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Diffstat (limited to 'roms/edk2/CryptoPkg/Library/OpensslLib/openssl/doc/man3/EVP_BytesToKey.pod')
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diff --git a/roms/edk2/CryptoPkg/Library/OpensslLib/openssl/doc/man3/EVP_BytesToKey.pod b/roms/edk2/CryptoPkg/Library/OpensslLib/openssl/doc/man3/EVP_BytesToKey.pod new file mode 100644 index 000000000..8d49648f1 --- /dev/null +++ b/roms/edk2/CryptoPkg/Library/OpensslLib/openssl/doc/man3/EVP_BytesToKey.pod @@ -0,0 +1,78 @@ +=pod + +=head1 NAME + +EVP_BytesToKey - password based encryption routine + +=head1 SYNOPSIS + + #include <openssl/evp.h> + + int EVP_BytesToKey(const EVP_CIPHER *type, const EVP_MD *md, + const unsigned char *salt, + const unsigned char *data, int datal, int count, + unsigned char *key, unsigned char *iv); + +=head1 DESCRIPTION + +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> 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> +and B<iv> respectively. + +=head1 NOTES + +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 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 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) + +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. + +The initial bytes are used for the key and the subsequent bytes for +the IV. + +=head1 RETURN VALUES + +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(7)>, L<RAND_bytes(3)>, +L<PKCS5_PBKDF2_HMAC(3)>, +L<EVP_EncryptInit(3)> + +=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 |