---
name: "evp"
section: "3ssl"
platform: "linux"
package: "libssl-doc"
version: "1.0.1t-1+deb8u8"
release: "Debian 8 (Jessie)"
platforms: ["linux"]
url: "https://new.carta.tech/evp"
---

# evp(3ssl)

high-level cryptographic functions

## NAME

evp - high-level cryptographic functions

## SYNOPSIS

```
 #include <openssl/evp.h>
```

## DESCRIPTION

The EVP library provides a high-level interface to cryptographic functions.

**EVP\_Seal***...* and **EVP\_Open***...* provide public key encryption and decryption to implement digital "envelopes".

The **EVP\_Sign***...* and **EVP\_Verify***...* functions implement digital signatures.

Symmetric encryption is available with the **EVP\_Encrypt***...* functions.  The **EVP\_Digest***...* functions provide message digests.

The **EVP\_PKEY***...* functions provide a high level interface to asymmetric algorithms.

The **EVP\_Encode***...* and **EVP\_Decode***...* functions implement base 64 encoding and decoding.

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. If ENGINE implementations of ciphers or digests are registered as defaults, then the various EVP functions will automatically use those implementations automatically in preference to built in software implementations. For more information, consult the *engine*(3) man page.

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. Also makes code harder to adapt to new algorithms and some options are not  cleanly supported at the low level and some operations are more efficient using the high level interface.

## SEE ALSO

*EVP\_DigestInit*(3), *EVP\_EncryptInit*(3), *EVP\_OpenInit*(3), *EVP\_SealInit*(3), *EVP\_SignInit*(3), *EVP\_VerifyInit*(3), *EVP\_EncodeInit*(3), *OpenSSL\_add\_all\_algorithms*(3), *engine*(3)