Key Property

The secret key for the hash algorithm.

Syntax

 hash.getKey([callback])
 hash.setKey( key_Buffer, [callback])

Default Value

""

Callback

The 'callback' parameter specifies a function which will be called when the operation completes (or an error is encountered). If the 'callback' parameter is not specified, then the method will block and will not return until the operation completes (or an error is encountered).

The callback for the getKey([callback]) method is defined as:

function(err, buffer){ }

'err' is the error that occurred. If there was no error, then 'err' is 'null'.

'buffer' is the value returned by the method.

The callback for the setKey([callback]) method is defined as:

function(err){ }

'err' is the error that occurred. If there was no error, then 'err' is 'null'.

'err' has 2 properties which hold detailed information:

err.code
err.message

Remarks

This property holds the secret key used when creating the hash. The key can be arbitrarily long.

Note: This property is only applicable when Algorithm is set to an HMAC algorithm.

It is recommended that the length of the key be equal to or larger than the hash size of the algorithm. Use of keys shorter than the hash size is discouraged.

Sizes (in bytes)

Key Length Details

As mentioned above it is recommended to use a key size equal to the hash size. Use of keys larger than the hash size does not typically significantly increase the function strength. Keys of any length are technically valid however see the below processing rules to understand how keys of varying lengths are treated:

• If the key length is equal to the hash size (recommended) it is used without modification.
• If the key length is less than the hash size it is used without modification.
• If the key length is less than or equal to the block size it is used without modification.
• If the key length is larger than the block size is it first hashed with the same algorithm.

Data Type

Buffer