digest (version 0.6.10)

AES: Create AES block cipher object

Description

This creates an object that can perform the Advanced Encryption Standard (AES) block cipher.

Usage

AES(key, mode=c("ECB", "CBC", "CTR"), IV=NULL)

Arguments

key
The key as a 16, 24 or 32 byte raw vector for AES-128, AES-192 or AES-256 respectively.
mode
The encryption mode to use. Currently only “electronic codebook” (ECB), “cipher-block chaining” (CBC) and “counter” (CTR) modes are supported.
IV
The initial vector for CBC mode or initial counter for CTR mode.

Value

An object of class "AES". This is a list containing the following component functions:

Details

The standard NIST definition of CTR mode doesn't define how the counter is updated, it just requires that it be updated with each block and not repeat itself for a long time. This implementation treats it as a 128 bit integer and adds 1 with each successive block.

References

United States National Institute of Standards and Technology (2001). "Announcing the ADVANCED ENCRYPTION STANDARD (AES)". Federal Information Processing Standards Publication 197. http://csrc.nist.gov/publications/fips/fips197/fips-197.pdf.

Morris Dworkin (2001). "Recommendation for Block Cipher Modes of Operation". NIST Special Publication 800-38A 2001 Edition. http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf.

Examples

Run this code
# First in ECB mode: the repeated block is coded the same way each time
msg <- as.raw(c(1:16, 1:16))
key <- as.raw(1:16)
aes <- AES(key, mode="ECB")
aes$encrypt(msg)
aes$decrypt(aes$encrypt(msg), raw=TRUE)

# Now in CBC mode:  each encoding is different
iv <- sample(0:255, 16, replace=TRUE)
aes <- AES(key, mode="CBC", iv)
code <- aes$encrypt(msg)
code

# Need a new object for decryption in CBC mode
aes <- AES(key, mode="CBC", iv)
aes$decrypt(code, raw=TRUE)

# FIPS-197 examples

hextextToRaw <- function(text) {
  vals <- matrix(as.integer(as.hexmode(strsplit(text, "")[[1]])), ncol=2, byrow=TRUE)
  vals <- vals %*% c(16, 1)
  as.raw(vals)
}

plaintext       <- hextextToRaw("00112233445566778899aabbccddeeff")

aes128key       <- hextextToRaw("000102030405060708090a0b0c0d0e0f")
aes128output    <- hextextToRaw("69c4e0d86a7b0430d8cdb78070b4c55a")
aes <- AES(aes128key)
aes128 <- aes$encrypt(plaintext)
stopifnot(identical(aes128, aes128output))
stopifnot(identical(plaintext, aes$decrypt(aes128, raw=TRUE)))

aes192key       <- hextextToRaw("000102030405060708090a0b0c0d0e0f1011121314151617")
aes192output    <- hextextToRaw("dda97ca4864cdfe06eaf70a0ec0d7191")
aes <- AES(aes192key)
aes192 <- aes$encrypt(plaintext)
stopifnot(identical(aes192, aes192output))
stopifnot(identical(plaintext, aes$decrypt(aes192, raw=TRUE)))

aes256key       <- hextextToRaw("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f")
aes256output     <- hextextToRaw("8ea2b7ca516745bfeafc49904b496089")
aes <- AES(aes256key)
aes256 <- aes$encrypt(plaintext)
stopifnot(identical(aes256, aes256output))
stopifnot(identical(plaintext, aes$decrypt(aes256, raw=TRUE)))

# SP800-38a examples

plaintext <- hextextToRaw(paste("6bc1bee22e409f96e93d7e117393172a",
                                "ae2d8a571e03ac9c9eb76fac45af8e51", 
                                "30c81c46a35ce411e5fbc1191a0a52ef", 
                                "f69f2445df4f9b17ad2b417be66c3710",sep=""))
key <- hextextToRaw("2b7e151628aed2a6abf7158809cf4f3c")
                                 
ecb128output <- hextextToRaw(paste("3ad77bb40d7a3660a89ecaf32466ef97",
                                   "f5d3d58503b9699de785895a96fdbaaf",
                                   "43b1cd7f598ece23881b00e3ed030688",
                                   "7b0c785e27e8ad3f8223207104725dd4",sep=""))
aes <- AES(key)
ecb128 <- aes$encrypt(plaintext)
stopifnot(identical(ecb128, ecb128output))
stopifnot(identical(plaintext, aes$decrypt(ecb128, raw=TRUE)))

cbc128output <- hextextToRaw(paste("7649abac8119b246cee98e9b12e9197d",
                                   "5086cb9b507219ee95db113a917678b2",
                                   "73bed6b8e3c1743b7116e69e22229516",
                                   "3ff1caa1681fac09120eca307586e1a7",sep=""))
iv <- hextextToRaw("000102030405060708090a0b0c0d0e0f")
aes <- AES(key, mode="CBC", IV=iv)
cbc128 <- aes$encrypt(plaintext)
stopifnot(identical(cbc128, cbc128output))
aes <- AES(key, mode="CBC", IV=iv)
stopifnot(identical(plaintext, aes$decrypt(cbc128, raw=TRUE)))
 
ctr128output <- hextextToRaw(paste("874d6191b620e3261bef6864990db6ce",
                                   "9806f66b7970fdff8617187bb9fffdff",
                                   "5ae4df3edbd5d35e5b4f09020db03eab",
                                   "1e031dda2fbe03d1792170a0f3009cee",sep=""))
iv <- hextextToRaw("f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff")
aes <- AES(key, mode="CTR", IV=iv)
ctr128 <- aes$encrypt(plaintext)
stopifnot(identical(ctr128, ctr128output))
aes <- AES(key, mode="CTR", IV=iv)
stopifnot(identical(plaintext, aes$decrypt(ctr128, raw=TRUE)))

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