EVP_MD5(3ossl)

💖 EVP_MD5 — the MD5 files (3ossl, from the OpenSSL fam) 💖

okay bestie, sit down, grab your boba, because we're talking about MD5 today and it's a whole saga 🫶

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✨ NAME ✨

EVP_md5, EVP_md5_sha1 — MD5, but make it EVP 💅

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🌸 SYNOPSIS 🌸

#include <openssl/evp.h>

const EVP_MD *EVP_md5(void);
const EVP_MD *EVP_md5_sha1(void);

like, that's it. two little functions. so cute. so simple. so compromised 😭

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🦋 DESCRIPTION 🦋

so MD5 is a cryptographic hash function, right? it's standardized in RFC 1321 and it was designed by Ronald Rivest. iconic name, iconic era, not-so-iconic security track record ngl.

and here's the tea: the CMU Software Engineering Institute considers MD5 unsuitable for further use since its security has been severely compromised. not me quoting that verbatim because it matters. 💀

🌈 EVP_md5()

The MD5 algorithm, which produces a 128-bit output from a given input. short king. 128 bits. that's the whole vibe.

🌈 EVP_md5_sha1()

A hash algorithm of SSL v3 that combines MD5 with SHA-1, as described in RFC 6101. it's giving "two hashes in a trench coat" energy fr fr.

⚠️ WARNING: this algorithm is not intended for non-SSL usage. like, read that again bestie. it said what it said. don't take it to the club (production) and act surprised. 🙈

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⭐ NOTES ⭐

devs, listen up, because this is the part that saves your perf: calling these functions multiple times has negative performance implications. so instead of doing that, consider using EVP_MD_fetch(3) with EVP_MD-MD5(7) or EVP_MD-MD5-SHA1(7) instead. 🎀

and if you want the whole story, go read "Performance" in crypto(7) for further information. it's right there, bestie, go look. 👑

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💜 RETURN VALUES 💜

These functions return an EVP_MD structure that contains the implementation of the message digest. and if you're like "okay but what IS the EVP_MD structure", see EVP_MD_meth_new(3) for details. iykyk. ✨

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🌸 CONFORMING TO 🌸

IETF RFC 1321. periodt. 💅

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🫶 SEE ALSO 🫶

• evp(7)
• EVP_DigestInit(3)

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👑 COPYRIGHT 👑

Copyright 2017-2023 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

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and that's the whole page, bestie 🧚 this was 3.5.9, dated 2026-09-29, and it lives in the OpenSSL manual as EVP_MD5(3ossl). mwah, go hash responsibly (or like, responsibly-ish, you know what MD5 is giving) 💖✨🎀