【OpenSSL】Generation of RSA key pair

Generating RSA key pair

code

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

# include <openssl/bio.h>
# include <openssl/err.h>
# include <openssl/bn.h>
# include <openssl/rsa.h>
# include <openssl/evp.h>
# include <openssl/x509.h>
# include <openssl/pem.h>
# include <openssl/rand.h>

int main(int argc, char * argv[])
{
BIO *out = BIO_new(BIO_s_file());
BIO_write_filename(out, (char*)"bobkey.pem");

BIGNUM *bn = BN_new();
BN_set_word(bn, RSA_F4);

RSA *rsa = RSA_new();
RSA_generate_key_ex(rsa, 2048 /*key bits*/, bn, NULL);

PEM_write_bio_RSAPrivateKey(out
, rsa
, EVP_des_ede3_cbc()
, NULL, 0
, NULL, (void*)"passphrase");

if (rsa) RSA_free(rsa);

if (bn)  BN_free(bn);

if (out) BIO_free(out);

return 0;
}

Build test code for MingW

#!/bin/bash
g++ -I/d/workspace/github/altcoin/bitcoin-3rd/ssl/include \
-o $1 -g -O0 $1.cpp \
-L/d/workspace/github/altcoin/bitcoin-3rd/ssl/lib -lcrypto -lssl -lgdi32

Output

cat bobkey.pem

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: DES-EDE3-CBC,7FEF95ED86DB694B

CkXz9WNTShfC7DzLYPLpu9RxAbWyPYn5fvHaB67nK58UfzK5u8giabKfk/XK6I2M
...
xYx+DDsXtF5rNz94LoGl/8KF7C4gT6Hq6Yd0mEHjJhHzWcDN3gJG0GOByQdNNMWG
-----END RSA PRIVATE KEY-----

Check key pair with openssl rsa utility

openssl rsa -in bobkey.pem -text -noout

Private-Key: (2048 bit)
modulus:
00:d2:a6:02:a5:2e:a1:f9:63:89:b1:19:01:97:7b:
b4:15:95:46:d0:5f:67:1a:db:a1:14:61:06:7d:1a:
...
a0:8d:36:95:9c:ae:71:fe:b1:2a:e9:b8:e4:af:85:
43:0f
publicExponent: 65537 (0x10001)
privateExponent:
38:31:97:25:0f:a2:a0:0f:e0:ac:80:da:3e:d9:fe:
...
04:60:b3:e0:77:00:32:a1:e7:bc:f8:ef:2a:3e:07:
d1
prime1:
00:eb:ac:d0:46:72:37:66:e5:bc:c3:93:44:48:62:
...
80:e6:8d:ba:43:80:0c:06:f7
prime2:
00:e4:d0:aa:41:ac:27:2b:29:c2:da:6c:dd:a3:7b:
...
94:0d:60:a0:66:b6:d4:26:a9
exponent1:
36:a3:78:1d:fc:f8:ef:38:30:0d:3f:a5:43:0a:ff:
...
52:db:64:e5:a5:58:24:7d
exponent2:
00:e1:ef:48:ae:60:16:ad:00:27:6f:16:60:23:b5:
...
20:3d:b5:53:ad:18:8a:93:41
coefficient:
00:8b:8e:98:7f:05:05:13:b5:00:cc:d3:33:bd:aa:
...
82:1c:75:97:2f:b2:39:16:70