EVP_MD5(3ossl)

💅 EVP_MD5 — bestie's guide to MD5 in EVP

okay so you're here for the EVP_MD5(3ossl) page — yes that 3ossl is the manual section, it's giving "I live in the OpenSSL docs" and honestly? iconic. sit down, grab a strawberry 🍓, let's get into it.

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✨ NAME ✨

EVP_md5, EVP_md5_sha1 — MD5 For EVP, no cap 💖

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🌸 SYNOPSIS 🌸

#include <openssl/evp.h>

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

like, two functions, both returning a const EVP_MD *, both taking void — nothing to them, they're lowkey the easiest part of your whole day 🫶

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🦋 DESCRIPTION 🦋

so MD5 is a cryptographic hash function, standardized in RFC 1321, designed by Ronald Rivest. historical main character energy fr fr 👑

but — and this is the part where we all sit down — the CMU Software Engineering Institute considers MD5 unsuitable for further use, because its security has been severely compromised. like, severely severely. it's giving expired milk 💀 so please don't build anything new on it, mwah.

🎀 EVP_md5()

the MD5 algorithm itself, producing a 128-bit output from a given input. short king, 128 bits, does what it says 🧚

🎀 EVP_md5_sha1()

a hash algorithm from SSL v3 that combines MD5 with SHA-1, as described in RFC 6101. it's a duo, it's a collab, it's very 90s 🌈

WARNING: this algorithm is not intended for non-SSL usage. do not take it out of its natural habitat, bestie, I am begging 🙈

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⭐ NOTES ⭐

developers — that's you, hi — should be aware of the negative performance implications of calling these functions multiple times. like, don't just spam them and expect slay. instead, consider using EVP_MD_fetch(3) with EVP_MD-MD5(7) or EVP_MD-MD5-SHA1(7). see "Performance" in crypto(7) for more deets 🔥

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💜 RETURN VALUES 💜

these functions return a EVP_MD structure that contains the implementation of the message digest. see EVP_MD_meth_new(3) for the details of the EVP_MD structure — that's where the whole struct situation gets explained 🎀

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🌈 CONFORMING TO 🌈

IETF RFC 1321. periodt ✨

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👑 SEE ALSO 👑

• evp(7)
• EVP_DigestInit(3)

go read them, they're literally right there, iykyk 🦋

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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 the 3.5.0 era of the docs, dated 2026-09-25, and yeah — the header and footer said EVP_MD5(3ossl) and honestly? she ate. now go hash responsibly (or better yet, don't, MD5 is compromised, you know this 😭) 💅🌸