port to golang

eszip-go/checksum.go

@@ -0,0 +1,82 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+package eszip
+
+import (
+	"bytes"
+	"crypto/sha256"
+
+	"github.com/zeebo/xxh3"
+)
+
+// ChecksumType represents the hash algorithm used for checksums
+type ChecksumType uint8
+
+const (
+	ChecksumNone   ChecksumType = 0
+	ChecksumSha256 ChecksumType = 1
+	ChecksumXxh3   ChecksumType = 2
+)
+
+// DigestSize returns the size in bytes of the hash digest
+func (c ChecksumType) DigestSize() uint8 {
+	switch c {
+	case ChecksumNone:
+		return 0
+	case ChecksumSha256:
+		return 32
+	case ChecksumXxh3:
+		return 8
+	default:
+		return 0
+	}
+}
+
+// Hash computes the checksum of the given data
+func (c ChecksumType) Hash(data []byte) []byte {
+	switch c {
+	case ChecksumNone:
+		return nil
+	case ChecksumSha256:
+		h := sha256.Sum256(data)
+		return h[:]
+	case ChecksumXxh3:
+		h := xxh3.Hash(data)
+		// Convert to big-endian bytes
+		return []byte{
+			byte(h >> 56),
+			byte(h >> 48),
+			byte(h >> 40),
+			byte(h >> 32),
+			byte(h >> 24),
+			byte(h >> 16),
+			byte(h >> 8),
+			byte(h),
+		}
+	default:
+		return nil
+	}
+}
+
+// Verify checks if the given hash matches the data
+func (c ChecksumType) Verify(data, hash []byte) bool {
+	if c == ChecksumNone {
+		return true
+	}
+	computed := c.Hash(data)
+	return bytes.Equal(computed, hash)
+}
+
+// FromU8 creates a ChecksumType from a byte value
+func ChecksumFromU8(b uint8) (ChecksumType, bool) {
+	switch b {
+	case 0:
+		return ChecksumNone, true
+	case 1:
+		return ChecksumSha256, true
+	case 2:
+		return ChecksumXxh3, true
+	default:
+		return ChecksumNone, false
+	}
+}