#Chapter 18: Rahash2
The it is quite easy to calculate a hash checksum of the current block using the '#' command.
$ radare2 /bin/ls
[0x08049790]> bf entry0
[0x08049790]> #md5
d2994c75adaa58392f953a448de5fba7
In the same way you can also calculate other hashing algorithms that are supported by 'rahash': md4, md5, crc16, crc32, sha1, sha256, sha384, sha512, par, xor, xorpair, mod255, hamdist, entropy, all.
The '#' command can accept a numeric argument to define the length in bytes to be hashed.
[0x08049A80]> #md5 32
9b9012b00ef7a94b5824105b7aaad83b
[0x08049A80]> #md5 64
a71b087d8166c99869c9781e2edcf183
[0x08049A80]> #md5 1024
a933cc94cd705f09a41ecc80c0041def
[0x08049A80]>
##18.1 Rahash2 tool
The rahash tool is the used by radare to realize these calculations. It
$ rahash2 -h
Usage: rahash2 [-rBhLkv] [-b sz] [-a algo] [-s str] [-f from] [-t to] [file] ...
-a algo comma separated list of algorithms (default is 'sha256')
-b bsize specify the size of the block (instead of full file)
-B show per-block hash
-e swap endian (use little endian)
-f from start hashing at given address
-i num repeat hash N iterations
-S seed use given seed (hexa or s:string) use ^ to prefix
-k show hash using the openssh's randomkey algorithm
-q run in quiet mode (only show results)
-L list all available algorithms (see -a)
-r output radare commands
-s string hash this string instead of files
-t to stop hashing at given address
-v show version information
It permits the calculation of the hashes from strings or files.
$ rahash2 -q -a md5 -s 'hello world'
5eb63bbbe01eeed093cb22bb8f5acdc3
It is possible to hash the full contents of a file . But dont do this for large files like disks or so, because rahash stores the buffer in memory before calculating the checksum instead of doing it progressively.
$ rahash2 -a all /bin/ls
/bin/ls: 0x00000000-0x0001ae08 md5: b5607b4dc7d896c0fab5c4a308239161
/bin/ls: 0x00000000-0x0001ae08 sha1: c8f5032c2dce807c9182597082b94f01a3bec495
/bin/ls: 0x00000000-0x0001ae08 sha256: 978317d58e3ed046305df92a19f7d3e0bfcb3c70cad979f24fee289ed1d266b0
/bin/ls: 0x00000000-0x0001ae08 sha384: 9e946efdbebb4e0ca00c86129ce2a71ee734ac30b620336c381aa929dd222709e4cf7a800b25fbc7d06fe3b184933845
/bin/ls: 0x00000000-0x0001ae08 sha512: 076806cedb5281fd15c21e493e12655c55c52537fc1f36e641b57648f7512282c03264cf5402b1b15cf03a20c9a60edfd2b4f76d4905fcec777c297d3134f41f
/bin/ls: 0x00000000-0x0001ae08 crc16: 4b83
/bin/ls: 0x00000000-0x0001ae08 crc32: 6e316348
/bin/ls: 0x00000000-0x0001ae08 md4: 3a75f925a6a197d26bc650213f12b074
/bin/ls: 0x00000000-0x0001ae08 xor: 3e
/bin/ls: 0x00000000-0x0001ae08 xorpair: 59
/bin/ls: 0x00000000-0x0001ae08 parity: 01
/bin/ls: 0x00000000-0x0001ae08 entropy: 0567f925
/bin/ls: 0x00000000-0x0001ae08 hamdist: 00
/bin/ls: 0x00000000-0x0001ae08 pcprint: 23
/bin/ls: 0x00000000-0x0001ae08 mod255: 1e
/bin/ls: 0x00000000-0x0001ae08 xxhash: 138c936d
/bin/ls: 0x00000000-0x0001ae08 adler32: fca7131b