# Io Reference

Digests / SHA1 / SHA1

|  | An object for calculating SHA1 hashes. Each hash calculation should instantiate its own SHA1 instance. Example:
    digest := SHA1 clone
    digest appendSeq("this is a message")
    out := digest md5String
|  | appendSeq(aSequence) Appends aSequence to the hash calculation. Returns self. hmac(key, data) Returns a hmac signature sequence or nil on error. sha1 Completes the SHA1 calculation and returns the hash as a Buffer. Once this method is called, append() should not be called again on the receiver or it will raise an exception. sha1String Returns a string containing a hexadecimal representation of the sha1 hash.