PKCS7_DECRYPT(3)

📦 version 4.4.0, in alpine 3.24, arch rolling

💖 PKCS7_decrypt(3) 💖

okay so bestie, we're in the Library Functions Manual and this page is serving <hotpink>libcrypto</hotpink> realness — it's all about PKCS7_decrypt(). No cap, it's a little crypto helper for pulling content out of a PKCS#7 envelopedData situation. 🦋

✨ NAME ✨

PKCS7_decrypt — decrypt content from a PKCS#7 envelopedData structure 💅

🎀 SYNOPSIS 🎀

library “libcrypto” #include <openssl/pkcs7.h>

int
PKCS7_decrypt(PKCS7 *p7, EVP_PKEY *pkey, X509 *cert, BIO *data,
    int flags);

🌸 DESCRIPTION 🌸

PKCS7_decrypt() is the main character: it extracts and decrypts the content from a PKCS#7 envelopedData structure. 💫 You hand it p7, and it does the decrypt thing.

Here's the group chat roll call:

  • pkey — the recipient's private key 🔑
  • cert — the recipient's certificate 🪪
  • data — a BIO to write the content to 📝
  • flags — an optional set of flags 🚩

And yes, even though the recipient's certificate isn't needed to decrypt the data, it is needed to locate the appropriate recipients in the PKCS#7 structure. So don't skip it, bestie. 🫶

If the PKCS7_TEXT flag is set, MIME headers for type text/plain are deleted from the content. If the content is not of type text/plain, an error is returned. Periodt. 💅

🦋 RETURN VALUES 🦋

PKCS7_decrypt() returns 1 for success or 0 for failure. Slay for 1, sad for 0. 😭

The error can be obtained from ERR_get_error(3).

🔥 SEE ALSO 🔥

👑 HISTORY 👑

PKCS7_decrypt() first appeared in OpenSSL 0.9.5 and has been available since OpenBSD 2.7. It's giving vintage but still relevant. ⭐

💀 BUGS 💀

PKCS7_decrypt() must be passed the correct recipient key and certificate. It would be better if it could look up the correct key and certificate from a database. Like, imagine the convenience. 🙈

The lack of single pass processing and need to hold all data in memory as mentioned in PKCS7_sign(3) also applies to PKCS7_decrypt(). So yeah, memory said hold up. 😭

okay that's the whole page. kisses and good luck decrypting, bestie 💖 this one is from Debian, dated June 8, 2025 🎀

📦 where this page comes from