[#PEM_write_PrivateKey_ex]
= PEM_write_PrivateKey_ex
:mrdocs:

Write a private key to a FILE as PEM with an explicit library context.

== Synopsis

Declared in `<openssl/pem.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
PEM_write_PrivateKey_ex(
    FILE* fp,
    xref:EVP_PKEY.adoc[EVP_PKEY] const* x,
    xref:EVP_CIPHER-07.adoc[EVP_CIPHER] const* enc,
    unsigned char const* kstr,
    int klen,
    xref:pem_password_cb.adoc[pem_password_cb]* cb,
    void* u,
    xref:OSSL_LIB_CTX.adoc[OSSL_LIB_CTX]* libctx,
    char const* propq);
----

== Return Value

1 on success, or 0 on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *fp*
| FILE to write to.
| *x*
| Private key to encode.
| *enc*
| Cipher for PKCS#8 encryption, or NULL for unencrypted PrivateKeyInfo.
| *kstr*
| Optional passphrase bytes; if NULL and `enc` is set, `cb` is used.
| *klen*
| Length of `kstr` when provided.
| *cb*
| Password callback when a passphrase is needed, or NULL.
| *u*
| Application data passed to `cb.`
| *libctx*
| Library context used for provider‐backed encoding, or NULL for the default.
| *propq*
| Property query for algorithm fetches, or NULL.
|===


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