PKI encryption/decryption functions

Description

PKI.encrypt encrypts a raw vector

PKI.decrypt decrypts a raw vector

Usage

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PKI.encrypt(what, key, cipher = NULL)
PKI.decrypt(what, key, cipher = NULL)

Arguments

what

raw vector to encrypt/decrypt. It must not exceed the key size minus padding

key

key to use for encryption/decryption

cipher

cipher to use for encryption/decryption

Value

Raw vector (encrypted/decrypted)

Note

The cipher is optional for key objects that already contain the cipher information such as RSA keys (in fact it is ignored in that case).

Supported symmetric ciphers are AES-128, AES-256 and BF (blowfish). Each cipher can be used in CBC (default), ECB or OFB modes which are specified as suffix, so "aes256ofb" would specify AES-256 in OFB mode. Case and non-alphanumeric characters are ignored, so the same could be specified as "AES-256-OFB". PKCS padding is used to fill up to the block size. Analogously, PKCS padding is expected when decoding.

Note that the payload for RSA encryption should be very small since it must fit into the key size including padding. For example, 1024-bit key can only encrypt 87 bytes, while 2048-bit key can encrypt 215 bytes. Therefore a typical use is to use RSA to transfer a symmeric key to the peer and subsequently use symmetric ciphers like AES for encryption of larger amounts of data.

Author(s)

Simon Urbanek

See Also

PKI.genRSAkey, PKI.pubkey

Examples

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  key <- PKI.genRSAkey(2048)
  x <- charToRaw("Hello, world!")
  e <- PKI.encrypt(x, key)
  y <- PKI.decrypt(e, key)
  stopifnot(identical(x, y))
  print(rawToChar(y))

  ## AES symmetric - use SHA256 to support arbitrarily long key strings
  key <- PKI.digest(charToRaw("hello"), "SHA256")
  ae <- PKI.encrypt(x, key, "aes256")
  ae
  ad <- PKI.decrypt(ae, key, "aes256")
  stopifnot(identical(x, ad))