I'm trying to create an R script that will execute the HMAC algorithm for key-hashing messages. My hope is to use this script for some web authentication via R.
The algorithm is found at http://www.ietf.org/rfc/rfc2104.txt Here is some example code that I have done that does not work for HMAC-MD5. I'm a big confused by the algorithm since I don't have a very good working knowledge of digests or hex strings. I would really appreciate some assistance if anyone can take a look at this code and offer advice. The RFC website does offer C code to execute the HMAC algorithm but I am not a C expert. ################ HMAC Code ############# library(digest) ########## hex to binary hexdat <- replicate(10, paste(format.hexmode(sample(16,4)-1),collapse='')) bin <- apply(outer(0:15,3:0,function(x,y) x%/%(2^y)%%2),1,paste,collapse="") names(bin) <- format.hexmode( 0:15 ) ## test ## cbind( hexdat, sapply( strsplit(hexdat,'') , function(x) paste( bin[x], collapse='' ) ) ) ########## binary to hex hex <- names(bin) names(hex) <- bin ############ Test HMAC_MD5 #################### ### B=64 ### L=16 #key <- "0x0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b" ##key_len = 16 bytes data <- "Hi There" ##data_len = 8 bytes ## digest = "0x9294727a3638bb1c13f48ef8158bfc9d" ipad <- rep("36",64) opad <- rep("5c",64) k <- rep("0b", 16) zeros <- rep("00",48) K <- c(k, zeros) K_bin <- cbind(K, sapply( strsplit(K,'') , function(x) paste( bin[x], collapse='' ) ) ) ipad_bin <- cbind(ipad, sapply( strsplit(ipad,'') , function(x) paste( bin[x], collapse='' ) ) ) #cbind(K_bin, sapply( strsplit(K_bin[,2],'') , as.numeric) ) K_binnum <- sapply( strsplit(K_bin[,2],'') , as.numeric) ipad_binnum <- sapply( strsplit(ipad_bin[,2],'') , as.numeric) InnerXOR <- as.numeric(xor(K_binnum, ipad_binnum)) InnerXOR <- matrix(InnerXOR, 4, 128) InnerXOR <- t(InnerXOR) InnerXORbin <- apply(InnerXOR, 1, paste, collapse='') InnerXORhex <- cbind(InnerXORbin, sapply(InnerXORbin, function(x) paste(hex[x], collapse='') )) InnerXORhex <- t(matrix(InnerXORhex[,2],2,64)) InnerXORhex <- apply(InnerXORhex, 1, paste, collapse='') dataHex <- charToRaw(data) cmb <- c(InnerXORhex, dataHex) cmb <- paste(cmb, collapse='') InnerHash <- digest(cmb, algo="md5") opad_bin <- cbind(opad, sapply( strsplit(opad,'') , function(x) paste( bin[x], collapse='' ) ) ) opad_binnum <- sapply( strsplit(opad_bin[,2],'') , as.numeric) OuterXOR <- as.numeric(xor(K_binnum, opad_binnum)) OuterXOR <- matrix(OuterXOR, 4, 128) OuterXOR <- t(OuterXOR) OuterXORbin <- apply(OuterXOR, 1, paste, collapse='') OuterXORhex <- cbind(OuterXORbin, sapply(OuterXORbin, function(x) paste(hex[x], collapse='') )) OuterXORhex <- t(matrix(OuterXORhex[,2],2,64)) OuterXORhex <- apply(OuterXORhex, 1, paste, collapse='') OuterXORhex <- paste(OuterXORhex, collapse='') outercmb <- paste(OuterXORhex, InnerHash, sep="") HMAC_MD5 <- digest(outercmb, algo="md5") ######## should equal the digest example above [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
