diff --git a/coordinator/internal/transitengine/crypto.go b/coordinator/internal/transitengine/crypto.go
new file mode 100644
index 000000000..47ce6e359
--- /dev/null
+++ b/coordinator/internal/transitengine/crypto.go
@@ -0,0 +1,114 @@
+// Copyright 2024 Edgeless Systems GmbH
+// SPDX-License-Identifier: AGPL-3.0-only
+
+package transitengine
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/json"
+	"strings"
+
+	"github.com/edgelesssys/contrast/internal/crypto"
+
+	b64 "encoding/base64"
+)
+
+const (
+	// aesGCMNonceSize specifies the default nonce size in bytes used in AES GCM.
+	aesGCMNonceSize = 12
+	// aesGCMKeySize specifies the default key size in bytes AES GCM.
+	aesGCMKeySize = 16
+)
+
+// symOpts holds parameters related to the performed symmetric encryption, specifyable as http request parameters.
+type symOpts struct {
+	// 1=encryption, 0=decryption
+	encrypt bool
+	// Convergent TODO(jmxzo): add parameter support
+	convergent bool
+	// Nonce
+	nonce []byte
+	// AdditionalData
+	additionalData []byte
+}
+
+type (
+	// b64Plaintext describes a base64-encoded plaintext.
+	b64Plaintext []byte
+	// prefixedb64Ciphertext describes a base64-encoded ciphertext with prefix 'vault:v1:'.
+	prefixedb64Ciphertext []byte
+)
+
+type encryptionMap struct {
+	Plaintext  b64Plaintext          `json:"plaintext"`
+	Ciphertext prefixedb64Ciphertext `json:"ciphertext"`
+	key        []byte
+	symOpts    symOpts
+}
+
+// encryptionFunc derscribes both subjacent functions: encryption and decryption, performing it's operation on an encryptionMap and returning an error on failure.
+// Note: The corresponding http error on failure is InternalServerError with status code 500.
+type encryptionFunc func(encryptionMap *encryptionMap) error
+
+// symmetricEncrypt returns the encrypted plaintext based on the symmetric options and encryption key handed in.
+func symmetricEncrypt(encryptionMap *encryptionMap) error {
+	aesCipher, err := aes.NewCipher(encryptionMap.key)
+	if err != nil {
+		return err
+	}
+	gcm, err := cipher.NewGCM(aesCipher)
+	if err != nil {
+		return err
+	}
+	nonce, err := crypto.GenerateRandomBytes(aesGCMNonceSize)
+	if err != nil {
+		return err
+	}
+	ciphertext := gcm.Seal(nil, nonce, encryptionMap.Plaintext, nil)
+	encryptionMap.Ciphertext = append(nonce, ciphertext...)
+	return nil
+}
+
+// symmetricDecrypt returns the decrypted ciphertext based on the symmetric options and encryption keys handed in.
+func symmetricDecrypt(encryptionMap *encryptionMap) error {
+	aesCipher, err := aes.NewCipher(encryptionMap.key)
+	if err != nil {
+		return err
+	}
+	gcm, err := cipher.NewGCM(aesCipher)
+	if err != nil {
+		return err
+	}
+	encryptionMap.Plaintext, err = gcm.Open(nil, encryptionMap.symOpts.nonce, encryptionMap.Ciphertext, nil)
+	return err
+}
+
+// UnmarshalJSON implements the json.Unmarshaler interface to automatically decode b64Plaintext into.
+func (b *b64Plaintext) UnmarshalJSON(data []byte) error {
+	var encoded string
+	if err := json.Unmarshal(data, &encoded); err != nil {
+		return err
+	}
+	decoded, err := b64.StdEncoding.DecodeString(encoded)
+	if err != nil {
+		return err
+	}
+	*b = decoded
+	return nil
+}
+
+// UnmarshalJSON implements the json.Unmarshaler interface to automatically decode prefixedb64Ciphertext .
+func (p *prefixedb64Ciphertext) UnmarshalJSON(data []byte) error {
+	var encoded string
+	if err := json.Unmarshal(data, &encoded); err != nil {
+		return err
+	}
+	encoded = strings.TrimPrefix(encoded, "vault:v1:")
+	decoded, err := b64.StdEncoding.DecodeString(encoded)
+	if err != nil {
+		return err
+	}
+	*p = decoded
+	return nil
+}
diff --git a/coordinator/internal/transitengine/crypto_test.go b/coordinator/internal/transitengine/crypto_test.go
new file mode 100644
index 000000000..2b6d8d929
--- /dev/null
+++ b/coordinator/internal/transitengine/crypto_test.go
@@ -0,0 +1,93 @@
+// Copyright 2024 Edgeless Systems GmbH
+// SPDX-License-Identifier: AGPL-3.0-only
+
+package transitengine
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/edgelesssys/contrast/coordinator/internal/seedengine"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCryptoAPICyclic(t *testing.T) {
+	data := []map[string]string{
+		{"Plaintext": "vpIhKQhFuGwLv5B/XLYr960uZQ==", "Ciphertext": "vault:v1:d01M+wZYaG9LFnuc18s8oh6PuVFw3+7DBX4LkXXQ6d64DvmQt6qwjj1MHmA88UE="},
+		{"Plaintext": "O/XShnapt5hNMCZnP+4BZjH84CcWAwhxOUnGwKH7ja1ZYsZdyZrGeLT4EZtA1vWey04bAsi+viGmpYO98YbkCvSn7HZvglLh2DMv3Ach9SP2qjWw0NBa2rrfToI1dsE=", "Ciphertext": "vault:v1:onRtviw8oJv5cY4EngPYySbYlAYgEqWXk5WbD2X+jpRDR5d87Y2qE0Otc4KUKja8LYVb1zB1P40yWTgNb7srG4D7kuxlRFFbtkYaCAC3bLbz+QuumLFQd9RbsN7avbLtEmT8nay/1qvvp2e/MDv5oPoDIT0vzHorVI40"},
+		{"Plaintext": "lT3rQGMlxq680DdSKfIYYcfyCfMnP9ikxaO5b0mGRKRl4qNL3W9xkSW3QmaMwozCRfNMZhhDCbYokn6KEiGotlVInKt66QjBgXR2Nk9hIcez0LYt8W5pxD0lwTxC", "Ciphertext": "vault:v1:taQ++Amvoj0G1V+OQb0PjldLh5BRXmAhwlO38LRjajVIuHTEa69kfytU3mMaFEpG5JNVg3Cq6vSWH58n1NEmM6WDV79q/hxzaji68joq9uQeoyH3To9iBoRHE2T7jbxUvYLeBwgzFvM/YNk5EaFpNkfIwwxzNZ5gmQ=="},
+		{"Plaintext": "WC0sC1KtNw76hGVQTpeFNtPg94tJc64dE3rf0mhENsBMLhWmYinA99YbIGx0gSQEOkOsR1sPgSnEmxTvycQdNA==", "Ciphertext": "vault:v1:vjeAbnpFxh+atxQsk6OeumH6irWPAuRbim2UQ8ggNGQFpB4wnYxjUiydGgYixZ6x1Ad+STfbjwxLvij5ZpmyMxFsmrYZIQKCYE48mVUNI+VJa87zuMabQCMClOs="},
+		{"Plaintext": "iZo0IezTmQ6Ms1GJUbbY4nrsRydO31b6xuqlJwi+R9xLt1K9uaI8ZiuInXc92qpulYNaAWAiBmNNghKM0dpAPdSXwc93+YCT1Zm2i1cuW7H6Uz5tL7E=", "Ciphertext": "vault:v1:qqjtmjUKfzoAb3VeUgWjbRDdYu3K/cdmi7sEVcKPRiOdbY5OyuQrNQHtYZ/mje8hcPyHnmgDJEDOpjLhQgUG6yoYamqksut//lv7DDbKYbzroro5BRiCqQjhfqnhmna79maV5okq8zI5YZBoSSn36ivu"},
+		{"Plaintext": "FLiOXWBy8oVETtiNzfw0rbMgCfa3DVSfKL4GhR86EcluUe78nLiDxt0HtP5vTwaaz7mvLXu2nOtsdlz8kYY1YrZCLLNlYzjm/vYe++CcH/x+fDKepJem5le0BCsdog==", "Ciphertext": "vault:v1:0qp8vsJ+JFf5m5HekxQeUw0+gj/NdoDcmy7ExSw0G7PB1RBQ80T+TUMjSvmmgu02eQ2oCKEkfFMolfNt1zq+sZkLQuTLpbW8p+Vd8ALPGdyyD20MIb2ez6dm9nMM4jiXL2FkfARuHcHoY3/LCBQVLE+kkJLAdwze/Z4="},
+		{"Plaintext": "Xqv9SzcpNK99JF1I7xRAJ0FOkzka", "Ciphertext": "vault:v1:N431rZS6bcuGDDJ8Jh93yvih4oc5wHGtz02M2vFQ5IioIlZFqfv29nDImWNaZUW7Zw=="},
+		{"Plaintext": "6HQ035OxE30=", "Ciphertext": "vault:v1:ZUuU9vMiCa3CE7PvmYlJYhHQOJm2/Rk6xuUA7DSJu4ExttPl"},
+		{"Plaintext": "yqUBQzznRjbXMxhQkwo5q2Az3/6nvgRQ86uffx8ZqT7rufplfhJz+xDfvi4EOw==", "Ciphertext": "vault:v1:fpjOfUK8hZEk6DmcH715zdyTMAqyW9ymAMxQFgoMR2Q5639NYCA3rbrR4OKfGwCqO7UrBg3LeFksYBPhiO4pbX6dHXGYIfjDdgo="},
+	}
+	t.Run("encrypt-decrypt handler", func(t *testing.T) {
+		for _, entry := range data {
+			t.Run("cyclic handler function testing", func(t *testing.T) {
+				var ciphertext, receivedPlaintext string
+				t.Run("encryption request handling", func(t *testing.T) {
+					require := require.New(t)
+					jsonBody, err := createReqBodyJSON("plaintext", entry["Plaintext"])
+					require.NoError(err)
+					req := httptest.NewRequest(http.MethodPut, "/v1/transit/encrypt/autounseal", bytes.NewReader(jsonBody))
+					req.Header.Set("Content-Type", "application/json")
+					require.NoError(err)
+					encRespBody := receiveResponseBody(t, *req)
+					require.NoError(err)
+					data, _ := encRespBody["data"].(map[string]any)
+					ciphertext, _ = data["ciphertext"].(string)
+				})
+
+				t.Run("decryption request handling", func(t *testing.T) {
+					require := require.New(t)
+					decryptReqBody, err := createReqBodyJSON("ciphertext", ciphertext)
+					require.NoError(err)
+					decryptReq := httptest.NewRequest(http.MethodPut, "/v1/transit/decrypt/autounseal", bytes.NewReader(decryptReqBody))
+					decryptReq.Header.Set("Content-Type", "application/json")
+					decRespBody := receiveResponseBody(t, *decryptReq)
+					data, _ := decRespBody["data"].(map[string]any)
+					receivedPlaintext, _ = data["plaintext"].(string)
+					require.Equal(entry["Plaintext"], receivedPlaintext, "Unexpected received plaintext after cycling handler functions")
+				})
+			})
+		}
+	})
+}
+
+func receiveResponseBody(t *testing.T, req http.Request) map[string]any {
+	require := require.New(t)
+	rec := httptest.NewRecorder()
+	salt := make([]byte, 32)       // 32-byte salt initialized with zeros
+	secretSeed := make([]byte, 32) // 32-byte secret seed initialized with zeros
+	seedEngine, err := seedengine.New(secretSeed, salt)
+	require.NoError(err)
+	httpHandlerFunc := customWrapperHandler(seedEngine, slog.Default())
+	httpHandlerFunc(rec, &req)
+	res := rec.Result()
+	defer res.Body.Close()
+	require.Equal(http.StatusOK, res.StatusCode)
+	respBody, err := io.ReadAll(res.Body)
+	require.NoError(err)
+	var respData map[string]any
+	err = json.Unmarshal(respBody, &respData)
+	require.NoError(err)
+	return respData
+}
+
+func createReqBodyJSON(bodyParameter, value string) ([]byte, error) {
+	body := map[string]string{
+		bodyParameter: value,
+	}
+	jsonBody, err := json.Marshal(body)
+	if err != nil {
+		return nil, err
+	}
+	return jsonBody, nil
+}
diff --git a/coordinator/internal/transitengine/transitengine.go b/coordinator/internal/transitengine/transitengine.go
new file mode 100644
index 000000000..1d217c119
--- /dev/null
+++ b/coordinator/internal/transitengine/transitengine.go
@@ -0,0 +1,130 @@
+// Copyright 2024 Edgeless Systems GmbH
+// SPDX-License-Identifier: AGPL-3.0-only
+
+package transitengine
+
+import (
+	b64 "encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"strings"
+
+	"github.com/edgelesssys/contrast/coordinator/internal/seedengine"
+)
+
+// NewTransitEngineAPI starts a transit engine API listening on the given port and is initialized with a seedengine getter for key derivation.
+func NewTransitEngineAPI(port int, _ *seedengine.SeedEngine, logger *slog.Logger) error {
+	salt := make([]byte, 32)       // 32-byte salt initialized with zeros
+	secretSeed := make([]byte, 32) // 32-byte secret seed initialized with zeros
+	seedEngine, err := seedengine.New(secretSeed, salt)
+	if err != nil {
+		return err
+	}
+	http.HandleFunc("/", customWrapperHandler(seedEngine, logger))
+
+	logger.Info(fmt.Sprintf("Serving transit engine API on port: %d", port))
+	return http.ListenAndServe(fmt.Sprintf(":%d", port), nil)
+}
+
+// customWrapperHandler returns a http.HandlerFunc that wraps error handling and logging of:
+// routing the request,
+// executing the encryption function on the request-representative encryptionMap and
+// returning the response.
+func customWrapperHandler(seedEngine *seedengine.SeedEngine, logger *slog.Logger) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var encryptionMap *encryptionMap
+		encryptionFunc, encryptionMap, err := parseEncryptionRequest(r, seedEngine)
+		if err != nil {
+			http.Error(w, fmt.Sprint("Parsing request: %w", err), http.StatusBadRequest)
+			return
+		}
+		if err = encryptionFunc(encryptionMap); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			logger.Error("Request failed", "addr", r.RemoteAddr, "method", r.Method, "url", r.URL, "error", err)
+			return
+		}
+		if err = writeJSONResponse(w, encryptionMap); err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		logger.Debug("Request successful", "addr", r.RemoteAddr, "method", r.Method, "url", r.URL)
+	}
+}
+
+// deriveEncryptionKey
+func deriveEncryptionKey(seedEngine *seedengine.SeedEngine, workloadSecretID string) ([]byte, error) {
+	// TODO(jmxnzo): authentication of client certs <-> parsed workloadSecretID
+	derivedWorkloadSecret, err := seedEngine.DeriveWorkloadSecret(workloadSecretID)
+	if err != nil {
+		return nil, err
+	}
+	return derivedWorkloadSecret[:aesGCMKeySize], nil
+}
+
+// parseEncryptionRequest routes the request by determining the encryption/decryption function and parses the request parameters into a representative encryptionMap.
+func parseEncryptionRequest(r *http.Request, seedEngine *seedengine.SeedEngine) (encryptionFunc encryptionFunc, encryptionMap *encryptionMap, err error) {
+	parts := strings.Split(strings.Trim(r.URL.Path, "/"), "/")
+	if len(parts) != 4 || parts[1] != "transit" {
+		return nil, nil, errors.New("Invalid URL format")
+	}
+	action, workloadSecretID := parts[2], parts[3]
+
+	key, err := deriveEncryptionKey(seedEngine, workloadSecretID)
+	if err != nil {
+		return nil, nil, err
+	}
+	switch action {
+	case "encrypt":
+		encryptionFunc = symmetricEncrypt
+	case "decrypt":
+		encryptionFunc = symmetricDecrypt
+	default:
+		return nil, nil, errors.New("Invalid URL: operation not existing")
+
+	}
+	defer r.Body.Close()
+	if err := json.NewDecoder(r.Body).Decode(&encryptionMap); err != nil {
+		return nil, nil, err
+	}
+	encryptionMap.key = key
+	encryptionMap.symOpts = symOpts{
+		encrypt:        (len(encryptionMap.Ciphertext) == 0),
+		convergent:     false,
+		additionalData: []byte("test"),
+	}
+	if !encryptionMap.symOpts.encrypt {
+		encryptionMap.symOpts.nonce = encryptionMap.Ciphertext[:aesGCMNonceSize]
+		encryptionMap.Ciphertext = encryptionMap.Ciphertext[aesGCMNonceSize:]
+
+	}
+	return encryptionFunc, encryptionMap, nil
+}
+
+// writeJSONResponse sends a http.StatusOK response, wrapping the provided encryptionMap into a data JSON body.
+func writeJSONResponse(w http.ResponseWriter, encryptionMap *encryptionMap) error {
+	// Formatting: data:{"ciphertext": "vault:v1:<base64encoding>"}
+	data := map[string]any{
+		"data": map[string]string{
+			func() string {
+				if encryptionMap.symOpts.encrypt {
+					return "ciphertext"
+				}
+				return "plaintext"
+			}(): func() string {
+				if encryptionMap.symOpts.encrypt {
+					return "vault:v1:" + b64.StdEncoding.EncodeToString(encryptionMap.Ciphertext)
+				}
+				return b64.StdEncoding.EncodeToString(encryptionMap.Plaintext)
+			}(),
+		},
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	if err := json.NewEncoder(w).Encode(data); err != nil {
+		return err
+	}
+	return nil
+}