diff --git a/coordination-layer/constraint.py b/coordination-layer/constraint.py
new file mode 100644
index 0000000..76c8066
--- /dev/null
+++ b/coordination-layer/constraint.py
@@ -0,0 +1,8 @@
+from dataclasses import dataclass
+
+
+@dataclass
+class Constraint:
+
+    def hash(self) -> bytes:
+        raise NotImplementedError()
diff --git a/coordination-layer/crypto.py b/coordination-layer/crypto.py
new file mode 100644
index 0000000..2ae1daa
--- /dev/null
+++ b/coordination-layer/crypto.py
@@ -0,0 +1,71 @@
+from keum import grumpkin
+import poseidon
+
+
+# !Important! The crypto primitives here must be in agreement with the proving system
+# E.g. if you are using noir with the Barretenberg, we must use the Grumpkin curve.
+
+Point = grumpkin.AffineWeierstrass
+Field = grumpkin.Fq
+
+
+def poseidon_grumpkin_field():
+    # TODO: These parameters are made up.
+    # return poseidon.Poseidon(
+    #     p=Field.ORDER,
+    #     security_level=128,
+    #     alpha=5,
+    #     input_rate=3,
+    #     t=9,
+    # )
+    h, _ = poseidon.case_simple()
+
+    # TODO: this is a hack to make poseidon take in arbitrary input length.
+    # Fix is to implement a sponge as described in section 2.1 of
+    # https://eprint.iacr.org/2019/458.pdf
+    def inner(data):
+        digest = 0
+        for i in range(0, len(data), h.input_rate - 1):
+            digest = h.run_hash([digest, *data[i : i + h.input_rate - 1]])
+        return digest
+
+    return inner
+
+
+POSEIDON = poseidon_grumpkin_field()
+
+
+def prf(domain, *elements):
+    return POSEIDON(str_to_vec(domain) + elements)
+
+
+def comm(*elements):
+    """
+    Returns a commitment to the sequence of elements.
+
+    The commitmtent can be opened at index 0..len(elements)
+    """
+    raise NotImplementedError()
+
+
+def merkle_root(data) -> Field:
+    data = _pad_to_power_of_2(data)
+    nodes = [CRH(d) for d in data]
+    while len(nodes) > 1:
+        nodes = [CRH(nodes[i], nodes[i + 1]) for i in range(0, len(nodes), 2)]
+
+    return nodes[0]
+
+
+def _pad_to_power_of_2(data):
+    import math
+
+    max_lower_bound = int(math.log2(len(data)))
+    if 2**max_lower_bound == len(data):
+        return data
+    to_pad = 2 ** (max_lower_bound + 1) - len(data)
+    return data + [0] * to_pad
+
+
+def _str_to_vec(s):
+    return list(map(ord, s))
diff --git a/coordination-layer/note.py b/coordination-layer/note.py
new file mode 100644
index 0000000..9e43ed5
--- /dev/null
+++ b/coordination-layer/note.py
@@ -0,0 +1,59 @@
+from dataclasses import dataclass
+
+from crypto import Field, Point
+
+
+@dataclass
+class Commitment:
+    cm: bytes
+
+
+@dataclass
+class Nullifier:
+    nf: bytes
+
+
+@dataclass
+class SecretNote:
+    note: InnerNote
+    nf_sk: Field
+
+    def to_public_note(self) -> PublicNote:
+        return PublicNote(
+            note=self.note,
+            nf_pk=Point.generator().mul(self.nf_sk),
+        )
+
+
+@dataclass
+class PublicNote:
+    note: InnerNote
+    nf_pk: Point
+
+    def commit(self) -> Commitment:
+        return crypto.COMM(
+            self.note.birth_constraint.hash(),
+            self.note.death_constraints_root(),
+            self.note.value,
+            self.note.unit,
+            self.note.state,
+            self.note.nonce,
+            self.nf_pk,
+        )
+
+
+@dataclass
+class InnerNote:
+    value: Field
+    unit: str
+    birth_constraint: Constraint
+    death_constraints: set[Constraint]
+    state: Field
+    nonce: Field
+    rand: Field
+
+    def death_constraints_root(self) -> Field:
+        """
+        Returns the merkle root over the set of death constraints
+        """
+        return crypto.merkle_root(self.death_constraints)
diff --git a/coordination-layer/state.py b/coordination-layer/state.py
new file mode 100644
index 0000000..358377c
--- /dev/null
+++ b/coordination-layer/state.py
@@ -0,0 +1,23 @@
+"""
+This module maintains the state of the CL.
+
+Namely we are interested in:
+- the set of note commitments
+- the set of note nullifiers (spent notes)
+- the set of constraints
+"""
+
+from dataclasses import dataclass
+
+import note
+import constraint
+
+
+@dataclass
+class State:
+    commitments: set[note.Commitment]
+    nullifiers: set[note.Nullifier]
+    constraints: dict[bytes, constraint.Constraint]
+
+    def add_constraint(self, c: constraint.Constraint):
+        self.constraints[c.hash()] = c
diff --git a/requirements.txt b/requirements.txt
index b0bbe16..e26da00 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -7,6 +7,8 @@ pysphinx==0.0.1
 scipy==1.11.4
 black==23.12.1
 sympy==1.12
-sh==2.0.6
-toml==0.10.2
-portalocker==2.8.2
+sh==2.0.6 # used for shelling out to noir
+toml==0.10.2 # used for noir
+portalocker==2.8.2 # portable file locking
+keum==0.2.0 # for CL's use of more obscure curves
+poseidon-hash==0.1.4 # used as the algebraic hash in CL