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    Command:

    EVP_EncryptInit

    
           EVP_DecryptFinal_ex, EVP_CipherInit_ex, EVP_CipherUpdate,
           EVP_CipherFinal_ex, EVP_CIPHER_CTX_set_key_length, EVP_CIPHER_CTX_ctrl,
           EVP_CIPHER_CTX_cleanup, EVP_EncryptInit, EVP_EncryptFinal,
           EVP_DecryptInit, EVP_DecryptFinal, EVP_CipherInit, EVP_CipherFinal,
           EVP_get_cipherbyname, EVP_get_cipherbynid, EVP_get_cipherbyobj,
           EVP_CIPHER_nid, EVP_CIPHER_block_size, EVP_CIPHER_key_length,
           EVP_CIPHER_iv_length, EVP_CIPHER_flags, EVP_CIPHER_mode,
           EVP_CIPHER_type, EVP_CIPHER_CTX_cipher, EVP_CIPHER_CTX_nid,
           EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length,
           EVP_CIPHER_CTX_iv_length, EVP_CIPHER_CTX_get_app_data,
           EVP_CIPHER_CTX_set_app_data, EVP_CIPHER_CTX_type, EVP_CIPHER_CTX_flags,
           EVP_CIPHER_CTX_mode, EVP_CIPHER_param_to_asn1,
           EVP_CIPHER_asn1_to_param, EVP_CIPHER_CTX_set_padding - EVP cipher
           routines
    
    
    

    SYNOPSIS

            #include <openssl/evp.h>
    
            void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *a);
    
            int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                    ENGINE *impl, unsigned char *key, unsigned char *iv);
            int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
                    int *outl, unsigned char *in, int inl);
            int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out,
                    int *outl);
    
            int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                    ENGINE *impl, unsigned char *key, unsigned char *iv);
            int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
                    int *outl, unsigned char *in, int inl);
            int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
                    int *outl);
    
            int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                    ENGINE *impl, unsigned char *key, unsigned char *iv, int enc);
            int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
                    int *outl, unsigned char *in, int inl);
            int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
                    int *outl);
    
            int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                    unsigned char *key, unsigned char *iv);
            int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
                    int *outl);
    
            int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
                    unsigned char *key, unsigned char *iv);
            int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
                    int *outl);
    
            int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
            #define EVP_CIPHER_block_size(e)       ((e)->block_size)
            #define EVP_CIPHER_key_length(e)       ((e)->key_len)
            #define EVP_CIPHER_iv_length(e)                ((e)->iv_len)
            #define EVP_CIPHER_flags(e)            ((e)->flags)
            #define EVP_CIPHER_mode(e)             ((e)->flags) & EVP_CIPH_MODE)
            int EVP_CIPHER_type(const EVP_CIPHER *ctx);
    
            #define EVP_CIPHER_CTX_cipher(e)       ((e)->cipher)
            #define EVP_CIPHER_CTX_nid(e)          ((e)->cipher->nid)
            #define EVP_CIPHER_CTX_block_size(e)   ((e)->cipher->block_size)
            #define EVP_CIPHER_CTX_key_length(e)   ((e)->key_len)
            #define EVP_CIPHER_CTX_iv_length(e)    ((e)->cipher->iv_len)
            #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data)
            #define EVP_CIPHER_CTX_set_app_data(e,d) ((e)->app_data=(char *)(d))
            #define EVP_CIPHER_CTX_type(c)         EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c))
            #define EVP_CIPHER_CTX_flags(e)                ((e)->cipher->flags)
            #define EVP_CIPHER_CTX_mode(e)         ((e)->cipher->flags & EVP_CIPH_MODE)
    
            int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
            int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
    
            const EVP_CIPHER *EVP_des_ede3(void);
            const EVP_CIPHER *EVP_des_ede3_ecb(void);
            const EVP_CIPHER *EVP_des_ede3_cfb64(void);
            const EVP_CIPHER *EVP_des_ede3_cfb1(void);
            const EVP_CIPHER *EVP_des_ede3_cfb8(void);
            const EVP_CIPHER *EVP_des_ede3_ofb(void);
            const EVP_CIPHER *EVP_des_ede3_cbc(void);
            const EVP_CIPHER *EVP_aes_128_ecb(void);
            const EVP_CIPHER *EVP_aes_128_cbc(void);
            const EVP_CIPHER *EVP_aes_128_cfb1(void);
            const EVP_CIPHER *EVP_aes_128_cfb8(void);
            const EVP_CIPHER *EVP_aes_128_cfb128(void);
            const EVP_CIPHER *EVP_aes_128_ofb(void);
            const EVP_CIPHER *EVP_aes_192_ecb(void);
            const EVP_CIPHER *EVP_aes_192_cbc(void);
            const EVP_CIPHER *EVP_aes_192_cfb1(void);
            const EVP_CIPHER *EVP_aes_192_cfb8(void);
            const EVP_CIPHER *EVP_aes_192_cfb128(void);
            const EVP_CIPHER *EVP_aes_192_ofb(void);
            const EVP_CIPHER *EVP_aes_256_ecb(void);
            const EVP_CIPHER *EVP_aes_256_cbc(void);
            const EVP_CIPHER *EVP_aes_256_cfb1(void);
            const EVP_CIPHER *EVP_aes_256_cfb8(void);
            const EVP_CIPHER *EVP_aes_256_cfb128(void);
            const EVP_CIPHER *EVP_aes_256_ofb(void);
    
    
    

    DESCRIPTION

           The EVP cipher routines are a high level interface to certain symmetric
           ciphers.
    
           EVP_CIPHER_CTX_init() initializes cipher contex ctx.
           times to encrypt successive blocks of data. The amount of data written
           depends on the block alignment of the encrypted data: as a result the
           amount of data written may be anything from zero bytes to (inl +
           cipher_block_size - 1) so outl should contain sufficient room. The
           actual number of bytes written is placed in outl.
    
           If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts
           the "final" data, that is any data that remains in a partial block.  It
           uses standard block padding (aka PKCS padding). The encrypted final
           data is written to out which should have sufficient space for one
           cipher block. The number of bytes written is placed in outl. After this
           function is called the encryption operation is finished and no further
           calls to EVP_EncryptUpdate() should be made.
    
           If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any
           more data and it will return an error if any data remains in a partial
           block: that is if the total data length is not a multiple of the block
           size.
    
           EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are
           the corresponding decryption operations. EVP_DecryptFinal() will return
           an error code if padding is enabled and the final block is not
           correctly formatted. The parameters and restrictions are identical to
           the encryption operations except that if padding is enabled the
           decrypted data buffer out passed to EVP_DecryptUpdate() should have
           sufficient room for (inl + cipher_block_size) bytes unless the cipher
           block size is 1 in which case inl bytes is sufficient.
    
           EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are
           functions that can be used for decryption or encryption. The operation
           performed depends on the value of the enc parameter. It should be set
           to 1 for encryption, 0 for decryption and -1 to leave the value
           unchanged (the actual value of 'enc' being supplied in a previous
           call).
    
           EVP_CIPHER_CTX_cleanup() clears all information from a cipher context
           and free up any allocated memory associate with it. It should be called
           after all operations using a cipher are complete so sensitive
           information does not remain in memory.
    
           EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a
           similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex and
           EVP_CipherInit_ex() except the ctx paramter does not need to be
           initialized and they always use the default cipher implementation.
    
           EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() behave in
           a similar way to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
           EVP_CipherFinal_ex() except ctx is automatically cleaned up after the
           call.
    
           EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
           return an EVP_CIPHER structure when passed a cipher name, a NID or an
           EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
           length of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX
           structure. The constant EVP_MAX_KEY_LENGTH is the maximum key length
           for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
           given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
           for variable key length ciphers.
    
           EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
           If the cipher is a fixed length cipher then attempting to set the key
           length to any value other than the fixed value is an error.
    
           EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
           length of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX.  It
           will return zero if the cipher does not use an IV.  The constant
           EVP_MAX_IV_LENGTH is the maximum IV length for all ciphers.
    
           EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the
           block size of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX
           structure. The constant EVP_MAX_IV_LENGTH is also the maximum block
           length for all ciphers.
    
           EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the
           passed cipher or context. This "type" is the actual NID of the cipher
           OBJECT IDENTIFIER as such it ignores the cipher parameters and 40 bit
           RC2 and 128 bit RC2 have the same NID. If the cipher does not have an
           object identifier or does not have ASN1 support this function will
           return NID_undef.
    
           EVP_CIPHER_CTX_cipher() returns the EVP_CIPHER structure when passed an
           EVP_CIPHER_CTX structure.
    
           EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher
           mode: EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE or
           EVP_CIPH_OFB_MODE. If the cipher is a stream cipher then
           EVP_CIPH_STREAM_CIPHER is returned.
    
           EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter"
           based on the passed cipher. This will typically include any parameters
           and an IV. The cipher IV (if any) must be set when this call is made.
           This call should be made before the cipher is actually "used" (before
           any EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This
           function may fail if the cipher does not have any ASN1 support.
    
           EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
           AlgorithmIdentifier "parameter". The precise effect depends on the
           cipher In the case of RC2, for example, it will set the IV and
           effective key length.  This function should be called after the base
           cipher type is set but before the key is set. For example
           EVP_CipherInit() will be called with the IV and key set to NULL,
           EVP_CIPHER_asn1_to_param() will be called and finally EVP_CipherInit()
           again with all parameters except the key set to NULL. It is possible
           for this function to fail if the cipher does not have any ASN1 support
    
           EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0
           for failure.  EVP_CipherFinal_ex() returns 0 for a decryption failure
           or 1 for success.
    
           EVP_CIPHER_CTX_cleanup() returns 1 for success and 0 for failure.
    
           EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
           return an EVP_CIPHER structure or NULL on error.
    
           EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
    
           EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the
           block size.
    
           EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
           length.
    
           EVP_CIPHER_CTX_set_padding() always returns 1.
    
           EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
           length or zero if the cipher does not use an IV.
    
           EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the
           cipher's OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT
           IDENTIFIER.
    
           EVP_CIPHER_CTX_cipher() returns an EVP_CIPHER structure.
    
           EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return 1 for
           success or zero for failure.
    
    
    

    CIPHER LISTING

           All algorithms have a fixed key length unless otherwise stated.
    
           EVP_enc_null()
               Null cipher: does nothing.
    
           EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void),
           EVP_des_ofb(void)
               DES in CBC, ECB, CFB and OFB modes respectively.
    
           EVP_des_ede_cbc(void), EVP_des_ede(), EVP_des_ede_ofb(void),
           EVP_des_ede_cfb(void)
               Two key triple DES in CBC, ECB, CFB and OFB modes respectively.
    
           EVP_des_ede3_cbc(void), EVP_des_ede3(), EVP_des_ede3_ofb(void),
           EVP_des_ede3_cfb(void)
               Three key triple DES in CBC, ECB, CFB and OFB modes respectively.
    
           EVP_desx_cbc(void)
               DESX algorithm in CBC mode.
    
           EVP_aes_256_cfb1(void), EVP_aes_256_cfb8(void),
           EVP_aes_256_cfb128(void)
               AES with 256 bit key length in CBC, ECB, OFB and CFB modes
               respectively.
    
           EVP_rc4(void)
               RC4 stream cipher. This is a variable key length cipher with
               default key length 128 bits.
    
           EVP_rc4_40(void)
               RC4 stream cipher with 40 bit key length. This is obsolete and new
               code should use EVP_rc4() and the EVP_CIPHER_CTX_set_key_length()
               function.
    
           EVP_idea_cbc() EVP_idea_ecb(void), EVP_idea_cfb(void),
           EVP_idea_ofb(void), EVP_idea_cbc(void)
               IDEA encryption algorithm in CBC, ECB, CFB and OFB modes
               respectively.
    
           EVP_rc2_cbc(void), EVP_rc2_ecb(void), EVP_rc2_cfb(void),
           EVP_rc2_ofb(void)
               RC2 encryption algorithm in CBC, ECB, CFB and OFB modes
               respectively. This is a variable key length cipher with an
               additional parameter called "effective key bits" or "effective key
               length".  By default both are set to 128 bits.
    
           EVP_rc2_40_cbc(void), EVP_rc2_64_cbc(void)
               RC2 algorithm in CBC mode with a default key length and effective
               key length of 40 and 64 bits.  These are obsolete and new code
               should use EVP_rc2_cbc(), EVP_CIPHER_CTX_set_key_length() and
               EVP_CIPHER_CTX_ctrl() to set the key length and effective key
               length.
    
           EVP_bf_cbc(void), EVP_bf_ecb(void), EVP_bf_cfb(void), EVP_bf_ofb(void);
               Blowfish encryption algorithm in CBC, ECB, CFB and OFB modes
               respectively. This is a variable key length cipher.
    
           EVP_cast5_cbc(void), EVP_cast5_ecb(void), EVP_cast5_cfb(void),
           EVP_cast5_ofb(void)
               CAST encryption algorithm in CBC, ECB, CFB and OFB modes
               respectively. This is a variable key length cipher.
    
           EVP_rc5_32_12_16_cbc(void), EVP_rc5_32_12_16_ecb(void),
           EVP_rc5_32_12_16_cfb(void), EVP_rc5_32_12_16_ofb(void)
               RC5 encryption algorithm in CBC, ECB, CFB and OFB modes
               respectively. This is a variable key length cipher with an
               additional "number of rounds" parameter. By default the key length
               is set to 128 bits and 12 rounds.
    
    
    

    NOTES

           Where possible the EVP interface to symmetric ciphers should be used in
           preference to the low level interfaces. This is because the code then
           A random block has better than 1 in 256 chance of being of the correct
           format and problems with the input data earlier on will not produce a
           final decrypt error.
    
           If padding is disabled then the decryption operation will always
           succeed if the total amount of data decrypted is a multiple of the
           block size.
    
           The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(),
           EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained
           for compatibility with existing code. New code should use
           EVP_EncryptInit_ex(), EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(),
           EVP_DecryptFinal_ex(), EVP_CipherInit_ex() and EVP_CipherFinal_ex()
           because they can reuse an existing context without allocating and
           freeing it up on each call.
    
    
    

    BUGS

           For RC5 the number of rounds can currently only be set to 8, 12 or 16.
           This is a limitation of the current RC5 code rather than the EVP
           interface.
    
           EVP_MAX_KEY_LENGTH and EVP_MAX_IV_LENGTH only refer to the internal
           ciphers with default key lengths. If custom ciphers exceed these values
           the results are unpredictable. This is because it has become standard
           practice to define a generic key as a fixed unsigned char array
           containing EVP_MAX_KEY_LENGTH bytes.
    
           The ASN1 code is incomplete (and sometimes inaccurate) it has only been
           tested for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC
           mode.
    
    
    

    EXAMPLES

           Get the number of rounds used in RC5:
    
            int nrounds;
            EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC5_ROUNDS, 0, &nrounds);
    
           Get the RC2 effective key length:
    
            int key_bits;
            EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC2_KEY_BITS, 0, &key_bits);
    
           Set the number of rounds used in RC5:
    
            int nrounds;
            EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC5_ROUNDS, nrounds, NULL);
    
           Set the effective key length used in RC2:
    
            int key_bits;
            EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC2_KEY_BITS, key_bits, NULL);
    
                   EVP_CIPHER_CTX_init(&ctx);
                   EVP_EncryptInit_ex(&ctx, EVP_bf_cbc(), NULL, key, iv);
    
                   if(!EVP_EncryptUpdate(&ctx, outbuf, &outlen, intext, strlen(intext)))
                           {
                           /* Error */
                           return 0;
                           }
                   /* Buffer passed to EVP_EncryptFinal() must be after data just
                    * encrypted to avoid overwriting it.
                    */
                   if(!EVP_EncryptFinal_ex(&ctx, outbuf + outlen, &tmplen))
                           {
                           /* Error */
                           return 0;
                           }
                   outlen += tmplen;
                   EVP_CIPHER_CTX_cleanup(&ctx);
                   /* Need binary mode for fopen because encrypted data is
                    * binary data. Also cannot use strlen() on it because
                    * it wont be null terminated and may contain embedded
                    * nulls.
                    */
                   out = fopen(outfile, "wb");
                   fwrite(outbuf, 1, outlen, out);
                   fclose(out);
                   return 1;
                   }
    
           The ciphertext from the above example can be decrypted using the
           openssl utility with the command line:
    
            S<openssl bf -in cipher.bin -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 -d>
    
           General encryption, decryption function example using FILE I/O and RC2
           with an 80 bit key:
    
            int do_crypt(FILE *in, FILE *out, int do_encrypt)
                   {
                   /* Allow enough space in output buffer for additional block */
                   inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
                   int inlen, outlen;
                   /* Bogus key and IV: we'd normally set these from
                    * another source.
                    */
                   unsigned char key[] = "0123456789";
                   unsigned char iv[] = "12345678";
                   /* Don't set key or IV because we will modify the parameters */
                   EVP_CIPHER_CTX_init(&ctx);
                   EVP_CipherInit_ex(&ctx, EVP_rc2(), NULL, NULL, NULL, do_encrypt);
                   EVP_CIPHER_CTX_set_key_length(&ctx, 10);
                   /* We finished modifying parameters so now we can set key and IV */
                   if(!EVP_CipherFinal_ex(&ctx, outbuf, &outlen))
                           {
                           /* Error */
                           EVP_CIPHER_CTX_cleanup(&ctx);
                           return 0;
                           }
                   fwrite(outbuf, 1, outlen, out);
    
                   EVP_CIPHER_CTX_cleanup(&ctx);
                   return 1;
                   }
    
    
    

    SEE ALSO

           evp(3)
    
    
    

    HISTORY

           EVP_CIPHER_CTX_init(), EVP_EncryptInit_ex(), EVP_EncryptFinal_ex(),
           EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(), EVP_CipherInit_ex(),
           EVP_CipherFinal_ex() and EVP_CIPHER_CTX_set_padding() appeared in
           OpenSSL 0.9.7.
    
    
    

    1.0.1e 2016-01-07 EVP_EncryptInit(3)

    
    
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