[#CKeyID]
= CKeyID
:mrdocs:

A reference to a CKey: the Hash160 of its serialized public key

== Synopsis

Declared in `<pubkey.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class CKeyID
    : public xref:uint160.adoc[uint160]
----

== Base Classes

[cols="1,4"]
|===
| Name| Description
| `xref:uint160.adoc[uint160]`
| 160‐bit opaque blob.
|===

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:CKeyID/2constructor-01.adoc[`CKeyID`]         [.small]#[constructor]#
| Constructors
| xref:uint160/GetHex.adoc[`GetHex`] 
| The hex representation used by GetHex(), ToString(), and FromHex() is unusual, since it shows bytes of the base_blob in reverse order. For example, a 4‐byte blob {0x12, 0x34, 0x56, 0x78} is represented as "78563412" instead of the more typical "12345678" representation that would be shown in a hex editor or used by typical byte‐array / hex conversion functions like python's bytes.hex() and bytes.fromhex().
| xref:uint160/GetUint64.adoc[`GetUint64`] 
| Reads a 64‐bit little‐endian word from the blob at a byte offset.
| xref:uint160/IsNull.adoc[`IsNull`] 
| Returns true if every byte of the blob is zero.
| xref:uint160/Serialize.adoc[`Serialize`] 
| Serializes the blob's raw bytes to a stream.
| xref:uint160/SetNull.adoc[`SetNull`] 
| Sets every byte of the blob to zero.
| xref:uint160/ToString.adoc[`ToString`] 
| Returns the blob as a hex string in reverse byte order.
| xref:uint160/Unserialize.adoc[`Unserialize`] 
| Deserializes the blob's raw bytes from a stream.
| xref:uint160/begin-0a.adoc[`begin`] 
| Returns a pointer to the first byte of the blob.
| xref:uint160/data-0e.adoc[`data`] 
| Returns a pointer to the blob's raw bytes.
| xref:uint160/end-0c.adoc[`end`] 
| Returns a pointer just past the last byte of the blob.
| xref:CKeyID/fingerprint.adoc[`fingerprint`] 
| Get the fingerprint (first four bytes) of this key identifier.
| xref:uint160/operator_eq.adoc[`operator==`] 
| Compares two blobs for byte‐wise equality.
| xref:uint160/operator_3way.adoc[`operator<=>`] 
| Lexicographic ordering
|===


== Static Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:uint160/FromHex.adoc[`FromHex`] 
| Parses a uint160 from a hex string.
| xref:uint160/size.adoc[`size`] 
| Returns the size of the blob in bytes.
|===


== Protected Data Members

[cols="1,4"]
|===
| Name| Description
| xref:uint160/m_data.adoc[`m_data`] 
| Fixed‐size byte storage holding the blob's raw bytes.
|===


== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:GetKeyForDestination.adoc[`GetKeyForDestination`]
| Return the CKeyID of the key involved in a script (if there is a unique one).
| xref:ToKeyID-00.adoc[`ToKeyID`]
| Convert a witness key‐hash destination back to a key identifier.
| xref:ToKeyID-09.adoc[`ToKeyID`]
| Convert a public‐key‐hash destination back to a key identifier.
|===


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