Rename OSSL_SERIALIZER / OSSL_DESERIALIZER to OSSL_ENCODE / OSSL_DECODE

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

diff --git a/doc/man3/EVP_EncryptInit.pod b/doc/man3/EVP_EncryptInit.pod
index 5dc60a0801cc3a83db8a1bb4ecafe2372f768124..6edd8dc1540a2dc8026aed60ec8520c73883f771 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.
@@ -210,10 +210,15 @@ specified.
 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<out> should contain sufficient
-room. The actual number of bytes written is placed in B<outl>. It also
+of data written depends on the block alignment of the encrypted data.
+For most ciphers and modes, the amount of data written can be anything
+from zero bytes to (inl + cipher_block_size - 1) bytes.
+For wrap cipher modes, the amount of data written can be anything
+from zero bytes to (inl + cipher_block_size) bytes.
+For stream ciphers, the amount of data written can be anything from zero
+bytes to inl bytes.
+Thus, B<out> should contain sufficient room for the operation being performed.
+The actual number of bytes written is placed in B<outl>. It also
 checks if B<in> and B<out> are partially overlapping, and if they are
 0 is returned to indicate failure.
 
@@ -558,7 +563,7 @@ 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.
 
@@ -642,10 +647,10 @@ 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
@@ -770,7 +775,7 @@ 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);
@@ -800,6 +805,50 @@ 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
 
@@ -837,7 +886,7 @@ 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