diff --git a/aes.c b/aes.c
index eaf2b69..dd77999 100644
--- a/aes.c
+++ b/aes.c
@@ -480,20 +480,18 @@ void AES_ECB_decrypt(const struct AES_ctx* ctx, uint8_t* buf)
 #endif // #if defined(ECB) && (ECB == 1)
 
 
-
-
-
-#if defined(CBC) && (CBC == 1)
-
-
+#if (defined(CBC) && (CBC == 1)) || (defined(CFB) && (CFB == 1))
 static void XorWithIv(uint8_t* buf, const uint8_t* Iv)
 {
-  uint8_t i;
-  for (i = 0; i < AES_BLOCKLEN; ++i) // The block in AES is always 128bit no matter the key size
-  {
-    buf[i] ^= Iv[i];
-  }
+    uint8_t i;
+    for (i = 0; i < AES_BLOCKLEN; ++i) // The block in AES is always 128bit no matter the key size
+    {
+        buf[i] ^= Iv[i];
+    }
 }
+#endif
+
+#if defined(CBC) && (CBC == 1)
 
 void AES_CBC_encrypt_buffer(struct AES_ctx *ctx, uint8_t* buf, uint32_t length)
 {
@@ -551,7 +549,7 @@ void AES_CTR_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length)
       {
 	/* inc will overflow */
         if (ctx->Iv[bi] == 255)
-	{
+        {
           ctx->Iv[bi] = 0;
           continue;
         } 
@@ -567,3 +565,34 @@ void AES_CTR_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length)
 
 #endif // #if defined(CTR) && (CTR == 1)
 
+#if defined(CFB) && (CFB == 1)
+
+
+void AES_CFB_encrypt_buffer(struct AES_ctx *ctx, uint8_t* buf, uint32_t length)
+{
+    uintptr_t i;
+    for (i = 0; i < length; i += AES_BLOCKLEN)
+    {
+        Cipher((state_t*)ctx->Iv, ctx->RoundKey);
+        XorWithIv(buf, ctx->Iv);
+        memcpy(ctx->Iv, buf, AES_BLOCKLEN);
+        buf += AES_BLOCKLEN;
+    }
+}
+
+void AES_CFB_decrypt_buffer(struct AES_ctx* ctx, uint8_t* buf,  uint32_t length)
+{
+    uintptr_t i;
+    uint8_t storeNextIv[AES_BLOCKLEN];
+    for (i = 0; i < length; i += AES_BLOCKLEN)
+    {
+        memcpy(storeNextIv, buf, AES_BLOCKLEN);
+        Cipher((state_t*)ctx->Iv, ctx->RoundKey);
+        XorWithIv(buf, ctx->Iv);
+        memcpy(ctx->Iv, storeNextIv, AES_BLOCKLEN);
+        buf += AES_BLOCKLEN;
+    }
+
+}
+
+#endif // #if defined(CFB) && (CFB == 1)
\ No newline at end of file
diff --git a/aes.h b/aes.h
index 0d3b2e0..0b9c146 100644
--- a/aes.h
+++ b/aes.h
@@ -22,6 +22,10 @@
   #define CTR 1
 #endif
 
+#ifndef CFB
+  #define CFB 1
+#endif
+
 
 #define AES128 1
 //#define AES192 1
@@ -43,13 +47,13 @@
 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(CFB) && (CFB == 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(CFB) && (CFB == 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
@@ -87,4 +91,15 @@ void AES_CTR_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length);
 #endif // #if defined(CTR) && (CTR == 1)
 
 
+#if defined(CFB) && (CFB == 1)
+// buffer size MUST be mutile of AES_BLOCKLEN;
+// Suggest https://en.wikipedia.org/wiki/Padding_(cryptography)#PKCS7 for padding scheme
+// NOTES: you need to set IV in ctx via AES_init_ctx_iv() or AES_ctx_set_iv()
+//        no IV should ever be reused with the same key
+void AES_CFB_encrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length);
+void AES_CFB_decrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length);
+
+#endif // #if defined(CFB) && (CFB == 1)
+
+
 #endif // _AES_H_
diff --git a/test.c b/test.c
index 6796283..262194f 100644
--- a/test.c
+++ b/test.c
@@ -18,6 +18,8 @@ static int test_encrypt_ctr(void);
 static int test_decrypt_ctr(void);
 static int test_encrypt_ecb(void);
 static int test_decrypt_ecb(void);
+static int test_encrypt_cfb(void);
+static int test_decrypt_cfb(void);
 static void test_encrypt_ecb_verbose(void);
 
 
@@ -38,7 +40,8 @@ int main(void)
 
     exit = test_encrypt_cbc() + test_decrypt_cbc() +
 	test_encrypt_ctr() + test_decrypt_ctr() +
-	test_decrypt_ecb() + test_encrypt_ecb();
+	test_decrypt_ecb() + test_encrypt_ecb() +
+    test_encrypt_cfb() + test_decrypt_cfb();
     test_encrypt_ecb_verbose();
 
     return exit;
@@ -314,3 +317,64 @@ static int test_decrypt_ecb(void)
 }
 
 
+static int test_decrypt_cfb(void)
+{
+
+#if defined(AES128)
+    uint8_t key[] = { 0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6, 0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c };
+    uint8_t out[]  = { 0x76, 0x49, 0xab, 0xac, 0x81, 0x19, 0xb2, 0x46, 0xce, 0xe9, 0x8e, 0x9b, 0x12, 0xe9, 0x19, 0x7d,
+                      0x50, 0x86, 0xcb, 0x9b, 0x50, 0x72, 0x19, 0xee, 0x95, 0xdb, 0x11, 0x3a, 0x91, 0x76, 0x78, 0xb2,
+                      0x73, 0xbe, 0xd6, 0xb8, 0xe3, 0xc1, 0x74, 0x3b, 0x71, 0x16, 0xe6, 0x9e, 0x22, 0x22, 0x95, 0x16,
+                      0x3f, 0xf1, 0xca, 0xa1, 0x68, 0x1f, 0xac, 0x09, 0x12, 0x0e, 0xca, 0x30, 0x75, 0x86, 0xe1, 0xa7 };
+    uint8_t iv[]  = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };
+    uint8_t in[] = { 0x26, 0xb7, 0xcc, 0x60, 0x18, 0x74, 0x80, 0xf0, 0x14, 0xe0, 0xb9, 0x72, 0x89, 0x46, 0xf5, 0x1d,
+                     0x48, 0xed, 0x40, 0x27, 0x59, 0x03, 0xbc, 0x8b, 0x9f, 0xf2, 0x7d, 0x3b, 0x1b, 0x20, 0x23, 0x45,
+                     0xeb, 0x0b, 0xa3, 0xbf, 0x0f, 0xf3, 0x63, 0xea, 0x23, 0xff, 0xc0, 0xf9, 0xc4, 0x2b, 0x6c, 0x87,
+                     0x0b, 0xaa, 0x99, 0xce, 0x5f, 0x13, 0xe6, 0x7d, 0x4e, 0xea, 0xe6, 0x8b, 0x3f, 0x00, 0x8c, 0x71 };
+#endif
+//  uint8_t buffer[64];
+    struct AES_ctx ctx;
+
+    AES_init_ctx_iv(&ctx, key, iv);
+    AES_CFB_decrypt_buffer(&ctx, in, 64);
+
+    printf("CFB decrypt: ");
+
+    if (0 == memcmp((char*) out, (char*) in, 64)) {
+        printf("SUCCESS!\n");
+        return(0);
+    } else {
+        printf("FAILURE!\n");
+        return(1);
+    }
+}
+
+static int test_encrypt_cfb(void)
+{
+#if defined(AES128)
+    uint8_t key[] = { 0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6, 0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c };
+    uint8_t in[]  = { 0x76, 0x49, 0xab, 0xac, 0x81, 0x19, 0xb2, 0x46, 0xce, 0xe9, 0x8e, 0x9b, 0x12, 0xe9, 0x19, 0x7d,
+                      0x50, 0x86, 0xcb, 0x9b, 0x50, 0x72, 0x19, 0xee, 0x95, 0xdb, 0x11, 0x3a, 0x91, 0x76, 0x78, 0xb2,
+                      0x73, 0xbe, 0xd6, 0xb8, 0xe3, 0xc1, 0x74, 0x3b, 0x71, 0x16, 0xe6, 0x9e, 0x22, 0x22, 0x95, 0x16,
+                      0x3f, 0xf1, 0xca, 0xa1, 0x68, 0x1f, 0xac, 0x09, 0x12, 0x0e, 0xca, 0x30, 0x75, 0x86, 0xe1, 0xa7 };
+    uint8_t iv[]  = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };
+    uint8_t out[] = { 0x26, 0xb7, 0xcc, 0x60, 0x18, 0x74, 0x80, 0xf0, 0x14, 0xe0, 0xb9, 0x72, 0x89, 0x46, 0xf5, 0x1d,
+                      0x48, 0xed, 0x40, 0x27, 0x59, 0x03, 0xbc, 0x8b, 0x9f, 0xf2, 0x7d, 0x3b, 0x1b, 0x20, 0x23, 0x45,
+                      0xeb, 0x0b, 0xa3, 0xbf, 0x0f, 0xf3, 0x63, 0xea, 0x23, 0xff, 0xc0, 0xf9, 0xc4, 0x2b, 0x6c, 0x87,
+                      0x0b, 0xaa, 0x99, 0xce, 0x5f, 0x13, 0xe6, 0x7d, 0x4e, 0xea, 0xe6, 0x8b, 0x3f, 0x00, 0x8c, 0x71 };
+#endif
+    struct AES_ctx ctx;
+
+    AES_init_ctx_iv(&ctx, key, iv);
+    AES_CFB_encrypt_buffer(&ctx, in, 64);
+
+    printf("CFB encrypt: ");
+
+    if (0 == memcmp((char*) out, (char*) in, 64)) {
+        printf("SUCCESS!\n");
+        return(0);
+    } else {
+        printf("FAILURE!\n");
+        return(1);
+    }
+}
\ No newline at end of file