeWeb/libs5-go/types"
+	"git.lumeweb.com/LumeWeb/libs5-go/utils"
+)
+
+type EncryptedCID struct {
+	Multibase
+	encryptedBlobHash   Multihash
+	originalCID         CID
+	encryptionAlgorithm byte
+	padding             uint32
+	chunkSizeAsPowerOf2 int
+	encryptionKey       []byte
+}
+
+func NewEncryptedCID(encryptedBlobHash Multihash, originalCID CID, encryptionKey []byte, padding uint32, chunkSizeAsPowerOf2 int, encryptionAlgorithm byte) *EncryptedCID {
+	e := &EncryptedCID{
+		encryptedBlobHash:   encryptedBlobHash,
+		originalCID:         originalCID,
+		encryptionKey:       encryptionKey,
+		padding:             padding,
+		chunkSizeAsPowerOf2: chunkSizeAsPowerOf2,
+		encryptionAlgorithm: encryptionAlgorithm,
+	}
+
+	m := NewMultibase(e)
+	e.Multibase = m
+
+	return e
+}
+
+func DecodeEncryptedCID(cid string) (*EncryptedCID, error) {
+	data, err := MultibaseDecodeString(cid)
+	if err != nil {
+		return nil, err
+	}
+	return FromBytes(data)
+}
+
+func FromBytes(data []byte) (*EncryptedCID, error) {
+	if types.CIDType(data[0]) != types.CIDTypeEncryptedStatic {
+		return nil, errors.New("Invalid CID type")
+	}
+
+	cid, err := CIDFromBytes(data[72:])
+	if err != nil {
+		return nil, err
+	}
+
+	encryptedBlobHash := NewMultihash(data[3:36])
+	encryptionKey := data[36:68]
+	padding := utils.DecodeEndian(data[68:72])
+	chunkSizeAsPowerOf2 := int(data[2])
+	encryptionAlgorithm := data[1]
+
+	return NewEncryptedCID(*encryptedBlobHash, *cid, encryptionKey, padding, chunkSizeAsPowerOf2, encryptionAlgorithm), nil
+}
+
+func (c *EncryptedCID) ChunkSize() int {
+	return 1 << uint(c.chunkSizeAsPowerOf2)
+}
+
+func (c *EncryptedCID) ToBytes() []byte {
+	data := []byte{
+		byte(types.CIDTypeEncryptedStatic),
+		c.encryptionAlgorithm,
+		byte(c.chunkSizeAsPowerOf2),
+	}
+	data = append(data, c.encryptedBlobHash.FullBytes...)
+	data = append(data, c.encryptionKey...)
+	data = append(data, utils.EncodeEndian(c.padding, 4)...)
+	data = append(data, c.originalCID.ToBytes()...)
+	return data
+}