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Thursday, August 25, 2016

R Script arguments from Command Line

Passing RScript arguments from Command Line

There may be situations where you might want to execute R scripts from command line and passing appropriate arguments as batch. So here is an example below

"C:\Program Files\R\R-3.3.0\bin\RScript.exe" args.R 2016-08-01 28 1 30 > args.t

In the above I have specified the location of the RScript.exe on my local computer and args.R is the R script that I want to run from command line and the arguments are 2016-08-01 which is a Date in the format yyyy-mm-dd, then 28 and then 1 and 30 and the result of the execution will get saved in args.txt file which is the output of the execution.

Here is the sample R script code below

args <- commandArgs(TRUE)

# test if there is at least one argument: if not, return an error
if (length(args)==0) {
  stop("First parameter is a required argumenst.n", call.=FALSE)


startDate <- as.Date(args[1])
sId <- eval(parse(text=args[2]))
min <- eval(parse(text=args[3]))
max <- eval(parse(text=args[4]))

#write the variables as observations of a dataframe
columnNames <- c('sId', 'startDate', 'min', 'max')
columnValues <- c(sId, startDate, min, max)
df = data.frame(columnNames, columnValues)
write.csv(df, file = "C:/args.csv", row.names=F)

The data frame created above gets saved as a csv file for review. Please note internally Date is represented as integer in R.

Wednesday, August 17, 2016

Self-Signed Certificates with Microsoft Enhanced RSA and AES Cryptographic Provider

Creating Enhanced SHA256 self-signed certificates

There are 2 options to create self-signed certificates very easily

using windows makecert

The following command can be run from the command prompt to create a self-signed certificate. Based on location of the makecert.exe on you machine, the path might differ. I am using a Windows 8.1
"C:\Program Files (x86)\Windows Kits\8.1\bin\x86\makecert.exe" -n "CN=Local" -r -pe -a sha256 -len 2048 -cy authority -e 03/03/2017 -sv Local.pvk Local.cer

"C:\Program Files (x86)\Windows Kits\8.1\bin\x86\pvk2pfx.exe" -pvk Local.pvk -spc Local.cer -pfx Local.pfx -po MyPassword -sy 24

using openSSL

you can use openSSL that comes with Apache Webserver to get the same thing done as follows

openssl.exe req -x509 -nodes -sha256 -days 3650 -subj "/CN=Local" -newkey rsa:2048 -keyout Local.key -out Local.crt

openssl.exe pkcs12 -export -in Local.crt -inkey Local.key -CSP "Microsoft Enhanced RSA and AES Cryptographic Provider" -out Local.pfx

Difference Between Above two

One major and most important difference between the 2 above is makecert is not able to create the certificate file with CSP of 24 as provided as provided as parameter so while using this *pfx file to sign any XML as SHA256 will give exception like "Invalid Algorithm Specified" because the CSP value remains 1 instead of 24.

The one created by Open SSL will come out with correct CSP value and will give any errors.

Check Keys of Generated Certificate

You can write a small test program to test the Keys generated by the certificates in the above 2 methods.

class Program
        static void Main(string[] args)
            var x509Certificate = new X509Certificate2(@"Local.pfx", 
                "LocalSTS", X509KeyStorageFlags.Exportable);