diff --git a/.github/workflows/codeql.yml b/.github/workflows/codeql.yml
index ba8d07f..94a11aa 100644
--- a/.github/workflows/codeql.yml
+++ b/.github/workflows/codeql.yml
@@ -13,10 +13,10 @@ name: "CodeQL"
 
 on:
   push:
-    branches: [ "main", "development" ]
+    branches: [ "main", "development", "eddsa" ]
   pull_request:
     # The branches below must be a subset of the branches above
-    branches: [ "main", "development" ]
+    branches: [ "main", "development", "eddsa" ]
   schedule:
     - cron: '23 5 * * 4'
   workflow_dispatch:
@@ -36,7 +36,7 @@ jobs:
         language: [ 'cpp', 'python' ]
         # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python', 'ruby' ]
         # Learn more about CodeQL language support at https://aka.ms/codeql-docs/language-support
-        mode: [ 'pico', 'esp32', 'local' ]
+        mode: [ 'pico', 'local' ]
 
     steps:
     - name: Checkout repository
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 0a55586..cf65236 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -13,10 +13,10 @@ name: "Emulation and test"
 
 on:
   push:
-    branches: [ "main", "development" ]
+    branches: [ "main", "development", "eddsa" ]
   pull_request:
     # The branches below must be a subset of the branches above
-    branches: [ "main", "development" ]
+    branches: [ "main", "development", "eddsa" ]
   schedule:
     - cron: '23 5 * * 4'
   workflow_dispatch:
diff --git a/README.md b/README.md
index 602182c..565da99 100644
--- a/README.md
+++ b/README.md
@@ -13,8 +13,8 @@ Pico FIDO includes the following features:
 - User verification with PIN
 - Discoverable credentials (resident keys)
 - Credential management
-- ECDSA authentication
-- Support for SECP256R1, SECP384R1, SECP521R1, and SECP256K1 curves
+- ECDSA and EDDSA authentication
+- Support for SECP256R1, SECP384R1, SECP521R1, SECP256K1 and Ed25519 curves
 - App registration and login
 - Device selection
 - Support for vendor configuration
diff --git a/build_pico_fido.sh b/build_pico_fido.sh
index a18a1dc..79873b3 100755
--- a/build_pico_fido.sh
+++ b/build_pico_fido.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
 VERSION_MAJOR="6"
-VERSION_MINOR="4"
+VERSION_MINOR="4-eddsa1"
 SUFFIX="${VERSION_MAJOR}.${VERSION_MINOR}"
 #if ! [[ -z "${GITHUB_SHA}" ]]; then
 #    SUFFIX="${SUFFIX}.${GITHUB_SHA}"
diff --git a/pico-keys-sdk b/pico-keys-sdk
index 07415e6..6ec374a 160000
--- a/pico-keys-sdk
+++ b/pico-keys-sdk
@@ -1 +1 @@
-Subproject commit 07415e6e8be36255fbcd3e5c3aeec394c7b76bac
+Subproject commit 6ec374a6ac53a4de34ed26ae19be126fe7c704e7
diff --git a/src/fido/cbor.c b/src/fido/cbor.c
index 68842b7..50f7f0f 100644
--- a/src/fido/cbor.c
+++ b/src/fido/cbor.c
@@ -210,6 +210,9 @@ CborError COSE_key(mbedtls_ecp_keypair *key, CborEncoder *mapEncoderParent,
     else if (key->grp.id == MBEDTLS_ECP_DP_CURVE25519) {
         alg = FIDO2_ALG_ECDH_ES_HKDF_256;
     }
+    else if (key->grp.id == MBEDTLS_ECP_DP_ED25519) {
+        alg = FIDO2_ALG_EDDSA;
+    }
     return COSE_key_params(crv, alg, &key->grp, &key->Q, mapEncoderParent, mapEncoder);
 }
 CborError COSE_key_shared(mbedtls_ecdh_context *key,
diff --git a/src/fido/cbor_get_assertion.c b/src/fido/cbor_get_assertion.c
index d4bb3b4..5838bc9 100644
--- a/src/fido/cbor_get_assertion.c
+++ b/src/fido/cbor_get_assertion.c
@@ -565,15 +565,27 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next) {
         else if (ekey.grp.id == MBEDTLS_ECP_DP_SECP521R1) {
             md = mbedtls_md_info_from_type(MBEDTLS_MD_SHA512);
         }
-        ret = mbedtls_md(md, aut_data, aut_data_len + clientDataHash.len, hash);
-        ret = mbedtls_ecdsa_write_signature(&ekey, mbedtls_md_get_type(md), hash, mbedtls_md_get_size(md), sig, sizeof(sig), &olen, random_gen, NULL);
+        else if (ekey.grp.id == MBEDTLS_ECP_DP_ED25519) {
+            md = NULL;
+        }
+        
+        if (md != NULL) {
+            ret = mbedtls_md(md, aut_data, aut_data_len + clientDataHash.len, hash);
+            ret = mbedtls_ecdsa_write_signature(&ekey, mbedtls_md_get_type(md), hash, mbedtls_md_get_size(md), sig, sizeof(sig), &olen, random_gen, NULL);
+        }
+        else {
+            ret = mbedtls_eddsa_write_signature(&ekey, aut_data, aut_data_len + clientDataHash.len, sig, sizeof(sig), &olen, MBEDTLS_EDDSA_PURE, NULL, 0, random_gen, NULL);
+        }
     }
     else {
         // Bogus signature
         olen = 64;
         memset(sig, 0x0B, olen);
     }
-    mbedtls_ecdsa_free(&ekey);
+    mbedtls_ecp_keypair_free(&ekey);
+    if (ret != 0) {
+        CBOR_ERROR(CTAP2_ERR_PROCESSING);
+    }
 
     uint8_t lfields = 3;
     if (selcred && selcred->opts.present == true && selcred->opts.rk == ptrue) {
diff --git a/src/fido/cbor_get_info.c b/src/fido/cbor_get_info.c
index ecdafe1..7594851 100644
--- a/src/fido/cbor_get_info.c
+++ b/src/fido/cbor_get_info.c
@@ -90,11 +90,14 @@ int cbor_get_info() {
     CBOR_CHECK(cbor_encode_uint(&mapEncoder, MAX_CRED_ID_LENGTH)); // MAX_CRED_ID_MAX_LENGTH
 
     CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x0A));
-    CBOR_CHECK(cbor_encoder_create_array(&mapEncoder, &arrayEncoder, 4));
+
+    CBOR_CHECK(cbor_encoder_create_array(&mapEncoder, &arrayEncoder, 5));
     CBOR_CHECK(COSE_public_key(FIDO2_ALG_ES256, &arrayEncoder, &mapEncoder2));
+    CBOR_CHECK(COSE_public_key(FIDO2_ALG_EDDSA, &arrayEncoder, &mapEncoder2));
     CBOR_CHECK(COSE_public_key(FIDO2_ALG_ES384, &arrayEncoder, &mapEncoder2));
     CBOR_CHECK(COSE_public_key(FIDO2_ALG_ES512, &arrayEncoder, &mapEncoder2));
     CBOR_CHECK(COSE_public_key(FIDO2_ALG_ES256K, &arrayEncoder, &mapEncoder2));
+
     CBOR_CHECK(cbor_encoder_close_container(&mapEncoder, &arrayEncoder));
 
     CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x0B));
diff --git a/src/fido/cbor_make_credential.c b/src/fido/cbor_make_credential.c
index 3a5fc83..6fa52b6 100644
--- a/src/fido/cbor_make_credential.c
+++ b/src/fido/cbor_make_credential.c
@@ -221,6 +221,11 @@ int cbor_make_credential(const uint8_t *data, size_t len) {
             if (curve <= 0) {
                 curve = FIDO2_CURVE_P256K1;
             }
+        }        
+        else if (pubKeyCredParams[i].alg == FIDO2_ALG_EDDSA) {
+            if (curve <= 0) {
+                curve = FIDO2_CURVE_ED25519;
+            }
         }
         else if (pubKeyCredParams[i].alg <= FIDO2_ALG_RS256 && pubKeyCredParams[i].alg >= FIDO2_ALG_RS512) {
             // pass
@@ -385,16 +390,16 @@ int cbor_make_credential(const uint8_t *data, size_t len) {
         ext_len = cbor_encoder_get_buffer_size(&encoder, ext);
         flags |= FIDO2_AUT_FLAG_ED;
     }
-    mbedtls_ecdsa_context ekey;
-    mbedtls_ecdsa_init(&ekey);
+    mbedtls_ecp_keypair ekey;
+    mbedtls_ecp_keypair_init(&ekey);
     int ret = fido_load_key(curve, cred_id, &ekey);
     if (ret != 0) {
-        mbedtls_ecdsa_free(&ekey);
+        mbedtls_ecp_keypair_free(&ekey);
         CBOR_ERROR(CTAP1_ERR_OTHER);
     }
     const mbedtls_ecp_curve_info *cinfo = mbedtls_ecp_curve_info_from_grp_id(ekey.grp.id);
     if (cinfo == NULL) {
-        mbedtls_ecdsa_free(&ekey);
+        mbedtls_ecp_keypair_free(&ekey);
         CBOR_ERROR(CTAP1_ERR_OTHER);
     }
     size_t olen = 0;
@@ -416,7 +421,7 @@ int cbor_make_credential(const uint8_t *data, size_t len) {
     memcpy(pa, cbor_buf, rs); pa += (uint16_t)rs;
     memcpy(pa, ext, ext_len); pa += (uint16_t)ext_len;
     if ((size_t)(pa - aut_data) != aut_data_len) {
-        mbedtls_ecdsa_free(&ekey);
+        mbedtls_ecp_keypair_free(&ekey);
         CBOR_ERROR(CTAP1_ERR_OTHER);
     }
 
@@ -429,12 +434,17 @@ int cbor_make_credential(const uint8_t *data, size_t len) {
     else if (ekey.grp.id == MBEDTLS_ECP_DP_SECP521R1) {
         md = mbedtls_md_info_from_type(MBEDTLS_MD_SHA512);
     }
-    ret = mbedtls_md(md, aut_data, aut_data_len + clientDataHash.len, hash);
+    else if (ekey.grp.id == MBEDTLS_ECP_DP_ED25519) {
+        md = NULL;
+    }
+    if (md != NULL) {
+        ret = mbedtls_md(md, aut_data, aut_data_len + clientDataHash.len, hash);
+    }
 
     bool self_attestation = true;
     if (enterpriseAttestation == 2 || (ka && ka->use_self_attestation == pfalse)) {
-        mbedtls_ecdsa_free(&ekey);
-        mbedtls_ecdsa_init(&ekey);
+        mbedtls_ecp_keypair_free(&ekey);
+        mbedtls_ecp_keypair_init(&ekey);
         uint8_t key[32] = {0};
         if (load_keydev(key) != 0) {
             CBOR_ERROR(CTAP1_ERR_OTHER);
@@ -444,8 +454,16 @@ int cbor_make_credential(const uint8_t *data, size_t len) {
         md = mbedtls_md_info_from_type(MBEDTLS_MD_SHA256);
         self_attestation = false;
     }
-    ret = mbedtls_ecdsa_write_signature(&ekey, mbedtls_md_get_type(md), hash, mbedtls_md_get_size(md), sig, sizeof(sig), &olen, random_gen, NULL);
-    mbedtls_ecdsa_free(&ekey);
+    if (md != NULL) {
+        ret = mbedtls_ecdsa_write_signature(&ekey, mbedtls_md_get_type(md), hash, mbedtls_md_get_size(md), sig, sizeof(sig), &olen, random_gen, NULL);
+    }
+    else {
+        ret = mbedtls_eddsa_write_signature(&ekey, aut_data, aut_data_len + clientDataHash.len, sig, sizeof(sig), &olen, MBEDTLS_EDDSA_PURE, NULL, 0, random_gen, NULL);
+    }
+    mbedtls_ecp_keypair_free(&ekey);
+    if (ret != 0) {
+        CBOR_ERROR(CTAP2_ERR_PROCESSING);
+    }
 
     if (user.id.len > 0 && user.parent.name.len > 0 && user.displayName.len > 0) {
        if (memcmp(user.parent.name.data, "+pico", 5) == 0) {
diff --git a/src/fido/fido.c b/src/fido/fido.c
index b7d39ef..9e11385 100644
--- a/src/fido/fido.c
+++ b/src/fido/fido.c
@@ -112,6 +112,12 @@ mbedtls_ecp_group_id fido_curve_to_mbedtls(int curve) {
     else if (curve == FIDO2_CURVE_X448) {
         return MBEDTLS_ECP_DP_CURVE448;
     }
+    else if (curve == FIDO2_CURVE_ED25519) {
+        return MBEDTLS_ECP_DP_ED25519;
+    }
+    else if (curve == FIDO2_CURVE_ED448) {
+        return MBEDTLS_ECP_DP_ED448;
+    }
     return MBEDTLS_ECP_DP_NONE;
 }
 int mbedtls_curve_to_fido(mbedtls_ecp_group_id id) {
@@ -133,10 +139,16 @@ int mbedtls_curve_to_fido(mbedtls_ecp_group_id id) {
     else if (id == MBEDTLS_ECP_DP_CURVE448) {
         return FIDO2_CURVE_X448;
     }
+    else if (id == MBEDTLS_ECP_DP_ED25519) {
+        return FIDO2_CURVE_ED25519;
+    }
+    else if (id == MBEDTLS_ECP_DP_ED448) {
+        return FIDO2_CURVE_ED448;
+    }
     return 0;
 }
 
-int fido_load_key(int curve, const uint8_t *cred_id, mbedtls_ecdsa_context *key) {
+int fido_load_key(int curve, const uint8_t *cred_id, mbedtls_ecp_keypair *key) {
     mbedtls_ecp_group_id mbedtls_curve = fido_curve_to_mbedtls(curve);
     if (mbedtls_curve == MBEDTLS_ECP_DP_NONE) {
         return CTAP2_ERR_UNSUPPORTED_ALGORITHM;
@@ -202,7 +214,7 @@ int load_keydev(uint8_t *key) {
     return PICOKEY_OK;
 }
 
-int verify_key(const uint8_t *appId, const uint8_t *keyHandle, mbedtls_ecdsa_context *key) {
+int verify_key(const uint8_t *appId, const uint8_t *keyHandle, mbedtls_ecp_keypair *key) {
     for (int i = 0; i < KEY_PATH_ENTRIES; i++) {
         uint32_t k = *(uint32_t *) &keyHandle[i * sizeof(uint32_t)];
         if (!(k & 0x80000000)) {
@@ -235,7 +247,7 @@ int verify_key(const uint8_t *appId, const uint8_t *keyHandle, mbedtls_ecdsa_con
     return memcmp(keyHandle + KEY_PATH_LEN, hmac, sizeof(hmac));
 }
 
-int derive_key(const uint8_t *app_id, bool new_key, uint8_t *key_handle, int curve, mbedtls_ecdsa_context *key) {
+int derive_key(const uint8_t *app_id, bool new_key, uint8_t *key_handle, int curve, mbedtls_ecp_keypair *key) {
     uint8_t outk[67] = { 0 }; //SECP521R1 key is 66 bytes length
     int r = 0;
     memset(outk, 0, sizeof(outk));
@@ -280,6 +292,9 @@ int derive_key(const uint8_t *app_id, bool new_key, uint8_t *key_handle, int cur
         if (r != 0) {
             return r;
         }
+        if (curve == MBEDTLS_ECP_DP_ED25519) {
+            return mbedtls_ecp_point_edwards(&key->grp, &key->Q, &key->d, random_gen, NULL);
+        }
         return mbedtls_ecp_mul(&key->grp, &key->Q, &key->d, &key->grp.G, random_gen, NULL);
     }
     mbedtls_platform_zeroize(outk, sizeof(outk));
diff --git a/src/fido/fido.h b/src/fido/fido.h
index 4666fda..f29b953 100644
--- a/src/fido/fido.h
+++ b/src/fido/fido.h
@@ -28,6 +28,7 @@
 #endif
 
 #include "mbedtls/ecdsa.h"
+#include "mbedtls/eddsa.h"
 #ifndef ENABLE_EMULATION
 #include "hid/ctap_hid.h"
 #else
@@ -45,13 +46,13 @@ extern int derive_key(const uint8_t *app_id,
                       bool new_key,
                       uint8_t *key_handle,
                       int,
-                      mbedtls_ecdsa_context *key);
-extern int verify_key(const uint8_t *appId, const uint8_t *keyHandle, mbedtls_ecdsa_context *);
+                      mbedtls_ecp_keypair *key);
+extern int verify_key(const uint8_t *appId, const uint8_t *keyHandle, mbedtls_ecp_keypair *);
 extern bool wait_button_pressed();
 extern void init_fido();
 extern mbedtls_ecp_group_id fido_curve_to_mbedtls(int curve);
 extern int mbedtls_curve_to_fido(mbedtls_ecp_group_id id);
-extern int fido_load_key(int curve, const uint8_t *cred_id, mbedtls_ecdsa_context *key);
+extern int fido_load_key(int curve, const uint8_t *cred_id, mbedtls_ecp_keypair *key);
 extern int load_keydev(uint8_t *key);
 extern int encrypt(uint8_t protocol, const uint8_t *key, const uint8_t *in, uint16_t in_len, uint8_t *out);
 extern int decrypt(uint8_t protocol, const uint8_t *key, const uint8_t *in, uint16_t in_len, uint8_t *out);
diff --git a/tests/pico-fido/test_020_register.py b/tests/pico-fido/test_020_register.py
index 78377d8..28c37e6 100644
--- a/tests/pico-fido/test_020_register.py
+++ b/tests/pico-fido/test_020_register.py
@@ -19,7 +19,7 @@
 
 
 from fido2.client import CtapError
-from fido2.cose import ES256, ES384, ES512
+from fido2.cose import ES256, ES384, ES512, EdDSA
 import fido2.features
 fido2.features.webauthn_json_mapping.enabled = False
 from utils import ES256K
@@ -124,7 +124,7 @@ def test_bad_type_pubKeyCredParams(device):
         device.doMC(key_params=["wrong"])
 
 @pytest.mark.parametrize(
-    "alg", [ES256.ALGORITHM, ES384.ALGORITHM, ES512.ALGORITHM, ES256K.ALGORITHM]
+    "alg", [ES256.ALGORITHM, ES384.ALGORITHM, ES512.ALGORITHM, ES256K.ALGORITHM, EdDSA.ALGORITHM]
 )
 def test_algorithms(device, info, alg):
     if ({'alg': alg, 'type': 'public-key'} in info.algorithms):
diff --git a/tests/pico-fido/test_021_authenticate.py b/tests/pico-fido/test_021_authenticate.py
index 2944779..14260b7 100644
--- a/tests/pico-fido/test_021_authenticate.py
+++ b/tests/pico-fido/test_021_authenticate.py
@@ -19,7 +19,7 @@
 
 
 from fido2.client import CtapError
-from fido2.cose import ES256, ES384, ES512
+from fido2.cose import ES256, ES384, ES512, EdDSA
 from utils import verify, ES256K
 import pytest
 
@@ -49,7 +49,7 @@ def test_empty_allowList(device):
     assert e.value.code == CtapError.ERR.NO_CREDENTIALS
 
 @pytest.mark.parametrize(
-    "alg", [ES256.ALGORITHM, ES384.ALGORITHM, ES512.ALGORITHM, ES256K.ALGORITHM]
+    "alg", [ES256.ALGORITHM, ES384.ALGORITHM, ES512.ALGORITHM, ES256K.ALGORITHM, EdDSA.ALGORITHM]
 )
 def test_algorithms(device, info, alg):
     if ({'alg': alg, 'type': 'public-key'} in info.algorithms):