diff --git a/md5-compress.c b/md5-compress.c
new file mode 100644
index 0000000000000000000000000000000000000000..9be4c1d2c9d82d864d0dcf21866de4dde3c629ec
--- /dev/null
+++ b/md5-compress.c
@@ -0,0 +1,149 @@
+/* md5-compress.c
+ *
+ * The compression function for the sha1 hash function.
+ *
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2001, 2005 Niels M�ller
+ *
+ * The nettle library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or (at your
+ * option) any later version.
+ *
+ * The nettle library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with the nettle library; see the file COPYING.LIB. If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/* Based on public domain code hacked by Colin Plumb, Andrew Kuchling, and
+ * Niels M�ller. */
+
+
+#if HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "md5.h"
+
+#include "macros.h"
+
+/* A block, treated as a sequence of 32-bit words. */
+#define MD5_DATA_LENGTH 16
+
+/* MD5 functions */
+
+#define F1(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
+#define F2(x, y, z) F1((z), (x), (y))
+#define F3(x, y, z) ((x) ^ (y) ^ (z))
+#define F4(x, y, z) ((y) ^ ((x) | ~(z)))
+
+#define ROUND(f, w, x, y, z, data, s) \
+( w += f(x, y, z) + data, w = w<<s | w>>(32-s), w += x )
+
+/* Perform the MD5 transformation on one full block of 16 32-bit
+ * words.
+ *
+ * Compresses 20 (_MD5_DIGEST_LENGTH + MD5_DATA_LENGTH) words into 4
+ * (_MD5_DIGEST_LENGTH) words. */
+
+void
+_nettle_md5_compress(uint32_t *digest, const uint8_t *input)
+{
+ uint32_t data[MD5_DATA_LENGTH];
+ uint32_t a, b, c, d;
+ unsigned i;
+
+ for (i = 0; i < MD5_DATA_LENGTH; i++, input += 4)
+ data[i] = LE_READ_UINT32(input);
+
+ a = digest[0];
+ b = digest[1];
+ c = digest[2];
+ d = digest[3];
+
+ ROUND(F1, a, b, c, d, data[ 0] + 0xd76aa478, 7);
+ ROUND(F1, d, a, b, c, data[ 1] + 0xe8c7b756, 12);
+ ROUND(F1, c, d, a, b, data[ 2] + 0x242070db, 17);
+ ROUND(F1, b, c, d, a, data[ 3] + 0xc1bdceee, 22);
+ ROUND(F1, a, b, c, d, data[ 4] + 0xf57c0faf, 7);
+ ROUND(F1, d, a, b, c, data[ 5] + 0x4787c62a, 12);
+ ROUND(F1, c, d, a, b, data[ 6] + 0xa8304613, 17);
+ ROUND(F1, b, c, d, a, data[ 7] + 0xfd469501, 22);
+ ROUND(F1, a, b, c, d, data[ 8] + 0x698098d8, 7);
+ ROUND(F1, d, a, b, c, data[ 9] + 0x8b44f7af, 12);
+ ROUND(F1, c, d, a, b, data[10] + 0xffff5bb1, 17);
+ ROUND(F1, b, c, d, a, data[11] + 0x895cd7be, 22);
+ ROUND(F1, a, b, c, d, data[12] + 0x6b901122, 7);
+ ROUND(F1, d, a, b, c, data[13] + 0xfd987193, 12);
+ ROUND(F1, c, d, a, b, data[14] + 0xa679438e, 17);
+ ROUND(F1, b, c, d, a, data[15] + 0x49b40821, 22);
+
+ ROUND(F2, a, b, c, d, data[ 1] + 0xf61e2562, 5);
+ ROUND(F2, d, a, b, c, data[ 6] + 0xc040b340, 9);
+ ROUND(F2, c, d, a, b, data[11] + 0x265e5a51, 14);
+ ROUND(F2, b, c, d, a, data[ 0] + 0xe9b6c7aa, 20);
+ ROUND(F2, a, b, c, d, data[ 5] + 0xd62f105d, 5);
+ ROUND(F2, d, a, b, c, data[10] + 0x02441453, 9);
+ ROUND(F2, c, d, a, b, data[15] + 0xd8a1e681, 14);
+ ROUND(F2, b, c, d, a, data[ 4] + 0xe7d3fbc8, 20);
+ ROUND(F2, a, b, c, d, data[ 9] + 0x21e1cde6, 5);
+ ROUND(F2, d, a, b, c, data[14] + 0xc33707d6, 9);
+ ROUND(F2, c, d, a, b, data[ 3] + 0xf4d50d87, 14);
+ ROUND(F2, b, c, d, a, data[ 8] + 0x455a14ed, 20);
+ ROUND(F2, a, b, c, d, data[13] + 0xa9e3e905, 5);
+ ROUND(F2, d, a, b, c, data[ 2] + 0xfcefa3f8, 9);
+ ROUND(F2, c, d, a, b, data[ 7] + 0x676f02d9, 14);
+ ROUND(F2, b, c, d, a, data[12] + 0x8d2a4c8a, 20);
+
+ ROUND(F3, a, b, c, d, data[ 5] + 0xfffa3942, 4);
+ ROUND(F3, d, a, b, c, data[ 8] + 0x8771f681, 11);
+ ROUND(F3, c, d, a, b, data[11] + 0x6d9d6122, 16);
+ ROUND(F3, b, c, d, a, data[14] + 0xfde5380c, 23);
+ ROUND(F3, a, b, c, d, data[ 1] + 0xa4beea44, 4);
+ ROUND(F3, d, a, b, c, data[ 4] + 0x4bdecfa9, 11);
+ ROUND(F3, c, d, a, b, data[ 7] + 0xf6bb4b60, 16);
+ ROUND(F3, b, c, d, a, data[10] + 0xbebfbc70, 23);
+ ROUND(F3, a, b, c, d, data[13] + 0x289b7ec6, 4);
+ ROUND(F3, d, a, b, c, data[ 0] + 0xeaa127fa, 11);
+ ROUND(F3, c, d, a, b, data[ 3] + 0xd4ef3085, 16);
+ ROUND(F3, b, c, d, a, data[ 6] + 0x04881d05, 23);
+ ROUND(F3, a, b, c, d, data[ 9] + 0xd9d4d039, 4);
+ ROUND(F3, d, a, b, c, data[12] + 0xe6db99e5, 11);
+ ROUND(F3, c, d, a, b, data[15] + 0x1fa27cf8, 16);
+ ROUND(F3, b, c, d, a, data[ 2] + 0xc4ac5665, 23);
+
+ ROUND(F4, a, b, c, d, data[ 0] + 0xf4292244, 6);
+ ROUND(F4, d, a, b, c, data[ 7] + 0x432aff97, 10);
+ ROUND(F4, c, d, a, b, data[14] + 0xab9423a7, 15);
+ ROUND(F4, b, c, d, a, data[ 5] + 0xfc93a039, 21);
+ ROUND(F4, a, b, c, d, data[12] + 0x655b59c3, 6);
+ ROUND(F4, d, a, b, c, data[ 3] + 0x8f0ccc92, 10);
+ ROUND(F4, c, d, a, b, data[10] + 0xffeff47d, 15);
+ ROUND(F4, b, c, d, a, data[ 1] + 0x85845dd1, 21);
+ ROUND(F4, a, b, c, d, data[ 8] + 0x6fa87e4f, 6);
+ ROUND(F4, d, a, b, c, data[15] + 0xfe2ce6e0, 10);
+ ROUND(F4, c, d, a, b, data[ 6] + 0xa3014314, 15);
+ ROUND(F4, b, c, d, a, data[13] + 0x4e0811a1, 21);
+ ROUND(F4, a, b, c, d, data[ 4] + 0xf7537e82, 6);
+ ROUND(F4, d, a, b, c, data[11] + 0xbd3af235, 10);
+ ROUND(F4, c, d, a, b, data[ 2] + 0x2ad7d2bb, 15);
+ ROUND(F4, b, c, d, a, data[ 9] + 0xeb86d391, 21);
+
+ digest[0] += a;
+ digest[1] += b;
+ digest[2] += c;
+ digest[3] += d;
+}
diff --git a/md5.h b/md5.h
index dc7c89a0372811561ec3ab49ee776ecef3dc2a3f..c06c2288813679d20f5ac013b24d2704924146e6 100644
--- a/md5.h
+++ b/md5.h
@@ -60,4 +60,9 @@ md5_digest(struct md5_ctx *ctx,
unsigned length,
uint8_t *digest);
+/* Internal compression function. STATE points to 4 uint32_t words,
+ and DATA points to 64 bytes of input data, possibly unaligned. */
+void
+_nettle_md5_compress(uint32_t *state, const uint8_t *data);
+
#endif /* NETTLE_MD5_H_INCLUDED */