X509_DIGEST(3)

💖 X509_DIGEST(3) 💖

okay bestie, so this is part of libcrypto and it's literally the manual for getting digests of a bunch of X.509-ish objects. no cap, the header on this one is X509_DIGEST(3) — we're in the Library Functions Manual, mwah 💅

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✨ NAME ✨

X509_digest, X509_CRL_digest, X509_pubkey_digest, X509_NAME_digest, X509_REQ_digest, PKCS7_ISSUER_AND_SERIAL_digest — get digests of various objects 🎀

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🌸 SYNOPSIS 🌸

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

int
X509_digest(const X509 *data, const EVP_MD *type, unsigned char *md,
    unsigned int *len);

int
X509_CRL_digest(const X509_CRL *data, const EVP_MD *type,
    unsigned char *md, unsigned int *len);

int
X509_pubkey_digest(const X509 *data, const EVP_MD *type,
    unsigned char *md, unsigned int *len);

int
X509_REQ_digest(const X509_REQ *data, const EVP_MD *type,
    unsigned char *md, unsigned int *len);

int
X509_NAME_digest(const X509_NAME *data, const EVP_MD *type,
    unsigned char *md, unsigned int *len);

#include <openssl/pkcs7.h>

int
PKCS7_ISSUER_AND_SERIAL_digest(PKCS7_ISSUER_AND_SERIAL *data,
    const EVP_MD *type, unsigned char *md, unsigned int *len);

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🦋 DESCRIPTION 🦋

so here's the tea, bestie ☕ X509_pubkey_digest() gives you a digest of the DER representation of the public key contained in data. and literally all the other functions on this page? they give you a digest of the DER representation of their entire data object. like, the whole thing, no holding back 💁‍♀️

the type parameter is where you say which digest you want — something like EVP_sha1(3) 👑

md is a pointer to the buffer where the digest gets copied, and it just assumes the buffer is big enough (rude but okay 🙈). a size of at least EVP_MAX_MD_SIZE bytes is suggested, ngl please listen to that ✨

and the len parameter? if it's not NULL, it points to a place where the digest size gets stored 🎯

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👑 RETURN VALUES 👑

these functions return 1 for success or 0 for failure. that's it, that's the vibe check 💀 periodt.

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🔥 SEE ALSO 🔥

EVP_get_digestbyname(3), X509_cmp(3), X509_CRL_new(3), X509_NAME_new(3), X509_new(3), X509_REQ_new(3) — go read these next bestie, iykyk 🫶

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🌈 HISTORY 🌈

so the lore goes deep, fr fr:

• X509_digest(), X509_NAME_digest(), and PKCS7_ISSUER_AND_SERIAL_digest() first appeared in SSLeay 0.6.5 and have been available since OpenBSD 2.4. iconic elders 👵✨
• X509_CRL_digest() and X509_REQ_digest() first appeared in OpenSSL 0.9.6 and have been available since OpenBSD 2.9. glow up era 🌱
• X509_pubkey_digest() first appeared in OpenSSL 0.9.7 and has been available since OpenBSD 3.2. late bloomer but we love her 🦋

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and that's the whole page, bestie 💖 this diva came to us from Debian, dated June 8, 2025, and it's the X509_DIGEST(3) manual page — go forth and digest responsibly, mwah 😭💅🎀