Add an EVP signature demo using DSA

Fixes openssl#14114

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19492)

4 files changed, 322 insertions, 4 deletions

diff --git a/demos/signature/EVP_DSA_Signature_demo.c b/demos/signature/EVP_DSA_Signature_demo.c
new file mode 100644
index 0000000000..ca41ef34d6
--- /dev/null
+++ b/demos/signature/EVP_DSA_Signature_demo.c
@@ -0,0 +1,317 @@
+/*-
+ * 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
+ */
+
+/*
+ * An example that uses the EVP_PKEY*, EVP_DigestSign* and EVP_DigestVerify*
+ * methods to calculate public/private DSA keypair and to sign and verify
+ * two static buffers.
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include <openssl/err.h>
+#include <openssl/evp.h>
+#include <openssl/decoder.h>
+#include <openssl/dsa.h>
+
+/*
+ * This demonstration will calculate and verify a signature of data using
+ * the soliloquy from Hamlet scene 1 act 3
+ */
+
+static const char *hamlet_1 =
+    "To be, or not to be, that is the question,\n"
+    "Whether tis nobler in the minde to suffer\n"
+    "The slings and arrowes of outragious fortune,\n"
+    "Or to take Armes again in a sea of troubles,\n"
+;
+static const char *hamlet_2 =
+    "And by opposing, end them, to die to sleep;\n"
+    "No more, and by a sleep, to say we end\n"
+    "The heart-ache, and the thousand natural shocks\n"
+    "That flesh is heir to? tis a consumation\n"
+;
+
+static const char ALG[] = "DSA";
+static const char DIGEST[] = "SHA256";
+static const int NUMBITS = 2048;
+static const char * const PROPQUERY = NULL;
+
+static int generate_dsa_params(OSSL_LIB_CTX *libctx,
+                               EVP_PKEY **p_params)
+{
+    int result = 0;
+
+    EVP_PKEY_CTX *pkey_ctx = NULL;
+    EVP_PKEY *params = NULL;
+
+    pkey_ctx = EVP_PKEY_CTX_new_from_name(libctx, ALG, PROPQUERY);
+    if (pkey_ctx == NULL)
+        goto end;
+
+    if (EVP_PKEY_paramgen_init(pkey_ctx) <= 0)
+        goto end;
+
+    if (EVP_PKEY_CTX_set_dsa_paramgen_bits(pkey_ctx, NUMBITS) <= 0)
+        goto end;
+    if (EVP_PKEY_paramgen(pkey_ctx, &params) <= 0)
+        goto end;
+    if (params == NULL)
+        goto end;
+
+    result = 1;
+end:
+    if(result != 1) {
+        EVP_PKEY_free(params);
+        params = NULL;
+    }
+    EVP_PKEY_CTX_free(pkey_ctx);
+    *p_params = params;
+    fprintf(stdout, "Params:\n");
+    EVP_PKEY_print_params_fp(stdout, params, 4, NULL);
+    fprintf(stdout, "\n");
+
+    return result;
+}
+
+static int generate_dsa_key(OSSL_LIB_CTX *libctx,
+                            EVP_PKEY *params,
+                            EVP_PKEY **p_pkey)
+{
+    int result = 0;
+
+    EVP_PKEY_CTX *ctx = NULL;
+    EVP_PKEY *pkey = NULL;
+
+    ctx = EVP_PKEY_CTX_new_from_pkey(libctx, params,
+                                     NULL);
+    if (ctx == NULL)
+        goto end;
+    if (EVP_PKEY_keygen_init(ctx) <= 0)
+        goto end;
+
+    if (EVP_PKEY_keygen(ctx, &pkey) <= 0)
+        goto end;
+    if (pkey == NULL)
+        goto end;
+
+    result = 1;
+end:
+    if(result != 1) {
+        EVP_PKEY_free(pkey);
+        pkey = NULL;
+    }
+    EVP_PKEY_CTX_free(ctx);
+    *p_pkey = pkey;
+    fprintf(stdout, "Generating public/private key pair:\n");
+    EVP_PKEY_print_public_fp(stdout, pkey, 4, NULL);
+    fprintf(stdout, "\n");
+    EVP_PKEY_print_private_fp(stdout, pkey, 4, NULL);
+    fprintf(stdout, "\n");
+    EVP_PKEY_print_params_fp(stdout, pkey, 4, NULL);
+    fprintf(stdout, "\n");
+
+    return result;
+}
+
+static int extract_public_key(const EVP_PKEY *pkey,
+                              OSSL_PARAM **p_public_key)
+{
+    int result = 0;
+    OSSL_PARAM *public_key = NULL;
+
+    if (EVP_PKEY_todata(pkey, EVP_PKEY_PUBLIC_KEY, &public_key) != 1)
+        goto end;
+
+    result = 1;
+end:
+    if (result != 1) {
+        OSSL_PARAM_free(public_key);
+        public_key = NULL;
+    }
+    *p_public_key = public_key;
+
+    return result;
+}
+
+static int extract_keypair(const EVP_PKEY *pkey,
+                           OSSL_PARAM **p_keypair)
+{
+    int result = 0;
+    OSSL_PARAM *keypair = NULL;
+
+    if (EVP_PKEY_todata(pkey, EVP_PKEY_KEYPAIR, &keypair) != 1)
+        goto end;
+
+    result = 1;
+end:
+    if (result != 1) {
+        OSSL_PARAM_free(keypair);
+        keypair = NULL;
+    }
+    *p_keypair = keypair;
+
+    return result;
+}
+
+static int demo_sign(OSSL_LIB_CTX *libctx,
+                     size_t *p_sig_len, unsigned char **p_sig_value,
+                     OSSL_PARAM keypair[])
+{
+    int result = 0;
+    size_t sig_len = 0;
+    unsigned char *sig_value = NULL;
+    EVP_MD_CTX *ctx = NULL;
+    EVP_PKEY_CTX *pkey_ctx = NULL;
+    EVP_PKEY *pkey = NULL;
+
+    pkey_ctx = EVP_PKEY_CTX_new_from_name(libctx, ALG, PROPQUERY);
+    if (pkey_ctx == NULL)
+        goto end;
+    if (EVP_PKEY_fromdata_init(pkey_ctx) != 1)
+        goto end;
+    if (EVP_PKEY_fromdata(pkey_ctx, &pkey, EVP_PKEY_KEYPAIR, keypair) != 1)
+        goto end;
+
+    ctx = EVP_MD_CTX_create();
+    if (ctx == NULL)
+        goto end;
+
+    if (EVP_DigestSignInit_ex(ctx, NULL, DIGEST, libctx, NULL, pkey, NULL) != 1)
+        goto end;
+
+    if (EVP_DigestSignUpdate(ctx, hamlet_1, sizeof(hamlet_1)) != 1)
+        goto end;
+
+    if (EVP_DigestSignUpdate(ctx, hamlet_2, sizeof(hamlet_2)) != 1)
+        goto end;
+
+    /* Calculate the signature size */
+    if (EVP_DigestSignFinal(ctx, NULL, &sig_len) != 1)
+        goto end;
+    if (sig_len == 0)
+        goto end;
+
+    sig_value = OPENSSL_malloc(sig_len);
+    if (sig_value == NULL)
+        goto end;
+
+    /* Calculate the signature */
+    if (EVP_DigestSignFinal(ctx, sig_value, &sig_len) != 1)
+        goto end;
+
+    result = 1;
+end:
+    EVP_MD_CTX_free(ctx);
+    if (result != 1) {
+        OPENSSL_free(sig_value);
+        sig_len = 0;
+        sig_value = NULL;
+    }
+    *p_sig_len = sig_len;
+    *p_sig_value = sig_value;
+    EVP_PKEY_free(pkey);
+    EVP_PKEY_CTX_free(pkey_ctx);
+
+    fprintf(stdout, "Generating signature:\n");
+    BIO_dump_indent_fp(stdout, sig_value, sig_len, 2);
+    fprintf(stdout, "\n");
+    return result;
+}
+
+static int demo_verify(OSSL_LIB_CTX *libctx,
+                       size_t sig_len, unsigned char *sig_value,
+                       OSSL_PARAM public_key[])
+{
+    int result = 0;
+    EVP_MD_CTX *ctx = NULL;
+    EVP_PKEY_CTX *pkey_ctx = NULL;
+    EVP_PKEY *pkey = NULL;
+
+    pkey_ctx = EVP_PKEY_CTX_new_from_name(libctx, ALG, PROPQUERY);
+    if (pkey_ctx == NULL)
+        goto end;
+    if (EVP_PKEY_fromdata_init(pkey_ctx) != 1)
+        goto end;
+    if (EVP_PKEY_fromdata(pkey_ctx, &pkey, EVP_PKEY_PUBLIC_KEY, public_key) != 1)
+        goto end;
+
+    ctx = EVP_MD_CTX_create();
+    if(ctx == NULL)
+        goto end;
+
+    if (EVP_DigestVerifyInit_ex(ctx, NULL, DIGEST, libctx, NULL, pkey, NULL) != 1)
+        goto end;
+
+    if (EVP_DigestVerifyUpdate(ctx, hamlet_1, sizeof(hamlet_1)) != 1)
+        goto end;
+
+    if (EVP_DigestVerifyUpdate(ctx, hamlet_2, sizeof(hamlet_2)) != 1)
+        goto end;
+
+    if (EVP_DigestVerifyFinal(ctx, sig_value, sig_len) != 1)
+        goto end;
+
+    result = 1;
+end:
+    EVP_PKEY_free(pkey);
+    EVP_PKEY_CTX_free(pkey_ctx);
+    EVP_MD_CTX_free(ctx);
+    return result;
+}
+
+int main(void)
+{
+    int result = 0;
+    OSSL_LIB_CTX *libctx = NULL;
+    EVP_PKEY *params = NULL;
+    EVP_PKEY *pkey = NULL;
+    OSSL_PARAM *public_key = NULL;
+    OSSL_PARAM *keypair = NULL;
+    size_t sig_len = 0;
+    unsigned char *sig_value = NULL;
+
+    libctx = OSSL_LIB_CTX_new();
+    if (libctx == NULL)
+        goto end;
+
+    if (generate_dsa_params(libctx, &params) != 1)
+        goto end;
+
+    if (generate_dsa_key(libctx, params, &pkey) != 1)
+        goto end;
+
+    if (extract_public_key(pkey, &public_key) != 1)
+        goto end;
+
+    if (extract_keypair(pkey, &keypair) != 1)
+        goto end;
+
+    /* The signer signs with his private key, and distributes his public key */
+    if (demo_sign(libctx, &sig_len, &sig_value, keypair) != 1)
+        goto end;
+
+    /* A verifier uses the signers public key to verify the signature */
+    if (demo_verify(libctx, sig_len, sig_value, public_key) != 1)
+        goto end;
+
+    result = 1;
+end:
+    if (result != 1)
+        ERR_print_errors_fp(stderr);
+
+    OPENSSL_free(sig_value);
+    EVP_PKEY_free(params);
+    EVP_PKEY_free(pkey);
+    OSSL_PARAM_free(public_key);
+    OSSL_PARAM_free(keypair);
+    OSSL_LIB_CTX_free(libctx);
+
+    return result ? 0 : 1;
+}
diff --git a/demos/signature/EVP_Signature_demo.c b/demos/signature/EVP_EC_Signature_demo.c
index 123c95c26a..b5270f398c 100644
--- a/demos/signature/EVP_Signature_demo.c
+++ b/demos/signature/EVP_EC_Signature_demo.c
@@ -17,7 +17,7 @@
 #include <openssl/err.h>
 #include <openssl/evp.h>
 #include <openssl/decoder.h>
-#include "EVP_Signature_demo.h"
+#include "EVP_EC_Signature_demo.h"
 
 /*
  * This demonstration will calculate and verify a signature of data using
diff --git a/demos/signature/EVP_Signature_demo.h b/demos/signature/EVP_EC_Signature_demo.h
index aef3e60783..aef3e60783 100644
--- a/demos/signature/EVP_Signature_demo.h
+++ b/demos/signature/EVP_EC_Signature_demo.h
diff --git a/demos/signature/Makefile b/demos/signature/Makefile
index 563ec7799f..394eef6d42 100644
--- a/demos/signature/Makefile
+++ b/demos/signature/Makefile
@@ -7,16 +7,17 @@ CFLAGS = -I../../include -g -Wall
 LDFLAGS = -L../..
 LDLIBS = -lcrypto
 
-all: EVP_Signature_demo rsa_pss_direct rsa_pss_hash
+all: EVP_EC_Signature_demo EVP_DSA_Signature_demo rsa_pss_direct rsa_pss_hash
 
 %.o: %.c
 	$(CC) $(CFLAGS) -c $<
 
-EVP_Signature_demo: EVP_Signature_demo.o
+EVP_EC_Signature_demo: EVP_EC_Signature_demo.o
+EVP_DSA_Signature_demo: EVP_DSA_Signature_demo.o
 rsa_pss_direct: rsa_pss_direct.o
 rsa_pss_hash: rsa_pss_hash.o
 
 test: ;
 
 clean:
-	$(RM) *.o EVP_Signature_demo rsa_pss_direct rsa_pss_hash
+	$(RM) *.o EVP_EC_Signature_demo EVP_DSA_Signature_demo rsa_pss_direct rsa_pss_hash