RFC 1321, "The MD5 Message-Digest Algorithm", April 1992

Note: This RFC has been updated by RFC 6151

Errata ID: 7814
Status: Reported
Type: Technical
Publication Format(s) : TEXT
Reported By: Nilstrieb
Date Reported: 2024-02-19

Appendix A.1 says:

/* POINTER defines a generic pointer type */
typedef unsigned char *POINTER;

/* UINT2 defines a two byte word */
typedef unsigned short int UINT2;

/* UINT4 defines a four byte word */
typedef unsigned long int UINT4;

It should say:

#include <stdint.h>

/* POINTER defines a generic pointer type */
typedef unsigned char *POINTER;

/* UINT2 defines a two byte word */
typedef uint16_t UINT2;

/* UINT4 defines a four byte word */
typedef uint32_t UINT4;

Notes:

On some modern systems like x86-64 Linux, unsigned long int is 8 bytes, which causes the original implementation to be incorrect.

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