First cut of a working code block that authenticates from R to Joyent Manta.

r_manta_api_test.R

# install.packages(c("RCurl","RJSONIO"), dependencies = TRUE)
require(RCurl); require(RJSONIO);
ACTION="/cwvhogue/stor"
MANTA_USER<-Sys.getenv("MANTA_USER");
MANTA_KEY_ID<-Sys.getenv("MANTA_KEY_ID");
MANTA_URL<-Sys.getenv("MANTA_URL");
USER_HOME<-Sys.getenv("HOME");
USER_KEY<-"/.ssh/id_rsa";
key_location<-paste(USER_HOME,USER_KEY,sep="");
openssl_cmd="openssl";
digest_args<-paste("dgst -sha256 -sign", key_location, "-out temp_digest.bin", sep=" ");
encrypt_args<-"enc -in temp_digest.bin -e -a";
alg<-"rsa-sha256";
keyID<-paste("/",MANTA_USER,"/keys/",MANTA_KEY_ID, sep="");
the_time_now<-format(as.POSIXlt(Sys.time(), "UTC"), "%a, %d %h %Y %H:%M:%S GMT");
sig_to_digest<-paste("date:",the_time_now, sep=" ");
# write sig_to_digest to a binary file without any CR
con <- file("sig_to_digest.bin", 'wb');
writeBin(charToRaw(sig_to_digest), con);
close(con);
system2(openssl_cmd, args=digest_args, stdin="sig_to_digest.bin", stdout=FALSE);
#this will need some kind of test to see if temp_digest.bin was formed 
sig_encrypted<-paste(system2(openssl_cmd, args=encrypt_args, stdout=TRUE), collapse='');
gone<-file.remove("temp_digest.bin");
gone<-file.remove("sig_to_digest.bin");
manta_url<-paste(
MANTA_URL,
ACTION, sep="");
auth_header<-paste("Signature keyId=", 
'\"', 
keyID, 
'\",',
'algorithm=\"', 
alg, 
'\"', 
',signature=\"',
sig_encrypted,
'\"', 
sep="");
R_version<-as.character(getRversion());
RAPI_USER<-paste("R/",R_version,"/",MANTA_USER,sep="");
manta_headers<-c( 'User-Agent'=RAPI_USER , date=the_time_now, Authorization=auth_header);
json_manta_reply<-getURL(manta_url, httpheader=manta_headers, verbose = TRUE);
fromJSON(json_manta_reply);
#