SHAKE256 Extendable Output Function

Returns a SHAKE256 hash of the supplied object or file.

Usage

shake256(x, bits = 256L, convert = TRUE, file)

Arguments

x

object to hash. A character string or raw vector (without attributes) is hashed as is. All other objects are stream hashed using native R serialization.

bits

integer output size of the returned hash. Value must be between 8 and 2^24.

convert

logical TRUE to convert the hash to its hex representation as a character string, FALSE to return directly as a raw vector, or NA to return as a vector of (32-bit) integers.

file

character file name / path. If specified, x is ignored. The file is stream hashed, and the file can be larger than memory.

Value

A character string, raw or integer vector depending on convert.

Details

To produce single integer values suitable for use as random seeds for R's pseudo random number generators (RNGs), set bits to 32 and convert to NA.

R Serialization Stream Hashing

Where this is used, serialization is always version 3 big-endian representation and the headers (containing R version and native encoding information) are skipped to ensure portability across platforms.

As hashing is performed in a streaming fashion, there is no materialization of, or memory allocation for, the serialized object.

References

This implementation is based on one by 'The Mbed TLS Contributors' under the 'Mbed TLS' Trusted Firmware Project at https://www.trustedfirmware.org/projects/mbed-tls.

Examples

# SHAKE256 hash as character string:
shake256("secret base")
#> [1] "995ebac18dbfeb170606cbbc0f2accce85db4db0dcf4fbe4d3efaf8ccf4e0a94"

# SHAKE256 hash as raw vector:
shake256("secret base", convert = FALSE)
#>  [1] 99 5e ba c1 8d bf eb 17 06 06 cb bc 0f 2a cc ce 85 db 4d b0 dc f4 fb e4 d3
#> [26] ef af 8c cf 4e 0a 94

# SHAKE256 hash to integer:
shake256("secret base", bits = 32L, convert = NA)
#> [1] -1044750695

# SHAKE256 hash a file:
file <- tempfile(); cat("secret base", file = file)
shake256(file = file)
#> [1] "995ebac18dbfeb170606cbbc0f2accce85db4db0dcf4fbe4d3efaf8ccf4e0a94"
unlink(file)