|EVP(3)||Library Functions Manual||EVP(3)|
The EVP_DigestSignInit(3) and EVP_DigestVerifyInit(3) functions implement digital signatures and Message Authentication Codes (MACs). Also see the older EVP_SignInit(3) and EVP_VerifyInit(3) functions.
Authenticated encryption with additional data (AEAD) is available with the EVP_AEAD_CTX_init(3) functions.
EVP_PKEY_*() functions provide a high
level interface to asymmetric algorithms. To create a new
EVP_PKEYs can be associated with a private key of a
particular algorithm by using the functions described in the
EVP_PKEY_set1_RSA(3) page, or
new keys can be generated using
EVP_PKEYs can be compared using
EVP_PKEY_cmp(3) or printed using
EVP_PKEY_*() functions support the
full range of asymmetric algorithm operations:
The EVP_BytesToKey(3) function provides some limited support for password based encryption. Careful selection of the parameters will provide a PKCS#5 PBKDF1 compatible implementation. However, new applications should typically not use this (preferring, for example, PBKDF2 from PCKS#5).
Algorithms are loaded with OpenSSL_add_all_algorithms(3).
All the symmetric algorithms (ciphers), digests and asymmetric algorithms (public key algorithms) can be replaced by ENGINE modules providing alternative implementations; see ENGINE_register_RSA(3) and the related manual pages for more information. If ENGINE implementations of ciphers or digests are registered as defaults, then the various EVP functions will automatically use those implementations in preference to built in software implementations.
Although low level algorithm specific functions exist for many algorithms, their use is discouraged. They cannot be used with an ENGINE, and ENGINE versions of new algorithms cannot be accessed using the low level functions. Using them also makes code harder to adapt to new algorithms, some options are not cleanly supported at the low level, and some operations are more efficient using the high level interfaces.
|March 21, 2019||OpenBSD-current|