SHA-256 Algorithm Implementation in C

Original site: rbtblog.com/posts/SHA256-Algorithm-Implementation-in-C

Author: Robert1037

Source: https://github.com/Robert1037/Crypto-in-C/tree/master/sha-256

Features

sha256full.c is the original version of sha256fast.c and sha256min.c. But sha256full.c and sha256fast.c are optimized, so their codes may be a little confusing. Thus I recommend reading sha256min.c first.

Here are the features (differences) :

features	sha256full.c	sha256fast.c	sha256min.c
timer	Yes (3)	Yes (1)	No
prompt	Yes (detailed)	Yes (brief)	No
repetition	Yes	No	No
string hashing	Yes	Yes (include NULL)	No
file hashing	Yes	Yes	Yes
unroll loop	Yes (1)	Yes (18)	No

Download

Windows

64-bit

win10_x64

OS

• Windows 10
• Windows 11

CPU

• Intel x64 (x86_64, amd64)
• AMD x64 (x86_64, amd64)

Build Info

Microsoft Windows 10

x64-based PC

GNU Make 4.2.1
Built for x86_64-w64-mingw32

gcc version 12.2.0 (x86_64-posix-seh-rev2, Built by MinGW-W64 project)
Using built-in specs.
COLLECT_GCC=D:\mingw64\bin\gcc.exe
COLLECT_LTO_WRAPPER=D:/mingw64/bin/../libexec/gcc/x86_64-w64-mingw32/12.2.0/lto-wrapper.exe
Target: x86_64-w64-mingw32
Configured with: ../../../src/gcc-12.2.0/configure --host=x86_64-w64-mingw32 --build=x86_64-w64-mingw32 --target=x86_64-w64-mingw32 --prefix=/mingw64 --with-sysroot=/c/mingw-builds/ucrt64-seh-posix/x86_64-1220-posix-seh-ucrt-rt_v10-rev2/mingw64 --enable-hot 
-shared --disable-multilib --enable-languages=c,c++,fortran,lto --enable-libstdcxx-time=yes --enable-threads=posix --enable-libgomp --enable-libatomic --enable-lto --enable-graphite --enable-checking=release --enable-fully-dynamic-string --enable-version-specific-runtime-libs --enable-libstdcxx-filesystem-ts=yes --disable-libstdcxx-pch --disable-libstdcxx-debug --enable-bootstrap --disable-rpath --disable-win32-registry --disable-nls --disable-werror --disable-symvers --with-gnu-as --with-gnu-ld --with-arch=nocona --with-tune=core2 --with-libiconv --with-system-zlib --with-gmp=/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-w64-mingw32-static --with-mpfr=/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-w64-mingw32-static --with-mpc=/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-w64-mingw32-static --with-isl=/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-w64-mingw32-static --with-pkgversion='x86_64-posix-seh-rev2, Built by MinGW-W64 project' --with-bugurl=https://sourceforge.net/projects/mingw-w64 CFLAGS='-O2 -pipe -fno-ident -I/c/mingw-builds/ucrt64-seh-posix/x86_64-1220-posix-seh-ucrt-rt_v10-rev2/mingw64/opt/include -I/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-zlib-static/include -I/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-w64-mingw32-static/include' CXXFLAGS='-O2 -pipe -fno-ident -I/c/mingw-builds/ucrt64-seh-posix/x86_64-1220-posix-seh-ucrt-rt_v10-rev2/mingw64/opt/include -I/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-zlib-static/include -I/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-w64-mingw32-static/include' CPPFLAGS=' -I/c/mingw-builds/ucrt64-seh-posix/x86_64-1220-posix-seh-ucrt-rt_v10-rev2/mingw64/opt/include -I/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-zlib-static/include -I/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-w64-mingw32-static/include' LDFLAGS='-pipe -fno-ident -L/c/mingw-builds/ucrt64-seh-posix/x86_64-1220-posix-seh-ucrt-rt_v10-rev2/mingw64/opt/lib -L/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-zlib-static/lib -L/c/mingw-builds/ucrt64-seh-posix/prerequisites/x86_64-w64-mingw32-static/lib ' LD_FOR_TARGET=/c/mingw-builds/ucrt64-seh-posix/x86_64-1220-posix-seh-ucrt-rt_v10-rev2/mingw64/bin/ld.exe --with-boot-ldflags=' -Wl,--disable-dynamicbase -static-libstdc++ -static-libgcc'
Thread model: posix
Supported LTO compression algorithms: zlib

Linux

64-bit

deb11_x64

OS

• Debian 11 (bullseye) amd64
• Debian 12 (bookworm) amd64
• Ubuntu 20.04 (focal) amd64
• Ubuntu 22.04 (jammy) amd64

CPU

• Intel x64 (x86_64, amd64)
• AMD x64 (x86_64, amd64)

Build Info

Debian GNU/Linux 11 (bullseye)

Linux version 5.10.0-18-cloud-amd64

GNU Make 4.3
Built for x86_64-pc-linux-gnu

gcc version 10.2.1 20210110 (Debian 10.2.1-6)
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/10/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa:hsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 10.2.1-6' --with-bugurl=file:///usr/share/doc/gcc-10/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-10 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-10-Km9U7s/gcc-10-10.2.1/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-10-Km9U7s/gcc-10-10.2.1/debian/tmp-gcn/usr,hsa --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-mutex
Thread model: posix
Supported LTO compression algorithms: zlib zstd

rasp4b_64

OS

• Raspbian 11 (i.e. Debian 11) aarch64
• Ubuntu 20.04 (focal) aarch64
• Ubuntu 22.04 (jammy) aarch64

Hardware

• Raspberry Pi 4 Model B

Build Info

Debian GNU/Linux 11 (bullseye)

Linux version 5.15.61-v8+

GNU Make 4.3
Built for aarch64-unknown-linux-gnu

gcc version 10.2.1 20210110 (Debian 10.2.1-6)
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/aarch64-linux-gnu/10/lto-wrapper
Target: aarch64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 10.2.1-6' --with-bugurl=file:///usr/share/doc/gcc-10/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-10 --program-prefix=aarch64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-libquadmath --disable-libquadmath-support --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --enable-fix-cortex-a53-843419 --disable-werror --enable-checking=release --build=aarch64-linux-gnu --host=aarch64-linux-gnu --target=aarch64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-mutex
Thread model: posix
Supported LTO compression algorithms: zlib zstd

32-bit

rasp4b_32

OS

• Raspbian 11 armhf
• Ubuntu 20.04 (focal) armhf
• Ubuntu 22.04 (jammy) armhf

Hardware

• Raspberry Pi 4 Model B

Build Info

Raspbian GNU/Linux 11 (bullseye)

Linux version 5.15.61-v7l+

GNU Make 4.3
Built for arm-unknown-linux-gnueabihf

gcc version 10.2.1 20210110 (Raspbian 10.2.1-6+rpi1)
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/arm-linux-gnueabihf/10/lto-wrapper
Target: arm-linux-gnueabihf
Configured with: ../src/configure -v --with-pkgversion='Raspbian 10.2.1-6+rpi1' --with-bugurl=file:///usr/share/doc/gcc-10/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-10 --program-prefix=arm-linux-gnueabihf- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-libitm --disable-libquadmath --disable-libquadmath-support --enable-plugin --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-sjlj-exceptions --with-arch=armv6 --with-fpu=vfp --with-float=hard --disable-werror --enable-checking=release --build=arm-linux-gnueabihf --host=arm-linux-gnueabihf --target=arm-linux-gnueabihf
Thread model: posix
Supported LTO compression algorithms: zlib zstd

Clone & Build

Download source_of_sha-256_v2.1_little-endian.zip

or source_of_sha-256_v2.1_little-endian.tar.gz

or

git clone https://github.com/Robert1037/Crypto-in-C.git

Windows

Build one of them: (e.g. sha256full)

> mingw32-make sha256full

Build all: (by default)

> mingw32-make

Linux

Prerequisites: gcc, make

Build one of them: (e.g. sha256full)

$ make sha256full

Build all: (by default)

$ make

Usage

Windows

sha256full

• [x] cmd or powershell
• [x] double click .exe

> .\sha256full
*************** sha-256 ***************
Please input a file name.
If the file dose not exist,
the inputted string will be computed.
(string length < 960, file size < 2 GB)
(ENTER without input to quit)
:

sha256fast

• [x] cmd or powershell
• [x] double click .exe

> .\sha256fast
filename or string :

sha256min

• [x] cmd or powershell
• [ ] double click .exe

> .\sha256min <filename>

Linux

sha256full

$ ./sha256full
*************** sha-256 ***************
Please input a file name.
If the file dose not exist,
the inputted string will be computed.
(string length < 960, file size < 2 GB)
(ENTER without input to quit)
:

sha256fast

$ ./sha256fast
filename or string :

sha256min

$ ./sha256min <filename>

Screenshots & Test Results

Windows10 x64

Verification tools:

https://coding.tools/sha256

and

> certutil -hashfile <filename> sha256

sha256full.exe

hello

null.txt

NIST.FIPS.180-4.pdf

..\..\test.mp4

..\..\movie.mp4

(Press ENTER key directly)

sha256fast.exe

(Press ENTER key directly)

hello

null.txt

NIST.FIPS.180-4.pdf

..\..\movie.mp4

sha256min.exe

(Press ENTER key directly)

null.txt

NIST.FIPS.180-4.pdf

..\..\movie.mp4

Ubuntu20.04 x64

Verification tool:

$ sha256sum <filename>

sha256full

hello

NIST.FIPS.180-4.pdf

sha256fast

(Press ENTER key directly)

hello

NIST.FIPS.180-4.pdf

sha256min

null.txt

NIST.FIPS.180-4.pdf

Verification:

References

[1] Wade Trappe, Lawrence C. Washington. Introduction to Cryptography with Coding Theory (3rd edition) [M]. Hoboken: Pearson Education, 2020: 499-521.

[2] FIPS PUB 180-4. Secure Hash Standard (SHS) [S]. http://dx.doi.org/10.6028/NIST.FIPS.180-4

[3] Datacruiser. 一文读懂SHA256算法原理及其实现. https://zhuanlan.zhihu.com/p/94619052

[4] 小Q谈移动安全. 【密码学】一文读懂SHA-2. https://zhuanlan.zhihu.com/p/404879837

Further Reading

[1] Henri Gilbert, Helena Handschuh. Security Analysis of SHA-256 and Sisters. https://link.springer.com/content/pdf/10.1007/978-3-540-24654-1_13.pdf

[2] in3rsha. sha256-animation. https://github.com/in3rsha/sha256-animation

[3] https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Standards-and-Guidelines/documents/examples/SHA256.pdf