| DESCRIPTION | 
| Purpose | A dkim_sigkey_t points to the private key to be
    used to sign messages.  It should be a contiguous block of memory
    containing the private key either in PEM format, or in base64-encoded
    DER format, terminated by a NUL character.  (For now, it is simply a
    pointer to a string of type unsigned char.) |  | 
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