=head1 NAME
-EVP_EncryptInit, EVP_EncryptUpdate, EVP_EncryptFinal - EVP cipher routines
+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>
- int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
- unsigned char *key, unsigned char *iv);
+ 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_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
- int *outl, unsigned char *in, int inl);
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_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
- int *outl, unsigned char *in, int inl);
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);
The EVP cipher routines are a high level interface to certain
symmetric ciphers.
-EVP_EncryptInit() initialises a cipher context B<ctx> for encryption
-with cipher B<type>. B<type> is normally supplied by a function such
-as EVP_des_cbc() . 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_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
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>.
+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.
-EVP_EncryptFinal() 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(), EVP_DecryptUpdate() and EVP_DecryptFinal() are the
+EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are the
corresponding decryption operations. EVP_DecryptFinal() will return an
-error code if the final block is not correctly formatted. The parameters
-and restrictions are identical to the encryption operations except that
-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(), EVP_CipherUpdate() and EVP_CipherFinal() 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.
-It should be called after all operations using a cipher are complete
-so sensitive information does not remain in memory.
+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
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
=head1 RETURN VALUES
-EVP_EncryptInit(), EVP_EncryptUpdate() and EVP_EncryptFinal() return 1 for success
-and 0 for failure.
+EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
+return 1 for success and 0 for failure.
-EVP_DecryptInit() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
-EVP_DecryptFinal() returns 0 if the decrypt failed or 1 for success.
+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() and EVP_CipherUpdate() return 1 for success and 0 for failure.
-EVP_CipherFinal() returns 1 for a decryption failure 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_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.
=item EVP_idea_cbc() EVP_idea_ecb(void), EVP_idea_cfb(void), EVP_idea_ofb(void), EVP_idea_cbc(void)
-IDES encryption algorothm in CBC, ECB, CFB and OFB modes respectively.
+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)
When decrypting the final block is checked to see if it has the correct form.
-Although the decryption operation can produce an error, 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.
+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_EncryptUpdate(), EVP_EncryptFinal(),
-EVP_DecryptInit(), EVP_DecryptUpdate(), EVP_CipherInit() and EVP_CipherUpdate()
-and EVP_CIPHER_CTX_cleanup() did not return errors in OpenSSL version 0.9.5a or
-earlier. Software only versions of encryption algorithms will never return
-error codes for these functions, unless there is a programming error (for example
-and attempt to set the key before the cipher is set in EVP_EncryptInit() ).
+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.
-It should be possible to disable PKCS padding: currently it isn't.
-
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 innacurate) it has only been tested
+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, &i);
+ 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, &i);
+ 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, i, NULL);
+ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC5_ROUNDS, nrounds, NULL);
-Set the number of rounds used in RC2:
+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;
+ }
- int nrounds;
- EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC2_KEY_BITS, i, NULL);
=head1 SEE ALSO
=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
projects / openssl.git / blobdiff