Add OpenSSL version detection

Versions of OpenSSL without the opaque structs won't work with code that
uses the functions for manipulating them, so we have to detect the
version of OpenSSL before we compile and only use the new method with
OpenSSL >= 1.1.

eschalot.c

@@ -67,6 +67,7 @@
 #include <openssl/pem.h>
 #include <openssl/rsa.h>
 #include <openssl/sha.h>
+#define OPENSSL_VERSION_1_1 0x10100000L
 
 /* Define NEED_HTOBE32 if htobe32() is not available on your platform. */
 /* #define NEED_HTOBE32 */
@@ -258,9 +259,16 @@ worker(void *arg)
 
 	while (!done) {
 		/* Generate a new RSA key every time e reaches RSA_E_LIMIT */
+#if OPENSSL_VERSION_NUMBER >= OPENSSL_VERSION_1_1
 		rsa = RSA_new();
 		if (!RSA_generate_key_ex(rsa, RSA_KEYS_BITLEN, big_e, NULL))
 			error("RSA Key Generation failed!\n");
+#else
+		rsa = RSA_generate_key(RSA_KEYS_BITLEN, RSA_E_START,
+		    NULL, NULL);
+		if (!rsa)
+			error("RSA Key Generation failed!\n");
+#endif
 		
 		/* Too chatty - disable. */
 		/* msg("Generated a new RSA key pair.\n"); */
@@ -308,12 +316,17 @@ worker(void *arg)
 			if (search(buf, onion)) {
 				/* Found a possible key,
 				 * from here on down performance is not critical. */
+#if OPENSSL_VERSION_NUMBER >= OPENSSL_VERSION_1_1
 				BIGNUM *new_e;
 				new_e = BN_bin2bn((uint8_t *)&e_be, SIZE_OF_E, NULL);
 				if (new_e == NULL)
 					error("Failed to convert e to BIGNUM!\n");
 				if(!RSA_set0_key(rsa, NULL, new_e, NULL))
 					error("Failed to set e in RSA key!\n");
+#else
+				if (!BN_bin2bn((uint8_t *)&e_be, SIZE_OF_E, rsa->e))
+					error("Failed to set e in RSA key!\n");
+#endif
 				if (!validkey(rsa))
 					error("A bad key was found!\n");
 				if (pflag)
@@ -426,6 +439,7 @@ validkey(RSA *rsa)
 		*gcd = BN_CTX_get(ctx),		/* GCD(p - 1, q - 1) */
 		*lambda = BN_CTX_get(ctx),	/* LCM(p - 1, q - 1) */
 		*tmp = BN_CTX_get(ctx);		/* temporary storage */
+#if OPENSSL_VERSION_NUMBER >= OPENSSL_VERSION_1_1
 	BIGNUM *n = BN_CTX_get(ctx),
 		   *e = BN_CTX_get(ctx),
 		   *d = BN_CTX_get(ctx);
@@ -449,13 +463,21 @@ validkey(RSA *rsa)
 
 	BN_sub(p1, p, BN_value_one());	/* p - 1 */
 	BN_sub(q1, q, BN_value_one());	/* q - 1 */
+#else
+	BN_sub(p1, rsa->p, BN_value_one());	/* p - 1 */
+	BN_sub(q1, rsa->q, BN_value_one());	/* q - 1 */
+#endif
 	BN_gcd(gcd, p1, q1, ctx);	   	/* gcd(p - 1, q - 1) */
 
 	BN_div(tmp, NULL, p1, gcd, ctx);
 	BN_mul(lambda, q1, tmp, ctx);		/* lambda(n) */
 
 	/* Check if e is coprime to lambda(n). */
+#if OPENSSL_VERSION_NUMBER >= OPENSSL_VERSION_1_1
 	BN_gcd(tmp, lambda, e, ctx);
+#else
+	BN_gcd(tmp, lambda, rsa->e, ctx);
+#endif
 	if (!BN_is_one(tmp)) {
 		verbose("WARNING: Key check failed - e is coprime to lambda!\n");
 		return 0;
@@ -463,16 +485,31 @@ validkey(RSA *rsa)
 
 	/* Check if public exponent e is less than n - 1. */
 	/* Subtract n from e to avoid checking BN_is_zero. */
+#if OPENSSL_VERSION_NUMBER >= OPENSSL_VERSION_1_1
 	BN_sub(tmp, n, BN_value_one());
 	if (BN_cmp(e, tmp) >= 0) {
 		verbose("WARNING: Key check failed - e is less than (n - 1)!\n");
 		return 0;
 	}
+#else
+	BN_sub(tmp, rsa->n, BN_value_one());
+	if (BN_cmp(rsa->e, tmp) >= 0) {
+		verbose("WARNING: Key check failed - e is less than (n - 1)!\n");
+		return 0;
+	}
+#endif
 
+#if OPENSSL_VERSION_NUMBER >= OPENSSL_VERSION_1_1
 	BN_mod_inverse(d, e, lambda, ctx);	/* d */
 	BN_mod(dmp1, d, p1, ctx);		/* d mod(p - 1) */
 	BN_mod(dmq1, d, q1, ctx);		/* d mod(q - 1) */
 	BN_mod_inverse(iqmp, q, p, ctx);	/* q ^ -1 mod p */
+#else
+	BN_mod_inverse(rsa->d, rsa->e, lambda, ctx);	/* d */
+	BN_mod(rsa->dmp1, rsa->d, p1, ctx);		/* d mod(p - 1) */
+	BN_mod(rsa->dmq1, rsa->d, q1, ctx);		/* d mod(q - 1) */
+	BN_mod_inverse(rsa->iqmp, rsa->q, rsa->p, ctx);	/* q ^ -1 mod p */
+#endif
 	BN_CTX_end(ctx);
 	BN_CTX_free(ctx);