PKCS5_PBE_KEYIVGEN(3ossl)

📦
version 3.5.9 · 8 versions
, in fedora 43, fedora 44

✨ PKCS5_PBE_KEYIVGEN ✨ — the 3ossl manual page, but make it make sense 💅

okay bestie, buckle up 🎀 this is the OpenSSL page all about PKCS#5 Password based encryption routines. it's a whole friend group of functions and yes we're gonna meet every single one of them, no skips, no cap.

🌸 NAME 🌸

PKCS5_PBE_keyivgen, PKCS5_PBE_keyivgen_ex, PKCS5_pbe2_set, PKCS5_pbe2_set_iv, PKCS5_pbe2_set_iv_ex, PKCS5_pbe_set, PKCS5_pbe_set_ex, PKCS5_pbe2_set_scrypt, PKCS5_pbe_set0_algor, PKCS5_pbe_set0_algor_ex, PKCS5_v2_PBE_keyivgen, PKCS5_v2_PBE_keyivgen_ex, PKCS5_v2_scrypt_keyivgen, PKCS5_v2_scrypt_keyivgen_ex, PKCS5_pbkdf2_set, PKCS5_pbkdf2_set_ex, EVP_PBE_scrypt, EVP_PBE_scrypt_ex — PKCS#5 Password based encryption routines

like… that's the whole squad 🫶

🌈 SYNOPSIS 🌈

#include <openssl/evp.h>

int PKCS5_PBE_keyivgen(EVP_CIPHER_CTX *ctx, const char *pass, int passlen,
                       ASN1_TYPE *param, const EVP_CIPHER *cipher,
                       const EVP_MD *md, int en_de);
int PKCS5_PBE_keyivgen_ex(EVP_CIPHER_CTX *cctx, const char *pass, int passlen,
                          ASN1_TYPE *param, const EVP_CIPHER *cipher,
                          const EVP_MD *md, int en_de, OSSL_LIB_CTX *libctx,
                          const char *propq);
int PKCS5_v2_PBE_keyivgen(EVP_CIPHER_CTX *ctx, const char *pass, int passlen,
                          ASN1_TYPE *param, const EVP_CIPHER *cipher,
                          const EVP_MD *md, int en_de);
int PKCS5_v2_PBE_keyivgen_ex(EVP_CIPHER_CTX *ctx, const char *pass, int passlen,
                             ASN1_TYPE *param, const EVP_CIPHER *cipher,
                             const EVP_MD *md, int en_de,
                             OSSL_LIB_CTX *libctx, const char *propq);
int EVP_PBE_scrypt(const char *pass, size_t passlen,
                   const unsigned char *salt, size_t saltlen,
                   uint64_t N, uint64_t r, uint64_t p, uint64_t maxmem,
                   unsigned char *key, size_t keylen);
int EVP_PBE_scrypt_ex(const char *pass, size_t passlen,
                      const unsigned char *salt, size_t saltlen,
                      uint64_t N, uint64_t r, uint64_t p, uint64_t maxmem,
                      unsigned char *key, size_t keylen,
                      OSSL_LIB_CTX *ctx, const char *propq);
int PKCS5_v2_scrypt_keyivgen(EVP_CIPHER_CTX *ctx, const char *pass,
                             int passlen, ASN1_TYPE *param,
                             const EVP_CIPHER *c, const EVP_MD *md, int en_de);
int PKCS5_v2_scrypt_keyivgen_ex(EVP_CIPHER_CTX *ctx, const char *pass,
                                int passlen, ASN1_TYPE *param,
                                const EVP_CIPHER *c, const EVP_MD *md, int en_de,
                                OSSL_LIB_CTX *libctx, const char *propq);

#include <openssl/x509.h>

int PKCS5_pbe_set0_algor(X509_ALGOR *algor, int alg, int iter,
                         const unsigned char *salt, int saltlen);
int PKCS5_pbe_set0_algor_ex(X509_ALGOR *algor, int alg, int iter,
                            const unsigned char *salt, int saltlen,
                            OSSL_LIB_CTX *libctx);

X509_ALGOR *PKCS5_pbe_set(int alg, int iter,
                          const unsigned char *salt, int saltlen);
X509_ALGOR *PKCS5_pbe_set_ex(int alg, int iter,
                             const unsigned char *salt, int saltlen,
                             OSSL_LIB_CTX *libctx);

X509_ALGOR *PKCS5_pbe2_set(const EVP_CIPHER *cipher, int iter,
                           unsigned char *salt, int saltlen);
X509_ALGOR *PKCS5_pbe2_set_iv(const EVP_CIPHER *cipher, int iter,
                              unsigned char *salt, int saltlen,
                              unsigned char *aiv, int prf_nid);
X509_ALGOR *PKCS5_pbe2_set_iv_ex(const EVP_CIPHER *cipher, int iter,
                                 unsigned char *salt, int saltlen,
                                 unsigned char *aiv, int prf_nid,
                                 OSSL_LIB_CTX *libctx);
X509_ALGOR *PKCS5_pbe2_set_scrypt(const EVP_CIPHER *cipher,
                                  const unsigned char *salt, int saltlen,
                                  unsigned char *aiv, uint64_t N, uint64_t r,
                                  uint64_t p);

X509_ALGOR *PKCS5_pbkdf2_set(int iter, unsigned char *salt, int saltlen,
                             int prf_nid, int keylen);
X509_ALGOR *PKCS5_pbkdf2_set_ex(int iter, unsigned char *salt, int saltlen,
                                int prf_nid, int keylen,
                                OSSL_LIB_CTX *libctx);

💖 DESCRIPTION 💖

🦋 Key Derivation 🦋

PKCS5_PBE_keyivgen() and PKCS5_PBE_keyivgen_ex() take a password pass of length passlen, parameters param and a message digest function md_type and does a whole key derivation according to PKCS#5 PBES1. then the resulting key gets used to initialise the cipher context ctx with a cipher cipher for encryption (en_de=1) or decryption (en_de=0). like, pick your lane bestie 💅

pass is optional, so it can be NULL — it's giving low-maintenance. and if passlen is -1, the function will just calculate the length of pass using strlen(). she does the math herself, iconic ✨

PKCS5_v2_PBE_keyivgen() and PKCS5_v2_PBE_keyivgen_ex() are literally the same vibe as above, except they use PKCS#5 PBES2 as the encryption algorithm with the supplied parameters instead. glow up 💅

PKCS5_v2_scrypt_keyivgen() and PKCS5_v2_scrypt_keyivgen_ex() use SCRYPT as the key derivation part of the encryption algorithm. scrypt girlies rise 🧚

salt is the salt used in the derivation, of length saltlen. if the salt is NULL, then saltlen must be 0. and no, the function will not attempt to calculate the length of the salt, because it is not assumed to be NULL terminated. she's not guessing, periodt.

iter is the iteration count and its value should be greater than or equal to 1. RFC 2898 suggests an iteration count of at least 1000. any iter less than 1 is treated as a single iteration. (so like, 0 → 1, no notes.)

digest is the message digest function used in the derivation.

aiv is the initialization vector (IV) to use for the encryption algorithm. if aiv is NULL, then a random IV will be generated. surprise! 🎀

prf_nid is the numeric identifier (NID) for the pseudo-random function to use with PBKDF2. if prf_nid is not specified (for example, prf_nid is set to 0), a default PRF is used, which is currently set to SHA-256 (NID_hmacWithSHA256). the default ate, ngl.

functions ending in _ex() take optional parameters libctx and propq which are used to select appropriate algorithm implementations. it's giving ✨customisation✨

🎀 Algorithm Identifier Creation 🎀

PKCS5_pbe_set(), PKCS5_pbe_set_ex(), PKCS5_pbe2_set(), PKCS5_pbe2_set_iv(), PKCS5_pbe2_set_iv_ex() and PKCS5_pbe2_set_scrypt() generate an X509_ALGOR object which represents an AlgorithmIdentifier containing the algorithm OID and associated parameters for the PBE algorithm. these functions encode the key derivation parameters (such as salt and iteration count) and the encryption parameters (such as the IV) into the ASN.1 structure. packing it all in, cute and tidy 🎀

PKCS5_pbkdf2_set() and PKCS5_pbkdf2_set_ex() generate an X509_ALGOR object which represents an AlgorithmIdentifier containing the algorithm OID and associated parameters for the PBKDF2 algorithm.

PKCS5_pbe_set0_algor() and PKCS5_pbe_set0_algor_ex() set the PBE algorithm OID and parameters into the supplied X509_ALGOR. filling in the blanks, love that for them 🫶

okay so about salt, this is the important bit:

  • if salt is NULL, then saltlen specifies the size in bytes of the random salt to generate.
  • if saltlen is 0 then a default size is used.
  • for PBE related functions such as PKCS5_pbe_set_ex() the default salt length is 8 bytes.
  • for PBE2 related functions that use PBKDF2 such as PKCS5_pbkdf2_set(), PKCS5_pbe2_set_scrypt() and PKCS5_pbe2_set() the default salt length is 16 bytes.

🍓 NOTES 🍓

the *_keyivgen() functions are typically used in PKCS#12 to encrypt objects. iykyk 💅

these functions make no assumption regarding the given password. it will simply be treated as a byte sequence. no judgement, no vibes-based parsing, just bytes fr fr.

💜 RETURN VALUES 💜

PKCS5_PBE_keyivgen(), PKCS5_v2_PBE_keyivgen(), PKCS5_v2_PBE_keyivgen_ex(), PKCS5_v2_scrypt_keyivgen(), PKCS5_v2_scrypt_keyivgen_ex(), PKCS5_pbe_set0_algor() and PKCS5_pbe_set0_algor_ex() return 1 for success and 0 if an error occurs.

PKCS5_pbe_set(), PKCS5_pbe_set_ex(), PKCS5_pbe2_set(), PKCS5_pbe2_set_iv(), PKCS5_pbe2_set_iv_ex(), PKCS5_pbe2_set_scrypt(), PKCS5_pbkdf2_set() and PKCS5_pbkdf2_set_ex() return an X509_ALGOR object or NULL if an error occurs.

so like, either a whole object or nothing. main character or ghost, no in-between 💀

⭐ CONFORMING TO ⭐

IETF RFC 8018 (<https://tools.ietf.org/html/rfc8018>)

👑 SEE ALSO 👑

EVP_PBE_CipherInit_ex(3), PKCS12_pbe_crypt_ex(3), passphrase-encoding(7)

🔥 HISTORY 🔥

PKCS5_v2_PBE_keyivgen_ex(), EVP_PBE_scrypt_ex(), PKCS5_v2_scrypt_keyivgen_ex(), PKCS5_pbe_set0_algor_ex(), PKCS5_pbe_set_ex(), PKCS5_pbe2_set_iv_ex() and PKCS5_pbkdf2_set_ex() were added in OpenSSL 3.0. glow-up era ✨

from OpenSSL 3.0 the PBKDF1 algorithm used in PKCS5_PBE_keyivgen() and PKCS5_PBE_keyivgen_ex() has been moved to the legacy provider as an EVP_KDF. she's retired to the legacy wing, respect her journey 🙈

in OpenSSL 3.2 the default salt length changed from 8 bytes to 16 bytes for PBE2 related functions such as PKCS5_pbe2_set(). this is required for PBKDF2 FIPS compliance. glow up for legal reasons, we love to see it 💅

Copyright 2021-2026 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>.

okay bestie that's the whole page 🫶 this was OpenSSL 3.5.9, dated 2026-09-29, and it's the PKCS5_PBE_KEYIVGEN(3ossl) manual — go forth and derive those keys responsibly, mwah 💖🌷✨

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