cMDA

Overview

cMDA is a portable, high-performance C library implementing the MD2, MD4, and MD5 message-digest algorithms. Key features:

• Single-message API — cMD2, cMD4, cMD5: always scalar, zero overhead.
• Multi-message SIMD API — cMD4_multi / cMD5_multi: processes N independent messages in parallel across SIMD lanes. The correct multi-buffer technique is used — each lane carries a separate message, so every intrinsic does real work:

  Backend	Register width	Messages in parallel
  Scalar fallback	—	1
  SSE2	128-bit	4
  AVX2	256-bit	8
  AVX-512F	512-bit	16
  The best backend is selected at runtime via CPUID — no recompilation needed.

• Fragment builds — link only what you need: libcMD2.a, libcMD4.a, libcMD5.a.
• Cross-platform — Linux, macOS, Windows (MinGW/MSYS2), and embedded (AVR, ESP32, ESP8266, STM32). Embedded targets automatically use the scalar path.
• CLI tools — md2, md4, md5 binaries for hashing messages and files, with hash comparison support.

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Installation

From Source

git clone https://github.com/Byte-Ocelots/cMDA
cd cMDA
make clean all

Install — all (libs + headers + CLI)

# Linux (default prefix /usr/local)
make install-all
make install-all PREFIX=/your/path

# macOS (default /usr/local/Byte-Ocelots)
make install-all INSTALL_DIR=/your/path

# Windows (default C:\Byte-Ocelots)
make install-all INSTALL_DIR="D:\MyLibs"

Install — libraries only (no CLI)

make install-libs-only

Install — CLI only

make install-cli-only

Uninstall

make uninstall

Pre-built Releases

Download from the Releases page. Each release provides archives for:

Platform	Architectures	Variants
Linux	x86_64, i686	libs-only, cli-only, all
macOS	x86_64, arm64	libs-only, cli-only, all
Windows	x86_64, i686	libs-only, cli-only, all
AVR	8-bit (avr-gcc)	libs-only
STM32	Cortex-M4 (arm-none-eabi)	libs-only

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Usage

Library API

#include <cMDA/all.h>   // all three, or include individual headers
#include <cMDA/md5.h>

// Single message
uint8_t digest[MD5_DIGEST_LENGTH];
cMD5((uint8_t *)"hello", 5, digest);

// Multiple messages in parallel (SIMD-accelerated)
uint8_t *msgs[4]    = { (uint8_t*)"a", (uint8_t*)"bb", (uint8_t*)"ccc", (uint8_t*)"dddd" };
uint64_t lens[4]    = { 1, 2, 3, 4 };
uint8_t  d[4][16];
uint8_t *digs[4]    = { d[0], d[1], d[2], d[3] };
cMD5_multi(msgs, lens, digs, 4);

Link with:

gcc your_program.c -lcMDA -lm -o your_program
# or fragment link (MD5 only):
gcc your_program.c -lcMD5 -lm -o your_program

CLI

# Hash a message
md5 "Hello, World!"

# Hash files
md5 -f file1.bin -f file2.bin

# Multiple messages at once
md5 "foo" "bar" "baz"

# Choose output format
md5 --format upper "abc"
md5 --format base64 "abc"

# Compare against a known hash (exit 0 = match, 1 = mismatch)
md5 --compare 900150983cd24fb0d6963f7d28e17f72 "abc"

# Compare using a hash stored in a file
md5 --compare-file expected.md5 "abc"

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Building

Default (all targets)

make all

Individual targets

make static          # libcMDA.a
make shared          # libcMDA.so / .dylib / .dll
make bins            # CLI binaries
make tests           # unit test binary

# Fragment libs (single-algorithm)
make lib-md5         # libcMD5.a  (static)
make shared-md5      # libcMD5.so (shared)
make lib-md2 lib-md4 lib-md5

# Run tests
./tests/bin/test_all -v
bash tests/test_cli.sh    # Linux/macOS
tests\test_cli.bat        # Windows

Architecture (Linux/macOS)

make all arch=64
make all arch=32

Embedded Cross-Compile

# AVR (default MCU: atmega328p)
make avr
make avr AVR_MCU=attiny85

# ESP32 (requires xtensa-esp32-elf-gcc)
make esp32

# ESP8266 (requires xtensa-lx106-elf-gcc)
make esp8266

# STM32 Cortex-M4 (requires arm-none-eabi-gcc)
make stm32
make stm32 STM32_MCU=cortex-m3

Output: lib/libcMDA_avr.a, lib/libcMDA_stm32.a, etc.

Note: embedded targets automatically disable all SIMD code (-DCMDA_NO_SIMD) and use the scalar path only.

Compiler Override

make CC=clang all

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CI / CD

• Every push / PR → build-and-test.yml runs on Linux (x86_64 + i686), macOS (x86_64 + arm64), and Windows (x86_64 + i686), plus AVR and STM32 cross-compile checks.
• Version tag push (v*.*.*) → release-on-tag.yml builds and attaches all release archives automatically.

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License

MIT — see LICENSE.

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RFC References

• MD2 — RFC 1319: The MD2 Message-Digest Algorithm — R. Rivest, April 1992.
• MD4 — RFC 1320: The MD4 Message-Digest Algorithm — R. Rivest, April 1992.
• MD5 — RFC 1321: The MD5 Message-Digest Algorithm — R. Rivest, April 1992.