From ad083f9b0ab81d094c2dbb8f5e2a5fb7738a0bfe Mon Sep 17 00:00:00 2001 From: Hugo Landau Date: Mon, 7 Mar 2022 13:29:49 +0000 Subject: Add EVP demo for RSA key generation Fixes #14111. Reviewed-by: Paul Dale Reviewed-by: Matt Caswell Reviewed-by: Tomas Mraz (Merged from https://github.com/openssl/openssl/pull/17824) --- demos/README.txt | 1 + demos/pkey/EVP_PKEY_EC_keygen.c | 2 +- demos/pkey/EVP_PKEY_RSA_keygen.c | 289 +++++++++++++++++++++++++++++++++++++++ demos/pkey/Makefile | 9 +- 4 files changed, 297 insertions(+), 4 deletions(-) create mode 100644 demos/pkey/EVP_PKEY_RSA_keygen.c diff --git a/demos/README.txt b/demos/README.txt index 045be5ffa1..d000c7c004 100644 --- a/demos/README.txt +++ b/demos/README.txt @@ -34,6 +34,7 @@ poly1305.c Demonstration of Poly1305-AES message authentication pkey: EVP_PKEY_EC_keygen.c Generate an EC key. +EVP_PKEY_RSA_keygen.c Generate an RSA key. smime: diff --git a/demos/pkey/EVP_PKEY_EC_keygen.c b/demos/pkey/EVP_PKEY_EC_keygen.c index 14efaea53a..a0bf1cb1fd 100644 --- a/demos/pkey/EVP_PKEY_EC_keygen.c +++ b/demos/pkey/EVP_PKEY_EC_keygen.c @@ -89,7 +89,7 @@ static int get_key_values(EVP_PKEY *pkey) unsigned char out_pubkey[80]; unsigned char out_privkey[80]; BIGNUM *out_priv = NULL; - size_t i, out_pubkey_len, out_privkey_len = 0; + size_t out_pubkey_len, out_privkey_len = 0; if (!EVP_PKEY_get_utf8_string_param(pkey, OSSL_PKEY_PARAM_GROUP_NAME, out_curvename, sizeof(out_curvename), diff --git a/demos/pkey/EVP_PKEY_RSA_keygen.c b/demos/pkey/EVP_PKEY_RSA_keygen.c new file mode 100644 index 0000000000..fbecfb6bdb --- /dev/null +++ b/demos/pkey/EVP_PKEY_RSA_keygen.c @@ -0,0 +1,289 @@ +/*- + * Copyright 2022 The OpenSSL Project Authors. All Rights Reserved. + * + * Licensed under the Apache License 2.0 (the "License"). You may not use + * this file except in compliance with the License. You can obtain a copy + * in the file LICENSE in the source distribution or at + * https://www.openssl.org/source/license.html + */ + +/* + * Example showing how to generate an RSA key pair. + * + * When generating an RSA key, you must specify the number of bits in the key. A + * reasonable value would be 4096. Avoid using values below 2048. These values + * are reasonable as of 2022. + */ + +#include +#include +#include +#include +#include +#include +#include + +/* A property query used for selecting algorithm implementations. */ +static const char *propq = NULL; + +/* + * Generates an RSA public-private key pair and returns it. + * The number of bits is specified by the bits argument. + * + * This uses the long way of generating an RSA key. + */ +static EVP_PKEY *generate_rsa_key_long(OSSL_LIB_CTX *libctx, unsigned int bits) +{ + EVP_PKEY_CTX *genctx = NULL; + EVP_PKEY *pkey = NULL; + unsigned int primes = 2; + + /* Create context using RSA algorithm. "RSA-PSS" could also be used here. */ + genctx = EVP_PKEY_CTX_new_from_name(libctx, "RSA", propq); + if (genctx == NULL) { + fprintf(stderr, "EVP_PKEY_CTX_new_from_name() failed\n"); + goto cleanup; + } + + /* Initialize context for key generation purposes. */ + if (EVP_PKEY_keygen_init(genctx) <= 0) { + fprintf(stderr, "EVP_PKEY_keygen_init() failed\n"); + goto cleanup; + } + + /* + * Here we set the number of bits to use in the RSA key. + * See comment at top of file for information on appropriate values. + */ + if (EVP_PKEY_CTX_set_rsa_keygen_bits(genctx, bits) <= 0) { + fprintf(stderr, "EVP_PKEY_CTX_set_rsa_keygen_bits() failed\n"); + goto cleanup; + } + + /* + * It is possible to create an RSA key using more than two primes. + * Do not do this unless you know why you need this. + * You ordinarily do not need to specify this, as the default is two. + * + * Both of these parameters can also be set via EVP_PKEY_CTX_set_params, but + * these functions provide a more concise way to do so. + */ + if (EVP_PKEY_CTX_set_rsa_keygen_primes(genctx, primes) <= 0) { + fprintf(stderr, "EVP_PKEY_CTX_set_rsa_keygen_primes() failed\n"); + goto cleanup; + } + + /* + * Generating an RSA key with a number of bits large enough to be secure for + * modern applications can take a fairly substantial amount of time (e.g. + * one second). If you require fast key generation, consider using an EC key + * instead. + * + * If you require progress information during the key generation process, + * you can set a progress callback using EVP_PKEY_set_cb; see the example in + * EVP_PKEY_generate(3). + */ + fprintf(stderr, "Generating RSA key, this may take some time...\n"); + if (EVP_PKEY_generate(genctx, &pkey) <= 0) { + fprintf(stderr, "EVP_PKEY_generate() failed\n"); + goto cleanup; + } + + /* pkey is now set to an object representing the generated key pair. */ + +cleanup: + EVP_PKEY_CTX_free(genctx); + return pkey; +} + +/* + * Generates an RSA public-private key pair and returns it. + * The number of bits is specified by the bits argument. + * + * This uses a more concise way of generating an RSA key, which is suitable for + * simple cases. It is used if -s is passed on the command line, otherwise the + * long method above is used. The ability to choose between these two methods is + * shown here only for demonstration; the results are equivalent. + */ +static EVP_PKEY *generate_rsa_key_short(OSSL_LIB_CTX *libctx, unsigned int bits) +{ + EVP_PKEY *pkey = NULL; + + fprintf(stderr, "Generating RSA key, this may take some time...\n"); + pkey = EVP_PKEY_Q_keygen(libctx, propq, "RSA", (size_t)bits); + + if (pkey == NULL) + fprintf(stderr, "EVP_PKEY_Q_keygen() failed\n"); + + return pkey; +} + +/* + * Prints information on an EVP_PKEY object representing an RSA key pair. + */ +static int dump_key(const EVP_PKEY *pkey) +{ + int rv = 0; + int bits = 0; + BIGNUM *n = NULL, *e = NULL, *d = NULL, *p = NULL, *q = NULL; + + /* + * Retrieve value of n. This value is not secret and forms part of the + * public key. + * + * Calling EVP_PKEY_get_bn_param with a NULL BIGNUM pointer causes + * a new BIGNUM to be allocated, so these must be freed subsequently. + */ + if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_N, &n) == 0) { + fprintf(stderr, "Failed to retrieve n\n"); + goto cleanup; + } + + /* + * Retrieve value of e. This value is not secret and forms part of the + * public key. It is typically 65537 and need not be changed. + */ + if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_E, &e) == 0) { + fprintf(stderr, "Failed to retrieve e\n"); + goto cleanup; + } + + /* + * Retrieve value of d. This value is secret and forms part of the private + * key. It must not be published. + */ + if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_D, &d) == 0) { + fprintf(stderr, "Failed to retrieve d\n"); + goto cleanup; + } + + /* + * Retrieve value of the first prime factor, commonly known as p. This value + * is secret and forms part of the private key. It must not be published. + */ + if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_FACTOR1, &p) == 0) { + fprintf(stderr, "Failed to retrieve p\n"); + goto cleanup; + } + + /* + * Retrieve value of the second prime factor, commonly known as q. This value + * is secret and forms part of the private key. It must not be published. + * + * If you are creating an RSA key with more than two primes for special + * applications, you can retrieve these primes with + * OSSL_PKEY_PARAM_RSA_FACTOR3, etc. + */ + if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_FACTOR2, &q) == 0) { + fprintf(stderr, "Failed to retrieve q\n"); + goto cleanup; + } + + /* + * We can also retrieve the key size in bits for informational purposes. + */ + if (EVP_PKEY_get_int_param(pkey, OSSL_PKEY_PARAM_BITS, &bits) == 0) { + fprintf(stderr, "Failed to retrieve bits\n"); + goto cleanup; + } + + /* Output hexadecimal representations of the BIGNUM objects. */ + fprintf(stdout, "\nNumber of bits: %d\n\n", bits); + fprintf(stderr, "Public values:\n"); + fprintf(stdout, " n = 0x"); + BN_print_fp(stdout, n); + fprintf(stdout, "\n"); + + fprintf(stdout, " e = 0x"); + BN_print_fp(stdout, e); + fprintf(stdout, "\n\n"); + + fprintf(stdout, "Private values:\n"); + fprintf(stdout, " d = 0x"); + BN_print_fp(stdout, d); + fprintf(stdout, "\n"); + + fprintf(stdout, " p = 0x"); + BN_print_fp(stdout, p); + fprintf(stdout, "\n"); + + fprintf(stdout, " q = 0x"); + BN_print_fp(stdout, q); + fprintf(stdout, "\n\n"); + + /* Output a PEM encoding of the public key. */ + if (PEM_write_PUBKEY(stdout, pkey) == 0) { + fprintf(stderr, "Failed to output PEM-encoded public key\n"); + goto cleanup; + } + + /* + * Output a PEM encoding of the private key. Please note that this output is + * not encrypted. You may wish to use the arguments to specify encryption of + * the key if you are storing it on disk. See PEM_write_PrivateKey(3). + */ + if (PEM_write_PrivateKey(stdout, pkey, NULL, NULL, 0, NULL, NULL) == 0) { + fprintf(stderr, "Failed to output PEM-encoded private key\n"); + goto cleanup; + } + + rv = 1; +cleanup: + BN_free(n); /* not secret */ + BN_free(e); /* not secret */ + BN_clear_free(d); /* secret - scrub before freeing */ + BN_clear_free(p); /* secret - scrub before freeing */ + BN_clear_free(q); /* secret - scrub before freeing */ + return rv; +} + +int main(int argc, char **argv) +{ + int rv = 1; + OSSL_LIB_CTX *libctx = NULL; + EVP_PKEY *pkey = NULL; + unsigned int bits = 4096; + int bits_i, use_short = 0; + + /* usage: [-s] [] */ + if (argc > 1 && strcmp(argv[1], "-s") == 0) { + --argc; + ++argv; + use_short = 1; + } + + if (argc > 1) { + bits_i = atoi(argv[1]); + if (bits < 512) { + fprintf(stderr, "Invalid RSA key size\n"); + return 1; + } + + bits = (unsigned int)bits_i; + } + + /* Avoid using key sizes less than 2048 bits; see comment at top of file. */ + if (bits < 2048) + fprintf(stderr, "Warning: very weak key size\n\n"); + + /* Generate RSA key. */ + if (use_short) + pkey = generate_rsa_key_short(libctx, bits); + else + pkey = generate_rsa_key_long(libctx, bits); + + if (pkey == NULL) + goto cleanup; + + /* Dump the integers comprising the key. */ + if (dump_key(pkey) == 0) { + fprintf(stderr, "Failed to dump key\n"); + goto cleanup; + } + + rv = 0; +cleanup: + EVP_PKEY_free(pkey); + OSSL_LIB_CTX_free(libctx); + return rv; +} diff --git a/demos/pkey/Makefile b/demos/pkey/Makefile index 35cdca229a..f19c0d14f4 100644 --- a/demos/pkey/Makefile +++ b/demos/pkey/Makefile @@ -2,19 +2,22 @@ # To run the demos when linked with a shared library (default): # # LD_LIBRARY_PATH=../.. ./EVP_PKEY_EC_keygen +# LD_LIBRARY_PATH=../.. ./EVP_PKEY_RSA_keygen -CFLAGS = -I../../include -g +CFLAGS = -I../../include -g -Wall LDFLAGS = -L../.. LDLIBS = -lcrypto -all: EVP_PKEY_EC_keygen +all: EVP_PKEY_EC_keygen EVP_PKEY_RSA_keygen %.o: %.c $(CC) $(CFLAGS) -c $< EVP_PKEY_EC_keygen: EVP_PKEY_EC_keygen.o +EVP_PKEY_RSA_keygen: EVP_PKEY_RSA_keygen.o + test: ; clean: - $(RM) *.o EVP_PKEY_EC_keygen + $(RM) *.o EVP_PKEY_EC_keygen EVP_PKEY_RSA_keygen -- cgit v1.2.3