122 lines
2.9 KiB
Markdown
122 lines
2.9 KiB
Markdown
# libft_ssl
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A C library implementing cryptographic hash functions from scratch.
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Each algorithm exposes a uniform streaming API — `init` / `update` / `final`
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## Algorithms
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| Algorithm | Digest | Block | Notes |
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|------------|--------|-------|-------|
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| MD5 | 128-bit | 512-bit | RFC 1321 - broken, non-security use only |
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| SHA-256 | 256-bit | 512-bit | SHA-2 family, NSA/NIST - widely used in TLS, Bitcoin |
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| Whirlpool | 512-bit | 512-bit | ISO/IEC 10118-3 - Miyaguchi-Preneel construction |
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## API
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The public interface lives in `<libft_ssl/libft_ssl.h>`.
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```c
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struct digest_algo {
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const char *name;
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size_t digest_size; /* bytes */
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size_t block_size; /* bytes */
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void (*init) (void *ctx);
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void (*update)(void *ctx, const uint8_t *data, size_t len);
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void (*final) (void *ctx, uint8_t *out);
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};
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union digest_ctx { /* one allocation covers all algorithm contexts */
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struct md5_ctx md5;
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struct sha256_ctx sha256;
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struct whirlpool_ctx whirlpool;
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};
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```
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One global instance is provided per algorithm: `g_md5`, `g_sha256`,
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`g_whirlpool`.
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### Example
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```c
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#include <libft_ssl/libft_ssl.h>
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#include <stdio.h>
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int main(void)
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{
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const struct digest_algo *algo = &g_sha256;
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union digest_ctx ctx;
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uint8_t digest[32];
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algo->init(&ctx);
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algo->update(&ctx, (const uint8_t *)"hello", 5);
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algo->final(&ctx, digest);
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for (size_t i = 0; i < algo->digest_size; i++)
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printf("%02x", digest[i]);
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puts("");
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}
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```
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Compile with:
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```sh
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cc example.c -lft_ssl -o example
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# or with pkg-config:
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cc example.c $(pkg-config --cflags --libs libft_ssl) -o example
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```
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## Building
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### Dependencies
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- C99 compiler
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- autoconf
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- automake
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- libtool
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- pdflatex — only if building documentation (`--enable-doc`)
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### Steps
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```sh
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./autogen.sh # generate the build system (first checkout only)
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./configure
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make
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make install # installs to /usr/local by default
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```
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Common `configure` options:
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| Flag | Default | Description |
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|------|---------|-------------|
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| `--prefix=PATH` | `/usr/local` | Installation prefix |
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| `--enable-debug` | no | Build with `-g -O0` instead of `-O2` |
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| `--enable-doc` | no | Build PDF documentation (requires `pdflatex`) |
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### pkg-config
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After installation the library registers itself with pkg-config:
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```sh
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pkg-config --cflags --libs libft_ssl
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```
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## Project structure
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```
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include/ public and internal headers
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src/
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md5/ MD5 init / update / compress / final
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sha256/ SHA-256 init / update / compress / final
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whirlpool/ Whirlpool init / update / compress / final
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libft_ssl.c algorithm descriptor table (X-macro generated)
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doc/ LaTeX source for the technical documentation
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```
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## Documentation
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The full technical write-up is available at <https://lohic.dev/libft_ssl.html> ([PDF](https://lohic.dev/libft_ssl.pdf)).
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## License
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GPLv3 — see [LICENSE](LICENSE).
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