diff --git a/include/mincrypt/hash-internal.h b/include/mincrypt/hash-internal.h
new file mode 100644
index 0000000..96806f7
--- /dev/null
+++ b/include/mincrypt/hash-internal.h
@@ -0,0 +1,40 @@
+// Copyright 2007 Google Inc. All Rights Reserved.
+// Author: mschilder@google.com (Marius Schilder)
+
+#ifndef SECURITY_UTIL_LITE_HASH_INTERNAL_H__
+#define SECURITY_UTIL_LITE_HASH_INTERNAL_H__
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif  // __cplusplus
+
+struct HASH_CTX;  // forward decl
+
+typedef struct HASH_VTAB {
+  void (* const init)(struct HASH_CTX*);
+  void (* const update)(struct HASH_CTX*, const void*, int);
+  const uint8_t* (* const final)(struct HASH_CTX*);
+  const uint8_t* (* const hash)(const void*, int, uint8_t*);
+  int size;
+} HASH_VTAB;
+
+typedef struct HASH_CTX {
+  const HASH_VTAB * f;
+  uint64_t count;
+  uint8_t buf[64];
+  uint32_t state[8];  // upto SHA2
+} HASH_CTX;
+
+#define HASH_init(ctx) (ctx)->f->init(ctx)
+#define HASH_update(ctx, data, len) (ctx)->f->update(ctx, data, len)
+#define HASH_final(ctx) (ctx)->f->final(ctx)
+#define HASH_hash(data, len, digest) (ctx)->f->hash(data, len, digest)
+#define HASH_size(ctx) (ctx)->f->size
+
+#ifdef __cplusplus
+}
+#endif  // __cplusplus
+
+#endif  // SECURITY_UTIL_LITE_HASH_INTERNAL_H__
diff --git a/include/mincrypt/rsa.h b/include/mincrypt/rsa.h
index d7429fc..cc0e800 100644
--- a/include/mincrypt/rsa.h
+++ b/include/mincrypt/rsa.h
@@ -48,7 +48,8 @@
 int RSA_verify(const RSAPublicKey *key,
                const uint8_t* signature,
                const int len,
-               const uint8_t* sha);
+               const uint8_t* hash,
+               const int hash_len);
 
 #ifdef __cplusplus
 }
diff --git a/include/mincrypt/sha.h b/include/mincrypt/sha.h
index af63e87..120ddcb 100644
--- a/include/mincrypt/sha.h
+++ b/include/mincrypt/sha.h
@@ -1,63 +1,30 @@
-/* sha.h
-**
-** Copyright 2008, The Android Open Source Project
-**
-** Redistribution and use in source and binary forms, with or without
-** modification, are permitted provided that the following conditions are met:
-**     * Redistributions of source code must retain the above copyright
-**       notice, this list of conditions and the following disclaimer.
-**     * Redistributions in binary form must reproduce the above copyright
-**       notice, this list of conditions and the following disclaimer in the
-**       documentation and/or other materials provided with the distribution.
-**     * Neither the name of Google Inc. nor the names of its contributors may
-**       be used to endorse or promote products derived from this software
-**       without specific prior written permission.
-**
-** THIS SOFTWARE IS PROVIDED BY Google Inc. ``AS IS'' AND ANY EXPRESS OR
-** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
-** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
-** EVENT SHALL Google Inc. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
-** PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
-** OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
-** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
-** OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
-** ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-*/
+// Copyright 2005 Google Inc. All Rights Reserved.
+// Author: mschilder@google.com (Marius Schilder)
 
-#ifndef _EMBEDDED_SHA_H_
-#define _EMBEDDED_SHA_H_
+#ifndef SECURITY_UTIL_LITE_SHA1_H__
+#define SECURITY_UTIL_LITE_SHA1_H__
 
-#include <inttypes.h>
+#include <stdint.h>
+#include "hash-internal.h"
 
 #ifdef __cplusplus
 extern "C" {
-#endif
+#endif // __cplusplus
 
-typedef struct SHA_CTX {
-    uint64_t count;
-    uint32_t state[5];
-#if defined(HAVE_ENDIAN_H) && defined(HAVE_LITTLE_ENDIAN)
-    union {
-        uint8_t b[64];
-        uint32_t w[16];
-    } buf;
-#else
-    uint8_t buf[64];
-#endif
-} SHA_CTX;
+typedef HASH_CTX SHA_CTX;
 
 void SHA_init(SHA_CTX* ctx);
 void SHA_update(SHA_CTX* ctx, const void* data, int len);
 const uint8_t* SHA_final(SHA_CTX* ctx);
 
-/* Convenience method. Returns digest parameter value. */
-const uint8_t* SHA(const void* data, int len, uint8_t* digest);
+// Convenience method. Returns digest address.
+// NOTE: *digest needs to hold SHA_DIGEST_SIZE bytes.
+const uint8_t* SHA_hash(const void* data, int len, uint8_t* digest);
 
 #define SHA_DIGEST_SIZE 20
 
 #ifdef __cplusplus
 }
-#endif
+#endif // __cplusplus
 
-#endif
+#endif  // SECURITY_UTIL_LITE_SHA1_H__
diff --git a/include/mincrypt/sha256.h b/include/mincrypt/sha256.h
new file mode 100644
index 0000000..0f3efb7
--- /dev/null
+++ b/include/mincrypt/sha256.h
@@ -0,0 +1,29 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+// Author: mschilder@google.com (Marius Schilder)
+
+#ifndef SECURITY_UTIL_LITE_SHA256_H__
+#define SECURITY_UTIL_LITE_SHA256_H__
+
+#include <stdint.h>
+#include "hash-internal.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+typedef HASH_CTX SHA256_CTX;
+
+void SHA256_init(SHA256_CTX* ctx);
+void SHA256_update(SHA256_CTX* ctx, const void* data, int len);
+const uint8_t* SHA256_final(SHA256_CTX* ctx);
+
+// Convenience method. Returns digest address.
+const uint8_t* SHA256_hash(const void* data, int len, uint8_t* digest);
+
+#define SHA256_DIGEST_SIZE 32
+
+#ifdef __cplusplus
+}
+#endif // __cplusplus
+
+#endif  // SECURITY_UTIL_LITE_SHA256_H__