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OPENSSL_ADD_ALL_ALGORITHMS(3) Library Functions Manual OPENSSL_ADD_ALL_ALGORITHMS(3)

NAME

OpenSSL_add_all_algorithms, OpenSSL_add_all_ciphers, OpenSSL_add_all_digests, EVP_cleanupadd algorithms to internal table

SYNOPSIS

#include <openssl/evp.h>
void
OpenSSL_add_all_algorithms(void);
void
OpenSSL_add_all_ciphers(void);
void
OpenSSL_add_all_digests(void);
void
EVP_cleanup(void);

DESCRIPTION

OpenSSL keeps an internal table of digest algorithms and ciphers. It uses this table to look up ciphers via functions such as EVP_get_cipherbyname(3).
OpenSSL_add_all_algorithms() adds all algorithms to the table (digests and ciphers).
OpenSSL_add_all_digests() adds all digest algorithms to the table.
OpenSSL_add_all_ciphers() adds all encryption algorithms to the table including password based encryption algorithms.
EVP_cleanup() removes all ciphers and digests from the table.
A typical application will call OpenSSL_add_all_algorithms() initially and EVP_cleanup() before exiting.
An application does not need to add algorithms to use them explicitly, for example by EVP_sha1(3). It just needs to add them if it (or any of the functions it calls) needs to look up algorithms.
The cipher and digest lookup functions are used in many parts of the library. If the table is not initialized, several functions will misbehave and complain they cannot find algorithms. This includes the PEM, PKCS#12, SSL and S/MIME libraries. This is a common query in the OpenSSL mailing lists.
Calling OpenSSL_add_all_algorithms() links in all algorithms: as a result a statically linked executable can be quite large. If this is important, it is possible to just add the required ciphers and digests.

SEE ALSO

evp(3), EVP_DigestInit(3), EVP_EncryptInit(3)

BUGS

Although the functions do not return error codes, it is possible for them to fail. This will only happen as a result of a memory allocation failure so this is not too much of a problem in practice.
November 28, 2016 OpenBSD-current