diff --git a/src/git.xdrm.io/schastsp/client/keyset/keyset.go b/src/git.xdrm.io/schastsp/client/keyset/keyset.go
new file mode 100644
index 0000000..60f09af
--- /dev/null
+++ b/src/git.xdrm.io/schastsp/client/keyset/keyset.go
@@ -0,0 +1,212 @@
+package keyset
+
+import (
+	"io"
+	"encoding/binary"
+	"errors"
+	"git.xdrm.io/schastsp/lib/scha"
+	"math/rand"
+	"time"
+)
+
+const a = 12
+
+/* Attributes */
+type Set struct {
+	min   uint16 // min depth
+	depth uint16 // cur depth
+	max   uint16 // max depth
+
+	sec         []byte // secret
+	consumption uint   // consumption level
+	// 0: none
+	// 1: need to migrate
+	// 2: waiting migration
+	// 3: validated migration
+}
+
+/* (1) Creates a new KeySet
+*
+* @min<uint16>						Minimum depth value
+* @max<uint16>						Maximum depth value
+*
+* @return outName<outType>			outDesc
+*
+---------------------------------------------------------*/
+func Create(min uint16, max uint16) (*Set, error) {
+
+	/* (1) Fail if min >= max */
+	if min >= max {
+		return nil, errors.New("Max depth is not greater than Min depth")
+	}
+
+	/* (2) Instanciate */
+	var instance = new(Set)
+
+	/* (3) Set attributes */
+	instance.min = min
+	instance.max = max
+
+	/* (4) Generate values if <nil> secret */
+	if instance.sec == nil {
+		instance.generate()
+	}
+
+	return instance, nil
+}
+
+/* (2) Generates a pseudo-random KeySet
+*
+---------------------------------------------------------*/
+func (s *Set) generate() {
+
+	/* (1) Seed randomness */
+	rand.Seed(time.Now().UTC().UnixNano())
+
+	/* (1) Generate new secret
+	---------------------------------------------------------*/
+	/* (1) Reset current secret */
+	s.sec = make([]byte, scha.HSIZE)
+
+	/* (2) Generate each char. until same length as hash digest */
+	for i := uint16(0); i < scha.HSIZE; i++ {
+		s.sec[i] = byte(rand.Int() % 256)
+	}
+
+	/* (2) Manage other attributes
+	---------------------------------------------------------*/
+	/* (1) Random depth pick init */
+	var randMin, randMax uint16 = s.min + (s.max-s.min)/2, s.max
+
+	/* (2) Select "random" depth */
+	s.depth = randMin + uint16(rand.Intn(int(randMax-randMin)))
+
+	/* (3) Reset comsumption level */
+	s.consumption = 0
+
+}
+
+/* (3) Get current hash
+*
+* @return digest<[]byte]>			Current hash representing the set
+*
+---------------------------------------------------------*/
+func (s Set) Hash() ([]byte, error) {
+
+	/* (1) Get digest */
+	digest, err := scha.Hash(s.sec, uint(s.depth), nil, nil)
+
+	/* (2) Dispatch error */
+	if err != nil {
+		return nil, err
+	}
+
+	/* (3) Else -> return digest */
+	return digest, nil
+
+}
+
+/* (4) Decrement depth
+*
+* @return remaining<uint>			Remaining hashes before migration
+*
+---------------------------------------------------------*/
+func (s *Set) Decrement() uint16 {
+
+	/* (1) Decrement the depth */
+	s.depth--
+
+	/* (2) If near minDepth (10 far): set consumption to 1 */
+	if s.depth <= s.min+10 {
+		s.consumption = 1
+	}
+
+	/* (3) Return remaining attempts */
+	return s.depth - s.max
+
+}
+
+/* (5) Serialisation
+*
+* @return serial<string>			String representation
+*
+*
+* === FORMAT ===
+*
+* |   hsize   |   secret   |  depth  |
+* +-----------+------------+---------+
+* |  16 bits  | hsize bits | 16 bits |
+*
+* == ENDIANNESS ==
+*
+* network endianness -> big-endian
+*
+---------------------------------------------------------*/
+func (s *Set) Write(writer io.Writer) error {
+
+	var err error;
+
+	/* (1) Copy hash size */
+	err = binary.Write(writer, binary.BigEndian, scha.HSIZE)
+	if err != nil { return err }
+
+	/* (2) Copy secret */
+	err = binary.Write(writer, binary.BigEndian, s.sec)
+	if err != nil { return err }
+
+	/* (3) Copy depth */
+	err = binary.Write(writer, binary.BigEndian, s.depth)
+	if err != nil { return err }
+
+	return nil
+
+}
+
+/* (6) Builds a KeySet from its serial representation
+*
+* @serial<string>			String representation
+*
+* @return instance<*Set>	The corresponding set
+* @return err<error>		Optional error
+*
+* === FORMAT ===
+*
+* |   hsize   |   secret   |  depth  |
+* +-----------+------------+---------+
+* |  16 bits  | hsize bits | 16 bits |
+*
+---------------------------------------------------------*/
+func (s *Set) Read(reader io.Reader) error {
+
+	var (
+		err error
+		secretLength uint16
+	)
+
+	/* (1) Read the secret size */
+	err = binary.Read(reader, binary.BigEndian, &secretLength)
+	if err != nil {
+		return err
+	}
+
+	/* (2) Fail if secretLength different than digest size */
+	if secretLength != scha.HSIZE {
+		return errors.New("Invalid secret size (must be the same as digest size)")
+	}
+
+	/* (3) Try to copy the secret */
+	err = binary.Read(reader, binary.BigEndian, &s.sec)
+	if err != nil { return err }
+
+	/* (4) Manage invalid secret size (mismatch secretLength) */
+	if uint16(len(s.sec)) != secretLength {
+		return errors.New("Mismatching secret size")
+	}
+
+	/* (5) Try to copy the depth */
+	err = binary.Read(reader, binary.BigEndian, &s.depth)
+	if err != nil { return err }
+
+	return nil
+
+}
diff --git a/src/git.xdrm.io/schastsp/client/keyset/keyset_test.go b/src/git.xdrm.io/schastsp/client/keyset/keyset_test.go
new file mode 100644
index 0000000..cd26580
--- /dev/null
+++ b/src/git.xdrm.io/schastsp/client/keyset/keyset_test.go
@@ -0,0 +1,124 @@
+package keyset
+
+import (
+	"git.xdrm.io/schastsp/lib/scha"
+	"testing"
+)
+
+func TestCreateNotMaxGreaterThanMin(t *testing.T) {
+
+	var _, err = Create(2, 1)
+
+	if err == nil {
+		t.Errorf("Expected an error")
+	}
+
+}
+
+func TestGenerationDepthBoundaries(t *testing.T) {
+
+	var min, max uint16 = 0x0f0, 0xfff
+	var rangeMin = min + (max-min)/2
+	var rangeMax = max
+
+	var created, err = Create(min, max)
+
+	if err != nil {
+		t.Errorf("Do not expected an error, got: %s", err)
+	}
+
+	if created.depth < min || created.depth > max {
+		t.Errorf("Expected 'depth' to be in the range [%d, %d], got '%d'", rangeMin, rangeMax, created.depth)
+	}
+
+}
+
+func TestSchaDecrementingProperty(t *testing.T) {
+
+	var h1, h2, hcheck []byte
+	var err error
+	var created *Set
+
+	created, err = Create(0x0f0, 0xfff)
+
+	if err != nil {
+		t.Errorf("Do not expected an error, got: %s", err)
+	}
+
+	/* (1) Get current hash */
+	h1, err = created.Hash()
+	if err != nil {
+		t.Errorf("Do not expected an error, got: %s", err)
+	}
+
+	/* (2) Decrement */
+	created.Decrement()
+
+	/* (3) Get new hash */
+	h2, err = created.Hash()
+	if err != nil {
+		t.Errorf("Do not expected an error, got: %s", err)
+	}
+
+	/* (4) Try to guess h1 from h2 */
+	hcheck, err = scha.Hash(h2, 1, nil, nil)
+	if err != nil {
+		t.Errorf("Do not expected an error, got: %s", err)
+	}
+
+	/* (5) Fail if property is not fulfilled */
+	for k, v := range h1 {
+
+		if v != hcheck[k] {
+			t.Errorf("Expected h(h[x-1]) to equel h[x]; expected '%x' ; got '%x'", h1, hcheck)
+			return
+		}
+
+	}
+
+}
+
+func TestDecrementMinimum(t *testing.T) {
+
+	var h1, h2, hcheck []byte
+	var err error
+	var created *Set
+
+	created, err = Create(0x0f0, 0xfff)
+
+	if err != nil {
+		t.Errorf("Do not expected an error, got: %s", err)
+	}
+
+	/* (1) Get current hash */
+	h1, err = created.Hash()
+	if err != nil {
+		t.Errorf("Do not expected an error, got: %s", err)
+	}
+
+	/* (2) Decrement */
+	created.Decrement()
+
+	/* (3) Get new hash */
+	h2, err = created.Hash()
+	if err != nil {
+		t.Errorf("Do not expected an error, got: %s", err)
+	}
+
+	/* (4) Try to guess h1 from h2 */
+	hcheck, err = scha.Hash(h2, 1, nil, nil)
+	if err != nil {
+		t.Errorf("Do not expected an error, got: %s", err)
+	}
+
+	/* (5) Fail if property is not fulfilled */
+	for k, v := range h1 {
+
+		if v != hcheck[k] {
+			t.Errorf("Expected h(h[x-1]) to equel h[x]; expected '%x' ; got '%x'", h1, hcheck)
+			return
+		}
+
+	}
+
+}