EVP_PKEY_CMP(3)

📦 version 4.4.0, in alpine 3.24, arch rolling

✨ NAME ✨

Hey bestie! Welcome to EVP_PKEY_CMP(3) from the libcrypto library — this page is all about the public key parameter and comparison functions. We're talking EVP_PKEY_missing_parameters, EVP_PKEY_copy_parameters, EVP_PKEY_cmp_parameters, and EVP_PKEY_cmp. 🎀 It's giving key-nerd excellence, fr fr.

🌸 SYNOPSIS 🌸

library “libcrypto” #include <openssl/evp.h>

int
EVP_PKEY_missing_parameters(const EVP_PKEY *pkey);

int
EVP_PKEY_copy_parameters(EVP_PKEY *destination, const EVP_PKEY *source);

int
EVP_PKEY_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b);

int
EVP_PKEY_cmp(const EVP_PKEY *a, const EVP_PKEY *b);

💅 DESCRIPTION 💅

okay so these functions are all about public key parameters and comparing keys. Let's go one by one, no cap. 💖

🦋 EVP_PKEY_missing_parameters()

This one checks whether any public key parameters are missing from pkey. That's it — it's giving parameter vibe check. ✨

🎀 EVP_PKEY_copy_parameters()

Copies all public key parameters from source to destination. If the algorithm does not use parameters, no action occurs. literally nothing happens, and that's fine. 🫶

🌈 EVP_PKEY_cmp_parameters()

Compares the public key parameters of a and b. This is only supported for algorithms that use parameters. iykyk. 💖

👑 EVP_PKEY_cmp()

Compares the public key components of a and b. If the algorithm uses public key parameters, it also compares the parameters. So it's a full-on key comparison moment. 🔥

The main purpose of EVP_PKEY_missing_parameters() and EVP_PKEY_copy_parameters() is to handle public keys in certificates where the parameters are sometimes omitted from a public key if they are inherited from the CA that signed it. Certificate drama, but make it cryptographic. 💀

Since OpenSSL private keys contain public key components too, EVP_PKEY_cmp() can also be used to determine if a private key matches a public key. Bestie matchmaking, but for keys. 💘

⭐ RETURN VALUES ⭐

  • EVP_PKEY_missing_parameters() — returns 1 if the public key parameters of pkey are missing or incomplete, or 0 if they are present and complete or if the algorithm doesn't use parameters. slay.
  • EVP_PKEY_copy_parameters() — returns 1 for success or 0 for failure. In particular, it fails if the key types mismatch or if the public key parameters in the source are missing or incomplete. no cap.
  • EVP_PKEY_cmp_parameters() and EVP_PKEY_cmp() — return 1 if the keys match, 0 if they don't match, -1 if the key types are different, and -2 if the operation is not supported. periodt.

🌸 SEE ALSO 🌸

💜 HISTORY 💜

  • EVP_PKEY_missing_parameters() and EVP_PKEY_copy_parameters() first appeared in SSLeay 0.8.0.
  • EVP_PKEY_cmp_parameters() first appeared in SSLeay 0.9.0.
  • These functions have been available since OpenBSD 2.4. 🫶
  • EVP_PKEY_cmp() first appeared in OpenSSL 0.9.8 and has been available since OpenBSD 4.5. ✨

That's the whole page, bestie. Big kiss from Debian, dated June 8, 2025 💋🎀

📦 where this page comes from