update docs with descriptions and deprecation

[openssl.git] / doc / crypto / EVP_BytesToKey.pod

diff --git a/doc/crypto/EVP_BytesToKey.pod b/doc/crypto/EVP_BytesToKey.pod
index 016381f3e994a1f3fbf6de207dc930da2979f7cc..003afb27e8e7412a62ea86c070e46801f9dba02a 100644 (file)
--- a/doc/crypto/EVP_BytesToKey.pod
+++ b/doc/crypto/EVP_BytesToKey.pod
@@ -17,7 +17,7 @@ EVP_BytesToKey - password based encryption routine
 
 EVP_BytesToKey() derives a key and IV from various parameters. B<type> is
 the cipher to derive the key and IV for. B<md> is the message digest to use.
-The B<salt> paramter is used as a salt in the derivation: it should point to
+The B<salt> parameter is used as a salt in the derivation: it should point to
 an 8 byte buffer or NULL if no salt is used. B<data> is a buffer containing
 B<datal> bytes which is used to derive the keying data. B<count> is the
 iteration count to use. The derived key and IV will be written to B<key>
@@ -29,24 +29,24 @@ A typical application of this function is to derive keying material for an
 encryption algorithm from a password in the B<data> parameter.
 
 Increasing the B<count> parameter slows down the algorithm which makes it
-harder for an attacker to peform a brute force attack using a large number
+harder for an attacker to perform a brute force attack using a large number
 of candidate passwords.
 
 If the total key and IV length is less than the digest length and
 B<MD5> is used then the derivation algorithm is compatible with PKCS#5 v1.5
 otherwise a non standard extension is used to derive the extra data.
 
-Newer applications should use more standard algorithms such as PKCS#5
-v2.0 for key derivation.
+Newer applications should use a more modern algorithm such as PBKDF2 as
+defined in PKCS#5v2.1 and provided by PKCS5_PBKDF2_HMAC.
 
 =head1 KEY DERIVATION ALGORITHM
 
 The key and IV is derived by concatenating D_1, D_2, etc until
 enough data is available for the key and IV. D_i is defined as:
 
-       D_i = HASH^count(D_(i-1) || data || salt)
+        D_i = HASH^count(D_(i-1) || data || salt)
 
-where || denotes concatentaion, D_0 is empty, HASH is the digest
+where || denotes concatenation, D_0 is empty, HASH is the digest
 algorithm in use, HASH^1(data) is simply HASH(data), HASH^2(data)
 is HASH(HASH(data)) and so on.
 
@@ -55,13 +55,24 @@ the IV.
 
 =head1 RETURN VALUES
 
-EVP_BytesToKey() returns the size of the derived key in bytes.
+If B<data> is NULL, then EVP_BytesToKey() returns the number of bytes
+needed to store the derived key.
+Otherwise, EVP_BytesToKey() returns the size of the derived key in bytes,
+or 0 on error.
 
 =head1 SEE ALSO
 
-L<evp(3)|evp(3)>, L<rand(3)|rand(3)>,
-L<EVP_EncryptInit(3)|EVP_EncryptInit(3)>,
+L<evp(3)>, L<rand(3)>,
+L<PKCS5_PBKDF2_HMAC(3)>,
+L<EVP_EncryptInit(3)>
 
-=head1 HISTORY
+=head1 COPYRIGHT
+
+Copyright 2001-2016 The OpenSSL Project Authors. All Rights Reserved.
+
+Licensed under the OpenSSL license (the "License").  You may not use
+this file except in compliance with the License.  You can obtain a copy
+in the file LICENSE in the source distribution or at
+L<https://www.openssl.org/source/license.html>.
 
 =cut