Add AES_CBC_CTS ciphers to providers

[openssl.git] / doc / man3 / EVP_EncryptInit.pod

diff --git a/doc/man3/EVP_EncryptInit.pod b/doc/man3/EVP_EncryptInit.pod
index a008d0f6f6e3b92c980465fa39bd36a4f44b1ebf..d40402ba1dce8bc0a3203493b41a3ead1c286161 100644 (file)
--- a/doc/man3/EVP_EncryptInit.pod
+++ b/doc/man3/EVP_EncryptInit.pod
@@ -165,7 +165,7 @@ EVP_CIPHER_do_all_provided
 
 =head1 DESCRIPTION
 
-The EVP cipher routines are a high level interface to certain
+The EVP cipher routines are a high-level interface to certain
 symmetric ciphers.
 
 The B<EVP_CIPHER> type is a structure for cipher method implementation.
@@ -338,6 +338,10 @@ B<NID_undef>.
 
 EVP_CIPHER_is_a() returns 1 if I<cipher> is an implementation of an
 algorithm that's identifiable with I<name>, otherwise 0.
+If I<cipher> is a legacy cipher (it's the return value from the likes
+of EVP_aes128() rather than the result of an EVP_CIPHER_fetch()), only
+cipher names registered with the default library context (see
+L<OPENSSL_CTX(3)>) will be considered.
 
 EVP_CIPHER_number() returns the internal dynamic number assigned to
 the I<cipher>.  This is only useful with fetched B<EVP_CIPHER>s.
@@ -554,7 +558,7 @@ Sets the CCM B<L> value. If not set a default is used (8 for AES).
 
 =item 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
+Sets the CCM nonce (IV) length. This call can only be made before specifying a 
 nonce value. The nonce length is given by B<15 - L> so it is 7 by default for
 AES.
 
@@ -638,10 +642,10 @@ This call is only valid when decrypting data.
 =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
+preference to the low-level interfaces. This is because the code then becomes
 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
+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
@@ -766,7 +770,7 @@ with a 128-bit key:
 
      /* Don't set key or IV right away; we want to check lengths */
      ctx = EVP_CIPHER_CTX_new();
-     EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
+     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);
@@ -796,6 +800,50 @@ with a 128-bit key:
      return 1;
  }
 
+Encryption using AES-CBC with a 256-bit key with "CS1" ciphertext stealing.
+
+ int encrypt(const unsigned char *key, const unsigned char *iv,
+             const unsigned char *msg, size_t msg_len, unsigned char *out)
+ {
+    /*
+     * This assumes that key size is 32 bytes and the iv is 16 bytes.
+     * For ciphertext stealing mode the length of the ciphertext "out" will be
+     * the same size as the plaintext size "msg_len".
+     * The "msg_len" can be any size >= 16.
+     */
+     int ret = 0, encrypt = 1, outlen, len;
+     EVP_CIPHER_CTX *ctx = NULL;
+     EVP_CIPHER *cipher = NULL;
+     OSSL_PARAM params[2];
+
+     ctx = EVP_CIPHER_CTX_new();
+     cipher = EVP_CIPHER_fetch(NULL, "AES-256-CBC-CTS", NULL);
+     if (ctx == NULL || cipher == NULL)
+         goto err;
+
+     if (!EVP_CipherInit_ex(ctx, cipher, NULL, key, iv, encrypt))
+         goto err;
+     /*
+      * The default is "CS1" so this is not really needed,
+      * but would be needed to set either "CS2" or "CS3".
+      */
+     params[0] = OSSL_PARAM_construct_utf8_string(OSSL_CIPHER_PARAM_CTS_MODE,
+                                                  "CS1", 0);
+     params[1] = OSSL_PARAM_construct_end();
+     if (!EVP_CIPHER_CTX_set_params(ctx, params))
+         goto err;
+
+     /* NOTE: CTS mode does not support multiple calls to EVP_CipherUpdate() */
+     if (!EVP_CipherUpdate(ctx, encrypted, &outlen, msg, msglen))
+         goto err;
+      if (!EVP_CipherFinal_ex(ctx, encrypted + outlen, &len))
+         goto err;
+     ret = 1;
+ err:
+     EVP_CIPHER_free(cipher);
+     EVP_CIPHER_CTX_free(ctx);
+     return ret;
+ }
 
 =head1 SEE ALSO
 
@@ -833,7 +881,7 @@ were added in 3.0.
 
 =head1 COPYRIGHT
 
-Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
 
 Licensed under the Apache License 2.0 (the "License").  You may not use
 this file except in compliance with the License.  You can obtain a copy