I am using following statement to create a RSA public and private key.
openssl genrsa -out ksign_private.pem 1024 openssl rsa -in ksign_private.pem -pubout > ksign_public.pem
Then I have program that uses, PEM_read_RSAPrivateKey, EVP_PKEY_assign_RSA, EVP_SignInit, EVP_SignUpdate, EVP_SignFinal functions from openssl libcrypto to generate signature file.
I also have routine that verifies that signature can be verified using PEM_read_RSA_PUBKEY, EVP_PKEY_assign_RSA, EVP_VerifyInit, EVP_VerifyUpdate, EVP_VerifyFinal. Source code for these routines is attached below.
When using these functions I can create SHA1 signature, encrypt it with private key, and decrypt it using public key.
However I tried to use the same data file, same private, public key using the openssl rsautl and the signature that is getting created by openssl rsautl is vastly different.
openssl dgst -sha1 -binary < myData > testfile.sha1
openssl rsautl -sign -in testfile.sha1 -inkey ksign_private.pem -keyform PEM -out testfile.sig
Can any one tell me what options I am using wrong when using openssl rsautl or dgst command?
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <ctype.h>
#include <unistd.h>
#include <string.h>
#include <openssl/sha.h>
#include <errno.h>
#include <getopt.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <openssl/evp.h>
#include <openssl/pem.h>
#include <openssl/rsa.h>
int ksignEvpSign(FILE * private_key, FILE * inFileFP, FILE * outFileFP);
int ksignEvpVerify(FILE * public_key, FILE * dataFileFP, FILE * signFileFP);
int ksignEvpSign(FILE * privateKeyFP, FILE * inFileFP, FILE * outFileFP)
{
RSA *rsa_pkey = NULL;
EVP_PKEY *pkey = EVP_PKEY_new();
EVP_MD_CTX ctx;
unsigned char buffer[4096];
size_t len;
unsigned char *sig;
unsigned int siglen;
if (!PEM_read_RSAPrivateKey(privateKeyFP, &rsa_pkey, NULL, NULL)) {
fprintf(stderr, "Error loading RSA Private Key File.\n");
return 2;
}
if (!EVP_PKEY_assign_RSA(pkey, rsa_pkey)) {
fprintf(stderr, "EVP_PKEY_assign_RSA: failed.\n");
return 3;
}
EVP_MD_CTX_init(&ctx);
if (!EVP_SignInit(&ctx, EVP_sha1())) {
fprintf(stderr, "EVP_SignInit: failed.\n");
EVP_PKEY_free(pkey);
return 3;
}
while ((len = fread(buffer, 1, sizeof buffer, inFileFP)) > 0) {
if (!EVP_SignUpdate(&ctx, buffer, len)) {
fprintf(stderr, "EVP_SignUpdate: failed.\n");
EVP_PKEY_free(pkey);
return 3;
}
}
if (ferror(inFileFP)) {
perror("input file");
EVP_PKEY_free(pkey);
return 4;
}
sig = malloc(EVP_PKEY_size(pkey));
if (!EVP_SignFinal(&ctx, sig, &siglen, pkey)) {
fprintf(stderr, "EVP_SignFinal: failed.\n");
free(sig);
EVP_PKEY_free(pkey);
return 3;
}
fwrite(sig, siglen, 1, outFileFP);
free(sig);
EVP_PKEY_free(pkey);
return 0;
}
int ksignEvpVerify(FILE * publicKeyFP, FILE * dataFileFP, FILE * sigFileFP)
{
RSA *rsa_pkey = NULL;
EVP_PKEY *pkey;
EVP_MD_CTX ctx;
unsigned char buffer[4096];
size_t len;
unsigned char *sig;
unsigned int siglen;
struct stat stat_buf;
if (!PEM_read_RSA_PUBKEY(publicKeyFP, &rsa_pkey, NULL, NULL)) {
fprintf(stderr, "Error loading RSA public Key File.\n");
return 2;
}
pkey = EVP_PKEY_new();
if (!EVP_PKEY_assign_RSA(pkey, rsa_pkey)) {
fprintf(stderr, "EVP_PKEY_assign_RSA: failed.\n");
return 3;
}
/* Read the signature */
if (fstat(fileno(sigFileFP), &stat_buf) == -1) {
fprintf(stderr, "Unable to read signature \n");
return 4;
}
siglen = stat_buf.st_size;
sig = (unsigned char *)malloc(siglen);
if (sig == NULL) {
fprintf(stderr, "Unable to allocated %d bytes for signature\n",
siglen);
return 5;
}
if ((fread(sig, 1, siglen, sigFileFP)) != siglen) {
fprintf(stderr, "Unable to read %d bytes for signature\n",
siglen);
return 6;
}
/*
printf("Signature:");
for (i = 0; i < siglen; i++) {
fprintf(stdout, "%02x", sig[i]);
if (i % 16 == 15)
fprintf(stdout, "\n");
}
fprintf(stdout, "\n");
*/
EVP_MD_CTX_init(&ctx);
if (!EVP_VerifyInit(&ctx, EVP_sha1())) {
fprintf(stderr, "EVP_SignInit: failed.\n");
EVP_PKEY_free(pkey);
return 7;
}
while ((len = fread(buffer, 1, sizeof buffer, dataFileFP)) > 0) {
if (!EVP_VerifyUpdate(&ctx, buffer, len)) {
fprintf(stderr, "EVP_SignUpdate: failed.\n");
EVP_PKEY_free(pkey);
return 8;
}
}
if (ferror(dataFileFP)) {
perror("input file");
EVP_PKEY_free(pkey);
return 9;
}
if (!EVP_VerifyFinal(&ctx, sig, siglen, pkey)) {
fprintf(stderr, "EVP_VerifyFinal: failed.\n");
free(sig);
EVP_PKEY_free(pkey);
return 10;
}
free(sig);
EVP_PKEY_free(pkey);
return 0;
}
The pkeyutl
command should be preferred to rsautl
since pkeyutl
can handle any algorithm. To obtain the same signature on the command line, you should use the following:
openssl pkeyutl -sign -in testfile.sha1 -inkey ksign_private.pem -pkeyopt digest:sha1 -outfile testfile.sig
The important part is telling openssl
that you're using a digest value. Otherwise it seems to be signing a digest of your digest.
You can directly use dgst
command to hash and sign data like:
openssl dgst -sha1 -binary -sign privkey.pem < myData > mySignature
see docs for all options.
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