Support multi-prime RSA (RFC 8017)

* Introduce RSA_generate_multi_prime_key to generate multi-prime
  RSA private key. As well as the following functions:
    RSA_get_multi_prime_extra_count
    RSA_get0_multi_prime_factors
    RSA_get0_multi_prime_crt_params
    RSA_set0_multi_prime_params
    RSA_get_version
* Support EVP operations for multi-prime RSA
* Support ASN.1 operations for multi-prime RSA
* Support multi-prime check in RSA_check_key_ex
* Support multi-prime RSA in apps/genrsa and apps/speed
* Support multi-prime RSA manipulation functions
* Test cases and documentation are added
* CHANGES is updated

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/4241)

1 files changed, 24 insertions, 3 deletions

diff --git a/crypto/rsa/rsa_pmeth.c b/crypto/rsa/rsa_pmeth.c
index 5e2df3e8ff..8a114cff89 100644
--- a/crypto/rsa/rsa_pmeth.c
+++ b/crypto/rsa/rsa_pmeth.c
@@ -25,6 +25,7 @@ typedef struct {
     /* Key gen parameters */
     int nbits;
     BIGNUM *pub_exp;
+    int primes;
     /* Keygen callback info */
     int gentmp[2];
     /* RSA padding mode */
@@ -54,6 +55,7 @@ static int pkey_rsa_init(EVP_PKEY_CTX *ctx)
     if (rctx == NULL)
         return 0;
     rctx->nbits = 1024;
+    rctx->primes = RSA_DEFAULT_PRIME_NUM;
     if (pkey_ctx_is_pss(ctx))
         rctx->pad_mode = RSA_PKCS1_PSS_PADDING;
     else
@@ -473,6 +475,14 @@ static int pkey_rsa_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
         rctx->pub_exp = p2;
         return 1;
 
+    case EVP_PKEY_CTRL_RSA_KEYGEN_PRIMES:
+        if (p1 < RSA_DEFAULT_PRIME_NUM || p1 > RSA_MAX_PRIME_NUM) {
+            RSAerr(RSA_F_PKEY_RSA_CTRL, RSA_R_KEY_PRIME_NUM_INVALID);
+            return -2;
+        }
+        rctx->primes = p1;
+        return 1;
+
     case EVP_PKEY_CTRL_RSA_OAEP_MD:
     case EVP_PKEY_CTRL_GET_RSA_OAEP_MD:
         if (rctx->pad_mode != RSA_PKCS1_OAEP_PADDING) {
@@ -583,6 +593,7 @@ static int pkey_rsa_ctrl_str(EVP_PKEY_CTX *ctx,
     }
     if (strcmp(type, "rsa_padding_mode") == 0) {
         int pm;
+
         if (strcmp(value, "pkcs1") == 0) {
             pm = RSA_PKCS1_PADDING;
         } else if (strcmp(value, "sslv23") == 0) {
@@ -606,6 +617,7 @@ static int pkey_rsa_ctrl_str(EVP_PKEY_CTX *ctx,
 
     if (strcmp(type, "rsa_pss_saltlen") == 0) {
         int saltlen;
+
         if (!strcmp(value, "digest"))
             saltlen = RSA_PSS_SALTLEN_DIGEST;
         else if (!strcmp(value, "max"))
@@ -618,13 +630,14 @@ static int pkey_rsa_ctrl_str(EVP_PKEY_CTX *ctx,
     }
 
     if (strcmp(type, "rsa_keygen_bits") == 0) {
-        int nbits;
-        nbits = atoi(value);
+        int nbits = atoi(value);
+
         return EVP_PKEY_CTX_set_rsa_keygen_bits(ctx, nbits);
     }
 
     if (strcmp(type, "rsa_keygen_pubexp") == 0) {
         int ret;
+
         BIGNUM *pubexp = NULL;
         if (!BN_asc2bn(&pubexp, value))
             return 0;
@@ -634,6 +647,12 @@ static int pkey_rsa_ctrl_str(EVP_PKEY_CTX *ctx,
         return ret;
     }
 
+    if (strcmp(type, "rsa_keygen_primes") == 0) {
+        int nprimes = atoi(value);
+
+        return EVP_PKEY_CTX_set_rsa_keygen_primes(ctx, nprimes);
+    }
+
     if (strcmp(type, "rsa_mgf1_md") == 0)
         return EVP_PKEY_CTX_md(ctx,
                                EVP_PKEY_OP_TYPE_SIG | EVP_PKEY_OP_TYPE_CRYPT,
@@ -664,6 +683,7 @@ static int pkey_rsa_ctrl_str(EVP_PKEY_CTX *ctx,
         unsigned char *lab;
         long lablen;
         int ret;
+
         lab = OPENSSL_hexstr2buf(value, &lablen);
         if (!lab)
             return 0;
@@ -718,7 +738,8 @@ static int pkey_rsa_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
     } else {
         pcb = NULL;
     }
-    ret = RSA_generate_key_ex(rsa, rctx->nbits, rctx->pub_exp, pcb);
+    ret = RSA_generate_multi_prime_key(rsa, rctx->nbits, rctx->primes,
+                                       rctx->pub_exp, pcb);
     BN_GENCB_free(pcb);
     if (ret > 0 && !rsa_set_pss_param(rsa, ctx)) {
         RSA_free(rsa);