/*

 * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <stdio.h>

#include <limits.h>

#include <assert.h>

#include "internal/cryptlib.h"

#include <openssl/evp.h>

#include <openssl/err.h>

#include <openssl/rand.h>

#include <openssl/rand_drbg.h>

#include <openssl/engine.h>

#include "crypto/evp.h"

#include "evp_local.h"

int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *c)

{

    if (c == NULL)

        return 1;

    if (c->cipher != NULL) {

        if (c->cipher->cleanup && !c->cipher->cleanup(c))

            return 0;

        /* Cleanse cipher context data */

        if (c->cipher_data && c->cipher->ctx_size)

            OPENSSL_cleanse(c->cipher_data, c->cipher->ctx_size);

    }

    OPENSSL_free(c->cipher_data);

#ifndef OPENSSL_NO_ENGINE

    ENGINE_finish(c->engine);

#endif

    memset(c, 0, sizeof(*c));

    return 1;

}

EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void)

{

    return OPENSSL_zalloc(sizeof(EVP_CIPHER_CTX));

}

void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx)

{

    EVP_CIPHER_CTX_reset(ctx);

    OPENSSL_free(ctx);

}

int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *cipher,

                   const unsigned char *key, const unsigned char *iv, int enc)

{

    if (cipher != NULL)

        EVP_CIPHER_CTX_reset(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 unnecessary.

     */

    if (ctx->engine && ctx->cipher

        && (cipher == NULL || 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_reset(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

                 * misspellings 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

        ctx->cipher = cipher;

        if (ctx->cipher->ctx_size) {

            ctx->cipher_data = OPENSSL_zalloc(ctx->cipher->ctx_size);

            if (ctx->cipher_data == NULL) {

                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

    /* 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_flags(EVP_CIPHER_CTX_cipher(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;

        }

    }

    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);

}

/*

 * According to the letter of standard difference between pointers

 * is specified to be valid only within same object. This makes

 * it formally challenging to determine if input and output buffers

 * are not partially overlapping with standard pointer arithmetic.

 */

#ifdef PTRDIFF_T

# undef PTRDIFF_T

#endif

#if defined(OPENSSL_SYS_VMS) && __INITIAL_POINTER_SIZE==64

/*

 * Then we have VMS that distinguishes itself by adhering to

 * sizeof(size_t)==4 even in 64-bit builds, which means that

 * difference between two pointers might be truncated to 32 bits.

 * In the context one can even wonder how comparison for

 * equality is implemented. To be on the safe side we adhere to

 * PTRDIFF_T even for comparison for equality.

 */

# define PTRDIFF_T uint64_t

#else

# define PTRDIFF_T size_t

#endif

int is_partially_overlapping(const void *ptr1, const void *ptr2, int len)

{

    PTRDIFF_T diff = (PTRDIFF_T)ptr1-(PTRDIFF_T)ptr2;

    /*

     * Check for partially overlapping buffers. [Binary logical

     * operations are used instead of boolean to minimize number

     * of conditional branches.]

     */

    int overlapped = (len > 0) & (diff != 0) & ((diff < (PTRDIFF_T)len) |

                                                (diff > (0 - (PTRDIFF_T)len)));

    return overlapped;

}

static int evp_EncryptDecryptUpdate(EVP_CIPHER_CTX *ctx,

                                    unsigned char *out, int *outl,

                                    const unsigned char *in, int inl)

{

    int i, j, bl, cmpl = inl;

    if (EVP_CIPHER_CTX_test_flags(ctx, EVP_CIPH_FLAG_LENGTH_BITS))

        cmpl = (cmpl + 7) / 8;

    bl = ctx->cipher->block_size;

    /*

     * CCM mode needs to know about the case where inl == 0 && in == NULL - it

     * means the plaintext/ciphertext length is 0

     */

    if (inl < 0

            || (inl == 0

                && EVP_CIPHER_mode(ctx->cipher) != EVP_CIPH_CCM_MODE)) {

        *outl = 0;

        return inl == 0;

    }

    if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER) {

        /* If block size > 1 then the cipher will have to do this check */

        if (bl == 1 && is_partially_overlapping(out, in, cmpl)) {

            EVPerr(EVP_F_EVP_ENCRYPTDECRYPTUPDATE, EVP_R_PARTIALLY_OVERLAPPING);

            return 0;

        }

        i = ctx->cipher->do_cipher(ctx, out, in, inl);

        if (i < 0)

            return 0;

        else

            *outl = i;

        return 1;

    }

    if (is_partially_overlapping(out + ctx->buf_len, in, cmpl)) {

        EVPerr(EVP_F_EVP_ENCRYPTDECRYPTUPDATE, EVP_R_PARTIALLY_OVERLAPPING);

        return 0;

    }

    if (ctx->buf_len == 0 && (inl & (ctx->block_mask)) == 0) {

        if (ctx->cipher->do_cipher(ctx, out, in, inl)) {

            *outl = inl;

            return 1;

        } else {

            *outl = 0;

            return 0;

        }

    }

    i = ctx->buf_len;

    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;

            /*

             * Once we've processed the first j bytes from in, the amount of

             * data left that is a multiple of the block length is:

             * (inl - j) & ~(bl - 1)

             * We must ensure that this amount of data, plus the one block that

             * we process from ctx->buf does not exceed INT_MAX

             */

            if (((inl - j) & ~(bl - 1)) > INT_MAX - bl) {

                EVPerr(EVP_F_EVP_ENCRYPTDECRYPTUPDATE,

                       EVP_R_OUTPUT_WOULD_OVERFLOW);

                return 0;

            }

            memcpy(&(ctx->buf[i]), in, j);

            inl -= j;

            in += j;

            if (!ctx->cipher->do_cipher(ctx, out, ctx->buf, bl))

                return 0;

            out += bl;

            *outl = bl;

        }

    } else

        *outl = 0;

    i = inl & (bl - 1);

    inl -= i;

    if (inl > 0) {

        if (!ctx->cipher->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 = ctx->cipher->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 = ctx->cipher->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, cmpl = inl;

    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;

    }

    b = ctx->cipher->block_size;

    if (EVP_CIPHER_CTX_test_flags(ctx, EVP_CIPH_FLAG_LENGTH_BITS))

        cmpl = (cmpl + 7) / 8;

    /*

     * CCM mode needs to know about the case where inl == 0 - it means the

     * plaintext/ciphertext length is 0

     */

    if (inl < 0

            || (inl == 0

                && EVP_CIPHER_mode(ctx->cipher) != EVP_CIPH_CCM_MODE)) {

        *outl = 0;

        return inl == 0;

    }

    if (ctx->cipher->flags & EVP_CIPH_FLAG_CUSTOM_CIPHER) {

        if (b == 1 && is_partially_overlapping(out, in, cmpl)) {

            EVPerr(EVP_F_EVP_DECRYPTUPDATE, EVP_R_PARTIALLY_OVERLAPPING);

            return 0;

        }

        fix_len = ctx->cipher->do_cipher(ctx, out, in, inl);

        if (fix_len < 0) {

            *outl = 0;

            return 0;

        } else

            *outl = fix_len;

        return 1;

    }

    if (ctx->flags & EVP_CIPH_NO_PADDING)

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

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

    if (ctx->final_used) {

        /* see comment about PTRDIFF_T comparison above */

        if (((PTRDIFF_T)out == (PTRDIFF_T)in)

            || is_partially_overlapping(out, in, b)) {

            EVPerr(EVP_F_EVP_DECRYPTUPDATE, EVP_R_PARTIALLY_OVERLAPPING);

            return 0;

        }

        /*

         * final_used is only ever set if buf_len is 0. Therefore the maximum

         * length output we will ever see from evp_EncryptDecryptUpdate is

         * the maximum multiple of the block length that is <= inl, or just:

         * inl & ~(b - 1)

         * Since final_used has been set then the final output length is:

         * (inl & ~(b - 1)) + b

         * This must never exceed INT_MAX

         */

        if ((inl & ~(b - 1)) > INT_MAX - b) {

            EVPerr(EVP_F_EVP_DECRYPTUPDATE, EVP_R_OUTPUT_WOULD_OVERFLOW);

            return 0;

        }

        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 = ctx->cipher->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;

}

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_priv_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_reset(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 == NULL) {

            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;

}