More secure storage of key material.

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

diff --git a/doc/crypto/BIO_f_md.pod b/doc/crypto/BIO_f_md.pod
index 67ba6e851653213adda965c94fdd0540f52dd9f9..2cc41f89d2fda1624b927844356ea31057189ffe 100644 (file)
--- a/doc/crypto/BIO_f_md.pod
+++ b/doc/crypto/BIO_f_md.pod
@@ -2,7 +2,7 @@
 
 =head1 NAME
 
-       BIO_f_md - message digest BIO
+BIO_f_md, BIO_set_md, BIO_get_md, BIO_get_md_ctx - message digest BIO filter
 
 =head1 SYNOPSIS
 
@@ -28,10 +28,10 @@ BIO_gets(), if its B<size> parameter is large enough finishes the
 digest calculation and returns the digest value. BIO_puts() is
 not supported.
 
-BIO_reset() reinitializes a digest BIO.
+BIO_reset() reinitialises a digest BIO.
 
 BIO_set_md() sets the message digest of BIO B<b> to B<md>: this
-must be called to initialise a digest BIO before any data is
+must be called to initialize a digest BIO before any data is
 passed through it. It is a BIO_ctrl() macro.
 
 BIO_get_md() places the a pointer to the digest BIOs digest method
@@ -39,8 +39,6 @@ in B<mdp>, it is a BIO_ctrl() macro.
 
 BIO_get_md_ctx() returns the digest BIOs context into B<mdcp>.
 
-
-
 =head1 NOTES
 
 The context returned by BIO_get_md_ctx() can be used in calls
@@ -60,6 +58,12 @@ If an application needs to call BIO_gets() or BIO_puts() through
 a chain containing digest BIOs then this can be done by prepending
 a buffering BIO.
 
+Before OpenSSL 1.0.0 the call to BIO_get_md_ctx() would only work if the BIO
+had been initialized for example by calling BIO_set_md() ). In OpenSSL
+1.0.0 and later the context is always returned and the BIO is state is set
+to initialized. This allows applications to initialize the context externally
+if the standard calls such as BIO_set_md() are not sufficiently flexible.
+
 =head1 RETURN VALUES
 
 BIO_f_md() returns the digest BIO method.