dropbear
Dropbear contains  a number of components from different sources, hence there
  are a few licenses  and authors involved. All licenses are fairly 
  non-restrictive.
The majority of code is written by Matt Johnston, under the license below.
Portions of the  client-mode work are (c) 2004 Mihnea Stoenescu, under the
  same license:
Copyright (c)  2002-2015 Matt Johnston
  Portions copyright  (c) 2004 Mihnea Stoenescu
  All rights  reserved.
Permission is  hereby granted, free of charge, to any person obtaining a copy
  of this software  and associated documentation files (the "Software"), to deal
  in the Software  without restriction, including without limitation the rights
  to use, copy,  modify, merge, publish, distribute, sublicense, and/or sell
  copies of the  Software, and to permit persons to whom the Software is
  furnished to do  so, subject to the following conditions:
The above  copyright notice and this permission notice shall be included in all
  copies or  substantial portions of the Software.
THE SOFTWARE IS  PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING  BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A  PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR  COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER  IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.
=====
LibTomCrypt and LibTomMath are written by Tom St Denis, and are Public Domain.
=====
sshpty.c is taken  from OpenSSH 3.5p1, 
  Copyright (c) 1995 Tatu Ylonen  <ylo@cs.hut.fi>, Espoo, Finland
  All rights reserved
  "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". "
=====
loginrec.c
  loginrec.h
  atomicio.h
  atomicio.c
  and strlcat()  (included in util.c) are from OpenSSH 3.6.1p2, and are licensed
  under the 2 point  BSD license.
loginrec is written primarily by Andre Lucas, atomicio.c by Theo de Raadt.
strlcat() is (c) Todd C. Miller
=====
Import code in  keyimport.c is modified from PuTTY's import.c, licensed as
  follows:
PuTTY is copyright 1997-2003 Simon Tatham.
Portions copyright  Robert de Bath, Joris van Rantwijk, Delian
  Delchev, Andreas  Schultz, Jeroen Massar, Wez Furlong, Nicolas Barry,
  Justin Bradford,  and CORE SDI S.A.
Permission is  hereby granted, free of charge, to any person
  obtaining a copy  of this software and associated documentation files
  (the  "Software"), to deal in the Software without restriction,
  including without  limitation the rights to use, copy, modify, merge,
  publish,  distribute, sublicense, and/or sell copies of the Software,
  and to permit  persons to whom the Software is furnished to do so,
  subject to the  following conditions:
The above  copyright notice and this permission notice shall be
  included in all  copies or substantial portions of the Software.
THE SOFTWARE IS  PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  EXPRESS OR  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY,  FITNESS FOR A PARTICULAR PURPOSE AND
  NONINFRINGEMENT.  IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE  LIABLE
  FOR ANY CLAIM,  DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
  CONTRACT, TORT OR  OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  WITH THE SOFTWARE  OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
=====
curve25519-donna:
/* Copyright 2008,  Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary  forms, with or without
  * modification, are permitted provided that  the following conditions are
  * met:
  *
  *     *  Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the  following disclaimer.
  *     *  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.
  *     *  Neither the name of Google Inc. nor the names of its
  * contributors may be used to endorse or  promote products derived from
  * this software without specific prior written  permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT  HOLDERS AND CONTRIBUTORS
  * "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 COPYRIGHT
  * OWNER OR CONTRIBUTORS 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.
  *
  * curve25519-donna: Curve25519 elliptic curve,  public key function
  *
  * http://code.google.com/p/curve25519-donna/
  *
  * Adam Langley <agl@imperialviolet.org>
  *
  * Derived from public domain C code by Daniel  J. Bernstein <djb@cr.yp.to>
  *
  * More information about curve25519 can be  found here
  *    http://cr.yp.to/ecdh.html
  *
  * djb's sample implementation of curve25519 is  written in a special assembly
  * language called qhasm and uses the floating  point registers.
  *
  * This is, almost, a clean room  reimplementation from the curve25519 paper. It
  * uses many of the tricks described therein.  Only the crecip function is taken
  * from the sample implementation.
  */
