Re: how to import external rsa public key in openssl.

[Sangsub <i_chacha@xxxxxxxxx>]

Thanks Matt for your reply.

The purpose I am doing this is to find the modulus and exponent in the RSA
public key.
My sample code and the current results are shown below.

=========================================================
void fnStr2Hex(char* out, char* in) {
	int data_len = strlen(in);
	char * pStr = in;
	int i;
	
	for(i=0; i<data_len/2; i++) {
		char buf[2] = {0,};
		memcpy(buf, pStr, sizeof(buf));
			
		out[i] = (unsigned char)strtol(buf, NULL, 16);

		// need to check strol 2nd arguments... for error checking..
		printf(&quot;i:%d, pArr[i]:%02X \n&quot;, i, out[i]);

		pStr+=2;
	}
}

int main() {
	char raw_data[] =
&quot;30819F300D06092A864886F70D010101050003818D0030818902818100AA18ABA43B50DEEF38598FAF87D2AB634E4571C130A9BCA7B878267414FAAB8B471BD8965F5C9FC3818485EAF529C26246F3055064A8DE19C8C338BE5496CBAEB059DC0B358143B44A35449EB264113121A455BD7FDE3FAC919E94B56FB9BB4F651CDB23EAD439D6CD523EB08191E75B35FD13A7419B3090F24787BD4F4E19670203010001&quot;;

	int data_len = strlen(raw_data);  // Q) I think this is the problem. How
many lengths should I allocate?
	
	unsigned char * pArr = (unsigned char *)malloc(data_len);
	memset(pArr, 0x00, data_len);
	
// raw_data is a string. Not in hex state. So I changed the contents of
raw_data [] to hex in pArr.
// The implementation of this function is above main function.
	fnStr2Hex(pArr, raw_data);		
	
	STDout=BIO_new_fp(stdout,BIO_NOCLOSE);
	
	pub_rsa=d2i_RSAPublicKey(NULL,&amp;pArr,(long)data_len);
	
	if(pub_rsa == NULL) {
		printf(&quot;error : failed d2i_RSAPublicKey \n&quot;);
		return -1;
	}
	
	BN_print(STDout,pub_rsa->n);   // print modulus bignum
	BN_print(STDout,pub_rsa->e);  //  print exponent bignum
		
	return 0;
}

result : error : failed d2i_RSAPublicKey

I wrote the above, but I think data_len is the problem. I do not know how
much size I should enter.
And do I have to enter the string source without the string to hex in the
d2i_RSAPublicKey function?


And you said you need prefix and postfix to do PEM format.
Is raw_data [] as shown below?

raw_data[] = {
"-----BEGIN PUBLIC KEY-----"\
"MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAirjFSROMxZ9gW1AmX2ns"\
"O4zjs+mvXhdNJs/iQmUBBL6gUQEYlnbHopLMa1rnGeEZ46wp6dOtna3NpJby9xhf"\
"nAxIcqLbEk8BmSsjjoP9WC2KKQ8pc/nPdE8eU/iqU6IlwSKZscw2WPtgfLWrpXmD"\
"LWwmh/cTAKTfPfHBQH4X0ipcGcgw7QxYJAcjCaYSuz5PsznyW7vP4pmfQ0IRBkmr"\
"rF9L/qKlnNOMFzl5pnmv3Iuqy06H61Cs+AbPt0B1BL2sEQz7y5nAQicDHhRrnzuD"\
"d8hwNWkDCfrphy4se5PoN1/M3rxPmL4dV0JpxROkNZT2uIYfdGSDKumeus6uD8w6"\
"xQIDAQAB"\
"-----END PUBLIC KEY----- "

After that, I coded as follows.

	int data_len = strlen(raw_data);
	BIO *bufio = NULL;
	RSA *pub_rsa = NULL;

	unsigned char * pArr = (unsigned char *)malloc(data_len);
	memset(pArr, 0x00, data_len);
	
	fnStr2Hex(pArr, raw_data);  // for converting hex
	
	bufio = BIO_new_mem_buf((void*)pArr, data_len);
	
	if(bufio == NULL) {
		printf("Error (1) \n");
		return -1;
	} 
	
	PEM_read_bio_RSAPublicKey(bufio, &pub_rsa, 0, NULL);
	
	if(pub_rsa == NULL) {
		printf("Error (2) \n");
		return -1;
	}
} // end of main

When I execute the above code, Error (2) is output.
I want to be helped with the above two (DER, PEM) situations.
Again, I want to find the modulus and public exponent in the RSA public key.

BR,






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