add support for DSA with SHA2
[openssl.git] / crypto / dsa / dsa_gen.c
index 6a6be3b..aa09955 100644 (file)
 #ifndef OPENSSL_NO_SHA
 
 #include <stdio.h>
-#include <time.h>
 #include "cryptlib.h"
 #include <openssl/evp.h>
 #include <openssl/bn.h>
-#include <openssl/dsa.h>
 #include <openssl/rand.h>
 #include <openssl/sha.h>
-
-static int dsa_builtin_paramgen(DSA *ret, int bits,
-               unsigned char *seed_in, int seed_len,
-               int *counter_ret, unsigned long *h_ret, BN_GENCB *cb);
+#include "dsa_locl.h"
 
 int DSA_generate_parameters_ex(DSA *ret, int bits,
                unsigned char *seed_in, int seed_len,
@@ -93,41 +88,72 @@ int DSA_generate_parameters_ex(DSA *ret, int bits,
        if(ret->meth->dsa_paramgen)
                return ret->meth->dsa_paramgen(ret, bits, seed_in, seed_len,
                                counter_ret, h_ret, cb);
-       return dsa_builtin_paramgen(ret, bits, seed_in, seed_len,
-                       counter_ret, h_ret, cb);
+       else
+               {
+               const EVP_MD *evpmd;
+               size_t qbits = bits >= 2048 ? 256 : 160;
+
+               if (bits >= 2048)
+                       {
+                       qbits = 256;
+                       evpmd = EVP_sha256();
+                       }
+               else
+                       {
+                       qbits = 160;
+                       evpmd = EVP_sha1();
+                       }
+
+               return dsa_builtin_paramgen(ret, bits, qbits, evpmd,
+                               seed_in, seed_len, counter_ret, h_ret, cb);
+               }
        }
 
-static int dsa_builtin_paramgen(DSA *ret, int bits,
-               unsigned char *seed_in, int seed_len,
-               int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
+int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
+       const EVP_MD *evpmd, unsigned char *seed_in, size_t seed_len,
+       int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
        {
        int ok=0;
-       unsigned char seed[SHA_DIGEST_LENGTH];
-       unsigned char md[SHA_DIGEST_LENGTH];
-       unsigned char buf[SHA_DIGEST_LENGTH],buf2[SHA_DIGEST_LENGTH];
+       unsigned char seed[SHA256_DIGEST_LENGTH];
+       unsigned char md[SHA256_DIGEST_LENGTH];
+       unsigned char buf[SHA256_DIGEST_LENGTH],buf2[SHA256_DIGEST_LENGTH];
        BIGNUM *r0,*W,*X,*c,*test;
        BIGNUM *g=NULL,*q=NULL,*p=NULL;
        BN_MONT_CTX *mont=NULL;
-       int k,n=0,i,b,m=0;
+       size_t i;
+       int k,n=0,b,m=0, qsize = qbits >> 3;
        int counter=0;
        int r=0;
        BN_CTX *ctx=NULL;
        unsigned int h=2;
 
-       if (bits < 512) bits=512;
-       bits=(bits+63)/64*64;
+       if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
+           qsize != SHA256_DIGEST_LENGTH)
+               /* invalid q size */
+               return 0;
 
-       if (seed_len < 20)
-               seed_in = NULL; /* seed buffer too small -- ignore */
-       if (seed_len > 20) 
-               seed_len = 20; /* App. 2.2 of FIPS PUB 186 allows larger SEED,
-                               * but our internal buffers are restricted to 160 bits*/
-       if ((seed_in != NULL) && (seed_len == 20))
-               memcpy(seed,seed_in,seed_len);
+       if (evpmd == NULL)
+               /* use SHA1 as default */
+               evpmd = EVP_sha1();
 
-       if ((ctx=BN_CTX_new()) == NULL) goto err;
+       if (bits < 512)
+               bits = 512;
 
-       if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
+       bits = (bits+63)/64*64;
+
+       if (seed_len < qsize)
+               seed_in = NULL;         /* seed buffer too small -- ignore */
+       if (seed_len > qsize) 
+               seed_len = qsize;       /* App. 2.2 of FIPS PUB 186 allows larger SEED,
+                                        * but our internal buffers are restricted to 160 bits*/
+       if (seed_in != NULL)
+               memcpy(seed, seed_in, seed_len);
+
+       if ((ctx=BN_CTX_new()) == NULL)
+               goto err;
+
+       if ((mont=BN_MONT_CTX_new()) == NULL)
+               goto err;
 
        BN_CTX_start(ctx);
        r0 = BN_CTX_get(ctx);
@@ -154,7 +180,7 @@ static int dsa_builtin_paramgen(DSA *ret, int bits,
 
                        if (!seed_len)
                                {
-                               RAND_pseudo_bytes(seed,SHA_DIGEST_LENGTH);
+                               RAND_pseudo_bytes(seed, qsize);
                                seed_is_random = 1;
                                }
                        else
@@ -162,25 +188,27 @@ static int dsa_builtin_paramgen(DSA *ret, int bits,
                                seed_is_random = 0;
                                seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
                                }
-                       memcpy(buf,seed,SHA_DIGEST_LENGTH);
-                       memcpy(buf2,seed,SHA_DIGEST_LENGTH);
+                       memcpy(buf , seed, qsize);
+                       memcpy(buf2, seed, qsize);
                        /* precompute "SEED + 1" for step 7: */
-                       for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
+                       for (i = qsize-1; i >= 0; i--)
                                {
                                buf[i]++;
-                               if (buf[i] != 0) break;
+                               if (buf[i] != 0)
+                                       break;
                                }
 
                        /* step 2 */
-                       EVP_Digest(seed,SHA_DIGEST_LENGTH,md,NULL,HASH, NULL);
-                       EVP_Digest(buf,SHA_DIGEST_LENGTH,buf2,NULL,HASH, NULL);
-                       for (i=0; i<SHA_DIGEST_LENGTH; i++)
+                       EVP_Digest(seed, qsize, md,   NULL, evpmd, NULL);
+                       EVP_Digest(buf,  qsize, buf2, NULL, evpmd, NULL);
+                       for (i = 0; i < qsize; i++)
                                md[i]^=buf2[i];
 
                        /* step 3 */
-                       md[0]|=0x80;
-                       md[SHA_DIGEST_LENGTH-1]|=0x01;
-                       if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,q)) goto err;
+                       md[0] |= 0x80;
+                       md[qsize-1] |= 0x01;
+                       if (!BN_bin2bn(md, qsize, q))
+                               goto err;
 
                        /* step 4 */
                        r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
@@ -215,18 +243,19 @@ static int dsa_builtin_paramgen(DSA *ret, int bits,
                        for (k=0; k<=n; k++)
                                {
                                /* obtain "SEED + offset + k" by incrementing: */
-                               for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
+                               for (i = qsize-1; i >= 0; i--)
                                        {
                                        buf[i]++;
-                                       if (buf[i] != 0) break;
+                                       if (buf[i] != 0)
+                                               break;
                                        }
 
-                               EVP_Digest(buf,SHA_DIGEST_LENGTH,md,NULL,HASH, NULL);
+                               EVP_Digest(buf, qsize, md ,NULL, evpmd, NULL);
 
                                /* step 8 */
-                               if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,r0))
+                               if (!BN_bin2bn(md, qsize, r0))
                                        goto err;
-                               if (!BN_lshift(r0,r0,160*k)) goto err;
+                               if (!BN_lshift(r0,r0,(qsize << 3)*k)) goto err;
                                if (!BN_add(W,W,r0)) goto err;
                                }
 
@@ -300,7 +329,7 @@ err:
                        ok=0;
                        goto err;
                        }
-               if ((m > 1) && (seed_in != NULL)) memcpy(seed_in,seed,20);
+               if ((m > 1) && (seed_in != NULL)) memcpy(seed_in,seed, qsize);
                if (counter_ret != NULL) *counter_ret=counter;
                if (h_ret != NULL) *h_ret=h;
                }