X509_FIND_BY_SUBJECT(3)

💅 X509_FIND_BY_SUBJECT(3) 💅

ok so bestie, this is a page from the Library Functions Manual for a couple of cert-hunting functions in libcrypto. No preamble needed, we're jumping straight in 🫶

---

✨ NAME ✨

X509_find_by_subject, X509_find_by_issuer_and_serial — search an array of X.509 certificates 🔍🎀

---

🌸 SYNOPSIS 🌸

First thing's first, you gotta link the library and pull in the header, like:

library “libcrypto”
#include <openssl/x509.h>

Then, the two icons themselves:

X509 *
X509_find_by_subject(STACK_OF(X509) *sk, X509_NAME *subject);

X509 *
X509_find_by_issuer_and_serial(STACK_OF(X509) *sk, X509_NAME *issuer,
    ASN1_INTEGER *serial);

---

🦋 DESCRIPTION 🦋

Okay so picture this: you've got a whole variable-sized array sk full of certificates, and you need one of them. That's literally the whole plot 💀

• X509_find_by_subject() — it goes through sk looking for a certificate whose subject name matches. That's it, that's the mission. subject match = found bestie 💖
• X509_find_by_issuer_and_serial() — this one's pickier. It searches the array for a certificate where both the issuer name and the serial number match the arguments. Two boxes to tick, no shortcuts ✨

---

👑 RETURN VALUES 👑

Both of these cuties return a pointer to the first matching certificate — first one wins, no queue-jumping 🎀

And if sk is NULL? Or the array just doesn't have a match? You get NULL back. That's the whole vibe check. 😭

---

🌈 SEE ALSO 🌈

Go read these next, iykyk:

• ASN1_INTEGER_new(3)
• STACK_OF(3)
• X509_cmp(3)
• X509_get_serialNumber(3)
• X509_get_subject_name(3)
• X509_NAME_new(3)
• X509_new(3)

---

⭐ HISTORY ⭐

These functions first appeared in SSLeay 0.8.1 and have been available since OpenBSD 2.4. absolute elders, we respect them 🫡💜

---

and that's the page!! mwah 💋 this one's from Debian, dated June 8, 2025 — ty for reading, go find those certificates bestie 🧚‍♀️🎀💖