sha256: SHA-256 Cryptographic Hash Algorithm

In secretbase: Cryptographic Hash, Extendable-Output and Base64 Functions

SHA-256 Cryptographic Hash Algorithm

Description

Returns a SHA-256 hash of the supplied object or file, or HMAC if a secret key is supplied.

Usage

sha256(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] If NULL, the SHA-256 hash of ‘x’ is returned. Alternatively, supply a character string or raw vector as a secret key to generate an HMAC. 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 SHA-256 Secure Hash Standard was published by the National Institute of Standards and Technology (NIST) in 2002 at https://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf.

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

# SHA-256 hash as character string:
sha256("secret base")

# SHA-256 hash as raw vector:
sha256("secret base", convert = FALSE)

# SHA-256 hash a file:
file <- tempfile(); cat("secret base", file = file)
sha256(file = file)
unlink(file)

# SHA-256 HMAC using a character string secret key:
sha256("secret", key = "base")

# SHA-256 HMAC using a raw vector secret key:
sha256("secret", key = charToRaw("base"))

secretbase documentation built on Oct. 2, 2024, 5:07 p.m.