diff --git a/bufbn.c b/bufbn.c
new file mode 100644
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--- /dev/null
+++ b/bufbn.c
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+/* $OpenBSD: bufbn.c,v 1.1 2006/04/18 10:44:28 dtucker Exp $*/
+/*
+ * Author: Tatu Ylonen <ylo@cs.hut.fi>
+ * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
+ *                    All rights reserved
+ * Auxiliary functions for storing and retrieving various data types to/from
+ * Buffers.
+ *
+ * As far as I am concerned, the code I have written for this software
+ * can be used freely for any purpose.  Any derived versions of this
+ * software must be clearly marked as such, and if the derived work is
+ * incompatible with the protocol description in the RFC file, it must be
+ * called by a name other than "ssh" or "Secure Shell".
+ *
+ *
+ * SSH2 packet format added by Markus Friedl
+ * Copyright (c) 2000 Markus Friedl.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#include <openssl/bn.h>
+#include "bufaux.h"
+#include "xmalloc.h"
+#include "log.h"
+#include "misc.h"
+
+/*
+ * Stores an BIGNUM in the buffer with a 2-byte msb first bit count, followed
+ * by (bits+7)/8 bytes of binary data, msb first.
+ */
+int
+buffer_put_bignum_ret(Buffer *buffer, const BIGNUM *value)
+{
+	int bits = BN_num_bits(value);
+	int bin_size = (bits + 7) / 8;
+	u_char *buf = xmalloc(bin_size);
+	int oi;
+	char msg[2];
+
+	/* Get the value of in binary */
+	oi = BN_bn2bin(value, buf);
+	if (oi != bin_size) {
+		error("buffer_put_bignum_ret: BN_bn2bin() failed: oi %d != bin_size %d",
+		    oi, bin_size);
+		xfree(buf);
+		return (-1);
+	}
+
+	/* Store the number of bits in the buffer in two bytes, msb first. */
+	put_u16(msg, bits);
+	buffer_append(buffer, msg, 2);
+	/* Store the binary data. */
+	buffer_append(buffer, buf, oi);
+
+	memset(buf, 0, bin_size);
+	xfree(buf);
+
+	return (0);
+}
+
+void
+buffer_put_bignum(Buffer *buffer, const BIGNUM *value)
+{
+	if (buffer_put_bignum_ret(buffer, value) == -1)
+		fatal("buffer_put_bignum: buffer error");
+}
+
+/*
+ * Retrieves an BIGNUM from the buffer.
+ */
+int
+buffer_get_bignum_ret(Buffer *buffer, BIGNUM *value)
+{
+	u_int bits, bytes;
+	u_char buf[2], *bin;
+
+	/* Get the number for bits. */
+	if (buffer_get_ret(buffer, (char *) buf, 2) == -1) {
+		error("buffer_get_bignum_ret: invalid length");
+		return (-1);
+	}
+	bits = get_u16(buf);
+	/* Compute the number of binary bytes that follow. */
+	bytes = (bits + 7) / 8;
+	if (bytes > 8 * 1024) {
+		error("buffer_get_bignum_ret: cannot handle BN of size %d", bytes);
+		return (-1);
+	}
+	if (buffer_len(buffer) < bytes) {
+		error("buffer_get_bignum_ret: input buffer too small");
+		return (-1);
+	}
+	bin = buffer_ptr(buffer);
+	BN_bin2bn(bin, bytes, value);
+	if (buffer_consume_ret(buffer, bytes) == -1) {
+		error("buffer_get_bignum_ret: buffer_consume failed");
+		return (-1);
+	}
+	return (0);
+}
+
+void
+buffer_get_bignum(Buffer *buffer, BIGNUM *value)
+{
+	if (buffer_get_bignum_ret(buffer, value) == -1)
+		fatal("buffer_get_bignum: buffer error");
+}
+
+/*
+ * Stores an BIGNUM in the buffer in SSH2 format.
+ */
+int
+buffer_put_bignum2_ret(Buffer *buffer, const BIGNUM *value)
+{
+	u_int bytes;
+	u_char *buf;
+	int oi;
+	u_int hasnohigh = 0;
+
+	if (BN_is_zero(value)) {
+		buffer_put_int(buffer, 0);
+		return 0;
+	}
+	if (value->neg) {
+		error("buffer_put_bignum2_ret: negative numbers not supported");
+		return (-1);
+	}
+	bytes = BN_num_bytes(value) + 1; /* extra padding byte */
+	if (bytes < 2) {
+		error("buffer_put_bignum2_ret: BN too small");
+		return (-1);
+	}
+	buf = xmalloc(bytes);
+	buf[0] = 0x00;
+	/* Get the value of in binary */
+	oi = BN_bn2bin(value, buf+1);
+	if (oi < 0 || (u_int)oi != bytes - 1) {
+		error("buffer_put_bignum2_ret: BN_bn2bin() failed: "
+		    "oi %d != bin_size %d", oi, bytes);
+		xfree(buf);
+		return (-1);
+	}
+	hasnohigh = (buf[1] & 0x80) ? 0 : 1;
+	buffer_put_string(buffer, buf+hasnohigh, bytes-hasnohigh);
+	memset(buf, 0, bytes);
+	xfree(buf);
+	return (0);
+}
+
+void
+buffer_put_bignum2(Buffer *buffer, const BIGNUM *value)
+{
+	if (buffer_put_bignum2_ret(buffer, value) == -1)
+		fatal("buffer_put_bignum2: buffer error");
+}
+
+int
+buffer_get_bignum2_ret(Buffer *buffer, BIGNUM *value)
+{
+	u_int len;
+	u_char *bin;
+
+	if ((bin = buffer_get_string_ret(buffer, &len)) == NULL) {
+		error("buffer_get_bignum2_ret: invalid bignum");
+		return (-1);
+	}
+
+	if (len > 0 && (bin[0] & 0x80)) {
+		error("buffer_get_bignum2_ret: negative numbers not supported");
+		xfree(bin);
+		return (-1);
+	}
+	if (len > 8 * 1024) {
+		error("buffer_get_bignum2_ret: cannot handle BN of size %d", len);
+		xfree(bin);
+		return (-1);
+	}
+	BN_bin2bn(bin, len, value);
+	xfree(bin);
+	return (0);
+}
+
+void
+buffer_get_bignum2(Buffer *buffer, BIGNUM *value)
+{
+	if (buffer_get_bignum2_ret(buffer, value) == -1)
+		fatal("buffer_get_bignum2: buffer error");
+}