PK: add nice interface functions

Also fix a const-corectness issue.

include/polarssl/error.h

@@ -84,7 +84,7 @@
  * ECP      4   4 (Started from top)
  * MD       5   4
  * CIPHER   6   5
- * SSL      6   5 (Started from top)
+ * SSL      6   6 (Started from top)
  * SSL      7   31
  *
  * Module dependent error code (5 bits 0x.08.-0x.F8.)

include/polarssl/pk.h

@@ -93,7 +93,7 @@ typedef struct
     const char *name;
 
     /** Get key size in bits */
-    size_t (*get_size)( void * );
+    size_t (*get_size)( const void * );
 
     /** Tell if the context implements this type (eg ECKEY can do ECDSA) */
     int (*can_do)( pk_type_t type );
@@ -146,6 +146,42 @@ void pk_free( pk_context *ctx );
  */
 int pk_set_type( pk_context *ctx, pk_type_t type );
 
+/**
+ * \brief           Get the size in bits of the underlying key
+ *
+ * \param ctx       Context to use
+ *
+ * \return          Key size in bits, or 0 on error
+ */
+size_t pk_get_size( const pk_context *ctx );
+
+/**
+ * \brief           Tell if a context can do the operation given by type
+ *
+ * \param ctx       Context to test
+ * \param type      Target type
+ *
+ * \return          0 if context can't do the operations,
+ *                  1 otherwise.
+ */
+int pk_can_do( pk_context *ctx, pk_type_t type );
+
+/**
+ * \brief           Verify signature
+ *
+ * \param ctx       PK context to use
+ * \param hash      Hash of the message to sign
+ * \param md_info   Information about the hash function used
+ * \param sig       Signature to verify
+ * \param sig_len   Signature length
+ *
+ * \return          0 on success (signature is valid),
+ *                  or a specific error code.
+ */
+int pk_verify( pk_context *ctx,
+               const unsigned char *hash, const md_info_t *md_info,
+               const unsigned char *sig, size_t sig_len );
+
 #ifdef __cplusplus
 }
 #endif

include/polarssl/ssl.h

@@ -110,7 +110,7 @@
 #define POLARSSL_ERR_SSL_BAD_HS_PROTOCOL_VERSION           -0x6E80  /**< Handshake protocol not within min/max boundaries */
 #define POLARSSL_ERR_SSL_BAD_HS_NEW_SESSION_TICKET         -0x6E00  /**< Processing of the NewSessionTicket handshake message failed. */
 #define POLARSSL_ERR_SSL_SESSION_TICKET_EXPIRED            -0x6D80  /**< Session ticket has expired. */
-
+#define POLARSSL_ERR_SSL_PK_TYPE_MISMATCH                  -0x6D00  /**< Public key type mismatch (eg, asked for RSA key exchange and presented EC key) */
 
 /*
  * Various constants

library/error.c

@@ -373,6 +373,8 @@ void polarssl_strerror( int ret, char *buf, size_t buflen )
             snprintf( buf, buflen, "SSL - Processing of the NewSessionTicket handshake message failed" );
         if( use_ret == -(POLARSSL_ERR_SSL_SESSION_TICKET_EXPIRED) )
             snprintf( buf, buflen, "SSL - Session ticket has expired" );
+        if( use_ret == -(POLARSSL_ERR_SSL_PK_TYPE_MISMATCH) )
+            snprintf( buf, buflen, "SSL - Public key type mismatch (eg, asked for RSA key exchange and presented EC key)" );
 #endif /* POLARSSL_SSL_TLS_C */
 
 #if defined(POLARSSL_X509_PARSE_C)

library/pk.c

@@ -124,3 +124,39 @@ int pk_set_type( pk_context *ctx, pk_type_t type )
 
     return( 0 );
 }
+
+/*
+ * Tell if a PK can do the operations of the given type
+ */
+int pk_can_do( pk_context *ctx, pk_type_t type )
+{
+    /* null of NONE context can't do anything */
+    if( ctx == NULL || ctx->info == NULL )
+        return( 0 );
+
+    return( ctx->info->can_do( type ) );
+}
+
+/*
+ * Verify a signature
+ */
+int pk_verify( pk_context *ctx,
+               const unsigned char *hash, const md_info_t *md_info,
+               const unsigned char *sig, size_t sig_len )
+{
+    if( ctx == NULL || ctx->info == NULL )
+        return( POLARSSL_ERR_PK_TYPE_MISMATCH ); // TODO
+
+    return( ctx->info->verify_func( ctx->data, hash, md_info, sig, sig_len ) );
+}
+
+/*
+ * Get key size in bits
+ */
+size_t pk_get_size( const pk_context *ctx )
+{
+    if( ctx == NULL || ctx->info == NULL )
+        return( 0 );
+
+    return( ctx->info->get_size( ctx->data ) );
+}

library/pk_wrap.c

@@ -53,9 +53,9 @@ static int rsa_can_do( pk_type_t type )
     return( type == POLARSSL_PK_RSA );
 }
 
-static size_t rsa_get_size( void * ctx )
+static size_t rsa_get_size( const void * ctx )
 {
-    return( mpi_size( &((rsa_context *) ctx)->N ) * 8 );
+    return( 8 * ((rsa_context *) ctx)->len );
 }
 
 static int rsa_verify_wrap( void *ctx,
@@ -101,7 +101,7 @@ int ecdsa_can_do( pk_type_t type )
     return( type == POLARSSL_PK_ECDSA );
 }
 
-static size_t ecdsa_get_size( void *ctx )
+static size_t ecdsa_get_size( const void *ctx )
 {
     return( ((ecdsa_context *) ctx)->grp.pbits );
 }
@@ -152,7 +152,7 @@ static int eckey_can_do( pk_type_t type )
             type == POLARSSL_PK_ECDSA );
 }
 
-static size_t eckey_get_size( void *ctx )
+static size_t eckey_get_size( const void *ctx )
 {
     return( ((ecp_keypair *) ctx)->grp.pbits );
 }

library/ssl_cli.c

@@ -1346,12 +1346,15 @@ static int ssl_parse_server_key_exchange( ssl_context *ssl )
             return( POLARSSL_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
         }
 
-        /* EC NOT IMPLEMENTED YET */
+        if( ! pk_can_do( &ssl->session_negotiate->peer_cert->pk,
-        if( ssl->session_negotiate->peer_cert->pk.type != POLARSSL_PK_RSA )
+                         POLARSSL_PK_RSA ) )
-            return( POLARSSL_ERR_SSL_FEATURE_UNAVAILABLE );
+        {
+            SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
+            return( POLARSSL_ERR_SSL_PK_TYPE_MISMATCH );
+        }
 
-        if( (unsigned int)( end - p ) !=
+        if( 8 * (unsigned int)( end - p ) !=
-            pk_rsa( ssl->session_negotiate->peer_cert->pk )->len )
+            pk_get_size( &ssl->session_negotiate->peer_cert->pk ) )
         {
             SSL_DEBUG_MSG( 1, ( "bad server key exchange message" ) );
             return( POLARSSL_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE );
@@ -1795,12 +1798,15 @@ static int ssl_write_client_key_exchange( ssl_context *ssl )
         if( ret != 0 )
             return( ret );
 
-        /* EC NOT IMPLEMENTED YET */
+        if( ! pk_can_do( &ssl->session_negotiate->peer_cert->pk,
-        if( ssl->session_negotiate->peer_cert->pk.type != POLARSSL_PK_RSA )
+                         POLARSSL_PK_RSA ) )
-            return( POLARSSL_ERR_SSL_FEATURE_UNAVAILABLE );
+        {
+            SSL_DEBUG_MSG( 1, ( "certificate key type mismatch" ) );
+            return( POLARSSL_ERR_SSL_PK_TYPE_MISMATCH );
+        }
 
         i = 4;
-        n = pk_rsa( ssl->session_negotiate->peer_cert->pk )->len;
+        n = pk_get_size( &ssl->session_negotiate->peer_cert->pk ) / 8;
 
         if( ssl->minor_ver != SSL_MINOR_VERSION_0 )
         {

library/ssl_srv.c

@@ -2517,10 +2517,13 @@ static int ssl_parse_certificate_verify( ssl_context *ssl )
     }
 
     /* EC NOT IMPLEMENTED YET */
-    if( ssl->session_negotiate->peer_cert->pk.type != POLARSSL_PK_RSA )
+    if( ! pk_can_do( &ssl->session_negotiate->peer_cert->pk,
+                     POLARSSL_PK_RSA ) )
+    {
         return( POLARSSL_ERR_SSL_FEATURE_UNAVAILABLE );
+    }
 
-    n1 = pk_rsa( ssl->session_negotiate->peer_cert->pk )->len;
+    n1 = pk_get_size( &ssl->session_negotiate->peer_cert->pk ) / 8;
     n2 = ( ssl->in_msg[4 + n] << 8 ) | ssl->in_msg[5 + n];
 
     if( n + n1 + 6 != ssl->in_hslen || n1 != n2 )

library/x509parse.c

@@ -3147,7 +3147,7 @@ int x509parse_cert_info( char *buf, size_t size, const char *prefix,
     }
 
     ret = snprintf( p, n, "\n%s%-" BC "s: %d bits\n", prefix, key_size_str,
-                          (int) crt->pk.info->get_size( crt->pk.data ) );
+                          (int) pk_get_size( &crt->pk ) );
     SAFE_SNPRINTF();
 
     return( (int) ( size - n ) );
@@ -3399,8 +3399,8 @@ static int x509parse_verifycrl(x509_cert *crt, x509_cert *ca,
 
         md( md_info, crl_list->tbs.p, crl_list->tbs.len, hash );
 
-        if( ca->pk.info->can_do( crl_list->sig_pk ) == 0 ||
+        if( pk_can_do( &ca->pk, crl_list->sig_pk ) == 0 ||
-                ca->pk.info->verify_func( ca->pk.data, hash, md_info,
+            pk_verify( &ca->pk, hash, md_info,
                        crl_list->sig.p, crl_list->sig.len ) != 0 )
         {
             flags |= BADCRL_NOT_TRUSTED;
@@ -3516,8 +3516,8 @@ static int x509parse_verify_top(
 
         md( md_info, child->tbs.p, child->tbs.len, hash );
 
-        if( trust_ca->pk.info->can_do( child->sig_pk ) == 0 ||
+        if( pk_can_do( &trust_ca->pk, child->sig_pk ) == 0 ||
-            trust_ca->pk.info->verify_func( trust_ca->pk.data, hash, md_info,
+            pk_verify( &trust_ca->pk, hash, md_info,
                        child->sig.p, child->sig.len ) != 0 )
         {
             trust_ca = trust_ca->next;
@@ -3593,8 +3593,8 @@ static int x509parse_verify_child(
     {
         md( md_info, child->tbs.p, child->tbs.len, hash );
 
-        if( parent->pk.info->can_do( child->sig_pk ) == 0 ||
+        if( pk_can_do( &parent->pk, child->sig_pk ) == 0 ||
-                parent->pk.info->verify_func( parent->pk.data, hash, md_info,
+            pk_verify( &parent->pk, hash, md_info,
                        child->sig.p, child->sig.len ) != 0 )
         {
             *flags |= BADCERT_NOT_TRUSTED;