[#CKey-Sign]
= xref:CKey.adoc[CKey]::Sign
:relfileprefix: ../
:mrdocs:

Create a DER‐serialized signature. The test_case parameter tweaks the deterministic nonce.

== Synopsis

Declared in `<key.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
bool
Sign(
    xref:uint256.adoc[uint256] const& hash,
    std::vector<unsigned char>& vchSig,
    bool grind = true,
    uint32_t test_case = 0) const;
----

== Return Value

true if signing succeeded.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *hash*
| The 32‐byte message hash to sign.
| *vchSig*
| Output buffer receiving the DER‐serialized signature.
| *grind*
| Whether to grind the nonce for a small (low‐R) signature.
| *test_case*
| Tweaks the deterministic nonce (for testing).
|===


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