- NAME
- SYNOPSIS
- DESCRIPTION

- Key Derivation
- Algorithm Identifier Creation

- NOTES
- RETURN VALUES
- CONFORMING TO
- SEE ALSO
- HISTORY
- COPYRIGHT

# 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

# 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 performs a key derivation according to PKCS#5 PBES1. The resulting key is then used to initialise the cipher context ctx with a cipher cipher for encryption (en_de=1) or decryption (en_de=0).

pass is an optional parameter and can be NULL. If passlen is -1, then the function will calculate the length of pass using `strlen()`.

PKCS5_v2_PBE_keyivgen() and PKCS5_v2_PBE_keyivgen_ex() are similar to the above but instead use PKCS#5 PBES2 as the encryption algorithm using the supplied parameters.

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

salt is the salt used in the derivation of length saltlen. If the salt is NULL, then saltlen must be 0. The function will not attempt to calculate the length of the salt because it is not assumed to be NULL terminated.

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.

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.

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).

Functions ending in `_ex()` take optional parameters libctx and propq which are used to select appropriate algorithm implementations.

## 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.

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.

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.

These functions make no assumption regarding the given password. It will simply be treated as a byte sequence.

# 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.

# 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.

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.

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.

# COPYRIGHT

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.