EVP_IDEA_CBC(3ossl)

💖 EVP_IDEA_CBC — the OpenSSL manual, but make it make sense 💖

okay bestie, gather round, because we're talking about the <openssl/evp.h> girlies today and this one is so specific. This is page EVP_IDEA_CBC(3ossl) from the OpenSSL manual, and it's all about the IDEA cipher family in EVP. short page, but every single line matters, so let's go 🫶

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✨ NAME ✨

EVP_idea_cbc, EVP_idea_cfb, EVP_idea_cfb64, EVP_idea_ecb, EVP_idea_ofb — the EVP IDEA cipher, that's the whole vibe 💅

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🌸 SYNOPSIS 🌸

first things first, you gotta pull in the header, no cap:

#include <openssl/evp.h>

and then these five little icons, each one returns a const EVP_CIPHER *:

const EVP_CIPHER *EVP_idea_cbc(void);
const EVP_CIPHER *EVP_idea_cfb(void);
const EVP_CIPHER *EVP_idea_cfb64(void);
const EVP_CIPHER *EVP_idea_ecb(void);
const EVP_CIPHER *EVP_idea_ofb(void);

like, no arguments, no drama, just a pointer to a cipher. periodt ✨

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🦋 DESCRIPTION 🦋

so the whole point here: this is the IDEA encryption algorithm for EVP. that's it, that's the description, she's concise.

and here's the lineup, one function per mode, fr fr:

• EVP_idea_cbc(), EVP_idea_cfb(), EVP_idea_cfb64(), EVP_idea_ecb(), EVP_idea_ofb() — these hand you the IDEA encryption algorithm in CBC, CFB, ECB and OFB modes respectively. so like: CBC mode, CFB mode, ECB mode, OFB mode. and yes, cfb and cfb64 are both in that list, they're both there, I'm not merging them, do not come for me 🙈

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👑 NOTES 👑

okay this is the part where I have to be the responsible bestie for a sec:

Developers should be aware of the negative performance implications of calling these functions multiple times and should consider using EVP_CIPHER_fetch(3) with EVP_CIPHER-IDEA(7) instead.

so basically: calling these over and over is not it, it's giving performance L. the glow-up move is EVP_CIPHER_fetch(3) paired with EVP_CIPHER-IDEA(7). if you wanna know why, go read "Performance" in crypto(7) — it's all laid out there, iykyk 💜

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💀 RETURN VALUES 💀

these functions return an EVP_CIPHER structure, and inside that structure lives the implementation of the symmetric cipher. if you wanna know what's actually in an EVP_CIPHER structure, the details are in EVP_CIPHER_meth_new(3). she's not mysterious, she's documented 🔥

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🌈 SEE ALSO 🌈

the required reading, the syllabus, the group chat links:

• evp(7)
• EVP_EncryptInit(3)
• EVP_CIPHER_meth_new(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>.

like, actually read the license bestie, it's not decorative 💅

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and that's the whole page, we ate, no crumbs left. this was OpenSSL 3.5.9, dated 2026-09-29 — so if you're reading this from the future, hey, hope the ciphers are ciphering 💖✨🦋