bio_enc.c

Go to the documentation of this file.

/* crypto/evp/bio_enc.c */
/* Copyright (C) 1995-1998 Eric Young ([email protected])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([email protected]).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson ([email protected]).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young ([email protected])"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson ([email protected])"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <stdio.h>
#include <errno.h>
#include "cryptlib.h"
#include <openssl/buffer.h>
#include <openssl/evp.h>

static int enc_write(BIO *h, const char *buf, int num);
static int enc_read(BIO *h, char *buf, int size);
/*static int enc_puts(BIO *h, const char *str); */
/*static int enc_gets(BIO *h, char *str, int size); */
static long enc_ctrl(BIO *h, int cmd, long arg1, void *arg2);
static int enc_new(BIO *h);
static int enc_free(BIO *data);
static long enc_callback_ctrl(BIO *h, int cmd, bio_info_cb *fps);
#define ENC_BLOCK_SIZE  (1024*4)
#define BUF_OFFSET  (EVP_MAX_BLOCK_LENGTH*2)

typedef struct enc_struct
    {
    int buf_len;
    int buf_off;
    int cont;       /* <= 0 when finished */
    int finished;
    int ok;         /* bad decrypt */
    EVP_CIPHER_CTX cipher;
    /* buf is larger than ENC_BLOCK_SIZE because EVP_DecryptUpdate
     * can return up to a block more data than is presented to it
     */
    char buf[ENC_BLOCK_SIZE+BUF_OFFSET+2];
    } BIO_ENC_CTX;

static BIO_METHOD methods_enc=
    {
    BIO_TYPE_CIPHER,"cipher",
    enc_write,
    enc_read,
    NULL, /* enc_puts, */
    NULL, /* enc_gets, */
    enc_ctrl,
    enc_new,
    enc_free,
    enc_callback_ctrl,
    };

BIO_METHOD *BIO_f_cipher(void)
    {
    return(&methods_enc);
    }

static int enc_new(BIO *bi)
    {
    BIO_ENC_CTX *ctx;

    ctx=(BIO_ENC_CTX *)OPENSSL_malloc(sizeof(BIO_ENC_CTX));
    if (ctx == NULL) return(0);
    EVP_CIPHER_CTX_init(&ctx->cipher);

    ctx->buf_len=0;
    ctx->buf_off=0;
    ctx->cont=1;
    ctx->finished=0;
    ctx->ok=1;

    bi->init=0;
    bi->ptr=(char *)ctx;
    bi->flags=0;
    return(1);
    }

static int enc_free(BIO *a)
    {
    BIO_ENC_CTX *b;

    if (a == NULL) return(0);
    b=(BIO_ENC_CTX *)a->ptr;
    EVP_CIPHER_CTX_cleanup(&(b->cipher));
    OPENSSL_cleanse(a->ptr,sizeof(BIO_ENC_CTX));
    OPENSSL_free(a->ptr);
    a->ptr=NULL;
    a->init=0;
    a->flags=0;
    return(1);
    }
    
static int enc_read(BIO *b, char *out, int outl)
    {
    int ret=0,i;
    BIO_ENC_CTX *ctx;

    if (out == NULL) return(0);
    ctx=(BIO_ENC_CTX *)b->ptr;

    if ((ctx == NULL) || (b->next_bio == NULL)) return(0);

    /* First check if there are bytes decoded/encoded */
    if (ctx->buf_len > 0)
        {
        i=ctx->buf_len-ctx->buf_off;
        if (i > outl) i=outl;
        memcpy(out,&(ctx->buf[ctx->buf_off]),i);
        ret=i;
        out+=i;
        outl-=i;
        ctx->buf_off+=i;
        if (ctx->buf_len == ctx->buf_off)
            {
            ctx->buf_len=0;
            ctx->buf_off=0;
            }
        }

    /* At this point, we have room of outl bytes and an empty
     * buffer, so we should read in some more. */

    while (outl > 0)
        {
        if (ctx->cont <= 0) break;

        /* read in at IV offset, read the EVP_Cipher
         * documentation about why */
        i=BIO_read(b->next_bio,&(ctx->buf[BUF_OFFSET]),ENC_BLOCK_SIZE);

        if (i <= 0)
            {
            /* Should be continue next time we are called? */
            if (!BIO_should_retry(b->next_bio))
                {
                ctx->cont=i;
                i=EVP_CipherFinal_ex(&(ctx->cipher),
                    (unsigned char *)ctx->buf,
                    &(ctx->buf_len));
                ctx->ok=i;
                ctx->buf_off=0;
                }
            else 
                {
                ret=(ret == 0)?i:ret;
                break;
                }
            }
        else
            {
            EVP_CipherUpdate(&(ctx->cipher),
                (unsigned char *)ctx->buf,&ctx->buf_len,
                (unsigned char *)&(ctx->buf[BUF_OFFSET]),i);
            ctx->cont=1;
            /* Note: it is possible for EVP_CipherUpdate to
             * decrypt zero bytes because this is or looks like
             * the final block: if this happens we should retry
             * and either read more data or decrypt the final
             * block
             */
            if(ctx->buf_len == 0) continue;
            }

        if (ctx->buf_len <= outl)
            i=ctx->buf_len;
        else
            i=outl;
        if (i <= 0) break;
        memcpy(out,ctx->buf,i);
        ret+=i;
        ctx->buf_off=i;
        outl-=i;
        out+=i;
        }

    BIO_clear_retry_flags(b);
    BIO_copy_next_retry(b);
    return((ret == 0)?ctx->cont:ret);
    }

static int enc_write(BIO *b, const char *in, int inl)
    {
    int ret=0,n,i;
    BIO_ENC_CTX *ctx;

    ctx=(BIO_ENC_CTX *)b->ptr;
    ret=inl;

    BIO_clear_retry_flags(b);
    n=ctx->buf_len-ctx->buf_off;
    while (n > 0)
        {
        i=BIO_write(b->next_bio,&(ctx->buf[ctx->buf_off]),n);
        if (i <= 0)
            {
            BIO_copy_next_retry(b);
            return(i);
            }
        ctx->buf_off+=i;
        n-=i;
        }
    /* at this point all pending data has been written */

    if ((in == NULL) || (inl <= 0)) return(0);

    ctx->buf_off=0;
    while (inl > 0)
        {
        n=(inl > ENC_BLOCK_SIZE)?ENC_BLOCK_SIZE:inl;
        EVP_CipherUpdate(&(ctx->cipher),
            (unsigned char *)ctx->buf,&ctx->buf_len,
            (unsigned char *)in,n);
        inl-=n;
        in+=n;

        ctx->buf_off=0;
        n=ctx->buf_len;
        while (n > 0)
            {
            i=BIO_write(b->next_bio,&(ctx->buf[ctx->buf_off]),n);
            if (i <= 0)
                {
                BIO_copy_next_retry(b);
                return (ret == inl) ? i : ret - inl;
                }
            n-=i;
            ctx->buf_off+=i;
            }
        ctx->buf_len=0;
        ctx->buf_off=0;
        }
    BIO_copy_next_retry(b);
    return(ret);
    }

static long enc_ctrl(BIO *b, int cmd, long num, void *ptr)
    {
    BIO *dbio;
    BIO_ENC_CTX *ctx,*dctx;
    long ret=1;
    int i;
    EVP_CIPHER_CTX **c_ctx;

    ctx=(BIO_ENC_CTX *)b->ptr;

    switch (cmd)
        {
    case BIO_CTRL_RESET:
        ctx->ok=1;
        ctx->finished=0;
        EVP_CipherInit_ex(&(ctx->cipher),NULL,NULL,NULL,NULL,
            ctx->cipher.encrypt);
        ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
        break;
    case BIO_CTRL_EOF:  /* More to read */
        if (ctx->cont <= 0)
            ret=1;
        else
            ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
        break;
    case BIO_CTRL_WPENDING:
        ret=ctx->buf_len-ctx->buf_off;
        if (ret <= 0)
            ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
        break;
    case BIO_CTRL_PENDING: /* More to read in buffer */
        ret=ctx->buf_len-ctx->buf_off;
        if (ret <= 0)
            ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
        break;
    case BIO_CTRL_FLUSH:
        /* do a final write */
again:
        while (ctx->buf_len != ctx->buf_off)
            {
            i=enc_write(b,NULL,0);
            if (i < 0)
                return i;
            }

        if (!ctx->finished)
            {
            ctx->finished=1;
            ctx->buf_off=0;
            ret=EVP_CipherFinal_ex(&(ctx->cipher),
                (unsigned char *)ctx->buf,
                &(ctx->buf_len));
            ctx->ok=(int)ret;
            if (ret <= 0) break;

            /* push out the bytes */
            goto again;
            }
        
        /* Finally flush the underlying BIO */
        ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
        break;
    case BIO_C_GET_CIPHER_STATUS:
        ret=(long)ctx->ok;
        break;
    case BIO_C_DO_STATE_MACHINE:
        BIO_clear_retry_flags(b);
        ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
        BIO_copy_next_retry(b);
        break;
    case BIO_C_GET_CIPHER_CTX:
        c_ctx=(EVP_CIPHER_CTX **)ptr;
        (*c_ctx)= &(ctx->cipher);
        b->init=1;
        break;
    case BIO_CTRL_DUP:
        dbio=(BIO *)ptr;
        dctx=(BIO_ENC_CTX *)dbio->ptr;
        EVP_CIPHER_CTX_init(&dctx->cipher);
        ret = EVP_CIPHER_CTX_copy(&dctx->cipher,&ctx->cipher);
        if (ret)
            dbio->init=1;
        break;
    default:
        ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
        break;
        }
    return(ret);
    }

static long enc_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp)
    {
    long ret=1;

    if (b->next_bio == NULL) return(0);
    switch (cmd)
        {
    default:
        ret=BIO_callback_ctrl(b->next_bio,cmd,fp);
        break;
        }
    return(ret);
    }

/*
void BIO_set_cipher_ctx(b,c)
BIO *b;
EVP_CIPHER_ctx *c;
    {
    if (b == NULL) return;

    if ((b->callback != NULL) &&
        (b->callback(b,BIO_CB_CTRL,(char *)c,BIO_CTRL_SET,e,0L) <= 0))
        return;

    b->init=1;
    ctx=(BIO_ENC_CTX *)b->ptr;
    memcpy(ctx->cipher,c,sizeof(EVP_CIPHER_CTX));
    
    if (b->callback != NULL)
        b->callback(b,BIO_CB_CTRL,(char *)c,BIO_CTRL_SET,e,1L);
    }
*/

void BIO_set_cipher(BIO *b, const EVP_CIPHER *c, const unsigned char *k,
         const unsigned char *i, int e)
    {
    BIO_ENC_CTX *ctx;

    if (b == NULL) return;

    if ((b->callback != NULL) &&
        (b->callback(b,BIO_CB_CTRL,(const char *)c,BIO_CTRL_SET,e,0L) <= 0))
        return;

    b->init=1;
    ctx=(BIO_ENC_CTX *)b->ptr;
    EVP_CipherInit_ex(&(ctx->cipher),c,NULL, k,i,e);
    
    if (b->callback != NULL)
        b->callback(b,BIO_CB_CTRL,(const char *)c,BIO_CTRL_SET,e,1L);
    }