[#EVP_CipherUpdate]
= EVP_CipherUpdate
:mrdocs:

Encrypt or decrypt a chunk of data using a cipher context already set for either direction.

== Synopsis

Declared in `<openssl/evp.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
EVP_CipherUpdate(
    xref:EVP_CIPHER_CTX.adoc[EVP_CIPHER_CTX]* ctx,
    unsigned char* out,
    int* outl,
    unsigned char const* in,
    int inl);
----

== Return Value

1 on success, or 0 on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| Cipher context initialized for encryption or decryption.
| *out*
| Output buffer for ciphertext or plaintext.
| *outl*
| Receives the number of bytes written to `out.`
| *in*
| Input bytes to process.
| *inl*
| Number of bytes at `in.`
|===


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