Semiconductor & Computer Engineering
$sha1 calculates the sha1 hash of a text, binary variable, or file. Hash is 160-bits, shown as 40 lower-case hexadecimal characters.
Contents
Synopsis
$sha1(plaintext|&binaryvar|filename,[N])
Parameters
plaintext - Used with N = 0, just the string you want the sha1 hash of
&binaryvar - A binary variable, used with N = 1, return the sha1 hash of the content of the binvar
filename - A filename, used with N = 2, return the sha1 hash of the content of the file
N: Optional integer 0-2, where 0 indicates data is treated as plaintext, 1 indicates a &binary variable, 2 treats data as contents of a filename
If the N parameter isn't used, the default 0 is used (which is different than $crc which has default of N=2.)
Properties
None
Example
Echo the SHA1 hash of plain text string abc to the active window:
//echo -a $sha1(abc) or //echo -a $sha1(abc,0)
The DATA is case-sensitive, so hash of "abc" is different than hash of "ABC"
Echo the SHA1 hash of the contents of the mIRC program you're running to the active window:
//echo -a $sha1($mircexe,2)
Echo the SHA1 hash of the first 1000 bytes of the mIRC program you're running to the active window:
//bread $qt($mircexe) 0 1000 &snip | echo -a $sha1(&snip,1)
Mode 0 allows string to be null, including %variable not existing.
//unset %a | var %b $null | echo -a $sha1(%a) is $sha1(%b) is $sha1()
Mode 1 allows binvar to be zero length but not undefined.
//noop $regsubex(foo,$null,,,&v) | echo -a $bvar(&v) $sha1(&v,1) | echo -a $bvar(&v2) $sha1(&v2,1)
Mode 2 allows filesize to be zero but not missing.
//btrunc zero.dat 0 | echo -a $sha1(zero.dat,2) | remove zero.dat | echo -a $sha1(zero.dat,2)
Suggested Uses:
- Quick way to compare if 2 files are identical. (First check should always be comparing file sizes.)
- Quick way to check if a file's contents have changed since stored sha1 hash was made.
- Verify downloaded file hasn't been corrupted, matches the sender's original.
Note that because the default is N=0, $sha1($mircexe) is the SHA1 hash for the plaintext text string of the drive:\path\filename for the mIRC you're running, and not the hash of the filename contents. This differs from $crc($mircexe) giving the checksum of the filename contents because $crc has default of N=2.
mIRC v7.x Unicode-encodes plaintext before providing to $sha1, so v7.x and v6.x return different answers for //echo -a $sha1($chr(233))
If the text doesn't have Unicode code points above 255, to avoid having Unicode points 128-255 encoded to 2-byte pairs, the text must be fed to $sha1 as a binary variable:
//bset -ta &string 1 chloé | echo -a $sha1(&string,1)
Warning
From v7.54 back through at least v6.35, $sha1 corrupts the &binvar if the length is 128+ and a multiple of 64 and contains at least 1 byte that isn't 0x00. This affects using sha1 against &binvar in $hmac too. It returns the correct hash of the input &binvar in spite of destroying it.
//bset &v 128 1 | noop $sha1(&v,1) | echo -a $bvar(&v,1-)
Error Messages
Note that $sha1 differs from $crc in that it generates error for non-existent files instead of returning hash of $null string. Also, hex string returned by $sha1 is lowercase while $crc returns uppercase hex.
* Error accessing file: $sha1
Either file does not exist, or file permissions don't allow the file to be read. i.e. $sha1(non-existent-file,2) or $sha1(c:\hiberfil.sys,2)
* Invalid parameters: $sha1
Either using a zero-length/non-existent binary variable or specifying an N where $int(%N) isn't 0-2.
Both above errors halt execution of the script
Compatibility
Added: mIRC v6.3
Added on: 16 Aug 2007
Note: Unless otherwise stated, this was the date of original functionality.
Further enhancements may have been made in later versions.
