RFC 1321 · INFORMATIONAL · 1992
WED · 29 JUL 2026
The MD5 Message-Digest Algorithm
Overview
RFC 1321, “The MD5 Message-Digest Algorithm”, is an Informational document published in April 1992 by R. Rivest. It has since been updated by RFC 6151. The canonical text is published by the RFC Editor.
Abstract
This document describes the MD5 message-digest algorithm. The algorithm takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input. This memo provides information for the Internet community. It does not specify an Internet standard.
What “Informational” means
Published for the general information of the community. It does not define an IETF standard and carries no standards-track status.
Read this RFC
The canonical text of RFC 1321 is hosted at rfc-editor.org. Available in TXT,HTML.
Relationships to other RFCs
Other RFCs from 1992
- RFC 1320 The MD4 Message-Digest Algorithm
- RFC 1322 A Unified Approach to Inter-Domain Routing
- RFC 1319 The MD2 Message-Digest Algorithm
- RFC 1323 TCP Extensions for High Performance
- RFC 1318 Definitions of Managed Objects for Parallel-printer-like Hardware Devices
- RFC 1324 A Discussion on Computer Network Conferencing
- RFC 1317 Definitions of Managed Objects for RS-232-like Hardware Devices
- RFC 1325 FYI on Questions and Answers Answers to Commonly asked "New Internet User" Questions