Index: src/OFHash.h
==================================================================
--- src/OFHash.h
+++ src/OFHash.h
@@ -26,10 +26,20 @@
 
 #ifdef OF_HAVE_PROPERTIES
 @property (readonly) BOOL isCalculated;
 #endif
 
+/**
+ * \return The digest size of the hash, in byte.
+ */
++ (size_t)digestSize;
+
+/**
+ * \return The block size of the hash, in byte.
+ */
++ (size_t)blockSize;
+
 /**
  * Adds a buffer to the hash to be calculated.
  *
  * \param buf The buffer which should be included into the calculation.
  * \param size The size of the buffer

Index: src/OFHash.m
==================================================================
--- src/OFHash.m
+++ src/OFHash.m
@@ -18,10 +18,22 @@
 
 #import "OFHash.h"
 #import "OFExceptions.h"
 
 @implementation OFHash
++ (size_t)digestSize
+{
+	@throw [OFNotImplementedException newWithClass: self
+					      selector: _cmd];
+}
+
++ (size_t)blockSize
+{
+	@throw [OFNotImplementedException newWithClass: self
+					      selector: _cmd];
+}
+
 - (void)updateWithBuffer: (const char*)buffer
 		  ofSize: (size_t)size
 {
 	@throw [OFNotImplementedException newWithClass: isa
 					      selector: _cmd];

Index: src/OFMD5Hash.m
==================================================================
--- src/OFMD5Hash.m
+++ src/OFMD5Hash.m
@@ -119,10 +119,20 @@
 @implementation OFMD5Hash
 + MD5Hash
 {
 	return [[[self alloc] init] autorelease];
 }
+
++ (size_t)digestSize
+{
+	return 16;
+}
+
++ (size_t)blockSize
+{
+	return 64;
+}
 
 - init
 {
 	self = [super init];
 

Index: src/OFSHA1Hash.m
==================================================================
--- src/OFSHA1Hash.m
+++ src/OFSHA1Hash.m
@@ -131,10 +131,20 @@
 @implementation OFSHA1Hash
 + SHA1Hash
 {
 	return [[[self alloc] init] autorelease];
 }
+
++ (size_t)digestSize
+{
+	return 20;
+}
+
++ (size_t)blockSize
+{
+	return 64;
+}
 
 - init
 {
 	self = [super init];