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
+EVP_CIPHER_CTX_set_padding, EVP_enc_null, EVP_des_cbc, EVP_des_ecb,
+EVP_des_cfb, EVP_des_ofb, EVP_des_ede_cbc, EVP_des_ede, EVP_des_ede_ofb,
+EVP_des_ede_cfb, EVP_des_ede3_cbc, EVP_des_ede3, EVP_des_ede3_ofb,
+EVP_des_ede3_cfb, EVP_desx_cbc, EVP_rc4, EVP_rc4_40, EVP_idea_cbc,
+EVP_idea_ecb, EVP_idea_cfb, EVP_idea_ofb, EVP_rc2_cbc,
+EVP_rc2_ecb, EVP_rc2_cfb, EVP_rc2_ofb, EVP_rc2_40_cbc, EVP_rc2_64_cbc,
+EVP_bf_cbc, EVP_bf_ecb, EVP_bf_cfb, EVP_bf_ofb, EVP_cast5_cbc,
+EVP_cast5_ecb, EVP_cast5_cfb, EVP_cast5_ofb, EVP_rc5_32_12_16_cbc,
+EVP_rc5_32_12_16_ecb, EVP_rc5_32_12_16_cfb, EVP_rc5_32_12_16_ofb,
+EVP_aes_128_cbc, EVP_aes_128_ecb, EVP_aes_128_cfb, EVP_aes_128_ofb,
+EVP_aes_192_cbc, EVP_aes_192_ecb, EVP_aes_192_cfb, EVP_aes_192_ofb,
+EVP_aes_256_cbc, EVP_aes_256_ecb, EVP_aes_256_cfb, EVP_aes_256_ofb,
+EVP_aes_128_gcm, EVP_aes_192_gcm, EVP_aes_256_gcm,
+EVP_aes_128_ccm, EVP_aes_192_ccm, EVP_aes_256_ccm - EVP cipher routines
=head1 SYNOPSIS
#include <openssl/evp.h>
- int EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *a);
+ 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);
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
+by a function such as EVP_aes_256_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
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
+to (inl + cipher_block_size - 1) so B<out> 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
+It uses standard block padding (aka PKCS padding) as described in
+the NOTES section, below. 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
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.
+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
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
+similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and
+EVP_CipherInit_ex() except the B<ctx> parameter 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_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
+identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
+EVP_CipherFinal_ex(). In previous releases they also cleaned up
+the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
+must be called to free any context resources.
EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
return an EVP_CIPHER structure when passed a cipher name, a NID or an
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.
+and set.
=head1 RETURN VALUES
-EVP_CIPHER_CTX_init, EVP_EncryptInit_ex(), EVP_EncryptUpdate() and
-EVP_EncryptFinal_ex() 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_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_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.
+EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater
+than zero for success and zero or a negative number.
=head1 CIPHER LISTING
Null cipher: does nothing.
-=item EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void), EVP_des_ofb(void)
+=item EVP_aes_128_cbc(), EVP_aes_128_ecb(), EVP_aes_128_cfb(), EVP_aes_128_ofb()
-DES in CBC, ECB, CFB and OFB modes respectively.
+AES with a 128-bit key 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)
+=item EVP_aes_192_cbc(), EVP_aes_192_ecb(), EVP_aes_192_cfb(), EVP_aes_192_ofb()
+
+AES with a 192-bit key in CBC, ECB, CFB and OFB modes respectively.
+
+=item EVP_aes_256_cbc(), EVP_aes_256_ecb(), EVP_aes_256_cfb(), EVP_aes_256_ofb()
+
+AES with a 256-bit key in CBC, ECB, CFB and OFB modes respectively.
+
+=item EVP_des_cbc(), EVP_des_ecb(), EVP_des_cfb(), EVP_des_ofb()
+
+DES in CBC, ECB, CFB and OFB modes respectively.
+
+=item EVP_des_ede_cbc(), EVP_des_ede(), EVP_des_ede_ofb(), EVP_des_ede_cfb()
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)
+=item EVP_des_ede3_cbc(), EVP_des_ede3(), EVP_des_ede3_ofb(), EVP_des_ede3_cfb()
Three key triple DES in CBC, ECB, CFB and OFB modes respectively.
-=item EVP_desx_cbc(void)
+=item EVP_desx_cbc()
DESX algorithm in CBC mode.
-=item EVP_rc4(void)
+=item EVP_rc4()
RC4 stream cipher. This is a variable key length cipher with default key length 128 bits.
-=item EVP_rc4_40(void)
+=item EVP_rc4_40()
-RC4 stream cipher with 40 bit key length. This is obsolete and new code should use EVP_rc4()
+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)
+=item EVP_idea_cbc() EVP_idea_ecb(), EVP_idea_cfb(), EVP_idea_ofb()
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)
+=item EVP_rc2_cbc(), EVP_rc2_ecb(), EVP_rc2_cfb(), EVP_rc2_ofb()
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)
+=item EVP_rc2_40_cbc(), EVP_rc2_64_cbc()
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);
+=item EVP_bf_cbc(), EVP_bf_ecb(), EVP_bf_cfb(), EVP_bf_ofb()
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)
+=item EVP_cast5_cbc(), EVP_cast5_ecb(), EVP_cast5_cfb(), EVP_cast5_ofb()
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)
+=item EVP_rc5_32_12_16_cbc(), EVP_rc5_32_12_16_ecb(), EVP_rc5_32_12_16_cfb(), EVP_rc5_32_12_16_ofb()
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.
+=item EVP_aes_128_gcm(), EVP_aes_192_gcm(), EVP_aes_256_gcm()
+
+AES Galois Counter Mode (GCM) for 128, 192 and 256 bit keys respectively.
+These ciphers require additional control operations to function correctly: see
+the L<GCM and OCB modes> section below for details.
+
+=item EVP_aes_128_ocb(void), EVP_aes_192_ocb(void), EVP_aes_256_ocb(void)
+
+Offest Codebook Mode (OCB) for 128, 192 and 256 bit keys respectively.
+These ciphers require additional control operations to function correctly: see
+the L<GCM and OCB modes> section below for details.
+
+=item EVP_aes_128_ccm(), EVP_aes_192_ccm(), EVP_aes_256_ccm()
+
+AES Counter with CBC-MAC Mode (CCM) for 128, 192 and 256 bit keys respectively.
+These ciphers require additional control operations to function correctly: see
+CCM mode section below for details.
+
=back
+=head1 GCM and OCB Modes
+
+For GCM and OCB mode ciphers the behaviour of the EVP interface is subtly
+altered and several additional ctrl operations are supported.
+
+To specify any additional authenticated data (AAD) a call to EVP_CipherUpdate(),
+EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output
+parameter B<out> set to B<NULL>.
+
+When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal()
+indicates if the operation was successful. If it does not indicate success
+the authentication operation has failed and any output data B<MUST NOT>
+be used as it is corrupted.
+
+The following ctrls are supported in both GCM and OCB modes:
+
+ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL);
+
+Sets the IV length: this call can only be made before specifying an IV. If
+not called a default IV length is used. For GCM AES and OCB AES the default is
+12 (i.e. 96 bits). For OCB mode the maximum is 15.
+
+ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);
+
+Writes B<taglen> bytes of the tag value to the buffer indicated by B<tag>.
+This call can only be made when encrypting data and B<after> all data has been
+processed (e.g. after an EVP_EncryptFinal() call). For OCB mode the taglen must
+either be 16 or the value previously set via EVP_CTRL_OCB_SET_TAGLEN.
+
+ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
+
+Sets the expected tag to B<taglen> bytes from B<tag>. This call is only legal
+when decrypting data and must be made B<before> any data is processed (e.g.
+before any EVP_DecryptUpdate() call). For OCB mode the taglen must
+either be 16 or the value previously set via EVP_CTRL_AEAD_SET_TAG.
+
+In OCB mode calling this with B<tag> set to NULL sets the tag length. The tag
+length can only be set before specifying an IV. If not called a default tag
+length is used. For OCB AES the default is 16 (i.e. 128 bits). This is also the
+maximum tag length for OCB.
+
+See L<EXAMPLES> below for an example of the use of GCM mode.
+
+=head1 CCM Mode
+
+The behaviour of CCM mode ciphers is similar to GCM mode but with a few
+additional requirements and different ctrl values.
+
+Like GCM and OCB modes any additional authenticated data (AAD) is passed by calling
+EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output
+parameter B<out> set to B<NULL>. Additionally the total plaintext or ciphertext
+length B<MUST> be passed to EVP_CipherUpdate(), EVP_EncryptUpdate() or
+EVP_DecryptUpdate() with the output and input parameters (B<in> and B<out>)
+set to B<NULL> and the length passed in the B<inl> parameter.
+
+The following ctrls are supported in CCM mode:
+
+ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
+
+This call is made to set the expected B<CCM> tag value when decrypting or
+the length of the tag (with the B<tag> parameter set to NULL) when encrypting.
+The tag length is often referred to as B<M>. If not set a default value is
+used (12 for AES).
+
+ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL);
+
+Sets the CCM B<L> value. If not set a default is used (8 for AES).
+
+ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL);
+
+Sets the CCM nonce (IV) length: this call can only be made before specifying
+an nonce value. The nonce length is given by B<15 - L> so it is 7 by default
+for AES.
+
+
+
=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.
+transparent to the cipher used and much more flexible. Additionally, the
+B<EVP> interface will ensure the use of platform specific cryptographic
+acceleration such as AES-NI (the low level interfaces do not provide the
+guarantee).
-PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
+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
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
+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
=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:
+Encrypt a string using IDEA:
int do_crypt(char *outfile)
{
char intext[] = "Some Crypto Text";
EVP_CIPHER_CTX ctx;
FILE *out;
+
EVP_CIPHER_CTX_init(&ctx);
- EVP_EncryptInit_ex(&ctx, NULL, EVP_bf_cbc(), key, iv);
+ EVP_EncryptInit_ex(&ctx, EVP_idea_cbc(), NULL, key, iv);
if(!EVP_EncryptUpdate(&ctx, outbuf, &outlen, intext, strlen(intext)))
{
}
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>
+utility with the command line (shown on two lines for clarity):
-General encryption, decryption function example using FILE I/O and RC2 with an
-80 bit key:
+ openssl idea -d <filename
+ -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708
+
+General encryption and decryption function example using FILE I/O and AES128
+with a 128-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];
+ unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
int inlen, outlen;
+ EVP_CIPHER_CTX ctx;
/* 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 */
+ unsigned char key[] = "0123456789abcdeF";
+ unsigned char iv[] = "1234567887654321";
+
+ /* Don't set key or IV right away; we want to check lengths */
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, EVP_aes_128_cbc(), NULL, NULL, NULL,
+ do_encrypt);
+ OPENSSL_assert(EVP_CIPHER_CTX_key_length(&ctx) == 16);
+ OPENSSL_assert(EVP_CIPHER_CTX_iv_length(&ctx) == 16);
+
+ /* Now we can set key and IV */
EVP_CipherInit_ex(&ctx, NULL, NULL, key, iv, do_encrypt);
- for(;;)
+ 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);
=head1 SEE ALSO
-L<evp(3)|evp(3)>
+L<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.
+
+IDEA appeared in OpenSSL 0.9.7 but was often disabled due to
+patent concerns; the last patents expired in 2012.
+
+Support for OCB mode was added in OpenSSL 1.1.0
=cut