[#CRYPTO_ocb128_setiv]
= CRYPTO_ocb128_setiv
:mrdocs:

Set the OCB IV / nonce and authentication tag length for an operation.

== Synopsis

Declared in `<openssl/modes.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
CRYPTO_ocb128_setiv(
    xref:OCB128_CONTEXT-0a.adoc[OCB128_CONTEXT]* ctx,
    unsigned char const* iv,
    size_t len,
    size_t taglen);
----

== Return Value

1 on success, or ‐1 if `len` or `taglen` is out of range.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| OCB context from CRYPTO_ocb128_new() or CRYPTO_ocb128_init().
| *iv*
| Nonce octets (1–15 bytes).
| *len*
| Length of `iv` in bytes.
| *taglen*
| Desired tag length in bytes (1–16).
|===


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