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+Network Working Group                                          R. Rivest
+Request for Comments: 1321           MIT Laboratory for Computer Science
+                                             and RSA Data Security, Inc.
+                                                              April 1992
+
+
+                     The MD5 Message-Digest Algorithm
+
+Status of this Memo
+
+   This memo provides information for the Internet community.  It does
+   not specify an Internet standard.  Distribution of this memo is
+   unlimited.
+
+Acknowlegements
+
+   We would like to thank Don Coppersmith, Burt Kaliski, Ralph Merkle,
+   David Chaum, and Noam Nisan for numerous helpful comments and
+   suggestions.
+
+Table of Contents
+
+   1. Executive Summary                                                1
+   2. Terminology and Notation                                         2
+   3. MD5 Algorithm Description                                        3
+   4. Summary                                                          6
+   5. Differences Between MD4 and MD5                                  6
+   References                                                          7
+   APPENDIX A - Reference Implementation                               7
+   Security Considerations                                            21
+   Author's Address                                                   21
+
+1. Executive Summary
+
+   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.
+   It is conjectured that it is computationally infeasible to produce
+   two messages having the same message digest, or to produce any
+   message having a given prespecified target message digest. The MD5
+   algorithm is intended for digital signature applications, where a
+   large file must be "compressed" in a secure manner before being
+   encrypted with a private (secret) key under a public-key cryptosystem
+   such as RSA.
+
+
+
+
+
+
+
+Rivest                                                          [Page 1]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+   The MD5 algorithm is designed to be quite fast on 32-bit machines. In
+   addition, the MD5 algorithm does not require any large substitution
+   tables; the algorithm can be coded quite compactly.
+
+   The MD5 algorithm is an extension of the MD4 message-digest algorithm
+   1,2]. MD5 is slightly slower than MD4, but is more "conservative" in
+   design. MD5 was designed because it was felt that MD4 was perhaps
+   being adopted for use more quickly than justified by the existing
+   critical review; because MD4 was designed to be exceptionally fast,
+   it is "at the edge" in terms of risking successful cryptanalytic
+   attack. MD5 backs off a bit, giving up a little in speed for a much
+   greater likelihood of ultimate security. It incorporates some
+   suggestions made by various reviewers, and contains additional
+   optimizations. The MD5 algorithm is being placed in the public domain
+   for review and possible adoption as a standard.
+
+   For OSI-based applications, MD5's object identifier is
+
+   md5 OBJECT IDENTIFIER ::=
+     iso(1) member-body(2) US(840) rsadsi(113549) digestAlgorithm(2) 5}
+
+   In the X.509 type AlgorithmIdentifier [3], the parameters for MD5
+   should have type NULL.
+
+2. Terminology and Notation
+
+   In this document a "word" is a 32-bit quantity and a "byte" is an
+   eight-bit quantity. A sequence of bits can be interpreted in a
+   natural manner as a sequence of bytes, where each consecutive group
+   of eight bits is interpreted as a byte with the high-order (most
+   significant) bit of each byte listed first. Similarly, a sequence of
+   bytes can be interpreted as a sequence of 32-bit words, where each
+   consecutive group of four bytes is interpreted as a word with the
+   low-order (least significant) byte given first.
+
+   Let x_i denote "x sub i". If the subscript is an expression, we
+   surround it in braces, as in x_{i+1}. Similarly, we use ^ for
+   superscripts (exponentiation), so that x^i denotes x to the i-th
+   power.
+
+   Let the symbol "+" denote addition of words (i.e., modulo-2^32
+   addition). Let X <<< s denote the 32-bit value obtained by circularly
+   shifting (rotating) X left by s bit positions. Let not(X) denote the
+   bit-wise complement of X, and let X v Y denote the bit-wise OR of X
+   and Y. Let X xor Y denote the bit-wise XOR of X and Y, and let XY
+   denote the bit-wise AND of X and Y.
+
+
+
+
+
+Rivest                                                          [Page 2]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+3. MD5 Algorithm Description
+
+   We begin by supposing that we have a b-bit message as input, and that
+   we wish to find its message digest. Here b is an arbitrary
+   nonnegative integer; b may be zero, it need not be a multiple of
+   eight, and it may be arbitrarily large. We imagine the bits of the
+   message written down as follows:
+
+          m_0 m_1 ... m_{b-1}
+
+   The following five steps are performed to compute the message digest
+   of the message.
+
+3.1 Step 1. Append Padding Bits
+
+   The message is "padded" (extended) so that its length (in bits) is
+   congruent to 448, modulo 512. That is, the message is extended so
+   that it is just 64 bits shy of being a multiple of 512 bits long.
+   Padding is always performed, even if the length of the message is
+   already congruent to 448, modulo 512.
+
+   Padding is performed as follows: a single "1" bit is appended to the
+   message, and then "0" bits are appended so that the length in bits of
+   the padded message becomes congruent to 448, modulo 512. In all, at
+   least one bit and at most 512 bits are appended.
+
+3.2 Step 2. Append Length
+
+   A 64-bit representation of b (the length of the message before the
+   padding bits were added) is appended to the result of the previous
+   step. In the unlikely event that b is greater than 2^64, then only
+   the low-order 64 bits of b are used. (These bits are appended as two
+   32-bit words and appended low-order word first in accordance with the
+   previous conventions.)
+
+   At this point the resulting message (after padding with bits and with
+   b) has a length that is an exact multiple of 512 bits. Equivalently,
+   this message has a length that is an exact multiple of 16 (32-bit)
+   words. Let M[0 ... N-1] denote the words of the resulting message,
+   where N is a multiple of 16.
+
+3.3 Step 3. Initialize MD Buffer
+
+   A four-word buffer (A,B,C,D) is used to compute the message digest.
+   Here each of A, B, C, D is a 32-bit register. These registers are
+   initialized to the following values in hexadecimal, low-order bytes
+   first):
+
+
+
+
+Rivest                                                          [Page 3]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+          word A: 01 23 45 67
+          word B: 89 ab cd ef
+          word C: fe dc ba 98
+          word D: 76 54 32 10
+
+3.4 Step 4. Process Message in 16-Word Blocks
+
+   We first define four auxiliary functions that each take as input
+   three 32-bit words and produce as output one 32-bit word.
+
+          F(X,Y,Z) = XY v not(X) Z
+          G(X,Y,Z) = XZ v Y not(Z)
+          H(X,Y,Z) = X xor Y xor Z
+          I(X,Y,Z) = Y xor (X v not(Z))
+
+   In each bit position F acts as a conditional: if X then Y else Z.
+   The function F could have been defined using + instead of v since XY
+   and not(X)Z will never have 1's in the same bit position.) It is
+   interesting to note that if the bits of X, Y, and Z are independent
+   and unbiased, the each bit of F(X,Y,Z) will be independent and
+   unbiased.
+
+   The functions G, H, and I are similar to the function F, in that they
+   act in "bitwise parallel" to produce their output from the bits of X,
+   Y, and Z, in such a manner that if the corresponding bits of X, Y,
+   and Z are independent and unbiased, then each bit of G(X,Y,Z),
+   H(X,Y,Z), and I(X,Y,Z) will be independent and unbiased. Note that
+   the function H is the bit-wise "xor" or "parity" function of its
+   inputs.
+
+   This step uses a 64-element table T[1 ... 64] constructed from the
+   sine function. Let T[i] denote the i-th element of the table, which
+   is equal to the integer part of 4294967296 times abs(sin(i)), where i
+   is in radians. The elements of the table are given in the appendix.
+
+   Do the following:
+
+   /* Process each 16-word block. */
+   For i = 0 to N/16-1 do
+
+     /* Copy block i into X. */
+     For j = 0 to 15 do
+       Set X[j] to M[i*16+j].
+     end /* of loop on j */
+
+     /* Save A as AA, B as BB, C as CC, and D as DD. */
+     AA = A
+     BB = B
+
+
+
+Rivest                                                          [Page 4]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+     CC = C
+     DD = D
+
+     /* Round 1. */
+     /* Let [abcd k s i] denote the operation
+          a = b + ((a + F(b,c,d) + X[k] + T[i]) <<< s). */
+     /* Do the following 16 operations. */
+     [ABCD  0  7  1]  [DABC  1 12  2]  [CDAB  2 17  3]  [BCDA  3 22  4]
+     [ABCD  4  7  5]  [DABC  5 12  6]  [CDAB  6 17  7]  [BCDA  7 22  8]
+     [ABCD  8  7  9]  [DABC  9 12 10]  [CDAB 10 17 11]  [BCDA 11 22 12]
+     [ABCD 12  7 13]  [DABC 13 12 14]  [CDAB 14 17 15]  [BCDA 15 22 16]
+
+     /* Round 2. */
+     /* Let [abcd k s i] denote the operation
+          a = b + ((a + G(b,c,d) + X[k] + T[i]) <<< s). */
+     /* Do the following 16 operations. */
+     [ABCD  1  5 17]  [DABC  6  9 18]  [CDAB 11 14 19]  [BCDA  0 20 20]
+     [ABCD  5  5 21]  [DABC 10  9 22]  [CDAB 15 14 23]  [BCDA  4 20 24]
+     [ABCD  9  5 25]  [DABC 14  9 26]  [CDAB  3 14 27]  [BCDA  8 20 28]
+     [ABCD 13  5 29]  [DABC  2  9 30]  [CDAB  7 14 31]  [BCDA 12 20 32]
+
+     /* Round 3. */
+     /* Let [abcd k s t] denote the operation
+          a = b + ((a + H(b,c,d) + X[k] + T[i]) <<< s). */
+     /* Do the following 16 operations. */
+     [ABCD  5  4 33]  [DABC  8 11 34]  [CDAB 11 16 35]  [BCDA 14 23 36]
+     [ABCD  1  4 37]  [DABC  4 11 38]  [CDAB  7 16 39]  [BCDA 10 23 40]
+     [ABCD 13  4 41]  [DABC  0 11 42]  [CDAB  3 16 43]  [BCDA  6 23 44]
+     [ABCD  9  4 45]  [DABC 12 11 46]  [CDAB 15 16 47]  [BCDA  2 23 48]
+
+     /* Round 4. */
+     /* Let [abcd k s t] denote the operation
+          a = b + ((a + I(b,c,d) + X[k] + T[i]) <<< s). */
+     /* Do the following 16 operations. */
+     [ABCD  0  6 49]  [DABC  7 10 50]  [CDAB 14 15 51]  [BCDA  5 21 52]
+     [ABCD 12  6 53]  [DABC  3 10 54]  [CDAB 10 15 55]  [BCDA  1 21 56]
+     [ABCD  8  6 57]  [DABC 15 10 58]  [CDAB  6 15 59]  [BCDA 13 21 60]
+     [ABCD  4  6 61]  [DABC 11 10 62]  [CDAB  2 15 63]  [BCDA  9 21 64]
+
+     /* Then perform the following additions. (That is increment each
+        of the four registers by the value it had before this block
+        was started.) */
+     A = A + AA
+     B = B + BB
+     C = C + CC
+     D = D + DD
+
+   end /* of loop on i */
+
+
+
+Rivest                                                          [Page 5]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+3.5 Step 5. Output
+
+   The message digest produced as output is A, B, C, D. That is, we
+   begin with the low-order byte of A, and end with the high-order byte
+   of D.
+
+   This completes the description of MD5. A reference implementation in
+   C is given in the appendix.
+
+4. Summary
+
+   The MD5 message-digest algorithm is simple to implement, and provides
+   a "fingerprint" or message digest of a message of arbitrary length.
+   It is conjectured that the difficulty of coming up with two messages
+   having the same message digest is on the order of 2^64 operations,
+   and that the difficulty of coming up with any message having a given
+   message digest is on the order of 2^128 operations. The MD5 algorithm
+   has been carefully scrutinized for weaknesses. It is, however, a
+   relatively new algorithm and further security analysis is of course
+   justified, as is the case with any new proposal of this sort.
+
+5. Differences Between MD4 and MD5
+
+     The following are the differences between MD4 and MD5:
+
+       1.   A fourth round has been added.
+
+       2.   Each step now has a unique additive constant.
+
+       3.   The function g in round 2 was changed from (XY v XZ v YZ) to
+       (XZ v Y not(Z)) to make g less symmetric.
+
+       4.   Each step now adds in the result of the previous step.  This
+       promotes a faster "avalanche effect".
+
+       5.   The order in which input words are accessed in rounds 2 and
+       3 is changed, to make these patterns less like each other.
+
+       6.   The shift amounts in each round have been approximately
+       optimized, to yield a faster "avalanche effect." The shifts in
+       different rounds are distinct.
+
+
+
+
+
+
+
+
+
+
+Rivest                                                          [Page 6]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+References
+
+   [1] Rivest, R., "The MD4 Message Digest Algorithm", RFC 1320, MIT and
+       RSA Data Security, Inc., April 1992.
+
+   [2] Rivest, R., "The MD4 message digest algorithm", in A.J.  Menezes
+       and S.A. Vanstone, editors, Advances in Cryptology - CRYPTO '90
+       Proceedings, pages 303-311, Springer-Verlag, 1991.
+
+   [3] CCITT Recommendation X.509 (1988), "The Directory -
+       Authentication Framework."
+
+APPENDIX A - Reference Implementation
+
+   This appendix contains the following files taken from RSAREF: A
+   Cryptographic Toolkit for Privacy-Enhanced Mail:
+
+     global.h -- global header file
+
+     md5.h -- header file for MD5
+
+     md5c.c -- source code for MD5
+
+   For more information on RSAREF, send email to <rsaref@rsa.com>.
+
+   The appendix also includes the following file:
+
+     mddriver.c -- test driver for MD2, MD4 and MD5
+
+   The driver compiles for MD5 by default but can compile for MD2 or MD4
+   if the symbol MD is defined on the C compiler command line as 2 or 4.
+
+   The implementation is portable and should work on many different
+   plaforms. However, it is not difficult to optimize the implementation
+   on particular platforms, an exercise left to the reader. For example,
+   on "little-endian" platforms where the lowest-addressed byte in a 32-
+   bit word is the least significant and there are no alignment
+   restrictions, the call to Decode in MD5Transform can be replaced with
+   a typecast.
+
+A.1 global.h
+
+/* GLOBAL.H - RSAREF types and constants
+ */
+
+/* PROTOTYPES should be set to one if and only if the compiler supports
+  function argument prototyping.
+The following makes PROTOTYPES default to 0 if it has not already
+
+
+
+Rivest                                                          [Page 7]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+  been defined with C compiler flags.
+ */
+#ifndef PROTOTYPES
+#define PROTOTYPES 0
+#endif
+
+/* 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;
+
+/* PROTO_LIST is defined depending on how PROTOTYPES is defined above.
+If using PROTOTYPES, then PROTO_LIST returns the list, otherwise it
+  returns an empty list.
+ */
+#if PROTOTYPES
+#define PROTO_LIST(list) list
+#else
+#define PROTO_LIST(list) ()
+#endif
+
+A.2 md5.h
+
+/* MD5.H - header file for MD5C.C
+ */
+
+/* Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
+rights reserved.
+
+License to copy and use this software is granted provided that it
+is identified as the "RSA Data Security, Inc. MD5 Message-Digest
+Algorithm" in all material mentioning or referencing this software
+or this function.
+
+License is also granted to make and use derivative works provided
+that such works are identified as "derived from the RSA Data
+Security, Inc. MD5 Message-Digest Algorithm" in all material
+mentioning or referencing the derived work.
+
+RSA Data Security, Inc. makes no representations concerning either
+the merchantability of this software or the suitability of this
+software for any particular purpose. It is provided "as is"
+without express or implied warranty of any kind.
+
+
+
+
+Rivest                                                          [Page 8]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+These notices must be retained in any copies of any part of this
+documentation and/or software.
+ */
+
+/* MD5 context. */
+typedef struct {
+  UINT4 state[4];                                   /* state (ABCD) */
+  UINT4 count[2];        /* number of bits, modulo 2^64 (lsb first) */
+  unsigned char buffer[64];                         /* input buffer */
+} MD5_CTX;
+
+void MD5Init PROTO_LIST ((MD5_CTX *));
+void MD5Update PROTO_LIST
+  ((MD5_CTX *, unsigned char *, unsigned int));
+void MD5Final PROTO_LIST ((unsigned char [16], MD5_CTX *));
+
+A.3 md5c.c
+
+/* MD5C.C - RSA Data Security, Inc., MD5 message-digest algorithm
+ */
+
+/* Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
+rights reserved.
+
+License to copy and use this software is granted provided that it
+is identified as the "RSA Data Security, Inc. MD5 Message-Digest
+Algorithm" in all material mentioning or referencing this software
+or this function.
+
+License is also granted to make and use derivative works provided
+that such works are identified as "derived from the RSA Data
+Security, Inc. MD5 Message-Digest Algorithm" in all material
+mentioning or referencing the derived work.
+
+RSA Data Security, Inc. makes no representations concerning either
+the merchantability of this software or the suitability of this
+software for any particular purpose. It is provided "as is"
+without express or implied warranty of any kind.
+
+These notices must be retained in any copies of any part of this
+documentation and/or software.
+ */
+
+#include "global.h"
+#include "md5.h"
+
+/* Constants for MD5Transform routine.
+ */
+
+
+
+Rivest                                                          [Page 9]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+#define S11 7
+#define S12 12
+#define S13 17
+#define S14 22
+#define S21 5
+#define S22 9
+#define S23 14
+#define S24 20
+#define S31 4
+#define S32 11
+#define S33 16
+#define S34 23
+#define S41 6
+#define S42 10
+#define S43 15
+#define S44 21
+
+static void MD5Transform PROTO_LIST ((UINT4 [4], unsigned char [64]));
+static void Encode PROTO_LIST
+  ((unsigned char *, UINT4 *, unsigned int));
+static void Decode PROTO_LIST
+  ((UINT4 *, unsigned char *, unsigned int));
+static void MD5_memcpy PROTO_LIST ((POINTER, POINTER, unsigned int));
+static void MD5_memset PROTO_LIST ((POINTER, int, unsigned int));
+
+static unsigned char PADDING[64] = {
+  0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+
+/* F, G, H and I are basic MD5 functions.
+ */
+#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
+#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
+#define H(x, y, z) ((x) ^ (y) ^ (z))
+#define I(x, y, z) ((y) ^ ((x) | (~z)))
+
+/* ROTATE_LEFT rotates x left n bits.
+ */
+#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
+
+/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
+Rotation is separate from addition to prevent recomputation.
+ */
+#define FF(a, b, c, d, x, s, ac) { \
+ (a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
+ (a) = ROTATE_LEFT ((a), (s)); \
+
+
+
+Rivest                                                         [Page 10]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+ (a) += (b); \
+  }
+#define GG(a, b, c, d, x, s, ac) { \
+ (a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
+ (a) = ROTATE_LEFT ((a), (s)); \
+ (a) += (b); \
+  }
+#define HH(a, b, c, d, x, s, ac) { \
+ (a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
+ (a) = ROTATE_LEFT ((a), (s)); \
+ (a) += (b); \
+  }
+#define II(a, b, c, d, x, s, ac) { \
+ (a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
+ (a) = ROTATE_LEFT ((a), (s)); \
+ (a) += (b); \
+  }
+
+/* MD5 initialization. Begins an MD5 operation, writing a new context.
+ */
+void MD5Init (context)
+MD5_CTX *context;                                        /* context */
+{
+  context->count[0] = context->count[1] = 0;
+  /* Load magic initialization constants.
+*/
+  context->state[0] = 0x67452301;
+  context->state[1] = 0xefcdab89;
+  context->state[2] = 0x98badcfe;
+  context->state[3] = 0x10325476;
+}
+
+/* MD5 block update operation. Continues an MD5 message-digest
+  operation, processing another message block, and updating the
+  context.
+ */
+void MD5Update (context, input, inputLen)
+MD5_CTX *context;                                        /* context */
+unsigned char *input;                                /* input block */
+unsigned int inputLen;                     /* length of input block */
+{
+  unsigned int i, index, partLen;
+
+  /* Compute number of bytes mod 64 */
+  index = (unsigned int)((context->count[0] >> 3) & 0x3F);
+
+  /* Update number of bits */
+  if ((context->count[0] += ((UINT4)inputLen << 3))
+
+
+
+Rivest                                                         [Page 11]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+   < ((UINT4)inputLen << 3))
+ context->count[1]++;
+  context->count[1] += ((UINT4)inputLen >> 29);
+
+  partLen = 64 - index;
+
+  /* Transform as many times as possible.
+*/
+  if (inputLen >= partLen) {
+ MD5_memcpy
+   ((POINTER)&context->buffer[index], (POINTER)input, partLen);
+ MD5Transform (context->state, context->buffer);
+
+ for (i = partLen; i + 63 < inputLen; i += 64)
+   MD5Transform (context->state, &input[i]);
+
+ index = 0;
+  }
+  else
+ i = 0;
+
+  /* Buffer remaining input */
+  MD5_memcpy
+ ((POINTER)&context->buffer[index], (POINTER)&input[i],
+  inputLen-i);
+}
+
+/* MD5 finalization. Ends an MD5 message-digest operation, writing the
+  the message digest and zeroizing the context.
+ */
+void MD5Final (digest, context)
+unsigned char digest[16];                         /* message digest */
+MD5_CTX *context;                                       /* context */
+{
+  unsigned char bits[8];
+  unsigned int index, padLen;
+
+  /* Save number of bits */
+  Encode (bits, context->count, 8);
+
+  /* Pad out to 56 mod 64.
+*/
+  index = (unsigned int)((context->count[0] >> 3) & 0x3f);
+  padLen = (index < 56) ? (56 - index) : (120 - index);
+  MD5Update (context, PADDING, padLen);
+
+  /* Append length (before padding) */
+  MD5Update (context, bits, 8);
+
+
+
+Rivest                                                         [Page 12]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+  /* Store state in digest */
+  Encode (digest, context->state, 16);
+
+  /* Zeroize sensitive information.
+*/
+  MD5_memset ((POINTER)context, 0, sizeof (*context));
+}
+
+/* MD5 basic transformation. Transforms state based on block.
+ */
+static void MD5Transform (state, block)
+UINT4 state[4];
+unsigned char block[64];
+{
+  UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];
+
+  Decode (x, block, 64);
+
+  /* Round 1 */
+  FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
+  FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
+  FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
+  FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
+  FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
+  FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
+  FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
+  FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
+  FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
+  FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
+  FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
+  FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
+  FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
+  FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
+  FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
+  FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */
+
+ /* Round 2 */
+  GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
+  GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
+  GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
+  GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
+  GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
+  GG (d, a, b, c, x[10], S22,  0x2441453); /* 22 */
+  GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
+  GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
+  GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
+  GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
+  GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
+
+
+
+Rivest                                                         [Page 13]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+  GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
+  GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
+  GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
+  GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
+  GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */
+
+  /* Round 3 */
+  HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
+  HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
+  HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
+  HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
+  HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
+  HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
+  HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
+  HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
+  HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
+  HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
+  HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
+  HH (b, c, d, a, x[ 6], S34,  0x4881d05); /* 44 */
+  HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
+  HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
+  HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
+  HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */
+
+  /* Round 4 */
+  II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
+  II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
+  II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
+  II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
+  II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
+  II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
+  II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
+  II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
+  II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
+  II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
+  II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
+  II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
+  II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
+  II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
+  II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
+  II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */
+
+  state[0] += a;
+  state[1] += b;
+  state[2] += c;
+  state[3] += d;
+
+  /* Zeroize sensitive information.
+
+
+
+Rivest                                                         [Page 14]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+*/
+  MD5_memset ((POINTER)x, 0, sizeof (x));
+}
+
+/* Encodes input (UINT4) into output (unsigned char). Assumes len is
+  a multiple of 4.
+ */
+static void Encode (output, input, len)
+unsigned char *output;
+UINT4 *input;
+unsigned int len;
+{
+  unsigned int i, j;
+
+  for (i = 0, j = 0; j < len; i++, j += 4) {
+ output[j] = (unsigned char)(input[i] & 0xff);
+ output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
+ output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
+ output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
+  }
+}
+
+/* Decodes input (unsigned char) into output (UINT4). Assumes len is
+  a multiple of 4.
+ */
+static void Decode (output, input, len)
+UINT4 *output;
+unsigned char *input;
+unsigned int len;
+{
+  unsigned int i, j;
+
+  for (i = 0, j = 0; j < len; i++, j += 4)
+ output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) |
+   (((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
+}
+
+/* Note: Replace "for loop" with standard memcpy if possible.
+ */
+
+static void MD5_memcpy (output, input, len)
+POINTER output;
+POINTER input;
+unsigned int len;
+{
+  unsigned int i;
+
+  for (i = 0; i < len; i++)
+
+
+
+Rivest                                                         [Page 15]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+ output[i] = input[i];
+}
+
+/* Note: Replace "for loop" with standard memset if possible.
+ */
+static void MD5_memset (output, value, len)
+POINTER output;
+int value;
+unsigned int len;
+{
+  unsigned int i;
+
+  for (i = 0; i < len; i++)
+ ((char *)output)[i] = (char)value;
+}
+
+A.4 mddriver.c
+
+/* MDDRIVER.C - test driver for MD2, MD4 and MD5
+ */
+
+/* Copyright (C) 1990-2, RSA Data Security, Inc. Created 1990. All
+rights reserved.
+
+RSA Data Security, Inc. makes no representations concerning either
+the merchantability of this software or the suitability of this
+software for any particular purpose. It is provided "as is"
+without express or implied warranty of any kind.
+
+These notices must be retained in any copies of any part of this
+documentation and/or software.
+ */
+
+/* The following makes MD default to MD5 if it has not already been
+  defined with C compiler flags.
+ */
+#ifndef MD
+#define MD MD5
+#endif
+
+#include <stdio.h>
+#include <time.h>
+#include <string.h>
+#include "global.h"
+#if MD == 2
+#include "md2.h"
+#endif
+#if MD == 4
+
+
+
+Rivest                                                         [Page 16]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+#include "md4.h"
+#endif
+#if MD == 5
+#include "md5.h"
+#endif
+
+/* Length of test block, number of test blocks.
+ */
+#define TEST_BLOCK_LEN 1000
+#define TEST_BLOCK_COUNT 1000
+
+static void MDString PROTO_LIST ((char *));
+static void MDTimeTrial PROTO_LIST ((void));
+static void MDTestSuite PROTO_LIST ((void));
+static void MDFile PROTO_LIST ((char *));
+static void MDFilter PROTO_LIST ((void));
+static void MDPrint PROTO_LIST ((unsigned char [16]));
+
+#if MD == 2
+#define MD_CTX MD2_CTX
+#define MDInit MD2Init
+#define MDUpdate MD2Update
+#define MDFinal MD2Final
+#endif
+#if MD == 4
+#define MD_CTX MD4_CTX
+#define MDInit MD4Init
+#define MDUpdate MD4Update
+#define MDFinal MD4Final
+#endif
+#if MD == 5
+#define MD_CTX MD5_CTX
+#define MDInit MD5Init
+#define MDUpdate MD5Update
+#define MDFinal MD5Final
+#endif
+
+/* Main driver.
+
+Arguments (may be any combination):
+  -sstring - digests string
+  -t       - runs time trial
+  -x       - runs test script
+  filename - digests file
+  (none)   - digests standard input
+ */
+int main (argc, argv)
+int argc;
+
+
+
+Rivest                                                         [Page 17]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+char *argv[];
+{
+  int i;
+
+  if (argc > 1)
+ for (i = 1; i < argc; i++)
+   if (argv[i][0] == '-' && argv[i][1] == 's')
+     MDString (argv[i] + 2);
+   else if (strcmp (argv[i], "-t") == 0)
+     MDTimeTrial ();
+   else if (strcmp (argv[i], "-x") == 0)
+     MDTestSuite ();
+   else
+     MDFile (argv[i]);
+  else
+ MDFilter ();
+
+  return (0);
+}
+
+/* Digests a string and prints the result.
+ */
+static void MDString (string)
+char *string;
+{
+  MD_CTX context;
+  unsigned char digest[16];
+  unsigned int len = strlen (string);
+
+  MDInit (&context);
+  MDUpdate (&context, string, len);
+  MDFinal (digest, &context);
+
+  printf ("MD%d (\"%s\") = ", MD, string);
+  MDPrint (digest);
+  printf ("\n");
+}
+
+/* Measures the time to digest TEST_BLOCK_COUNT TEST_BLOCK_LEN-byte
+  blocks.
+ */
+static void MDTimeTrial ()
+{
+  MD_CTX context;
+  time_t endTime, startTime;
+  unsigned char block[TEST_BLOCK_LEN], digest[16];
+  unsigned int i;
+
+
+
+
+Rivest                                                         [Page 18]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+  printf
+ ("MD%d time trial. Digesting %d %d-byte blocks ...", MD,
+  TEST_BLOCK_LEN, TEST_BLOCK_COUNT);
+
+  /* Initialize block */
+  for (i = 0; i < TEST_BLOCK_LEN; i++)
+ block[i] = (unsigned char)(i & 0xff);
+
+  /* Start timer */
+  time (&startTime);
+
+  /* Digest blocks */
+  MDInit (&context);
+  for (i = 0; i < TEST_BLOCK_COUNT; i++)
+ MDUpdate (&context, block, TEST_BLOCK_LEN);
+  MDFinal (digest, &context);
+
+  /* Stop timer */
+  time (&endTime);
+
+  printf (" done\n");
+  printf ("Digest = ");
+  MDPrint (digest);
+  printf ("\nTime = %ld seconds\n", (long)(endTime-startTime));
+  printf
+ ("Speed = %ld bytes/second\n",
+  (long)TEST_BLOCK_LEN * (long)TEST_BLOCK_COUNT/(endTime-startTime));
+}
+
+/* Digests a reference suite of strings and prints the results.
+ */
+static void MDTestSuite ()
+{
+  printf ("MD%d test suite:\n", MD);
+
+  MDString ("");
+  MDString ("a");
+  MDString ("abc");
+  MDString ("message digest");
+  MDString ("abcdefghijklmnopqrstuvwxyz");
+  MDString
+ ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789");
+  MDString
+ ("1234567890123456789012345678901234567890\
+1234567890123456789012345678901234567890");
+}
+
+/* Digests a file and prints the result.
+
+
+
+Rivest                                                         [Page 19]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+ */
+static void MDFile (filename)
+char *filename;
+{
+  FILE *file;
+  MD_CTX context;
+  int len;
+  unsigned char buffer[1024], digest[16];
+
+  if ((file = fopen (filename, "rb")) == NULL)
+ printf ("%s can't be opened\n", filename);
+
+  else {
+ MDInit (&context);
+ while (len = fread (buffer, 1, 1024, file))
+   MDUpdate (&context, buffer, len);
+ MDFinal (digest, &context);
+
+ fclose (file);
+
+ printf ("MD%d (%s) = ", MD, filename);
+ MDPrint (digest);
+ printf ("\n");
+  }
+}
+
+/* Digests the standard input and prints the result.
+ */
+static void MDFilter ()
+{
+  MD_CTX context;
+  int len;
+  unsigned char buffer[16], digest[16];
+
+  MDInit (&context);
+  while (len = fread (buffer, 1, 16, stdin))
+ MDUpdate (&context, buffer, len);
+  MDFinal (digest, &context);
+
+  MDPrint (digest);
+  printf ("\n");
+}
+
+/* Prints a message digest in hexadecimal.
+ */
+static void MDPrint (digest)
+unsigned char digest[16];
+{
+
+
+
+Rivest                                                         [Page 20]
+
+RFC 1321              MD5 Message-Digest Algorithm            April 1992
+
+
+  unsigned int i;
+
+  for (i = 0; i < 16; i++)
+ printf ("%02x", digest[i]);
+}
+
+A.5 Test suite
+
+   The MD5 test suite (driver option "-x") should print the following
+   results:
+
+MD5 test suite:
+MD5 ("") = d41d8cd98f00b204e9800998ecf8427e
+MD5 ("a") = 0cc175b9c0f1b6a831c399e269772661
+MD5 ("abc") = 900150983cd24fb0d6963f7d28e17f72
+MD5 ("message digest") = f96b697d7cb7938d525a2f31aaf161d0
+MD5 ("abcdefghijklmnopqrstuvwxyz") = c3fcd3d76192e4007dfb496cca67e13b
+MD5 ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789") =
+d174ab98d277d9f5a5611c2c9f419d9f
+MD5 ("123456789012345678901234567890123456789012345678901234567890123456
+78901234567890") = 57edf4a22be3c955ac49da2e2107b67a
+
+Security Considerations
+
+   The level of security discussed in this memo is considered to be
+   sufficient for implementing very high security hybrid digital-
+   signature schemes based on MD5 and a public-key cryptosystem.
+
+Author's Address
+
+   Ronald L. Rivest
+   Massachusetts Institute of Technology
+   Laboratory for Computer Science
+   NE43-324
+   545 Technology Square
+   Cambridge, MA  02139-1986
+
+   Phone: (617) 253-5880
+   EMail: rivest@theory.lcs.mit.edu
+
+
+
+
+
+
+
+
+
+
+
+
+Rivest                                                         [Page 21]
+
\ No newline at end of file