hmac {digest}

compute a hash-based message authentication code

Description

The hmac function calculates a message authentication code (MAC) involving the specified cryptographic hash function in combination with a given secret key.

Usage

hmac(key, object,
     algo = c("md5", "sha1", "crc32", "sha256", "sha512"),
     serialize = FALSE, raw = FALSE, ...)

Arguments

key

An arbitrary character or numeric vector, to use as pre-shared secret key.

object

An arbitrary R object which will then be passed to the serialize function, unless the serialize argument is set to FALSE.

algo

The algorithms to be used; currently available choices are md5, which is also the default, sha1, crc32 and sha256.

serialize

default value of serialize is here FALSE, not TRUE as it is in digest.

raw

This flag alters the type of the output. Setting this to TRUE causes the function to return an object of type "raw" instead of "character".

...

All remaining arguments are passed to digest.

Value

The hmac function uses the digest to return a hash digest as specified in the RFC 2104.

Author(s)

Mario Frasca [e-mail].

References

MD5: https://www.ietf.org/rfc/rfc1321.txt.

SHA-1: https://en.wikipedia.org/wiki/SHA-1. SHA-256: https://csrc.nist.gov/publications/fips/fips180-2/fips180-2withchangenotice.pdf. CRC32: The original reference webpage at rocksoft.com has vanished from the web; see https://en.wikipedia.org/wiki/Cyclic_redundancy_check for general information on CRC algorithms.

https://aarongifford.com/computers/sha.html for the integrated C implementation of sha-512.

The page for the code underlying the C functions used here for sha-1 and md5, and further references, is no longer accessible. Please see https://en.wikipedia.org/wiki/SHA-1 and https://en.wikipedia.org/wiki/MD5.

https://zlib.net for documentation on the zlib library which supplied the code for crc32.

https://en.wikipedia.org/wiki/SHA_hash_functions for documentation on the sha functions.

See Also

digest

Examples

## Standard RFC 2104 test vectors
current <- hmac('Jefe', 'what do ya want for nothing?', "md5")
target <- '750c783e6ab0b503eaa86e310a5db738'
stopifnot(identical(target, as.character(current)))

current <- hmac(rep(0x0b, 16), 'Hi There', "md5")
target <- '9294727a3638bb1c13f48ef8158bfc9d'
stopifnot(identical(target, as.character(current)))

current <- hmac(rep(0xaa, 16), rep(0xdd, 50), "md5")
target <- '56be34521d144c88dbb8c733f0e8b3f6'
stopifnot(identical(target, as.character(current)))

## SHA1 tests inspired to the RFC 2104 and checked against the python
## hmac implementation.
current <- hmac('Jefe', 'what do ya want for nothing?', "sha1")
target <- 'effcdf6ae5eb2fa2d27416d5f184df9c259a7c79'
stopifnot(identical(target, as.character(current)))

current <- hmac(rep(0x0b, 16), 'Hi There', "sha1")
target <- '675b0b3a1b4ddf4e124872da6c2f632bfed957e9'
stopifnot(identical(target, as.character(current)))

current <- hmac(rep(0xaa, 16), rep(0xdd, 50), "sha1")
target <- 'd730594d167e35d5956fd8003d0db3d3f46dc7bb'
stopifnot(identical(target, as.character(current)))