[#EVP_DecryptInit]
= EVP_DecryptInit
:mrdocs:

Initialize a cipher context for decryption (legacy ENGINE‐aware form).

== Synopsis

Declared in `<openssl/evp.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
EVP_DecryptInit(
    xref:EVP_CIPHER_CTX.adoc[EVP_CIPHER_CTX]* ctx,
    xref:EVP_CIPHER-07.adoc[EVP_CIPHER] const* cipher,
    unsigned char const* key,
    unsigned char const* iv);
----

== Description

Prefer EVP_DecryptInit_ex2() for new code.

== Return Value

1 on success, or 0 on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| Cipher context to initialize.
| *cipher*
| Cipher algorithm to use.
| *key*
| Decryption key bytes, or NULL to set later.
| *iv*
| Initialization vector, or NULL when not yet required.
|===


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