signature_create {openssl}

Signatures

Description

Sign and verify a message digest. RSA supports both MD5 and SHA signatures whereas DSA and EC keys only support SHA. ED25591 can sign any payload so you can set hash to NULL to sign the raw input data.

Usage

signature_create(data, hash = sha1, key = my_key(), password = askpass)

signature_verify(data, sig, hash = sha1, pubkey = my_pubkey())

ecdsa_parse(sig)

ecdsa_write(r, s)

Arguments

data

raw data vector or file path for message to be signed. If hash == NULL then data must be a hash string or raw vector.

hash

the digest function to use. Must be one of md5(), sha1(), sha256(), sha512() or NULL.

key

private key or file path. See read_key().

password

string or a function to read protected keys. See read_key().

sig

raw vector or file path for the signature data.

pubkey

public key or file path. See read_pubkey().

r

bignum value for r parameter

s

bignum value for s parameter

Details

The ecdsa_parse and ecdsa_write functions convert (EC)DSA signatures between the conventional DER format and the raw ⁠(r,s)⁠ bignum pair. Most users won't need this, it is mostly here to support the JWT format (which does not use DER).

Examples

# Generate a keypair
key <- rsa_keygen()
pubkey <- key$pubkey

# Sign a file
data <- system.file("DESCRIPTION")
sig <- signature_create(data, key = key)
stopifnot(signature_verify(data, sig, pubkey = pubkey))

# Sign raw data
data <- serialize(iris, NULL)
sig <- signature_create(data, sha256, key = key)
stopifnot(signature_verify(data, sig, sha256, pubkey = pubkey))

# Sign a hash
md <- md5(data)
sig <- signature_create(md, hash = NULL, key = key)
stopifnot(signature_verify(md, sig, hash = NULL, pubkey = pubkey))
#
# ECDSA example
data <- serialize(iris, NULL)
key <- ec_keygen()
pubkey <- key$pubkey
sig <- signature_create(data, sha256, key = key)
stopifnot(signature_verify(data, sig, sha256, pubkey = pubkey))

# Convert signature to (r, s) parameters and then back
params <- ecdsa_parse(sig)
out <- ecdsa_write(params$r, params$s)
identical(sig, out)