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_idea_cbc, 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_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
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
+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_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure.
-EVP_CipherFinal_ex() returns 1 for a decryption failure or 1 for success.
+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.
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(void), EVP_aes_192_gcm(void), EVP_aes_256_gcm(void)
+
+AES Galois Counter Mode (GCM) for 128, 192 and 256 bit keys respectively.
+These ciphers require additional control operations to function correctly: see
+L<GCM mode> section below for details.
+
+=item EVP_aes_128_ccm(void), EVP_aes_192_ccm(void), EVP_aes_256_ccm(void)
+
+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 Mode
+
+For GCM mode ciphers the behaviour of the EVP interface is subtly altered and
+several GCM specific 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 GCM mode:
+
+ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, ivlen, NULL);
+
+Sets the GCM IV length: this call can only be made before specifying an IV. If
+not called a default IV length is used (96 bits for AES).
+
+ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_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).
+
+ EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_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).
+
+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 CCM mode but with a few
+additional requirements and different ctrl values.
+
+Like GCM mode 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_CCM_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_CCM_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
length of the encrypted data a multiple of the block size. Padding is always
=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:
+utility with the command line (shown on two lines for clarity):
- S<openssl bf -in cipher.bin -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 -d>
+ openssl idea -d <filename
+ -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708
-General encryption, decryption function example using FILE I/O and RC2 with an
-80 bit key:
+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(;;)
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 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.
+
=cut