md4-final

Arguments: context &key return

Finalize and return the MD4 hash from context in a format determined by the return keyword argument.

return can be one of the following values:

• :integer (the default): the return value is an integer of up to 128 bits representing the digest. Warning: note that an integer representation of the digest potentially loses information if the generated signature has leading octets containing only zeroes. Care should be taking when using this return type if you intend to further encode the signature (such as to a base64-encoded string). See the example below.
• :usb8: return an (unsigned-byte 8) array containing the digest.
• :hex: return a string containing the hexadecimal representation of the digest. See hex-string-to-integer.

cl-user(4): (setq c (md4-init))
#S(excl::md-context :ctx 24752192 :size 16)
cl-user(5): (md4-update c "foo")
cl-user(6): (md4-final c :return :usb8)
#(10 198 112 12 73 29 112 251 134 80 ...)

;;  Potential problem with :return :integer (or :return unspecified
;;  as the default is :integer). The call is to MD4-FILE which calls
;;  MD4-FINAL and returns the value MD4-FINAL returns.
;;
;;  Here we get the md4 value in a shell:
% openssl dgst -md4 -hex image-lubm-report.jpg 
MD4(image-lubm-report.jpg)= fafa002127c737695df8449a51cbecb5

;; Now we get it with MD4-FILE:
cl-user(7): (md4-file "~/image-lubm-report.jpg")
333605075787702791398779221664703704245
cl-user(8): (format t "~x" *)
fafa002127c737695df8449a51cbecb5
nil
cl-user(9): 

;; Note the hex values are the same but if there is a leading 0
;; it is not printed by Lisp, which is dealing with the value 
;; as an integer. The leading 0 is preserved when the :return is :hex.

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

Copyright (c) 1998-2022, Franz Inc. Lafayette, CA., USA. All rights reserved.
This page was not revised from the 10.0 page.
Created 2019.8.20.