diff --git a/aes.c b/aes.c
index 4481f7b..695e5f4 100644
--- a/aes.c
+++ b/aes.c
@@ -486,7 +486,7 @@ void AES_ECB_decrypt(const struct AES_ctx* ctx, uint8_t* buf)
 
 
 
-#if defined(CBC) && (CBC == 1)
+#if defined(CBC) && (CBC == 1) || (defined(OFB) && (OFB == 1)) 
 
 
 static void XorWithIv(uint8_t* buf, const uint8_t* Iv)
@@ -497,7 +497,9 @@ static void XorWithIv(uint8_t* buf, const uint8_t* Iv)
     buf[i] ^= Iv[i];
   }
 }
+#endif // #if defined(CBC) && (CBC == 1) || (defined(OFB) && (OFB == 1))
 
+#if defined(CBC) && (CBC == 1) 
 void AES_CBC_encrypt_buffer(struct AES_ctx *ctx, uint8_t* buf, size_t length)
 {
   size_t i;
@@ -570,3 +572,23 @@ void AES_CTR_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length)
 
 #endif // #if defined(CTR) && (CTR == 1)
 
+#if defined(OFB) && (OFB == 1)
+
+// Same function for encrypting as for decrypting. 
+// NOTES: you need to set IV in ctx with AES_init_ctx_iv() or AES_ctx_set_iv()
+//        no IV should ever be reused with the same key
+void AES_OFB_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length) 
+{
+  size_t i;
+  uint8_t *Iv = ctx->Iv;
+  for (i = 0; i < length; i += AES_BLOCKLEN)
+  {
+    Cipher((state_t*)Iv, ctx->RoundKey);
+	  XorWithIv(buf, Iv);
+    buf += AES_BLOCKLEN;
+  }
+  /* store Iv in ctx for next call */
+  memcpy(ctx->Iv, Iv, AES_BLOCKLEN);
+}
+
+#endif // #if defined(OFB) && (OFB == 1)
diff --git a/aes.h b/aes.h
index b29b668..7b9866a 100644
--- a/aes.h
+++ b/aes.h
@@ -8,6 +8,7 @@
 //
 // CBC enables AES encryption in CBC-mode of operation.
 // CTR enables encryption in counter-mode.
+// OFB enables encryption in output feedback mode
 // ECB enables the basic ECB 16-byte block algorithm. All can be enabled simultaneously.
 
 // The #ifndef-guard allows it to be configured before #include'ing or at compile time.
@@ -23,6 +24,9 @@
   #define CTR 1
 #endif
 
+#ifndef OFB
+	#define OFB 1
+#endif
 
 #define AES128 1
 //#define AES192 1
@@ -44,13 +48,13 @@
 struct AES_ctx
 {
   uint8_t RoundKey[AES_keyExpSize];
-#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
+#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1)) || (defined(OFB) && (OFB == 1)) 
   uint8_t Iv[AES_BLOCKLEN];
 #endif
 };
 
 void AES_init_ctx(struct AES_ctx* ctx, const uint8_t* key);
-#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1))
+#if (defined(CBC) && (CBC == 1)) || (defined(CTR) && (CTR == 1)) || (defined(OFB) && (OFB == 1)) 
 void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, const uint8_t* iv);
 void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv);
 #endif
@@ -62,7 +66,7 @@ void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv);
 void AES_ECB_encrypt(const struct AES_ctx* ctx, uint8_t* buf);
 void AES_ECB_decrypt(const struct AES_ctx* ctx, uint8_t* buf);
 
-#endif // #if defined(ECB) && (ECB == !)
+#endif // #if defined(ECB) && (ECB == 1)
 
 
 #if defined(CBC) && (CBC == 1)
@@ -87,5 +91,14 @@ void AES_CTR_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length);
 
 #endif // #if defined(CTR) && (CTR == 1)
 
+#if defined(OFB) && (OFB == 1)
+
+// Same function for encrypting as for decrypting. 
+// NOTES: you need to set IV in ctx with AES_init_ctx_iv() or AES_ctx_set_iv()
+//        no IV should ever be reused with the same key
+void AES_OFB_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length);
+
+#endif // #if defined(OFB) && (OFB == 1)
+
 
 #endif // _AES_H_
diff --git a/test.c b/test.c
index 6796283..d0961f2 100644
--- a/test.c
+++ b/test.c
@@ -7,6 +7,7 @@
 #define CBC 1
 #define CTR 1
 #define ECB 1
+#define OFB 1
 
 #include "aes.h"
 
@@ -19,6 +20,8 @@ static int test_decrypt_ctr(void);
 static int test_encrypt_ecb(void);
 static int test_decrypt_ecb(void);
 static void test_encrypt_ecb_verbose(void);
+static int test_encrypt_ofb(void);
+static int test_decrypt_ofb(void);
 
 
 int main(void)
@@ -38,6 +41,7 @@ int main(void)
 
     exit = test_encrypt_cbc() + test_decrypt_cbc() +
 	test_encrypt_ctr() + test_decrypt_ctr() +
+    test_encrypt_ofb() + test_decrypt_ofb() +
 	test_decrypt_ecb() + test_encrypt_ecb();
     test_encrypt_ecb_verbose();
 
@@ -280,6 +284,60 @@ static int test_xcrypt_ctr(const char* xcrypt)
     }
 }
 
+static int test_xcrypt_ofb(const char* xcrypt);
+static int test_encrypt_ofb(void)
+{
+    return test_xcrypt_ofb("encrypt");
+}
+
+static int test_decrypt_ofb(void)
+{
+    return test_xcrypt_ofb("decrypt");
+}
+
+static int test_xcrypt_ofb(const char* xcrypt)
+{
+#if defined(AES256)
+    uint8_t key[32] = { 0x60, 0x3d, 0xeb, 0x10, 0x15, 0xca, 0x71, 0xbe, 0x2b, 0x73, 0xae, 0xf0, 0x85, 0x7d, 0x77, 0x81,
+                        0x1f, 0x35, 0x2c, 0x07, 0x3b, 0x61, 0x08, 0xd7, 0x2d, 0x98, 0x10, 0xa3, 0x09, 0x14, 0xdf, 0xf4 };
+    uint8_t in[64]  = { 0xDC, 0x7E, 0x84, 0xBF, 0xDA, 0x79, 0x16, 0x4B, 0x7E, 0xCD, 0x84, 0x86, 0x98, 0x5D, 0x38, 0x60, 
+                        0x4F, 0xEB, 0xDC, 0x67, 0x40, 0xD2, 0x0B, 0x3A, 0xC8, 0x8F, 0x6A, 0xD8, 0x2A, 0x4F, 0xB0, 0x8D, 
+                        0x71, 0xAB, 0x47, 0xA0, 0x86, 0xE8, 0x6E, 0xED, 0xF3, 0x9D, 0x1C, 0x5B, 0xBA, 0x97, 0xC4, 0x08, 
+                        0x01, 0x26, 0x14, 0x1D, 0x67, 0xF3, 0x7B, 0xE8, 0x53, 0x8F, 0x5A, 0x8B, 0xE7, 0x40, 0xE4, 0x84 };
+#elif defined(AES192)
+    uint8_t key[24] = { 0x8e, 0x73, 0xb0, 0xf7, 0xda, 0x0e, 0x64, 0x52, 0xc8, 0x10, 0xf3, 0x2b, 0x80, 0x90, 0x79, 0xe5, 
+                        0x62, 0xf8, 0xea, 0xd2, 0x52, 0x2c, 0x6b, 0x7b };
+    uint8_t in[64]  = { 0xCD, 0xC8, 0x0D, 0x6F, 0xDD, 0xF1, 0x8C, 0xAB, 0x34, 0xC2, 0x59, 0x09, 0xC9, 0x9A, 0x41, 0x74, 
+                        0xFC, 0xC2, 0x8B, 0x8D, 0x4C, 0x63, 0x83, 0x7C, 0x09, 0xE8, 0x17, 0x00, 0xC1, 0x10, 0x04, 0x01, 
+                        0x8D, 0x9A, 0x9A, 0xEA, 0xC0, 0xF6, 0x59, 0x6F, 0x55, 0x9C, 0x6D, 0x4D, 0xAF, 0x59, 0xA5, 0xF2, 
+                        0x6D, 0x9F, 0x20, 0x08, 0x57, 0xCA, 0x6C, 0x3E, 0x9C, 0xAC, 0x52, 0x4B, 0xD9, 0xAC, 0xC9, 0x2A };
+#elif defined(AES128)
+    uint8_t key[16] = { 0x2B, 0x7E, 0x15, 0x16, 0x28, 0xAE, 0xD2, 0xA6, 0xAB, 0xF7, 0x15, 0x88, 0x09, 0xCF, 0x4F, 0x3C };
+    uint8_t in[64]  = { 0x3B, 0x3F, 0xD9, 0x2E, 0xB7, 0x2D, 0xAD, 0x20, 0x33, 0x34, 0x49, 0xF8, 0xE8, 0x3C, 0xFB, 0x4A, 
+                        0x77, 0x89, 0x50, 0x8D, 0x16, 0x91, 0x8F, 0x03, 0xF5, 0x3C, 0x52, 0xDA, 0xC5, 0x4E, 0xD8, 0x25, 
+                        0x97, 0x40, 0x05, 0x1E, 0x9C, 0x5F, 0xEC, 0xF6, 0x43, 0x44, 0xF7, 0xA8, 0x22, 0x60, 0xED, 0xCC, 
+                        0x30, 0x4C, 0x65, 0x28, 0xF6, 0x59, 0xC7, 0x78, 0x66, 0xA5, 0x10, 0xD9, 0xC1, 0xD6, 0xAE, 0x5E };
+#endif
+    uint8_t iv[16]  = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };
+    uint8_t out[64] = { 0x6B, 0xC1, 0xBE, 0xE2, 0x2E, 0x40, 0x9F, 0x96, 0xE9, 0x3D, 0x7E, 0x11, 0x73, 0x93, 0x17, 0x2A, 
+                        0xAE, 0x2D, 0x8A, 0x57, 0x1E, 0x03, 0xAC, 0x9C, 0x9E, 0xB7, 0x6F, 0xAC, 0x45, 0xAF, 0x8E, 0x51, 
+                        0x30, 0xC8, 0x1C, 0x46, 0xA3, 0x5C, 0xE4, 0x11, 0xE5, 0xFB, 0xC1, 0x19, 0x1A, 0x0A, 0x52, 0xEF, 
+                        0xF6, 0x9F, 0x24, 0x45, 0xDF, 0x4F, 0x9B, 0x17, 0xAD, 0x2B, 0x41, 0x7B, 0xE6, 0x6C, 0x37, 0x10 };
+    struct AES_ctx ctx;
+    
+    AES_init_ctx_iv(&ctx, key, iv);
+    AES_OFB_xcrypt_buffer(&ctx, in, 64);
+  
+    printf("OFB %s: ", xcrypt);
+
+    if (0 == memcmp((char *) out, (char *) in, 64)) {
+        printf("SUCCESS!\n");
+	return(0);
+    } else {
+        printf("FAILURE!\n");
+	return(1);
+    }
+}
 
 static int test_decrypt_ecb(void)
 {