[#ASN1_item_verify_ctx]
= ASN1_item_verify_ctx
:mrdocs:

Verify `signature` over the ASN.1 encoding of `data` using digest context `ctx.`

== Synopsis

Declared in `<openssl/x509.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
ASN1_item_verify_ctx(
    xref:ASN1_ITEM.adoc[ASN1_ITEM] const* it,
    xref:X509_ALGOR.adoc[X509_ALGOR] const* alg,
    xref:ASN1_BIT_STRING.adoc[ASN1_BIT_STRING] const* signature,
    void const* data,
    xref:EVP_MD_CTX.adoc[EVP_MD_CTX]* ctx);
----

== Return Value

1 if the signature is valid, 0 if invalid, or a negative value on error.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *it*
| ASN.1 item describing the signed structure type of `data.`
| *alg*
| Signature AlgorithmIdentifier.
| *signature*
| BIT STRING signature value.
| *data*
| Pointer to the structure instance to re‐encode and verify.
| *ctx*
| Digest/verify context already configured with the public key and algorithm.
|===


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