[#OSSL_HPKE_open]
= OSSL_HPKE_open
:mrdocs:

Decrypt ciphertext with AEAD using secrets derived by a prior OSSL_HPKE_decap().

== Synopsis

Declared in `<openssl/hpke.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
OSSL_HPKE_open(
    xref:OSSL_HPKE_CTX.adoc[OSSL_HPKE_CTX]* ctx,
    unsigned char* pt,
    size_t* ptlen,
    unsigned char const* aad,
    size_t aadlen,
    unsigned char const* ct,
    size_t ctlen);
----

== Return Value

1 on success, or 0 on error.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| Receiver HPKE context after successful decapsulation.
| *pt*
| Destination plaintext buffer; on input *`ptlen` is its capacity.
| *ptlen*
| In/out plaintext length (updated with bytes written).
| *aad*
| Optional additional authenticated data, or NULL if `aadlen` is 0.
| *aadlen*
| Length of `aad` in bytes.
| *ct*
| Ciphertext to decrypt (same order as produced by OSSL_HPKE_seal()).
| *ctlen*
| Length of `ct` in bytes.
|===


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