Add sha 256 library and adapt license sections in documentation

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### GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
### Preamble
The licenses for most software are designed to take away your freedom
to share and change it. By contrast, the GNU General Public License is
intended to guarantee your freedom to share and change free
software--to make sure the software is free for all its users. This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it. (Some other Free Software Foundation software is covered by
the GNU Lesser General Public License instead.) You can apply it to
your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if
you distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have. You must make sure that they, too, receive or can get the
source code. And you must show them these terms so they know their
rights.
We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.
Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software. If the software is modified by someone else and passed on,
we want its recipients to know that what they have is not the
original, so that any problems introduced by others will not reflect
on the original authors' reputations.
Finally, any free program is threatened constantly by software
patents. We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary. To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at
all.
The precise terms and conditions for copying, distribution and
modification follow.
### TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
**0.** This License applies to any program or other work which
contains a notice placed by the copyright holder saying it may be
distributed under the terms of this General Public License. The
"Program", below, refers to any such program or work, and a "work
based on the Program" means either the Program or any derivative work
under copyright law: that is to say, a work containing the Program or
a portion of it, either verbatim or with modifications and/or
translated into another language. (Hereinafter, translation is
included without limitation in the term "modification".) Each licensee
is addressed as "you".
Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope. The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the Program
(independent of having been made by running the Program). Whether that
is true depends on what the Program does.
**1.** You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.
You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a
fee.
**2.** You may modify your copy or copies of the Program or any
portion of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:
**a)** You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.
**b)** You must cause any work that you distribute or publish, that in
whole or in part contains or is derived from the Program or any part
thereof, to be licensed as a whole at no charge to all third parties
under the terms of this License.
**c)** If the modified program normally reads commands interactively
when run, you must cause it, when started running for such interactive
use in the most ordinary way, to print or display an announcement
including an appropriate copyright notice and a notice that there is
no warranty (or else, saying that you provide a warranty) and that
users may redistribute the program under these conditions, and telling
the user how to view a copy of this License. (Exception: if the
Program itself is interactive but does not normally print such an
announcement, your work based on the Program is not required to print
an announcement.)
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works. But when you
distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote
it.
Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.
In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.
**3.** You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:
**a)** Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of Sections 1
and 2 above on a medium customarily used for software interchange; or,
**b)** Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your cost of
physically performing source distribution, a complete machine-readable
copy of the corresponding source code, to be distributed under the
terms of Sections 1 and 2 above on a medium customarily used for
software interchange; or,
**c)** Accompany it with the information you received as to the offer
to distribute corresponding source code. (This alternative is allowed
only for noncommercial distribution and only if you received the
program in object code or executable form with such an offer, in
accord with Subsection b above.)
The source code for a work means the preferred form of the work for
making modifications to it. For an executable work, complete source
code means all the source code for all modules it contains, plus any
associated interface definition files, plus the scripts used to
control compilation and installation of the executable. However, as a
special exception, the source code distributed need not include
anything that is normally distributed (in either source or binary
form) with the major components (compiler, kernel, and so on) of the
operating system on which the executable runs, unless that component
itself accompanies the executable.
If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.
**4.** You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License. Any attempt otherwise
to copy, modify, sublicense or distribute the Program is void, and
will automatically terminate your rights under this License. However,
parties who have received copies, or rights, from you under this
License will not have their licenses terminated so long as such
parties remain in full compliance.
**5.** You are not required to accept this License, since you have not
signed it. However, nothing else grants you permission to modify or
distribute the Program or its derivative works. These actions are
prohibited by law if you do not accept this License. Therefore, by
modifying or distributing the Program (or any work based on the
Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying
the Program or works based on it.
**6.** Each time you redistribute the Program (or any work based on
the Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program subject to
these terms and conditions. You may not impose any further
restrictions on the recipients' exercise of the rights granted herein.
You are not responsible for enforcing compliance by third parties to
this License.
**7.** If, as a consequence of a court judgment or allegation of
patent infringement or for any other reason (not limited to patent
issues), conditions are imposed on you (whether by court order,
agreement or otherwise) that contradict the conditions of this
License, they do not excuse you from the conditions of this License.
If you cannot distribute so as to satisfy simultaneously your
obligations under this License and any other pertinent obligations,
then as a consequence you may not distribute the Program at all. For
example, if a patent license would not permit royalty-free
redistribution of the Program by all those who receive copies directly
or indirectly through you, then the only way you could satisfy both it
and this License would be to refrain entirely from distribution of the
Program.
If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other
circumstances.
It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system, which is
implemented by public license practices. Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is willing
to distribute software through any other system and a licensee cannot
impose that choice.
This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.
**8.** If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
those countries, so that distribution is permitted only in or among
countries not thus excluded. In such case, this License incorporates
the limitation as if written in the body of this License.
**9.** The Free Software Foundation may publish revised and/or new
versions of the General Public License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.
Each version is given a distinguishing version number. If the Program
specifies a version number of this License which applies to it and
"any later version", you have the option of following the terms and
conditions either of that version or of any later version published by
the Free Software Foundation. If the Program does not specify a
version number of this License, you may choose any version ever
published by the Free Software Foundation.
**10.** If you wish to incorporate parts of the Program into other
free programs whose distribution conditions are different, write to
the author to ask for permission. For software which is copyrighted by
the Free Software Foundation, write to the Free Software Foundation;
we sometimes make exceptions for this. Our decision will be guided by
the two goals of preserving the free status of all derivatives of our
free software and of promoting the sharing and reuse of software
generally.
**NO WARRANTY**
**11.** BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.
EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR
OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY
KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE
PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME
THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
**12.** IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY
AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU
FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR
CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF
SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES.
### END OF TERMS AND CONDITIONS
### How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these
terms.
To do so, attach the following notices to the program. It is safest to
attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.
one line to give the program's name and an idea of what it does.
Copyright (C) yyyy name of author
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
Also add information on how to contact you by electronic and paper
mail.
If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) year name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
type `show w'. This is free software, and you are welcome
to redistribute it under certain conditions; type `show c'
for details.
The hypothetical commands \`show w' and \`show c' should show the
appropriate parts of the General Public License. Of course, the
commands you use may be called something other than \`show w' and
\`show c'; they could even be mouse-clicks or menu items--whatever
suits your program.
You should also get your employer (if you work as a programmer) or
your school, if any, to sign a "copyright disclaimer" for the program,
if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright
interest in the program `Gnomovision'
(which makes passes at compilers) written
by James Hacker.
signature of Ty Coon, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your program
into proprietary programs. If your program is a subroutine library,
you may consider it more useful to permit linking proprietary
applications with the library. If this is what you want to do, use the
[GNU Lesser General Public
License](https://www.gnu.org/licenses/lgpl.html) instead of this
License.

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@ -1,361 +1,10 @@
### GNU GENERAL PUBLIC LICENSE
# License of the Relow Oven Control Firmware
Version 2, June 1991
This software is licsensed according to the GPLv2. See GPLv2.md for details.
However, this software includes various third party libraries for which different licenses apply:
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
### Preamble
The licenses for most software are designed to take away your freedom
to share and change it. By contrast, the GNU General Public License is
intended to guarantee your freedom to share and change free
software--to make sure the software is free for all its users. This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it. (Some other Free Software Foundation software is covered by
the GNU Lesser General Public License instead.) You can apply it to
your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if
you distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have. You must make sure that they, too, receive or can get the
source code. And you must show them these terms so they know their
rights.
We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.
Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software. If the software is modified by someone else and passed on,
we want its recipients to know that what they have is not the
original, so that any problems introduced by others will not reflect
on the original authors' reputations.
Finally, any free program is threatened constantly by software
patents. We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary. To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at
all.
The precise terms and conditions for copying, distribution and
modification follow.
### TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
**0.** This License applies to any program or other work which
contains a notice placed by the copyright holder saying it may be
distributed under the terms of this General Public License. The
"Program", below, refers to any such program or work, and a "work
based on the Program" means either the Program or any derivative work
under copyright law: that is to say, a work containing the Program or
a portion of it, either verbatim or with modifications and/or
translated into another language. (Hereinafter, translation is
included without limitation in the term "modification".) Each licensee
is addressed as "you".
Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope. The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the Program
(independent of having been made by running the Program). Whether that
is true depends on what the Program does.
**1.** You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.
You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a
fee.
**2.** You may modify your copy or copies of the Program or any
portion of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:
**a)** You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.
**b)** You must cause any work that you distribute or publish, that in
whole or in part contains or is derived from the Program or any part
thereof, to be licensed as a whole at no charge to all third parties
under the terms of this License.
**c)** If the modified program normally reads commands interactively
when run, you must cause it, when started running for such interactive
use in the most ordinary way, to print or display an announcement
including an appropriate copyright notice and a notice that there is
no warranty (or else, saying that you provide a warranty) and that
users may redistribute the program under these conditions, and telling
the user how to view a copy of this License. (Exception: if the
Program itself is interactive but does not normally print such an
announcement, your work based on the Program is not required to print
an announcement.)
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works. But when you
distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote
it.
Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.
In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.
**3.** You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:
**a)** Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of Sections 1
and 2 above on a medium customarily used for software interchange; or,
**b)** Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your cost of
physically performing source distribution, a complete machine-readable
copy of the corresponding source code, to be distributed under the
terms of Sections 1 and 2 above on a medium customarily used for
software interchange; or,
**c)** Accompany it with the information you received as to the offer
to distribute corresponding source code. (This alternative is allowed
only for noncommercial distribution and only if you received the
program in object code or executable form with such an offer, in
accord with Subsection b above.)
The source code for a work means the preferred form of the work for
making modifications to it. For an executable work, complete source
code means all the source code for all modules it contains, plus any
associated interface definition files, plus the scripts used to
control compilation and installation of the executable. However, as a
special exception, the source code distributed need not include
anything that is normally distributed (in either source or binary
form) with the major components (compiler, kernel, and so on) of the
operating system on which the executable runs, unless that component
itself accompanies the executable.
If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.
**4.** You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License. Any attempt otherwise
to copy, modify, sublicense or distribute the Program is void, and
will automatically terminate your rights under this License. However,
parties who have received copies, or rights, from you under this
License will not have their licenses terminated so long as such
parties remain in full compliance.
**5.** You are not required to accept this License, since you have not
signed it. However, nothing else grants you permission to modify or
distribute the Program or its derivative works. These actions are
prohibited by law if you do not accept this License. Therefore, by
modifying or distributing the Program (or any work based on the
Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying
the Program or works based on it.
**6.** Each time you redistribute the Program (or any work based on
the Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program subject to
these terms and conditions. You may not impose any further
restrictions on the recipients' exercise of the rights granted herein.
You are not responsible for enforcing compliance by third parties to
this License.
**7.** If, as a consequence of a court judgment or allegation of
patent infringement or for any other reason (not limited to patent
issues), conditions are imposed on you (whether by court order,
agreement or otherwise) that contradict the conditions of this
License, they do not excuse you from the conditions of this License.
If you cannot distribute so as to satisfy simultaneously your
obligations under this License and any other pertinent obligations,
then as a consequence you may not distribute the Program at all. For
example, if a patent license would not permit royalty-free
redistribution of the Program by all those who receive copies directly
or indirectly through you, then the only way you could satisfy both it
and this License would be to refrain entirely from distribution of the
Program.
If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other
circumstances.
It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system, which is
implemented by public license practices. Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is willing
to distribute software through any other system and a licensee cannot
impose that choice.
This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.
**8.** If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
those countries, so that distribution is permitted only in or among
countries not thus excluded. In such case, this License incorporates
the limitation as if written in the body of this License.
**9.** The Free Software Foundation may publish revised and/or new
versions of the General Public License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns.
Each version is given a distinguishing version number. If the Program
specifies a version number of this License which applies to it and
"any later version", you have the option of following the terms and
conditions either of that version or of any later version published by
the Free Software Foundation. If the Program does not specify a
version number of this License, you may choose any version ever
published by the Free Software Foundation.
**10.** If you wish to incorporate parts of the Program into other
free programs whose distribution conditions are different, write to
the author to ask for permission. For software which is copyrighted by
the Free Software Foundation, write to the Free Software Foundation;
we sometimes make exceptions for this. Our decision will be guided by
the two goals of preserving the free status of all derivatives of our
free software and of promoting the sharing and reuse of software
generally.
**NO WARRANTY**
**11.** BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.
EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR
OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY
KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE
PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME
THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
**12.** IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY
AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU
FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR
CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF
SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGES.
### END OF TERMS AND CONDITIONS
### How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these
terms.
To do so, attach the following notices to the program. It is safest to
attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.
one line to give the program's name and an idea of what it does.
Copyright (C) yyyy name of author
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
Also add information on how to contact you by electronic and paper
mail.
If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) year name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
type `show w'. This is free software, and you are welcome
to redistribute it under certain conditions; type `show c'
for details.
The hypothetical commands \`show w' and \`show c' should show the
appropriate parts of the General Public License. Of course, the
commands you use may be called something other than \`show w' and
\`show c'; they could even be mouse-clicks or menu items--whatever
suits your program.
You should also get your employer (if you work as a programmer) or
your school, if any, to sign a "copyright disclaimer" for the program,
if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright
interest in the program `Gnomovision'
(which makes passes at compilers) written
by James Hacker.
signature of Ty Coon, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your program
into proprietary programs. If your program is a subroutine library,
you may consider it more useful to permit linking proprietary
applications with the library. If this is what you want to do, use the
[GNU Lesser General Public
License](https://www.gnu.org/licenses/lgpl.html) instead of this
License.
- Shellmatta Shell implementation by Stefan Strobel: Licensed under ``Mozilla Public License Version 2.0``
- CMSIS by ARM Limited <https://github.com/ARM-software/CMSIS_5>, licensed under ``Apache License Version 2.0, January 2004``
- STM Header Files etc. by ST Microelectronics icensed under a custom license. See the sphinx documentation (section License) for details.
- FatFs: Custom License (See source files of FatFS)
- SHA256 Library <https://github.com/amosnier/sha-2> licensed under the ``Unilicense``

View File

@ -9,6 +9,3 @@ Safety Controller
safety-adc
.. doxygengroup:: safety-controller
:project: Reflow Controller Firmware

View File

@ -9,8 +9,36 @@ The firmware includes following third-party software libraries:
- ``shellmatta`` by ``Stefan Strobel`` <https://git.shimatta.net/shimatta/shellmatta>, licensed under ``Mozilla Public License Version 2.0``
- ``CMSIS`` by ``ARM Limited`` <https://github.com/ARM-software/CMSIS_5>, licensed under ``Apache License Version 2.0, January 2004``
- ``STM Header files and startup code`` by ``ST Microelectronics``, licensed under a `custom license <ST License for Used Header Files_>`_
- ``SHA-256 Library`` by ``Alain Mosnier`` <https://github.com/amosnier/sha-2>, licensed under ``Zero Clause BSD License`` or the ``Unlicense``
- ``FatFS`` Library by ``ChaN`` licensed under a `custom license <FatFS License_>`_
FatFS License
-------------
FatFs has being developped as a personal project of the author, ChaN. It is free from the code anyone else wrote at current release. Following code block shows a copy of the FatFs license document that heading the source files.::
/*----------------------------------------------------------------------------/
/ FatFs - Generic FAT Filesystem Module Rx.xx /
/-----------------------------------------------------------------------------/
/
/ Copyright (C) 20xx, ChaN, all right reserved.
/
/ FatFs module is an open source software. Redistribution and use of FatFs in
/ source and binary forms, with or without modification, are permitted provided
/ that the following condition is met:
/
/ 1. Redistributions of source code must retain the above copyright notice,
/ this condition and the following disclaimer.
/
/ This software is provided by the copyright holder and contributors "AS IS"
/ and any warranties related to this software are DISCLAIMED.
/ The copyright owner or contributors be NOT LIABLE for any damages caused
/ by use of this software.
/----------------------------------------------------------------------------*/
Therefore FatFs license is one of the BSD-style licenses, but there is a significant feature. FatFs is mainly intended for embedded systems. In order to extend the usability for commercial products, the redistributions of FatFs in binary form, such as embedded code, binary library and any forms without source code, do not need to include about FatFs in the documentations. This is equivalent to the 1-clause BSD license. Of course FatFs is compatible with the most of open source software licenses include GNU GPL. When you redistribute the FatFs source code with changes or create a fork, the license can also be changed to GNU GPL, BSD-style license or any open source software license that not conflict with FatFs license.
ST License for Used Header Files
--------------------------------

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@ -0,0 +1,46 @@
# Licensing Information
Except as otherwise noted (below and/or in individual files), this project is
licensed under the [Unlicense](#the-unlicense)
(https://opensource.org/licenses/unlicense) or the [Zero Clause BSD
license](#zero-clause-bsd-license) (https://opensource.org/licenses/0bsd), at
your option.
## The Unlicense
This is free and unencumbered software released into the public domain.
Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
software, either in source code form or as a compiled binary, for any purpose,
commercial or non-commercial, and by any means.
In jurisdictions that recognize copyright laws, the author or authors of this
software dedicate any and all copyright interest in the software to the public
domain. We make this dedication for the benefit of the public at large and to
the detriment of our heirs and successors. We intend this dedication to be an
overt act of relinquishment in perpetuity of all present and future rights to
this software under copyright law.
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 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.
For more information, please refer to <http://unlicense.org>
## Zero Clause BSD License
&copy; 2021 Alain Mosnier
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.

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@ -0,0 +1,134 @@
# sha-2 [![Build Status](https://travis-ci.com/amosnier/sha-2.svg?branch=master)](https://travis-ci.com/amosnier/sha-2)
## Disclaimer
The SHA256 implementation used in thsi project is taken from https://github.com/amosnier/sha-2. Check the appropriate license file.
## Contents
SHA-2 algorithm implementations.
At the moment, only SHA-256 is implemented.
## NEW: streaming API
In response to [an enhancement
request](https://github.com/amosnier/sha-2/issues/9), a new streaming
API has been created.
The following code is a silly but complete example:
```C
struct Sha_256 sha_256;
uint8_t hash[32];
sha_256_init(&sha_256, hash);
sha_256_write(&sha_256, "ab", strlen("ab"));
sha_256_write(&sha_256, "c", strlen("c"));
sha_256_close(&sha_256);
```
That is the equivalent of the (of course still supported) legacy way:
```C
uint8_t hash[32];
calc_sha_256(hash, "abc", strlen("abc"));
```
See [header file](https://github.com/amosnier/sha-2/blob/master/sha-256.h)
for more information.
Since the streaming API is a generalization of the non-streaming one,
the latter has been ported to the former, without measurable performance
impact. However, [a legacy
branch](https://github.com/amosnier/sha-2/tree/legacy) has been created
in order to make the legacy implementation easily available. If you can
measure a significant difference between the two, please post an issue.
## Design criteria
- Easy to test, include in any project, compile and link.
- ANSI C with as little specific C99 as possible (e.g. extended
integer types are used, but not bool).
- Portable. Makes no assumptions on the target system's endianess or
word size.
- The SHA-256 implementation is a straightforward implementation of
the algorithm specified on
[Wikipedia](https://en.wikipedia.org/wiki/SHA-2).
## Notes
The Makefile is as minimal as possible. No effort was put into making
it general. Its purpose is mainly to ease testing for the developer's
host machine. The actual implementation is however extremely easy to
include in any project, may it use GNU make or any other build tool.
## Code review
This code has been reviewed at [Stack Exchange CODE
REVIEW](https://codereview.stackexchange.com/questions/182812/self-contained-sha-256-implementation-in-c),
and the implementation has been improved accordingly.
## Testing
Testing is continuously performed on Travis CI (see above).
Apart from that, the implementation has been successfully tested on an x86-64 machine
under Linux as well as on a 16-bit DSP. On the x86-64 machine, all the
available NIST test vectors where successfully tested ([SHA-256
examples](https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Standards-and-Guidelines/documents/examples/SHA256.pdf)
and [SHA-2 Additional
examples](https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Standards-and-Guidelines/documents/examples/SHA2_Additional.pdf),
plus a few others).
In particular:
```
Input Message: "abc"
Message Digest is BA7816BF 8F01CFEA 414140DE 5DAE2223 B00361A3 96177A9C B410FF61 F20015AD
```
```
Input Message: "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"
Message Digest is 248D6A61 D20638B8 E5C02693 0C3E6039 A33CE459 64FF2167 F6ECEDD4 19DB06C1
```
```
SHA-256 Test Data
#1) 1 byte 0xbd
68325720 aabd7c82 f30f554b 313d0570 c95accbb 7dc4b5aa e11204c0 8ffe732b
#2) 4 bytes 0xc98c8e55
7abc22c0 ae5af26c e93dbb94 433a0e0b 2e119d01 4f8e7f65 bd56c61c cccd9504
#3) 55 bytes of zeros
02779466 cdec1638 11d07881 5c633f21 90141308 1449002f 24aa3e80 f0b88ef7
#4) 56 bytes of zeros
d4817aa5 497628e7 c77e6b60 6107042b bba31308 88c5f47a 375e6179 be789fbb
#5) 57 bytes of zeros
65a16cb7 861335d5 ace3c607 18b5052e 44660726 da4cd13b b745381b 235a1785
#6) 64 bytes of zeros
f5a5fd42 d16a2030 2798ef6e d309979b 43003d23 20d9f0e8 ea9831a9 2759fb4b
#7) 1000 bytes of zeros
541b3e9d aa09b20b f85fa273 e5cbd3e8 0185aa4e c298e765 db87742b 70138a53
#8) 1000 bytes of 0x41 A
c2e68682 3489ced2 017f6059 b8b23931 8b6364f6 dcd835d0 a519105a 1eadd6e4
#9) 1005 bytes of 0x55 U
f4d62dde c0f3dd90 ea1380fa 16a5ff8d c4c54b21 740650f2 4afc4120 903552b0
#10) 1000000 bytes of zeros
d29751f2 649b32ff 572b5e0a 9f541ea6 60a50f94 ff0beedf b0b692b9 24cc8025
#11) 0x20000000 (536870912) bytes of 0x5a Z
15a1868c 12cc5395 1e182344 277447cd 0979536b adcc512a d24c67e9 b2d4f3dd
#12) 0x41000000 (1090519040) bytes of zeros
461c19a9 3bd4344f 9215f5ec 64357090 342bc66b 15a14831 7d276e31 cbc20b53
#13) 0x6000003e (1610612798) bytes of 0x42 B
c23ce8a7 895f4b21 ec0daf37 920ac0a2 62a22004 5a03eb2d fed48ef9 b05aabea
```
## License
This repository is made available under a permissive license. See
[LICENSE FILE](LICENSE.md).
## Reference implementation
I had missed that when I made this implementation but [RFC 6234, chapter 8](https://tools.ietf.org/html/rfc6234#section-8) actually includes a reference implementation in C that is (at least in ambition) broader in scope than this one. I have however neither compiled nor tested it.

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@ -0,0 +1,226 @@
#include "sha-256.h"
#define TOTAL_LEN_LEN 8
/*
* ABOUT bool: this file does not use bool in order to be as pre-C99 compatible as possible.
*/
/*
* Comments from pseudo-code at https://en.wikipedia.org/wiki/SHA-2 are reproduced here.
* When useful for clarification, portions of the pseudo-code are reproduced here too.
*/
/*
* @brief Rotate a 32-bit value by a number of bits to the right.
* @param value The value to be rotated.
* @param count The number of bits to rotate by.
* @return The rotated value.
*/
static inline uint32_t right_rot(uint32_t value, unsigned int count)
{
/*
* Defined behaviour in standard C for all count where 0 < count < 32, which is what we need here.
*/
return value >> count | value << (32 - count);
}
/*
* @brief Update a hash value under calculation with a new chunk of data.
* @param h Pointer to the first hash item, of a total of eight.
* @param p Pointer to the chunk data, which has a standard length.
*
* @note This is the SHA-256 work horse.
*/
static inline void consume_chunk(uint32_t *h, const uint8_t *p)
{
unsigned i, j;
uint32_t ah[8];
/* Initialize working variables to current hash value: */
for (i = 0; i < 8; i++)
ah[i] = h[i];
/*
* The w-array is really w[64], but since we only need 16 of them at a time, we save stack by
* calculating 16 at a time.
*
* This optimization was not there initially and the rest of the comments about w[64] are kept in their
* initial state.
*/
/*
* create a 64-entry message schedule array w[0..63] of 32-bit words (The initial values in w[0..63]
* don't matter, so many implementations zero them here) copy chunk into first 16 words w[0..15] of the
* message schedule array
*/
uint32_t w[16];
/* Compression function main loop: */
for (i = 0; i < 4; i++) {
for (j = 0; j < 16; j++) {
if (i == 0) {
w[j] =
(uint32_t)p[0] << 24 | (uint32_t)p[1] << 16 | (uint32_t)p[2] << 8 | (uint32_t)p[3];
p += 4;
} else {
/* Extend the first 16 words into the remaining 48 words w[16..63] of the
* message schedule array: */
const uint32_t s0 = right_rot(w[(j + 1) & 0xf], 7) ^ right_rot(w[(j + 1) & 0xf], 18) ^
(w[(j + 1) & 0xf] >> 3);
const uint32_t s1 = right_rot(w[(j + 14) & 0xf], 17) ^
right_rot(w[(j + 14) & 0xf], 19) ^ (w[(j + 14) & 0xf] >> 10);
w[j] = w[j] + s0 + w[(j + 9) & 0xf] + s1;
}
const uint32_t s1 = right_rot(ah[4], 6) ^ right_rot(ah[4], 11) ^ right_rot(ah[4], 25);
const uint32_t ch = (ah[4] & ah[5]) ^ (~ah[4] & ah[6]);
/*
* Initialize array of round constants:
* (first 32 bits of the fractional parts of the cube roots of the first 64 primes 2..311):
*/
static const uint32_t k[] = {
0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4,
0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe,
0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f,
0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc,
0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070, 0x19a4c116,
0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7,
0xc67178f2};
const uint32_t temp1 = ah[7] + s1 + ch + k[i << 4 | j] + w[j];
const uint32_t s0 = right_rot(ah[0], 2) ^ right_rot(ah[0], 13) ^ right_rot(ah[0], 22);
const uint32_t maj = (ah[0] & ah[1]) ^ (ah[0] & ah[2]) ^ (ah[1] & ah[2]);
const uint32_t temp2 = s0 + maj;
ah[7] = ah[6];
ah[6] = ah[5];
ah[5] = ah[4];
ah[4] = ah[3] + temp1;
ah[3] = ah[2];
ah[2] = ah[1];
ah[1] = ah[0];
ah[0] = temp1 + temp2;
}
}
/* Add the compressed chunk to the current hash value: */
for (i = 0; i < 8; i++)
h[i] += ah[i];
}
/*
* Public functions. See header file for documentation.
*/
void sha_256_init(struct Sha_256 *sha_256, uint8_t hash[SIZE_OF_SHA_256_HASH])
{
sha_256->hash = hash;
sha_256->chunk_pos = sha_256->chunk;
sha_256->space_left = SIZE_OF_SHA_256_CHUNK;
sha_256->total_len = 0;
/*
* Initialize hash values (first 32 bits of the fractional parts of the square roots of the first 8 primes
* 2..19):
*/
sha_256->h[0] = 0x6a09e667;
sha_256->h[1] = 0xbb67ae85;
sha_256->h[2] = 0x3c6ef372;
sha_256->h[3] = 0xa54ff53a;
sha_256->h[4] = 0x510e527f;
sha_256->h[5] = 0x9b05688c;
sha_256->h[6] = 0x1f83d9ab;
sha_256->h[7] = 0x5be0cd19;
}
void sha_256_write(struct Sha_256 *sha_256, const void *data, size_t len)
{
sha_256->total_len += len;
const uint8_t *p = data;
while (len > 0) {
/*
* If the input chunks have sizes that are multiples of the calculation chunk size, no copies are
* necessary. We operate directly on the input data instead.
*/
if (sha_256->space_left == SIZE_OF_SHA_256_CHUNK && len >= SIZE_OF_SHA_256_CHUNK) {
consume_chunk(sha_256->h, p);
len -= SIZE_OF_SHA_256_CHUNK;
p += SIZE_OF_SHA_256_CHUNK;
continue;
}
/* General case, no particular optimization. */
const size_t consumed_len = len < sha_256->space_left ? len : sha_256->space_left;
memcpy(sha_256->chunk_pos, p, consumed_len);
sha_256->space_left -= consumed_len;
len -= consumed_len;
p += consumed_len;
if (sha_256->space_left == 0) {
consume_chunk(sha_256->h, sha_256->chunk);
sha_256->chunk_pos = sha_256->chunk;
sha_256->space_left = SIZE_OF_SHA_256_CHUNK;
} else {
sha_256->chunk_pos += consumed_len;
}
}
}
uint8_t *sha_256_close(struct Sha_256 *sha_256)
{
uint8_t *pos = sha_256->chunk_pos;
size_t space_left = sha_256->space_left;
uint32_t *const h = sha_256->h;
/*
* The current chunk cannot be full. Otherwise, it would already have be consumed. I.e. there is space left for
* at least one byte. The next step in the calculation is to add a single one-bit to the data.
*/
*pos++ = 0x80;
--space_left;
/*
* Now, the last step is to add the total data length at the end of the last chunk, and zero padding before
* that. But we do not necessarily have enough space left. If not, we pad the current chunk with zeroes, and add
* an extra chunk at the end.
*/
if (space_left < TOTAL_LEN_LEN) {
memset(pos, 0x00, space_left);
consume_chunk(h, sha_256->chunk);
pos = sha_256->chunk;
space_left = SIZE_OF_SHA_256_CHUNK;
}
const size_t left = space_left - TOTAL_LEN_LEN;
memset(pos, 0x00, left);
pos += left;
size_t len = sha_256->total_len;
pos[7] = (uint8_t)(len << 3);
len >>= 5;
int i;
for (i = 6; i >= 0; --i) {
pos[i] = (uint8_t)len;
len >>= 8;
}
consume_chunk(h, sha_256->chunk);
/* Produce the final hash value (big-endian): */
int j;
uint8_t *const hash = sha_256->hash;
for (i = 0, j = 0; i < 8; i++) {
hash[j++] = (uint8_t)(h[i] >> 24);
hash[j++] = (uint8_t)(h[i] >> 16);
hash[j++] = (uint8_t)(h[i] >> 8);
hash[j++] = (uint8_t)h[i];
}
return sha_256->hash;
}
void calc_sha_256(uint8_t hash[SIZE_OF_SHA_256_HASH], const void *input, size_t len)
{
struct Sha_256 sha_256;
sha_256_init(&sha_256, hash);
sha_256_write(&sha_256, input, len);
(void)sha_256_close(&sha_256);
}

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@ -0,0 +1,103 @@
#ifndef SHA_256_H
#define SHA_256_H
#include <stdint.h>
#include <string.h>
#ifdef __cplusplus
extern "C" {
#endif
/*
* @brief Size of the SHA-256 sum. This times eight is 256 bits.
*/
#define SIZE_OF_SHA_256_HASH 32
/*
* @brief Size of the chunks used for the calculations.
*
* @note This should mostly be ignored by the user, although when using the streaming API, it has an impact for
* performance. Add chunks whose size is a multiple of this, and you will avoid a lot of superfluous copying in RAM!
*/
#define SIZE_OF_SHA_256_CHUNK 64
/*
* @brief The opaque SHA-256 type, that should be instantiated when using the streaming API.
*
* @note Although the details are exposed here, in order to make instantiation easy, you should refrain from directly
* accessing the fields, as they may change in the future.
*/
struct Sha_256 {
uint8_t *hash;
uint8_t chunk[SIZE_OF_SHA_256_CHUNK];
uint8_t *chunk_pos;
size_t space_left;
size_t total_len;
uint32_t h[8];
};
/*
* @brief The simple SHA-256 calculation function.
* @param hash Hash array, where the result is delivered.
* @param input Pointer to the data the hash shall be calculated on.
* @param len Length of the input data, in byte.
*
* @note If all of the data you are calculating the hash value on is available in a contiguous buffer in memory, this is
* the function you should use.
*
* @note If either of the passed pointers is NULL, the results are unpredictable.
*/
void calc_sha_256(uint8_t hash[SIZE_OF_SHA_256_HASH], const void *input, size_t len);
/*
* @brief Initialize a SHA-256 streaming calculation.
* @param sha_256 A pointer to a SHA-256 structure.
* @param hash Hash array, where the result will be delivered.
*
* @note If all of the data you are calculating the hash value on is not available in a contiguous buffer in memory, this is
* where you should start. Instantiate a SHA-256 structure, for instance by simply declaring it locally, make your hash
* buffer available, and invoke this function. Once a SHA-256 hash has been calculated (see further below) a SHA-256
* structure can be initialized again for the next calculation.
*
* @note If either of the passed pointers is NULL, the results are unpredictable.
*/
void sha_256_init(struct Sha_256 *sha_256, uint8_t hash[SIZE_OF_SHA_256_HASH]);
/*
* @brief Stream more input data for an on-going SHA-256 calculation.
* @param sha_256 A pointer to a previously initialized SHA-256 structure.
* @param data Pointer to the data to be added to the calculation.
* @param len Length of the data to add, in byte.
*
* @note This function may be invoked an arbitrary number of times between initialization and closing, but the maximum
* data length is limited by the SHA-256 algorithm: the total number of bits (i.e. the total number of bytes times
* eight) must be representable by a 64-bit unsigned integer. While that is not a practical limitation, the results are
* unpredictable if that limit is exceeded.
*
* @note This function may be invoked on empty data (zero length), although that obviously will not add any data.
*
* @note If either of the passed pointers is NULL, the results are unpredictable.
*/
void sha_256_write(struct Sha_256 *sha_256, const void *data, size_t len);
/*
* @brief Conclude a SHA-256 streaming calculation, making the hash value available.
* @param sha_256 A pointer to a previously initialized SHA-256 structure.
* @return Pointer to the hash array, where the result is delivered.
*
* @note After this function has been invoked, the result is available in the hash buffer that initially was provided. A
* pointer to the hash value is returned for convenience, but you should feel free to ignore it: it is simply a pointer
* to the first byte of your initially provided hash array.
*
* @note If the passed pointer is NULL, the results are unpredictable.
*
* @note Invoking this function for a calculation with no data (the writing function has never been invoked, or it only
* has been invoked with empty data) is legal. It will calculate the SHA-256 value of the empty string.
*/
uint8_t *sha_256_close(struct Sha_256 *sha_256);
#ifdef __cplusplus
}
#endif
#endif