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| Allegro CL version 9.0 Moderately revised from 8.2. 8.2 version

## sha1-update

Arguments: context data &key start end external-format

Add data to the running SHA1 computation in context (sha1-init returns a context). data may be a string or an (unsigned-byte 8) vector.

If data is a string, the start and end keyword arguments specify character positions in the string. start defaults to 0 and end defaults to `nil`, equivalent to the length of the string. external-format specifies the external hashing of the string that will be used to update the context. If not specified, the default external format will be used.

If data is an (unsigned-byte 8) vector, start and end refer to locations in the vector (again defaulting to 0 and `nil`, meaning the length of the vector). external-format is ignored.

Earlier versions of sha1-update had two required and one optional argument, len, specifying the number of characters of the argument string to use (that is, start was hardwired to 0 and the optional argument specified a value for end). This argument style is still accepted, though with a warning. Note len refers to the number of characters, not the number of bytes in the external hashing.

This function returns no values, but side-effects context.

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

Copyright (c) 1998-2019, Franz Inc. Oakland, CA., USA. All rights reserved.
This page has had moderate revisions compared to the 8.2 page.
Created 2019.8.20.

|  | ToC | DocOverview | CGDoc | RelNotes | FAQ | Index | PermutedIndex
| Allegro CL version 9.0 Moderately revised from 8.2. 8.2 version