siphash13 {secretbase}

SipHash Pseudorandom Function

Description

Returns a fast, cryptographically-strong SipHash keyed hash of the supplied object or file. SipHash-1-3 is optimised for performance. Note: SipHash is not a cryptographic hash algorithm.

Usage

siphash13(x, key = NULL, 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 R serialization (but without allocation of the serialized object).

key

[default NULL] a character string or raw vector comprising the 16 byte (128 bit) key data, or else NULL which is equivalent to '0'. If a longer vector is supplied, only the first 16 bytes are used, and if shorter, padded with trailing '0'. Note: for character vectors only the first element is used.

convert

[default TRUE] if TRUE, the hash is converted to its hex representation as a character string, if FALSE, output directly as a raw vector, or if NA, a vector of (32-bit) integer values.

file

character file name / path. If specified, 'x' is ignored. The file is stream hashed, thus capable of handling files larger than memory.

Value

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

R Serialization Stream Hashing

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

References

The SipHash family of cryptographically-strong pseudorandom functions (PRFs) are described in 'SipHash: a fast short-input PRF', Jean-Philippe Aumasson and Daniel J. Bernstein, Paper 2012/351, 2012, Cryptology ePrint Archive at https://ia.cr/2012/351.

This implementation is based on the SipHash streaming implementation by Daniele Nicolodi, David Rheinsberg and Tom Gundersen at https://github.com/c-util/c-siphash. This is in turn based on the SipHash reference implementation by Jean-Philippe Aumasson and Daniel J. Bernstein released to the public domain at https://github.com/veorq/SipHash.

Examples

# SipHash-1-3 hash as character string:
siphash13("secret base")

# SipHash-1-3 hash as raw vector:
siphash13("secret base", convert = FALSE)

# SipHash-1-3 hash using a character string key:
siphash13("secret", key = "base")

# SipHash-1-3 hash using a raw vector key:
siphash13("secret", key = charToRaw("base"))

# SipHash-1-3 hash a file:
file <- tempfile(); cat("secret base", file = file)
siphash13(file = file)
unlink(file)