10564b1175
groff 1.23.0 added .MR to its -man macro package. The NEWS file states
that the inclusion of the macro "was prompted by its introduction to
Plan 9 from User Space's troff in August 2020." From d32deab it seems
that the name for Plan 9 from User Space's implementation was suggested
by groff maintainer G. Brandon Robinson.
Not sure if the intention was to make these definitions compatible, but
it would be nice if they were.
Currently, Plan 9 from User Space's .MR expects its second argument to
be parenthesized. groff's .MR does not. This results in extra
parentheses appearing in manual references when viewing Plan 9 from User
Space's manual pages on a system using groff.
88 lines
2.0 KiB
Groff
88 lines
2.0 KiB
Groff
.TH ENCRYPT 3
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.SH NAME
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encrypt, decrypt, netcrypt \- DES encryption
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.SH SYNOPSIS
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.B #include <u.h>
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.br
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.B #include <libc.h>
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.PP
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.B
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int encrypt(void *key, void *data, int len)
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.PP
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.B
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int decrypt(void *key, void *data, int len)
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.PP
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.B
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int netcrypt(void *key, void *data)
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.SH DESCRIPTION
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.I Encrypt
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and
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.I decrypt
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perform DES encryption and decryption.
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.I Key
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is an array of
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.B DESKEYLEN
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(defined as 7 in
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.BR <auth.h> )
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bytes containing the encryption key.
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.I Data
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is an array of
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.I len
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bytes;
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it must be at least 8 bytes long.
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The bytes are encrypted or decrypted in place.
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.PP
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The DES algorithm encrypts an individual 8-byte block of data.
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.I Encrypt
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uses the following method to encrypt data longer than 8 bytes.
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The first 8 bytes are encrypted as usual.
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The last byte of the encrypted result
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is prefixed to the next 7 unencrypted bytes to make the next 8
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bytes to encrypt.
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This is repeated until fewer than 7 bytes remain unencrypted.
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Any remaining unencrypted bytes are encrypted with enough of the preceding
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encrypted bytes to make a full 8-byte block.
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.I Decrypt
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uses the inverse algorithm.
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.PP
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.I Netcrypt
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performs the same encryption as a SecureNet Key.
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.I Data
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points to an
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.SM ASCII
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string of decimal digits with numeric value between 0 and 10000.
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These digits are copied into an 8-byte buffer with trailing binary zero fill
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and encrypted as one DES block.
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The first four bytes are each formatted as two digit
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.SM ASCII
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hexadecimal numbers,
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and the string is copied into
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.IR data .
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.SH SOURCE
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.B \*9/src/lib9
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.SH DIAGNOSTICS
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These routines return 1 if the data was encrypted,
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and 0 if the encryption fails.
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.I Encrypt
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and
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.I decrypt
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fail if the data passed is less than 8 bytes long.
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.I Netcrypt
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can fail if it is passed invalid data.
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.\" .SH SEE ALSO
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.\" .IR securenet (8)
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.SH BUGS
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The implementation is broken in a way that makes
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it unsuitable for anything but authentication.
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.PP
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To avoid name conflicts with the underlying system,
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.IR encrypt
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and
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.IR decrypt
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are preprocessor macros defined as
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.IR p9encrypt
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and
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.IR p9decrypt ;
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see
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.MR intro 3 .
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