Adding minio-hash with streaming crypto hashes

pkgs/crypto/md5/md5.go

@@ -0,0 +1,22 @@
+package md5
+
+import (
+	"crypto/md5"
+	"io"
+)
+
+func Sum(reader io.Reader) ([]byte, error) {
+	hash := md5.New()
+	var err error
+	for err == nil {
+		length := 0
+		byteBuffer := make([]byte, 1024*1024)
+		length, err = reader.Read(byteBuffer)
+		byteBuffer = byteBuffer[0:length]
+		hash.Write(byteBuffer)
+	}
+	if err != io.EOF {
+		return nil, err
+	}
+	return hash.Sum(nil), nil
+}