1 files changed, 511 insertions, 0 deletions

diff --git a/src/lib/libcrypto/doc/EVP_EncryptInit.pod b/src/lib/libcrypto/doc/EVP_EncryptInit.pod
new file mode 100644
index 0000000000..8271d3dfc4
--- /dev/null
+++ b/src/lib/libcrypto/doc/EVP_EncryptInit.pod
@@ -0,0 +1,511 @@
+=pod
+
+=head1 NAME
+
+EVP_CIPHER_CTX_init, EVP_EncryptInit_ex, EVP_EncryptUpdate,
+EVP_EncryptFinal_ex, EVP_DecryptInit_ex, EVP_DecryptUpdate,
+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
+
+=head1 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,
+         unsigned char *key, unsigned char *iv, int enc);
+ int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
+         int *outl);
+
+ int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
+ int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
+ int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
+ int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a);
+
+ const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
+ #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a))
+ #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a))
+
+ #define EVP_CIPHER_nid(e)              ((e)->nid)
+ #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);
+
+=head1 DESCRIPTION
+
+The EVP cipher routines are a high level interface to certain
+symmetric ciphers.
+
+EVP_CIPHER_CTX_init() initializes cipher contex B<ctx>.
+
+EVP_EncryptInit_ex() sets up cipher context B<ctx> for encryption
+with cipher B<type> from ENGINE B<impl>. B<ctx> must be initialized
+before calling this function. B<type> is normally supplied
+by a function such as EVP_des_cbc(). If B<impl> is NULL then the
+default implementation is used. B<key> is the symmetric key to use
+and B<iv> is the IV to use (if necessary), the actual number of bytes
+used for the key and IV depends on the cipher. It is possible to set
+all parameters to NULL except B<type> in an initial call and supply
+the remaining parameters in subsequent calls, all of which have B<type>
+set to NULL. This is done when the default cipher parameters are not
+appropriate.
+
+EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and
+writes the encrypted version to B<out>. This function can be called
+multiple 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 B<outl> should contain sufficient
+room. The actual number of bytes written is placed in B<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 L<standard block padding|/NOTES> (aka PKCS padding). The encrypted
+final data is written to B<out> which should have sufficient space for
+one cipher block. The number of bytes written is placed in B<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 B<out>
+passed to EVP_DecryptUpdate() should have sufficient room for
+(B<inl> + cipher_block_size) bytes unless the cipher block size is 1 in
+which case B<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 B<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 B<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 B<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
+ASN1_OBJECT structure.
+
+EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
+passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure.  The actual NID
+value is an internal value which may not have a corresponding OBJECT
+IDENTIFIER.
+
+EVP_CIPHER_CTX_set_padding() enables or disables padding. By default
+encryption operations are padded using standard block padding and the
+padding is checked and removed when decrypting. If the B<pad> parameter
+is zero then no padding is performed, the total amount of data encrypted
+or decrypted must then be a multiple of the block size or an error will
+occur.
+
+EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
+length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
+structure. The constant B<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 B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
+It will return zero if the cipher does not use an IV.  The constant
+B<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 B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
+structure. The constant B<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
+B<NID_undef>.
+
+EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed
+an B<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
+or the parameters cannot be set (for example the RC2 effective key length
+is not supported.
+
+EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
+and set. Currently only the RC2 effective key length and the number of rounds of
+RC5 can be set.
+
+=head1 RETURN VALUES
+
+EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
+return 1 for success and 0 for failure.
+
+EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
+EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
+
+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 B<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 B<EVP_CIPHER> structure.
+
+EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return 1 for 
+success or zero for failure.
+
+=head1 CIPHER LISTING
+
+All algorithms have a fixed key length unless otherwise stated.
+
+=over 4
+
+=item EVP_enc_null()
+
+Null cipher: does nothing.
+
+=item 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. 
+
+=item 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.
+
+=item 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.
+
+=item EVP_desx_cbc(void)
+
+DESX algorithm in CBC mode.
+
+=item EVP_rc4(void)
+
+RC4 stream cipher. This is a variable key length cipher with default key length 128 bits.
+
+=item 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.
+
+=item 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.
+
+=item 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.
+
+=item 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.
+
+=item 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.
+
+=item 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.
+
+=item 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.
+
+=back
+
+=head1 NOTES
+
+Where possible the B<EVP> interface to symmetric ciphers should be used in
+preference to the low level interfaces. This is because the code then becomes
+transparent to the cipher used and much more flexible.
+
+PKCS padding works by adding B<n> padding bytes of value B<n> to make the total 
+length of the encrypted data a multiple of the block size. Padding is always
+added so if the data is already a multiple of the block size B<n> will equal
+the block size. For example if the block size is 8 and 11 bytes are to be
+encrypted then 5 padding bytes of value 5 will be added.
+
+When decrypting the final block is checked to see if it has the correct form.
+
+Although the decryption operation can produce an error if padding is enabled,
+it is not a strong test that the input data or key is correct. 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.
+
+=head1 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.
+
+=head1 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);
+
+Encrypt a string using blowfish:
+
+ int do_crypt(char *outfile)
+        {
+        unsigned char outbuf[1024];
+        int outlen, tmplen;
+        /* Bogus key and IV: we'd normally set these from
+         * another source.
+         */
+        unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
+        unsigned char iv[] = {1,2,3,4,5,6,7,8};
+        char intext[] = "Some Crypto Text";
+        EVP_CIPHER_CTX ctx;
+        FILE *out;
+        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 B<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 */
+        EVP_CipherInit_ex(&ctx, NULL, NULL, key, iv, do_encrypt);
+
+        for(;;) 
+                {
+                inlen = fread(inbuf, 1, 1024, in);
+                if(inlen <= 0) break;
+                if(!EVP_CipherUpdate(&ctx, outbuf, &outlen, inbuf, inlen))
+                        {
+                        /* Error */
+                        EVP_CIPHER_CTX_cleanup(&ctx);
+                        return 0;
+                        }
+                fwrite(outbuf, 1, outlen, out);
+                }
+        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;
+        }
+
+
+=head1 SEE ALSO
+
+L<evp(3)|evp(3)>
+
+=head1 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.
+
+=cut