FunctionPackage: exclToCDocOverviewCGDocRelNotesFAQIndexPermutedIndex
Allegro CL version 9.0
Moderately revised from 8.2.
8.2 version


Arguments: context &key return

Finalize and return the SHA1 hash from context in a format determined by the return keyword argument.

return can be one of the following values:

cl-user(4): (setq c (sha1-init))
#S(excl::md-context :ctx 156672 :size 20)
cl-user(5): (sha1-update c "foo")
cl-user(6): (sha1-final c :return :usb8)
#(11 238 199 181 234 63 15 219 201 93 ...)

;;  Potential problem with :return :integer (or :return unspecified
;;  as the default is :integer). The call is to SHA1-FILE which calls
;;  SHA1-FINAL and returns the value SHA1-FINAL returns.
;;  Here we get the sha1 value in a shell:
%  openssl dgst -sha1 -hex cmp05-optdialog.jpg
SHA1(cmp05-optdialog.jpg)= 9bd9c1bbd45ec006e281cf056227898c5996bb87

;; Now we get it with SHA1-FILE:
cl-user(17): (sha1-file "~/cmp05-optdialog.jpg")
cl-user(18): (format t "~x" *)

;; Note the hex values are the same but the leading 0 is not printed
;; by Lisp, which is dealing with the value as an integer. The leading
;; 0 is preserved when the :return is :hex:
cl-user(21): (sha1-file "~/cmp05-optdialog.jpg" :return :hex)

See MD*, SHA*, HMAC, and other message digest support in miscellaneous.htm. See also digest-final.

Copyright (c) 1998-2017, Franz Inc. Oakland, CA., USA. All rights reserved.
This page has had moderate revisions compared to the 8.2 page.
Created 2017.2.15.

Allegro CL version 9.0
Moderately revised from 8.2.
8.2 version