openssl1.0/crypto/evp/evp_enc.c

/* crypto/evp/evp_enc.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * 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 (tjh@cryptsoft.com).
 *
 * 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 (eay@cryptsoft.com)"
 *    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 (tjh@cryptsoft.com)"
 *
 * 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 "cryptlib.h"
#include <openssl/evp.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#ifndef OPENSSL_NO_ENGINE
# include <openssl/engine.h>
#endif
#ifdef OPENSSL_FIPS
# include <openssl/fips.h>
#endif
#include "evp_locl.h"

#ifdef OPENSSL_FIPS
# define M_do_cipher(ctx, out, in, inl) FIPS_cipher(ctx, out, in, inl)
#else
# define M_do_cipher(ctx, out, in, inl) ctx->cipher->do_cipher(ctx, out, in, inl)
#endif

const char EVP_version[] = "EVP" OPENSSL_VERSION_PTEXT;

void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *ctx)
{
    memset(ctx, 0, sizeof(EVP_CIPHER_CTX));
    /* ctx->cipher=NULL; */
}

EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void)
{
    EVP_CIPHER_CTX *ctx = OPENSSL_malloc(sizeof(*ctx));
    if (ctx)
        EVP_CIPHER_CTX_init(ctx);
    return ctx;
}

int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
                   const unsigned char *key, const unsigned char *iv, int enc)
{
    if (cipher)
        EVP_CIPHER_CTX_init(ctx);
    return EVP_CipherInit_ex(ctx, cipher, NULL, key, iv, enc);
}

int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
                      ENGINE *impl, const unsigned char *key,
                      const unsigned char *iv, int enc)
{
    if (enc == -1)
        enc = ctx->encrypt;
    else {
        if (enc)
            enc = 1;
        ctx->encrypt = enc;
    }
#ifndef OPENSSL_NO_ENGINE
    /*
     * Whether it's nice or not, "Inits" can be used on "Final"'d contexts so
     * this context may already have an ENGINE! Try to avoid releasing the
     * previous handle, re-querying for an ENGINE, and having a
     * reinitialisation, when it may all be unecessary.
     */
    if (ctx->engine && ctx->cipher && (!cipher ||
                                       (cipher
                                        && (cipher->nid ==
                                            ctx->cipher->nid))))
        goto skip_to_init;
#endif
    if (cipher) {
        /*
         * Ensure a context left lying around from last time is cleared (the
         * previous check attempted to avoid this if the same ENGINE and
         * EVP_CIPHER could be used).
         */
        if (ctx->cipher) {
            unsigned long flags = ctx->flags;
            EVP_CIPHER_CTX_cleanup(ctx);
            /* Restore encrypt and flags */
            ctx->encrypt = enc;
            ctx->flags = flags;
        }
#ifndef OPENSSL_NO_ENGINE
        if (impl) {
            if (!ENGINE_init(impl)) {
                EVPerr(EVP_F_EVP_CIPHERINIT_EX, EVP_R_INITIALIZATION_ERROR);
                return 0;
            }
        } else
            /* Ask if an ENGINE is reserved for this job */
            impl = ENGINE_get_cipher_engine(cipher->nid);
        if (impl) {
            /* There's an ENGINE for this job ... (apparently) */
            const EVP_CIPHER *c = ENGINE_get_cipher(impl, cipher->nid);
            if (!c) {
                /*
                 * One positive side-effect of US's export control history,
                 * is that we should at least be able to avoid using US
                 * mispellings of "initialisation"?
                 */
                EVPerr(EVP_F_EVP_CIPHERINIT_EX, EVP_R_INITIALIZATION_ERROR);
                return 0;
            }
            /* We'll use the ENGINE's private cipher definition */
            cipher = c;
            /*
             * Store the ENGINE functional reference so we know 'cipher' came
             * from an ENGINE and we need to release it when done.
             */
            ctx->engine = impl;
        } else
            ctx->engine = NULL;
#endif

#ifdef OPENSSL_FIPS
        if (FIPS_mode()) {
            const EVP_CIPHER *fcipher = NULL;
            if (cipher)
                fcipher = evp_get_fips_cipher(cipher);
            if (fcipher)
                cipher = fcipher;
            return FIPS_cipherinit(ctx, cipher, key, iv, enc);
        }
#endif
        ctx->cipher = cipher;
        if (ctx->cipher->ctx_size) {
            ctx->cipher_data = OPENSSL_malloc(ctx->cipher->ctx_size);
            if (!ctx->cipher_data) {
                ctx->cipher = NULL;
                EVPerr(EVP_F_EVP_CIPHERINIT_EX, ERR_R_MALLOC_FAILURE);
                return 0;
            }
        } else {
            ctx->cipher_data = NULL;
        }
        ctx->key_len = cipher->key_len;
        /* Preserve wrap enable flag, zero everything else */
        ctx->flags &= EVP_CIPHER_CTX_FLAG_WRAP_ALLOW;
        if (ctx->cipher->flags & EVP_CIPH_CTRL_INIT) {
            if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_INIT, 0, NULL)) {
                ctx->cipher = NULL;
                EVPerr(EVP_F_EVP_CIPHERINIT_EX, EVP_R_INITIALIZATION_ERROR);
                return 0;
            }
        }
    } else if (!ctx->cipher) {
        EVPerr(EVP_F_EVP_CIPHERINIT_EX, EVP_R_NO_CIPHER_SET);
        return 0;
    }
#ifndef OPENSSL_NO_ENGINE
 skip_to_init:
#endif
#ifdef OPENSSL_FIPS
    if (FIPS_mode())
        return FIPS_cipherinit(ctx, cipher, key, iv, enc);
#endif
    /* we assume block size is a power of 2 in *cryptUpdate */
    OPENSSL_assert(ctx->cipher->block_size == 1
                   || ctx->cipher->block_size == 8
                   || ctx->cipher->block_size == 16);

    if (!(ctx->flags & EVP_CIPHER_CTX_FLAG_WRAP_ALLOW)
        && EVP_CIPHER_CTX_mode(ctx) == EVP_CIPH_WRAP_MODE) {
        EVPerr(EVP_F_EVP_CIPHERINIT_EX, EVP_R_WRAP_MODE_NOT_ALLOWED);
        return 0;
    }

    if (!(EVP_CIPHER_CTX_flags(ctx) & EVP_CIPH_CUSTOM_IV)) {
        switch (EVP_CIPHER_CTX_mode(ctx)) {

        case EVP_CIPH_STREAM_CIPHER:
        case EVP_CIPH_ECB_MODE:
            break;

        case EVP_CIPH_CFB_MODE:
        case EVP_CIPH_OFB_MODE:

            ctx->num = 0;
            /* fall-through */

        case EVP_CIPH_CBC_MODE:

            OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) <=
                           (int)sizeof(ctx->iv));
            if (iv)
                memcpy(ctx->oiv, iv, EVP_CIPHER_CTX_iv_length(ctx));
            memcpy(ctx->iv, ctx->oiv, EVP_CIPHER_CTX_iv_length(ctx));
            break;

        case EVP_CIPH_CTR_MODE:
            ctx->num = 0;
            /* Don't reuse IV for CTR mode */
            if (iv)
                memcpy(ctx->iv, iv, EVP_CIPHER_CTX_iv_length(ctx));
            break;

        default:
            return 0;
            break;
        }
    }

    if (key || (ctx->cipher->flags & EVP_CIPH_ALWAYS_CALL_INIT)) {
        if (!ctx->cipher->init(ctx, key, iv, enc))
            return 0;
    }
    ctx->buf_len = 0;
    ctx->final_used = 0;
    ctx->block_mask = ctx->cipher->block_size - 1;
    return 1;
}

int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
                     const unsigned char *in, int inl)
{
    if (ctx->encrypt)
        return EVP_EncryptUpdate(ctx, out, outl, in, inl);
    else
        return EVP_DecryptUpdate(ctx, out, outl, in, inl);
}

int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
{
    if (ctx->encrypt)
        return EVP_EncryptFinal_ex(ctx, out, outl);
    else
        return EVP_DecryptFinal_ex(ctx, out, outl);
}

int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
{
    if (ctx->encrypt)
        return EVP_EncryptFinal(ctx, out, outl);
    else
        return EVP_DecryptFinal(ctx, out, outl);
}

int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
                    const unsigned char *key, const unsigned char *iv)
{
    return EVP_CipherInit(ctx, cipher, key, iv, 1);
}

int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
                       ENGINE *impl, const unsigned char *key,
                       const unsigned char *iv)
{
    return EVP_CipherInit_ex(ctx, cipher, impl, key, iv, 1);
}

int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
                    const unsigned char *key, const unsigned char *iv)
{
    return EVP_CipherInit(ctx, cipher, key, iv, 0);
}

int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,
                       ENGINE *impl, const unsigned char *key,
                       const unsigned char *iv)
{
    return EVP_CipherInit_ex(ctx, cipher, impl, key, iv, 0);
}

static int evp_EncryptDecryptUpdate(EVP_CIPHER_CTX *ctx,
                                    unsigned char *out, int *outl,
                                    const unsigned char *in, int inl)
{
    int i, j, bl;

    if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER) {
        i = M_do_cipher(ctx, out, in, inl);
        if (i < 0)
            return 0;
        else
            *outl = i;
        return 1;
    }

    if (inl <= 0) {
        *outl = 0;
        return inl == 0;
    }

    if (ctx->buf_len == 0 && (inl & (ctx->block_mask)) == 0) {
        if (M_do_cipher(ctx, out, in, inl)) {
            *outl = inl;
            return 1;
        } else {
            *outl = 0;
            return 0;
        }
    }
    i = ctx->buf_len;
    bl = ctx->cipher->block_size;
    OPENSSL_assert(bl <= (int)sizeof(ctx->buf));
    if (i != 0) {
        if (bl - i > inl) {
            memcpy(&(ctx->buf[i]), in, inl);
            ctx->buf_len += inl;
            *outl = 0;
            return 1;
        } else {
            j = bl - i;
            memcpy(&(ctx->buf[i]), in, j);
            if (!M_do_cipher(ctx, out, ctx->buf, bl))
                return 0;
            inl -= j;
            in += j;
            out += bl;
            *outl = bl;
        }
    } else
        *outl = 0;
    i = inl & (bl - 1);
    inl -= i;
    if (inl > 0) {
        if (!M_do_cipher(ctx, out, in, inl))
            return 0;
        *outl += inl;
    }

    if (i != 0)
        memcpy(ctx->buf, &(in[inl]), i);
    ctx->buf_len = i;
    return 1;
}

int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
                      const unsigned char *in, int inl)
{
    /* Prevent accidental use of decryption context when encrypting */
    if (!ctx->encrypt) {
        EVPerr(EVP_F_EVP_ENCRYPTUPDATE, EVP_R_INVALID_OPERATION);
        return 0;
    }

    return evp_EncryptDecryptUpdate(ctx, out, outl, in, inl);
}

int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
{
    int ret;
    ret = EVP_EncryptFinal_ex(ctx, out, outl);
    return ret;
}

int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
{
    int n, ret;
    unsigned int i, b, bl;

    /* Prevent accidental use of decryption context when encrypting */
    if (!ctx->encrypt) {
        EVPerr(EVP_F_EVP_ENCRYPTFINAL_EX, EVP_R_INVALID_OPERATION);
        return 0;
    }

    if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER) {
        ret = M_do_cipher(ctx, out, NULL, 0);
        if (ret < 0)
            return 0;
        else
            *outl = ret;
        return 1;
    }

    b = ctx->cipher->block_size;
    OPENSSL_assert(b <= sizeof(ctx->buf));
    if (b == 1) {
        *outl = 0;
        return 1;
    }
    bl = ctx->buf_len;
    if (ctx->flags & EVP_CIPH_NO_PADDING) {
        if (bl) {
            EVPerr(EVP_F_EVP_ENCRYPTFINAL_EX,
                   EVP_R_DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH);
            return 0;
        }
        *outl = 0;
        return 1;
    }

    n = b - bl;
    for (i = bl; i < b; i++)
        ctx->buf[i] = n;
    ret = M_do_cipher(ctx, out, ctx->buf, b);

    if (ret)
        *outl = b;

    return ret;
}

int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl,
                      const unsigned char *in, int inl)
{
    int fix_len;
    unsigned int b;

    /* Prevent accidental use of encryption context when decrypting */
    if (ctx->encrypt) {
        EVPerr(EVP_F_EVP_DECRYPTUPDATE, EVP_R_INVALID_OPERATION);
        return 0;
    }

    if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER) {
        fix_len = M_do_cipher(ctx, out, in, inl);
        if (fix_len < 0) {
            *outl = 0;
            return 0;
        } else
            *outl = fix_len;
        return 1;
    }

    if (inl <= 0) {
        *outl = 0;
        return inl == 0;
    }

    if (ctx->flags & EVP_CIPH_NO_PADDING)
        return evp_EncryptDecryptUpdate(ctx, out, outl, in, inl);

    b = ctx->cipher->block_size;
    OPENSSL_assert(b <= sizeof(ctx->final));

    if (ctx->final_used) {
        memcpy(out, ctx->final, b);
        out += b;
        fix_len = 1;
    } else
        fix_len = 0;

    if (!evp_EncryptDecryptUpdate(ctx, out, outl, in, inl))
        return 0;

    /*
     * if we have 'decrypted' a multiple of block size, make sure we have a
     * copy of this last block
     */
    if (b > 1 && !ctx->buf_len) {
        *outl -= b;
        ctx->final_used = 1;
        memcpy(ctx->final, &out[*outl], b);
    } else
        ctx->final_used = 0;

    if (fix_len)
        *outl += b;

    return 1;
}

int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
{
    int ret;
    ret = EVP_DecryptFinal_ex(ctx, out, outl);
    return ret;
}

int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl)
{
    int i, n;
    unsigned int b;

    /* Prevent accidental use of encryption context when decrypting */
    if (ctx->encrypt) {
        EVPerr(EVP_F_EVP_DECRYPTFINAL_EX, EVP_R_INVALID_OPERATION);
        return 0;
    }

    *outl = 0;

    if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER) {
        i = M_do_cipher(ctx, out, NULL, 0);
        if (i < 0)
            return 0;
        else
            *outl = i;
        return 1;
    }

    b = ctx->cipher->block_size;
    if (ctx->flags & EVP_CIPH_NO_PADDING) {
        if (ctx->buf_len) {
            EVPerr(EVP_F_EVP_DECRYPTFINAL_EX,
                   EVP_R_DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH);
            return 0;
        }
        *outl = 0;
        return 1;
    }
    if (b > 1) {
        if (ctx->buf_len || !ctx->final_used) {
            EVPerr(EVP_F_EVP_DECRYPTFINAL_EX, EVP_R_WRONG_FINAL_BLOCK_LENGTH);
            return (0);
        }
        OPENSSL_assert(b <= sizeof(ctx->final));

        /*
         * The following assumes that the ciphertext has been authenticated.
         * Otherwise it provides a padding oracle.
         */
        n = ctx->final[b - 1];
        if (n == 0 || n > (int)b) {
            EVPerr(EVP_F_EVP_DECRYPTFINAL_EX, EVP_R_BAD_DECRYPT);
            return (0);
        }
        for (i = 0; i < n; i++) {
            if (ctx->final[--b] != n) {
                EVPerr(EVP_F_EVP_DECRYPTFINAL_EX, EVP_R_BAD_DECRYPT);
                return (0);
            }
        }
        n = ctx->cipher->block_size - n;
        for (i = 0; i < n; i++)
            out[i] = ctx->final[i];
        *outl = n;
    } else
        *outl = 0;
    return (1);
}

void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx)
{
    if (ctx) {
        EVP_CIPHER_CTX_cleanup(ctx);
        OPENSSL_free(ctx);
    }
}

int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *c)
{
#ifndef OPENSSL_FIPS
    if (c->cipher != NULL) {
        if (c->cipher->cleanup && !c->cipher->cleanup(c))
            return 0;
        /* Cleanse cipher context data */
        if (c->cipher_data)
            OPENSSL_cleanse(c->cipher_data, c->cipher->ctx_size);
    }
    if (c->cipher_data)
        OPENSSL_free(c->cipher_data);
#endif
#ifndef OPENSSL_NO_ENGINE
    if (c->engine)
        /*
         * The EVP_CIPHER we used belongs to an ENGINE, release the
         * functional reference we held for this reason.
         */
        ENGINE_finish(c->engine);
#endif
#ifdef OPENSSL_FIPS
    FIPS_cipher_ctx_cleanup(c);
#endif
    memset(c, 0, sizeof(EVP_CIPHER_CTX));
    return 1;
}

int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *c, int keylen)
{
    if (c->cipher->flags & EVP_CIPH_CUSTOM_KEY_LENGTH)
        return EVP_CIPHER_CTX_ctrl(c, EVP_CTRL_SET_KEY_LENGTH, keylen, NULL);
    if (c->key_len == keylen)
        return 1;
    if ((keylen > 0) && (c->cipher->flags & EVP_CIPH_VARIABLE_LENGTH)) {
        c->key_len = keylen;
        return 1;
    }
    EVPerr(EVP_F_EVP_CIPHER_CTX_SET_KEY_LENGTH, EVP_R_INVALID_KEY_LENGTH);
    return 0;
}

int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *ctx, int pad)
{
    if (pad)
        ctx->flags &= ~EVP_CIPH_NO_PADDING;
    else
        ctx->flags |= EVP_CIPH_NO_PADDING;
    return 1;
}

int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr)
{
    int ret;
    if (!ctx->cipher) {
        EVPerr(EVP_F_EVP_CIPHER_CTX_CTRL, EVP_R_NO_CIPHER_SET);
        return 0;
    }

    if (!ctx->cipher->ctrl) {
        EVPerr(EVP_F_EVP_CIPHER_CTX_CTRL, EVP_R_CTRL_NOT_IMPLEMENTED);
        return 0;
    }

    ret = ctx->cipher->ctrl(ctx, type, arg, ptr);
    if (ret == -1) {
        EVPerr(EVP_F_EVP_CIPHER_CTX_CTRL,
               EVP_R_CTRL_OPERATION_NOT_IMPLEMENTED);
        return 0;
    }
    return ret;
}

int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key)
{
    if (ctx->cipher->flags & EVP_CIPH_RAND_KEY)
        return EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_RAND_KEY, 0, key);
    if (RAND_bytes(key, ctx->key_len) <= 0)
        return 0;
    return 1;
}

int EVP_CIPHER_CTX_copy(EVP_CIPHER_CTX *out, const EVP_CIPHER_CTX *in)
{
    if ((in == NULL) || (in->cipher == NULL)) {
        EVPerr(EVP_F_EVP_CIPHER_CTX_COPY, EVP_R_INPUT_NOT_INITIALIZED);
        return 0;
    }
#ifndef OPENSSL_NO_ENGINE
    /* Make sure it's safe to copy a cipher context using an ENGINE */
    if (in->engine && !ENGINE_init(in->engine)) {
        EVPerr(EVP_F_EVP_CIPHER_CTX_COPY, ERR_R_ENGINE_LIB);
        return 0;
    }
#endif

    EVP_CIPHER_CTX_cleanup(out);
    memcpy(out, in, sizeof(*out));

    if (in->cipher_data && in->cipher->ctx_size) {
        out->cipher_data = OPENSSL_malloc(in->cipher->ctx_size);
        if (!out->cipher_data) {
            out->cipher = NULL;
            EVPerr(EVP_F_EVP_CIPHER_CTX_COPY, ERR_R_MALLOC_FAILURE);
            return 0;
        }
        memcpy(out->cipher_data, in->cipher_data, in->cipher->ctx_size);
    }

    if (in->cipher->flags & EVP_CIPH_CUSTOM_COPY)
        if (!in->cipher->ctrl((EVP_CIPHER_CTX *)in, EVP_CTRL_COPY, 0, out)) {
            out->cipher = NULL;
            EVPerr(EVP_F_EVP_CIPHER_CTX_COPY, EVP_R_INITIALIZATION_ERROR);
            return 0;
        }
    return 1;
}