diff --git a/Makefile b/Makefile
index 9be9a9e6..3dd65d73 100644
--- a/Makefile
+++ b/Makefile
@@ -115,7 +115,12 @@ DES_SRC =						ft_des_initial_permutation.c 				\
 								ft_des_s_box_7.c 							\
 								ft_des_s_box_8.c 							\
 								ft_des_feistel_function_permutation.c 		\
-								ft_des_feistel_function.c
+								ft_des_feistel_function.c 					\
+								ft_des_key_permuted_choice_one.c 			\
+								ft_des_encryption_round_key.c 				\
+								ft_des_rotate_half_key_left.c 				\
+								ft_des_rotate_half_key_right.c 				\
+								ft_des_key_permuted_choice_two.c
 
 SRC =							main.c										\
 								ft_ssl_usage.c
diff --git a/inc/ft_des.h b/inc/ft_des.h
index 68add0ee..eefd7556 100644
--- a/inc/ft_des.h
+++ b/inc/ft_des.h
@@ -20,6 +20,8 @@
 # define FT_DES_S_BOX_TABLE_ROWS 4
 # define FT_DES_S_BOX_TABLE_COLUMNS 16
 # define FT_DES_FEISTEL_FUNCTION_KEY_SIZE 48
+# define FT_DES_INITIAL_KEY_SIZE 64
+# define FT_DES_REDUCED_KEY_SIZE 56
 
 typedef unsigned char	t_byte1;
 
@@ -109,4 +111,35 @@ void					ft_des_feistel_function
 	t_byte1 output[FT_DES_BIT_BLOCK_SIZE / 2]
 );
 
+void					ft_des_key_permuted_choice_one
+(
+	t_byte1 initial_key[FT_DES_INITIAL_KEY_SIZE],
+	t_byte1 reduced_key[FT_DES_REDUCED_KEY_SIZE]
+);
+
+void					ft_des_key_permuted_choice_two
+(
+	t_byte1 input_key[FT_DES_REDUCED_KEY_SIZE],
+	t_byte1 round_key[FT_DES_FEISTEL_FUNCTION_KEY_SIZE]
+);
+
+void					ft_des_encryption_round_key
+(
+	t_byte1 input_key[FT_DES_REDUCED_KEY_SIZE],
+	t_byte1 round,
+	t_byte1 round_key[FT_DES_FEISTEL_FUNCTION_KEY_SIZE]
+);
+
+void					ft_des_rotate_half_key_left
+(
+	t_byte1 half[FT_DES_REDUCED_KEY_SIZE / 2],
+	t_byte1 rotation_number
+);
+
+void					ft_des_rotate_half_key_right
+(
+	t_byte1 half[FT_DES_REDUCED_KEY_SIZE / 2],
+	t_byte1 rotation_number
+);
+
 #endif
diff --git a/src/des/ft_des_encryption_round_key.c b/src/des/ft_des_encryption_round_key.c
new file mode 100644
index 00000000..6c2472b1
--- /dev/null
+++ b/src/des/ft_des_encryption_round_key.c
@@ -0,0 +1,21 @@
+#include "ft_des.h"
+
+void	ft_des_encryption_round_key
+(
+	t_byte1 input_key[FT_DES_REDUCED_KEY_SIZE],
+	t_byte1 round,
+	t_byte1 round_key[FT_DES_FEISTEL_FUNCTION_KEY_SIZE]
+)
+{
+	if (round == 1 || round == 2 || round == 9 || round == 16)
+	{
+		ft_des_rotate_half_key_left(input_key, 1);
+		ft_des_rotate_half_key_left(input_key + FT_DES_REDUCED_KEY_SIZE / 2, 1);
+	}
+	else
+	{
+		ft_des_rotate_half_key_left(input_key, 2);
+		ft_des_rotate_half_key_left(input_key + FT_DES_REDUCED_KEY_SIZE / 2, 2);
+	}
+	ft_des_key_permuted_choice_two(input_key, round_key);
+}
\ No newline at end of file
diff --git a/src/des/ft_des_key_permuted_choice_one.c b/src/des/ft_des_key_permuted_choice_one.c
new file mode 100644
index 00000000..5ecab164
--- /dev/null
+++ b/src/des/ft_des_key_permuted_choice_one.c
@@ -0,0 +1,26 @@
+#include "ft_des.h"
+
+void	ft_des_key_permuted_choice_one
+(
+	t_byte1 initial_key[FT_DES_INITIAL_KEY_SIZE],
+	t_byte1 reduced_key[FT_DES_REDUCED_KEY_SIZE]
+)
+{
+	static t_byte1 table[FT_DES_REDUCED_KEY_SIZE] = {
+		57, 49, 41, 33, 25, 17,  9,  1,
+		58, 50, 42, 34, 26, 18, 10,  2,
+		59, 51, 43, 35, 27, 19, 11,  3,
+		60, 52, 44, 36, 63, 55, 47, 39,
+		31, 23, 15,  7, 62, 54, 46, 38,
+		30, 22, 14,  6, 61, 53, 45, 37,
+		29, 21, 13,  5, 28, 20, 12,  4,
+	};
+	int i;
+
+	i = 0;
+	while(i < FT_DES_REDUCED_KEY_SIZE)
+	{
+		reduced_key[i] = initial_key[table[i] - 1];
+		i++;
+	}
+}
\ No newline at end of file
diff --git a/src/des/ft_des_key_permuted_choice_two.c b/src/des/ft_des_key_permuted_choice_two.c
new file mode 100644
index 00000000..af739a64
--- /dev/null
+++ b/src/des/ft_des_key_permuted_choice_two.c
@@ -0,0 +1,25 @@
+#include "ft_des.h"
+
+void	ft_des_key_permuted_choice_two
+(
+	t_byte1 input_key[FT_DES_REDUCED_KEY_SIZE],
+	t_byte1 round_key[FT_DES_FEISTEL_FUNCTION_KEY_SIZE]
+)
+{
+	static t_byte1 table[FT_DES_FEISTEL_FUNCTION_KEY_SIZE] = {
+		14, 17, 11, 24,  1,  5,  3, 28,
+		15,  6, 21, 10, 23, 19, 12,  4,
+		26,  8, 16,  7, 27, 20, 13,  2,
+		41, 52, 31, 37, 47, 55, 30, 40,
+		51, 45, 33, 48, 44, 49, 39, 56,
+		34, 53, 46, 42, 50, 36, 29, 32,
+	};
+	int i;
+
+	i = 0;
+	while(i < FT_DES_FEISTEL_FUNCTION_KEY_SIZE)
+	{
+		round_key[i] = input_key[table[i] - 1];
+		i++;
+	}
+}
\ No newline at end of file
diff --git a/src/des/ft_des_rotate_half_key_left.c b/src/des/ft_des_rotate_half_key_left.c
new file mode 100644
index 00000000..3e0fb285
--- /dev/null
+++ b/src/des/ft_des_rotate_half_key_left.c
@@ -0,0 +1,26 @@
+#include "ft_des.h"
+
+void	ft_des_rotate_half_key_left
+(
+	t_byte1 half[FT_DES_REDUCED_KEY_SIZE / 2],
+	t_byte1 rotation_number
+)
+{
+	t_byte1 i;
+	t_byte1 j;
+	t_byte1 tmp;
+
+	tmp = half[0];
+	i = 0;
+	while(i < rotation_number)
+	{
+		j = 0;
+		while(j < FT_DES_REDUCED_KEY_SIZE / 2 - 1)
+		{
+			half[j] = half[j + 1];
+			j++;
+		}
+		half[FT_DES_REDUCED_KEY_SIZE / 2 - 1] = tmp;
+		i++;
+	}
+}
\ No newline at end of file
diff --git a/src/des/ft_des_rotate_half_key_right.c b/src/des/ft_des_rotate_half_key_right.c
new file mode 100644
index 00000000..033a9a25
--- /dev/null
+++ b/src/des/ft_des_rotate_half_key_right.c
@@ -0,0 +1,26 @@
+#include "ft_des.h"
+
+void	ft_des_rotate_half_key_right
+(
+	t_byte1 half[FT_DES_REDUCED_KEY_SIZE / 2],
+	t_byte1 rotation_number
+)
+{
+	t_byte1 i;
+	t_byte1 j;
+	t_byte1 tmp;
+
+	tmp = half[FT_DES_REDUCED_KEY_SIZE / 2 - 1];
+	i = 0;
+	while(i < rotation_number)
+	{
+		j = FT_DES_REDUCED_KEY_SIZE / 2 - 1;
+		while(j > 0)
+		{
+			half[j] = half[j - 1];
+			j--;
+		}
+		half[0] = tmp;
+		i++;
+	}
+}
\ No newline at end of file
diff --git a/t/des_tests.c b/t/des_tests.c
index 741e0a63..5945c3b1 100644
--- a/t/des_tests.c
+++ b/t/des_tests.c
@@ -378,6 +378,127 @@ int perform_feistel_function()
 	_end("feistel function should encode half of a block");
 }
 
+int reduce_key_to_56_bits()
+{
+	t_byte1 initial_key[FT_DES_INITIAL_KEY_SIZE] = {
+		1, 1, 1, 1, 1, 1, 1, 0,
+		1, 1, 1, 1, 1, 1, 1, 0,
+		1, 1, 1, 1, 1, 1, 1, 0,
+		1, 1, 1, 1, 1, 1, 1, 0,
+		1, 1, 1, 1, 1, 1, 1, 0,
+		1, 1, 1, 1, 1, 1, 1, 0,
+		1, 1, 1, 1, 1, 1, 1, 0,
+		1, 1, 1, 1, 1, 1, 1, 0,
+	};
+
+	t_byte1 expected_reduced_key[FT_DES_REDUCED_KEY_SIZE] = {
+		1, 1, 1, 1, 1, 1, 1,
+		1, 1, 1, 1, 1, 1, 1,
+		1, 1, 1, 1, 1, 1, 1,
+		1, 1, 1, 1, 1, 1, 1,
+		1, 1, 1, 1, 1, 1, 1,
+		1, 1, 1, 1, 1, 1, 1,
+		1, 1, 1, 1, 1, 1, 1,
+		1, 1, 1, 1, 1, 1, 1,
+	};
+	t_byte1 actual_reduced[FT_DES_REDUCED_KEY_SIZE];
+
+	ft_des_key_permuted_choice_one(initial_key, actual_reduced);
+
+	int i = 0;
+	while(i < FT_DES_REDUCED_KEY_SIZE)
+	{
+		_is(actual_reduced[i] == expected_reduced_key[i]);
+		i++;
+	}
+
+	_end("should reduce key size to 56 bits");
+}
+
+int rotate_half_key()
+{
+	t_byte1 half_key[FT_DES_REDUCED_KEY_SIZE / 2] = {
+		1, 1, 1, 1, 0, 0, 0,
+		0, 1, 1, 0, 0, 1, 1,
+		0, 0, 1, 0, 1, 0, 1,
+		0, 1, 0, 1, 1, 1, 1,
+	};
+
+	t_byte1 expected[FT_DES_REDUCED_KEY_SIZE / 2];
+
+	ft_memcpy(expected, half_key, FT_DES_REDUCED_KEY_SIZE / 2);
+
+	ft_des_rotate_half_key_left(half_key, 1);
+	ft_des_rotate_half_key_left(half_key, 1);
+	ft_des_rotate_half_key_right(half_key, 2);
+
+	int i = 0;
+
+	while(i < FT_DES_REDUCED_KEY_SIZE / 2)
+	{
+		_is(half_key[i] == expected[i]);
+		i++;
+	}
+	_end("should rotate half of reduced key");
+}
+
+int derive_round_key()
+{
+	t_byte1 reduced_key[FT_DES_REDUCED_KEY_SIZE] = {
+		1, 1, 1, 1, 0, 0, 0,
+		0, 1, 1, 0, 0, 1, 1,
+		0, 0, 1, 0, 1, 0, 1,
+		0, 1, 0, 1, 1, 1, 1,
+		0, 1, 0, 1, 0, 1, 0,
+		1, 0, 1, 1, 0, 0, 1,
+		1, 0, 0, 1, 1, 1, 1,
+		0, 0, 0, 1, 1, 1, 1,
+	};
+
+	t_byte1 shifted_reduced_key[FT_DES_REDUCED_KEY_SIZE] = {
+		1, 1, 1, 0, 0, 0, 0,
+		1, 1, 0, 0, 1, 1, 0,
+		0, 1, 0, 1, 0, 1, 0,
+		1, 0, 1, 1, 1, 1, 1,
+		1, 0, 1, 0, 1, 0, 1,
+		0, 1, 1, 0, 0, 1, 1,
+		0, 0, 1, 1, 1, 1, 0,
+		0, 0, 1, 1, 1, 1, 0,
+	};
+
+	t_byte1 expected_round_key[FT_DES_FEISTEL_FUNCTION_KEY_SIZE] = {
+		0, 0, 0, 1, 1, 0,
+		1, 1, 0, 0, 0, 0,
+		0, 0, 1, 0, 1, 1,
+		1, 0, 1, 1, 1, 1,
+		1, 1, 1, 1, 1, 1,
+		0, 0, 0, 1, 1, 1,
+		0, 0, 0, 0, 0, 1,
+		1, 1, 0, 0, 1, 0,
+	};
+
+	t_byte1 round_key[FT_DES_FEISTEL_FUNCTION_KEY_SIZE];
+
+	ft_des_encryption_round_key(reduced_key, 1, round_key);
+
+	int i;
+
+	i = 0;
+	while(i < FT_DES_REDUCED_KEY_SIZE)
+	{
+		_is(shifted_reduced_key[i] == reduced_key[i]);
+		i++;
+	}
+
+	i = 0;
+	while(i < FT_DES_FEISTEL_FUNCTION_KEY_SIZE)
+	{
+		_is(round_key[i] == expected_round_key[i]);
+		i++;
+	}
+	_end("should derive round key");
+}
+
 int des_tests()
 {
 	_should(perform_initial_permutation);
@@ -387,5 +508,8 @@ int des_tests()
 	_should(s_boxes_confuse);
 	_should(perform_premutation_in_feistel_function);
 	_should(perform_feistel_function);
+	_should(reduce_key_to_56_bits);
+	_should(rotate_half_key);
+	_should(derive_round_key);
 	return 0;
 }
\ No newline at end of file