diff --git a/identity/aidl/default/FakeSecureHardwareProxy.cpp b/identity/aidl/default/FakeSecureHardwareProxy.cpp
index 9b9a749..8551ab7 100644
--- a/identity/aidl/default/FakeSecureHardwareProxy.cpp
+++ b/identity/aidl/default/FakeSecureHardwareProxy.cpp
@@ -596,10 +596,10 @@
     return eicPresentationStartRetrieveEntries(&ctx_);
 }
 
-bool FakeSecureHardwarePresentationProxy::calcMacKey(
+bool FakeSecureHardwarePresentationProxy::prepareDeviceAuthentication(
         const vector<uint8_t>& sessionTranscript, const vector<uint8_t>& readerEphemeralPublicKey,
         const vector<uint8_t>& signingKeyBlob, const string& docType,
-        unsigned int numNamespacesWithValues, size_t expectedProofOfProvisioningSize) {
+        unsigned int numNamespacesWithValues, size_t expectedDeviceNamespacesSize) {
     if (!validateId(__func__)) {
         return false;
     }
@@ -608,10 +608,10 @@
         eicDebug("Unexpected size %zd of signingKeyBlob, expected 60", signingKeyBlob.size());
         return false;
     }
-    return eicPresentationCalcMacKey(&ctx_, sessionTranscript.data(), sessionTranscript.size(),
-                                     readerEphemeralPublicKey.data(), signingKeyBlob.data(),
-                                     docType.c_str(), docType.size(), numNamespacesWithValues,
-                                     expectedProofOfProvisioningSize);
+    return eicPresentationPrepareDeviceAuthentication(
+            &ctx_, sessionTranscript.data(), sessionTranscript.size(),
+            readerEphemeralPublicKey.data(), readerEphemeralPublicKey.size(), signingKeyBlob.data(),
+            docType.c_str(), docType.size(), numNamespacesWithValues, expectedDeviceNamespacesSize);
 }
 
 AccessCheckResult FakeSecureHardwarePresentationProxy::startRetrieveEntryValue(
@@ -673,6 +673,25 @@
     return content;
 }
 
+optional<pair<vector<uint8_t>, vector<uint8_t>>>
+FakeSecureHardwarePresentationProxy::finishRetrievalWithSignature() {
+    if (!validateId(__func__)) {
+        return std::nullopt;
+    }
+
+    vector<uint8_t> mac(32);
+    size_t macSize = 32;
+    vector<uint8_t> ecdsaSignature(EIC_ECDSA_P256_SIGNATURE_SIZE);
+    size_t ecdsaSignatureSize = EIC_ECDSA_P256_SIGNATURE_SIZE;
+    if (!eicPresentationFinishRetrievalWithSignature(&ctx_, mac.data(), &macSize,
+                                                     ecdsaSignature.data(), &ecdsaSignatureSize)) {
+        return std::nullopt;
+    }
+    mac.resize(macSize);
+    ecdsaSignature.resize(ecdsaSignatureSize);
+    return std::make_pair(mac, ecdsaSignature);
+}
+
 optional<vector<uint8_t>> FakeSecureHardwarePresentationProxy::finishRetrieval() {
     if (!validateId(__func__)) {
         return std::nullopt;
diff --git a/identity/aidl/default/FakeSecureHardwareProxy.h b/identity/aidl/default/FakeSecureHardwareProxy.h
index 2512074..b56ab93 100644
--- a/identity/aidl/default/FakeSecureHardwareProxy.h
+++ b/identity/aidl/default/FakeSecureHardwareProxy.h
@@ -175,11 +175,11 @@
                                 const vector<uint8_t>& requestMessage, int coseSignAlg,
                                 const vector<uint8_t>& readerSignatureOfToBeSigned) override;
 
-    bool calcMacKey(const vector<uint8_t>& sessionTranscript,
-                    const vector<uint8_t>& readerEphemeralPublicKey,
-                    const vector<uint8_t>& signingKeyBlob, const string& docType,
-                    unsigned int numNamespacesWithValues,
-                    size_t expectedProofOfProvisioningSize) override;
+    bool prepareDeviceAuthentication(const vector<uint8_t>& sessionTranscript,
+                                     const vector<uint8_t>& readerEphemeralPublicKey,
+                                     const vector<uint8_t>& signingKeyBlob, const string& docType,
+                                     unsigned int numNamespacesWithValues,
+                                     size_t expectedDeviceNamespacesSize) override;
 
     AccessCheckResult startRetrieveEntryValue(
             const string& nameSpace, const string& name, unsigned int newNamespaceNumEntries,
@@ -191,6 +191,8 @@
 
     optional<vector<uint8_t>> finishRetrieval() override;
 
+    optional<pair<vector<uint8_t>, vector<uint8_t>>> finishRetrievalWithSignature() override;
+
     optional<vector<uint8_t>> deleteCredential(const string& docType,
                                                const vector<uint8_t>& challenge,
                                                bool includeChallenge,
diff --git a/identity/aidl/default/common/IdentityCredential.cpp b/identity/aidl/default/common/IdentityCredential.cpp
index ff80752..4c3b7b2 100644
--- a/identity/aidl/default/common/IdentityCredential.cpp
+++ b/identity/aidl/default/common/IdentityCredential.cpp
@@ -457,17 +457,16 @@
     }
 
     if (session_) {
-        // If presenting in a session, the TA has already done this check.
-
+        // If presenting in a session, the TA has already done the check for (X, Y) as done
+        // below, see eicSessionSetSessionTranscript().
     } else {
-        // To prevent replay-attacks, we check that the public part of the ephemeral
-        // key we previously created, is present in the DeviceEngagement part of
-        // SessionTranscript as a COSE_Key, in uncompressed form.
+        // If mdoc session encryption is in use, check that the
+        // public part of the ephemeral key we previously created, is
+        // present in the DeviceEngagement part of SessionTranscript
+        // as a COSE_Key, in uncompressed form.
         //
         // We do this by just searching for the X and Y coordinates.
-        //
-        // Would be nice to move this check to the TA.
-        if (sessionTranscript.size() > 0) {
+        if (sessionTranscript.size() > 0 && ephemeralPublicKey_.size() > 0) {
             auto [getXYSuccess, ePubX, ePubY] = support::ecPublicKeyGetXandY(ephemeralPublicKey_);
             if (!getXYSuccess) {
                 return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
@@ -608,33 +607,36 @@
     // Finally, pass info so the HMAC key can be derived and the TA can start
     // creating the DeviceNameSpaces CBOR...
     if (!session_) {
-        if (sessionTranscript_.size() > 0 && readerPublicKey_.size() > 0 &&
-            signingKeyBlob.size() > 0) {
-            // We expect the reader ephemeral public key to be same size and curve
-            // as the ephemeral key we generated (e.g. P-256 key), otherwise ECDH
-            // won't work. So its length should be 65 bytes and it should be
-            // starting with 0x04.
-            if (readerPublicKey_.size() != 65 || readerPublicKey_[0] != 0x04) {
-                return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
-                        IIdentityCredentialStore::STATUS_FAILED,
-                        "Reader public key is not in expected format"));
+        if (sessionTranscript_.size() > 0 && signingKeyBlob.size() > 0) {
+            vector<uint8_t> eReaderKeyP256;
+            if (readerPublicKey_.size() > 0) {
+                // If set, we expect the reader ephemeral public key to be same size and curve
+                // as the ephemeral key we generated (e.g. P-256 key), otherwise ECDH won't
+                // work. So its length should be 65 bytes and it should be starting with 0x04.
+                if (readerPublicKey_.size() != 65 || readerPublicKey_[0] != 0x04) {
+                    return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
+                            IIdentityCredentialStore::STATUS_FAILED,
+                            "Reader public key is not in expected format"));
+                }
+                eReaderKeyP256 =
+                        vector<uint8_t>(readerPublicKey_.begin() + 1, readerPublicKey_.end());
             }
-            vector<uint8_t> pubKeyP256(readerPublicKey_.begin() + 1, readerPublicKey_.end());
-            if (!hwProxy_->calcMacKey(sessionTranscript_, pubKeyP256, signingKeyBlob, docType_,
-                                      numNamespacesWithValues, expectedDeviceNameSpacesSize_)) {
+            if (!hwProxy_->prepareDeviceAuthentication(
+                        sessionTranscript_, eReaderKeyP256, signingKeyBlob, docType_,
+                        numNamespacesWithValues, expectedDeviceNameSpacesSize_)) {
                 return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
                         IIdentityCredentialStore::STATUS_FAILED,
                         "Error starting retrieving entries"));
             }
         }
     } else {
-        if (session_->getSessionTranscript().size() > 0 &&
-            session_->getReaderEphemeralPublicKey().size() > 0 && signingKeyBlob.size() > 0) {
+        if (session_->getSessionTranscript().size() > 0 && signingKeyBlob.size() > 0) {
             // Don't actually pass the reader ephemeral public key in, the TA will get
             // it from the session object.
             //
-            if (!hwProxy_->calcMacKey(sessionTranscript_, {}, signingKeyBlob, docType_,
-                                      numNamespacesWithValues, expectedDeviceNameSpacesSize_)) {
+            if (!hwProxy_->prepareDeviceAuthentication(sessionTranscript_, {}, signingKeyBlob,
+                                                       docType_, numNamespacesWithValues,
+                                                       expectedDeviceNameSpacesSize_)) {
                 return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
                         IIdentityCredentialStore::STATUS_FAILED,
                         "Error starting retrieving entries"));
@@ -924,8 +926,9 @@
     return ndk::ScopedAStatus::ok();
 }
 
-ndk::ScopedAStatus IdentityCredential::finishRetrieval(vector<uint8_t>* outMac,
-                                                       vector<uint8_t>* outDeviceNameSpaces) {
+ndk::ScopedAStatus IdentityCredential::finishRetrievalWithSignature(
+        vector<uint8_t>* outMac, vector<uint8_t>* outDeviceNameSpaces,
+        vector<uint8_t>* outEcdsaSignature) {
     ndk::ScopedAStatus status = ensureHwProxy();
     if (!status.isOk()) {
         return status;
@@ -948,17 +951,34 @@
                         .c_str()));
     }
 
+    optional<vector<uint8_t>> digestToBeMaced;
+    optional<vector<uint8_t>> signatureToBeSigned;
+
+    // This relies on the fact that binder calls never pass a nullptr
+    // for out parameters. Hence if it's null here we know this was
+    // called from finishRetrieval() below.
+    if (outEcdsaSignature == nullptr) {
+        digestToBeMaced = hwProxy_->finishRetrieval();
+        if (!digestToBeMaced) {
+            return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
+                    IIdentityCredentialStore::STATUS_INVALID_DATA,
+                    "Error generating digestToBeMaced"));
+        }
+    } else {
+        auto macAndSignature = hwProxy_->finishRetrievalWithSignature();
+        if (!macAndSignature) {
+            return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
+                    IIdentityCredentialStore::STATUS_INVALID_DATA,
+                    "Error generating digestToBeMaced and signatureToBeSigned"));
+        }
+        digestToBeMaced = macAndSignature->first;
+        signatureToBeSigned = macAndSignature->second;
+    }
+
     // If the TA calculated a MAC (it might not have), format it as a COSE_Mac0
     //
-    optional<vector<uint8_t>> mac;
-    optional<vector<uint8_t>> digestToBeMaced = hwProxy_->finishRetrieval();
-
-    // The MAC not being set means an error occurred.
-    if (!digestToBeMaced) {
-        return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
-                IIdentityCredentialStore::STATUS_INVALID_DATA, "Error generating digestToBeMaced"));
-    }
     // Size 0 means that the MAC isn't set. If it's set, it has to be 32 bytes.
+    optional<vector<uint8_t>> mac;
     if (digestToBeMaced.value().size() != 0) {
         if (digestToBeMaced.value().size() != 32) {
             return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
@@ -967,12 +987,27 @@
         }
         mac = support::coseMacWithDigest(digestToBeMaced.value(), {} /* data */);
     }
-
     *outMac = mac.value_or(vector<uint8_t>({}));
+
+    optional<vector<uint8_t>> signature;
+    if (signatureToBeSigned && signatureToBeSigned.value().size() != 0) {
+        signature = support::coseSignEcDsaWithSignature(signatureToBeSigned.value(), {},  // data
+                                                        {});  // certificateChain
+    }
+    if (outEcdsaSignature != nullptr) {
+        *outEcdsaSignature = signature.value_or(vector<uint8_t>({}));
+    }
+
     *outDeviceNameSpaces = encodedDeviceNameSpaces;
+
     return ndk::ScopedAStatus::ok();
 }
 
+ndk::ScopedAStatus IdentityCredential::finishRetrieval(vector<uint8_t>* outMac,
+                                                       vector<uint8_t>* outDeviceNameSpaces) {
+    return finishRetrievalWithSignature(outMac, outDeviceNameSpaces, nullptr);
+}
+
 ndk::ScopedAStatus IdentityCredential::generateSigningKeyPair(
         vector<uint8_t>* outSigningKeyBlob, Certificate* outSigningKeyCertificate) {
     if (session_) {
diff --git a/identity/aidl/default/common/IdentityCredential.h b/identity/aidl/default/common/IdentityCredential.h
index 5929829..1e0cd64 100644
--- a/identity/aidl/default/common/IdentityCredential.h
+++ b/identity/aidl/default/common/IdentityCredential.h
@@ -92,6 +92,10 @@
     ndk::ScopedAStatus updateCredential(
             shared_ptr<IWritableIdentityCredential>* outWritableCredential) override;
 
+    ndk::ScopedAStatus finishRetrievalWithSignature(vector<uint8_t>* outMac,
+                                                    vector<uint8_t>* outDeviceNameSpaces,
+                                                    vector<uint8_t>* outEcdsaSignature) override;
+
   private:
     ndk::ScopedAStatus deleteCredentialCommon(const vector<uint8_t>& challenge,
                                               bool includeChallenge,
diff --git a/identity/aidl/default/common/PresentationSession.cpp b/identity/aidl/default/common/PresentationSession.cpp
index 2eb7f2e..cf5b066 100644
--- a/identity/aidl/default/common/PresentationSession.cpp
+++ b/identity/aidl/default/common/PresentationSession.cpp
@@ -54,19 +54,6 @@
     }
     id_ = id.value();
 
-    optional<vector<uint8_t>> ephemeralKeyPriv = hwProxy_->getEphemeralKeyPair();
-    if (!ephemeralKeyPriv) {
-        LOG(ERROR) << "Error getting ephemeral private key for session";
-        return IIdentityCredentialStore::STATUS_FAILED;
-    }
-    optional<vector<uint8_t>> ephemeralKeyPair =
-            support::ecPrivateKeyToKeyPair(ephemeralKeyPriv.value());
-    if (!ephemeralKeyPair) {
-        LOG(ERROR) << "Error creating ephemeral key-pair";
-        return IIdentityCredentialStore::STATUS_FAILED;
-    }
-    ephemeralKeyPair_ = ephemeralKeyPair.value();
-
     optional<uint64_t> authChallenge = hwProxy_->getAuthChallenge();
     if (!authChallenge) {
         LOG(ERROR) << "Error getting authChallenge for session";
@@ -78,6 +65,23 @@
 }
 
 ndk::ScopedAStatus PresentationSession::getEphemeralKeyPair(vector<uint8_t>* outKeyPair) {
+    if (ephemeralKeyPair_.size() == 0) {
+        optional<vector<uint8_t>> ephemeralKeyPriv = hwProxy_->getEphemeralKeyPair();
+        if (!ephemeralKeyPriv) {
+            LOG(ERROR) << "Error getting ephemeral private key for session";
+            return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
+                    IIdentityCredentialStore::STATUS_FAILED,
+                    "Error getting ephemeral private key for session"));
+        }
+        optional<vector<uint8_t>> ephemeralKeyPair =
+                support::ecPrivateKeyToKeyPair(ephemeralKeyPriv.value());
+        if (!ephemeralKeyPair) {
+            LOG(ERROR) << "Error creating ephemeral key-pair";
+            return ndk::ScopedAStatus(AStatus_fromServiceSpecificErrorWithMessage(
+                    IIdentityCredentialStore::STATUS_FAILED, "Error creating ephemeral key-pair"));
+        }
+        ephemeralKeyPair_ = ephemeralKeyPair.value();
+    }
     *outKeyPair = ephemeralKeyPair_;
     return ndk::ScopedAStatus::ok();
 }
diff --git a/identity/aidl/default/common/PresentationSession.h b/identity/aidl/default/common/PresentationSession.h
index 4cb174a..b3d46f9 100644
--- a/identity/aidl/default/common/PresentationSession.h
+++ b/identity/aidl/default/common/PresentationSession.h
@@ -72,9 +72,11 @@
 
     // Set by initialize()
     uint64_t id_;
-    vector<uint8_t> ephemeralKeyPair_;
     uint64_t authChallenge_;
 
+    // Set by getEphemeralKeyPair()
+    vector<uint8_t> ephemeralKeyPair_;
+
     // Set by setReaderEphemeralPublicKey()
     vector<uint8_t> readerPublicKey_;
 
diff --git a/identity/aidl/default/common/SecureHardwareProxy.h b/identity/aidl/default/common/SecureHardwareProxy.h
index 9f63ad8..6463318 100644
--- a/identity/aidl/default/common/SecureHardwareProxy.h
+++ b/identity/aidl/default/common/SecureHardwareProxy.h
@@ -194,11 +194,12 @@
                                         const vector<uint8_t>& requestMessage, int coseSignAlg,
                                         const vector<uint8_t>& readerSignatureOfToBeSigned) = 0;
 
-    virtual bool calcMacKey(const vector<uint8_t>& sessionTranscript,
-                            const vector<uint8_t>& readerEphemeralPublicKey,
-                            const vector<uint8_t>& signingKeyBlob, const string& docType,
-                            unsigned int numNamespacesWithValues,
-                            size_t expectedProofOfProvisioningSize) = 0;
+    virtual bool prepareDeviceAuthentication(const vector<uint8_t>& sessionTranscript,
+                                             const vector<uint8_t>& readerEphemeralPublicKey,
+                                             const vector<uint8_t>& signingKeyBlob,
+                                             const string& docType,
+                                             unsigned int numNamespacesWithValues,
+                                             size_t expectedDeviceNamespacesSize) = 0;
 
     virtual AccessCheckResult startRetrieveEntryValue(
             const string& nameSpace, const string& name, unsigned int newNamespaceNumEntries,
@@ -209,6 +210,7 @@
             const vector<int32_t>& accessControlProfileIds) = 0;
 
     virtual optional<vector<uint8_t>> finishRetrieval();
+    virtual optional<pair<vector<uint8_t>, vector<uint8_t>>> finishRetrievalWithSignature();
 
     virtual optional<vector<uint8_t>> deleteCredential(const string& docType,
                                                        const vector<uint8_t>& challenge,
diff --git a/identity/aidl/default/identity-default.xml b/identity/aidl/default/identity-default.xml
index cc0ddc7..d0d43af 100644
--- a/identity/aidl/default/identity-default.xml
+++ b/identity/aidl/default/identity-default.xml
@@ -1,7 +1,7 @@
 <manifest version="1.0" type="device">
     <hal format="aidl">
         <name>android.hardware.identity</name>
-        <version>4</version>
+        <version>5</version>
         <interface>
             <name>IIdentityCredentialStore</name>
             <instance>default</instance>
diff --git a/identity/aidl/default/libeic/EicPresentation.c b/identity/aidl/default/libeic/EicPresentation.c
index 104a559..23fd0b3 100644
--- a/identity/aidl/default/libeic/EicPresentation.c
+++ b/identity/aidl/default/libeic/EicPresentation.c
@@ -557,87 +557,11 @@
     return true;
 }
 
-bool eicPresentationCalcMacKey(EicPresentation* ctx, const uint8_t* sessionTranscript,
-                               size_t sessionTranscriptSize,
-                               const uint8_t readerEphemeralPublicKey[EIC_P256_PUB_KEY_SIZE],
-                               const uint8_t signingKeyBlob[60], const char* docType,
-                               size_t docTypeLength, unsigned int numNamespacesWithValues,
-                               size_t expectedDeviceNamespacesSize) {
-    if (ctx->sessionId != 0) {
-        EicSession* session = eicSessionGetForId(ctx->sessionId);
-        if (session == NULL) {
-            eicDebug("Error looking up session for sessionId %" PRIu32, ctx->sessionId);
-            return false;
-        }
-        EicSha256Ctx sha256;
-        uint8_t sessionTranscriptSha256[EIC_SHA256_DIGEST_SIZE];
-        eicOpsSha256Init(&sha256);
-        eicOpsSha256Update(&sha256, sessionTranscript, sessionTranscriptSize);
-        eicOpsSha256Final(&sha256, sessionTranscriptSha256);
-        if (eicCryptoMemCmp(sessionTranscriptSha256, session->sessionTranscriptSha256,
-                            EIC_SHA256_DIGEST_SIZE) != 0) {
-            eicDebug("SessionTranscript mismatch");
-            return false;
-        }
-        readerEphemeralPublicKey = session->readerEphemeralPublicKey;
-    }
-
-    uint8_t signingKeyPriv[EIC_P256_PRIV_KEY_SIZE];
-    if (!eicOpsDecryptAes128Gcm(ctx->storageKey, signingKeyBlob, 60, (const uint8_t*)docType,
-                                docTypeLength, signingKeyPriv)) {
-        eicDebug("Error decrypting signingKeyBlob");
-        return false;
-    }
-
-    uint8_t sharedSecret[EIC_P256_COORDINATE_SIZE];
-    if (!eicOpsEcdh(readerEphemeralPublicKey, signingKeyPriv, sharedSecret)) {
-        eicDebug("ECDH failed");
-        return false;
-    }
-
-    EicCbor cbor;
-    eicCborInit(&cbor, NULL, 0);
-    eicCborAppendSemantic(&cbor, EIC_CBOR_SEMANTIC_TAG_ENCODED_CBOR);
-    eicCborAppendByteString(&cbor, sessionTranscript, sessionTranscriptSize);
-    uint8_t salt[EIC_SHA256_DIGEST_SIZE];
-    eicCborFinal(&cbor, salt);
-
-    const uint8_t info[7] = {'E', 'M', 'a', 'c', 'K', 'e', 'y'};
-    uint8_t derivedKey[32];
-    if (!eicOpsHkdf(sharedSecret, EIC_P256_COORDINATE_SIZE, salt, sizeof(salt), info, sizeof(info),
-                    derivedKey, sizeof(derivedKey))) {
-        eicDebug("HKDF failed");
-        return false;
-    }
-
-    eicCborInitHmacSha256(&ctx->cbor, NULL, 0, derivedKey, sizeof(derivedKey));
-    ctx->buildCbor = true;
-
-    // What we're going to calculate the HMAC-SHA256 is the COSE ToBeMaced
-    // structure which looks like the following:
-    //
-    // MAC_structure = [
-    //   context : "MAC" / "MAC0",
-    //   protected : empty_or_serialized_map,
-    //   external_aad : bstr,
-    //   payload : bstr
-    // ]
-    //
-    eicCborAppendArray(&ctx->cbor, 4);
-    eicCborAppendStringZ(&ctx->cbor, "MAC0");
-
-    // The COSE Encoded protected headers is just a single field with
-    // COSE_LABEL_ALG (1) -> COSE_ALG_HMAC_256_256 (5). For simplicitly we just
-    // hard-code the CBOR encoding:
-    static const uint8_t coseEncodedProtectedHeaders[] = {0xa1, 0x01, 0x05};
-    eicCborAppendByteString(&ctx->cbor, coseEncodedProtectedHeaders,
-                            sizeof(coseEncodedProtectedHeaders));
-
-    // We currently don't support Externally Supplied Data (RFC 8152 section 4.3)
-    // so external_aad is the empty bstr
-    static const uint8_t externalAad[0] = {};
-    eicCborAppendByteString(&ctx->cbor, externalAad, sizeof(externalAad));
-
+// Helper used to append the DeviceAuthencation prelude, used for both MACing and ECDSA signing.
+static size_t appendDeviceAuthentication(EicCbor* cbor, const uint8_t* sessionTranscript,
+                                         size_t sessionTranscriptSize, const char* docType,
+                                         size_t docTypeLength,
+                                         size_t expectedDeviceNamespacesSize) {
     // For the payload, the _encoded_ form follows here. We handle this by simply
     // opening a bstr, and then writing the CBOR. This requires us to know the
     // size of said bstr, ahead of time... the CBOR to be written is
@@ -674,26 +598,148 @@
     dabCalculatedSize += calculatedSize;
 
     // Begin the bytestring for DeviceAuthenticationBytes;
-    eicCborBegin(&ctx->cbor, EIC_CBOR_MAJOR_TYPE_BYTE_STRING, dabCalculatedSize);
+    eicCborBegin(cbor, EIC_CBOR_MAJOR_TYPE_BYTE_STRING, dabCalculatedSize);
 
-    eicCborAppendSemantic(&ctx->cbor, EIC_CBOR_SEMANTIC_TAG_ENCODED_CBOR);
+    eicCborAppendSemantic(cbor, EIC_CBOR_SEMANTIC_TAG_ENCODED_CBOR);
 
     // Begins the bytestring for DeviceAuthentication;
-    eicCborBegin(&ctx->cbor, EIC_CBOR_MAJOR_TYPE_BYTE_STRING, calculatedSize);
+    eicCborBegin(cbor, EIC_CBOR_MAJOR_TYPE_BYTE_STRING, calculatedSize);
 
-    eicCborAppendArray(&ctx->cbor, 4);
-    eicCborAppendStringZ(&ctx->cbor, "DeviceAuthentication");
-    eicCborAppend(&ctx->cbor, sessionTranscript, sessionTranscriptSize);
-    eicCborAppendString(&ctx->cbor, docType, docTypeLength);
+    eicCborAppendArray(cbor, 4);
+    eicCborAppendStringZ(cbor, "DeviceAuthentication");
+    eicCborAppend(cbor, sessionTranscript, sessionTranscriptSize);
+    eicCborAppendString(cbor, docType, docTypeLength);
 
     // For the payload, the _encoded_ form follows here. We handle this by simply
     // opening a bstr, and then writing the CBOR. This requires us to know the
     // size of said bstr, ahead of time.
-    eicCborAppendSemantic(&ctx->cbor, EIC_CBOR_SEMANTIC_TAG_ENCODED_CBOR);
-    eicCborBegin(&ctx->cbor, EIC_CBOR_MAJOR_TYPE_BYTE_STRING, expectedDeviceNamespacesSize);
-    ctx->expectedCborSizeAtEnd = expectedDeviceNamespacesSize + ctx->cbor.size;
+    eicCborAppendSemantic(cbor, EIC_CBOR_SEMANTIC_TAG_ENCODED_CBOR);
+    eicCborBegin(cbor, EIC_CBOR_MAJOR_TYPE_BYTE_STRING, expectedDeviceNamespacesSize);
+    size_t expectedCborSizeAtEnd = expectedDeviceNamespacesSize + cbor->size;
 
-    eicCborAppendMap(&ctx->cbor, numNamespacesWithValues);
+    return expectedCborSizeAtEnd;
+}
+
+bool eicPresentationPrepareDeviceAuthentication(
+        EicPresentation* ctx, const uint8_t* sessionTranscript, size_t sessionTranscriptSize,
+        const uint8_t* readerEphemeralPublicKey, size_t readerEphemeralPublicKeySize,
+        const uint8_t signingKeyBlob[60], const char* docType, size_t docTypeLength,
+        unsigned int numNamespacesWithValues, size_t expectedDeviceNamespacesSize) {
+    if (ctx->sessionId != 0) {
+        if (readerEphemeralPublicKeySize != 0) {
+            eicDebug("In a session but readerEphemeralPublicKeySize is non-zero");
+            return false;
+        }
+        EicSession* session = eicSessionGetForId(ctx->sessionId);
+        if (session == NULL) {
+            eicDebug("Error looking up session for sessionId %" PRIu32, ctx->sessionId);
+            return false;
+        }
+        EicSha256Ctx sha256;
+        uint8_t sessionTranscriptSha256[EIC_SHA256_DIGEST_SIZE];
+        eicOpsSha256Init(&sha256);
+        eicOpsSha256Update(&sha256, sessionTranscript, sessionTranscriptSize);
+        eicOpsSha256Final(&sha256, sessionTranscriptSha256);
+        if (eicCryptoMemCmp(sessionTranscriptSha256, session->sessionTranscriptSha256,
+                            EIC_SHA256_DIGEST_SIZE) != 0) {
+            eicDebug("SessionTranscript mismatch");
+            return false;
+        }
+        readerEphemeralPublicKey = session->readerEphemeralPublicKey;
+        readerEphemeralPublicKeySize = session->readerEphemeralPublicKeySize;
+    }
+
+    // Stash the decrypted DeviceKey in context since we'll need it later in
+    // eicPresentationFinishRetrievalWithSignature()
+    if (!eicOpsDecryptAes128Gcm(ctx->storageKey, signingKeyBlob, 60, (const uint8_t*)docType,
+                                docTypeLength, ctx->deviceKeyPriv)) {
+        eicDebug("Error decrypting signingKeyBlob");
+        return false;
+    }
+
+    // We can only do MACing if EReaderKey has been set... it might not have been set if for
+    // example mdoc session encryption isn't in use. In that case we can still do ECDSA
+    if (readerEphemeralPublicKeySize > 0) {
+        if (readerEphemeralPublicKeySize != EIC_P256_PUB_KEY_SIZE) {
+            eicDebug("Unexpected size %zd for readerEphemeralPublicKeySize",
+                     readerEphemeralPublicKeySize);
+            return false;
+        }
+
+        uint8_t sharedSecret[EIC_P256_COORDINATE_SIZE];
+        if (!eicOpsEcdh(readerEphemeralPublicKey, ctx->deviceKeyPriv, sharedSecret)) {
+            eicDebug("ECDH failed");
+            return false;
+        }
+
+        EicCbor cbor;
+        eicCborInit(&cbor, NULL, 0);
+        eicCborAppendSemantic(&cbor, EIC_CBOR_SEMANTIC_TAG_ENCODED_CBOR);
+        eicCborAppendByteString(&cbor, sessionTranscript, sessionTranscriptSize);
+        uint8_t salt[EIC_SHA256_DIGEST_SIZE];
+        eicCborFinal(&cbor, salt);
+
+        const uint8_t info[7] = {'E', 'M', 'a', 'c', 'K', 'e', 'y'};
+        uint8_t derivedKey[32];
+        if (!eicOpsHkdf(sharedSecret, EIC_P256_COORDINATE_SIZE, salt, sizeof(salt), info,
+                        sizeof(info), derivedKey, sizeof(derivedKey))) {
+            eicDebug("HKDF failed");
+            return false;
+        }
+
+        eicCborInitHmacSha256(&ctx->cbor, NULL, 0, derivedKey, sizeof(derivedKey));
+
+        // What we're going to calculate the HMAC-SHA256 is the COSE ToBeMaced
+        // structure which looks like the following:
+        //
+        // MAC_structure = [
+        //   context : "MAC" / "MAC0",
+        //   protected : empty_or_serialized_map,
+        //   external_aad : bstr,
+        //   payload : bstr
+        // ]
+        //
+        eicCborAppendArray(&ctx->cbor, 4);
+        eicCborAppendStringZ(&ctx->cbor, "MAC0");
+
+        // The COSE Encoded protected headers is just a single field with
+        // COSE_LABEL_ALG (1) -> COSE_ALG_HMAC_256_256 (5). For simplicitly we just
+        // hard-code the CBOR encoding:
+        static const uint8_t coseEncodedProtectedHeaders[] = {0xa1, 0x01, 0x05};
+        eicCborAppendByteString(&ctx->cbor, coseEncodedProtectedHeaders,
+                                sizeof(coseEncodedProtectedHeaders));
+
+        // We currently don't support Externally Supplied Data (RFC 8152 section 4.3)
+        // so external_aad is the empty bstr
+        static const uint8_t externalAad[0] = {};
+        eicCborAppendByteString(&ctx->cbor, externalAad, sizeof(externalAad));
+
+        // Append DeviceAuthentication prelude and open the DeviceSigned map...
+        ctx->expectedCborSizeAtEnd =
+                appendDeviceAuthentication(&ctx->cbor, sessionTranscript, sessionTranscriptSize,
+                                           docType, docTypeLength, expectedDeviceNamespacesSize);
+        eicCborAppendMap(&ctx->cbor, numNamespacesWithValues);
+        ctx->buildCbor = true;
+    }
+
+    // Now do the same for ECDSA signatures...
+    //
+    eicCborInit(&ctx->cborEcdsa, NULL, 0);
+    eicCborAppendArray(&ctx->cborEcdsa, 4);
+    eicCborAppendStringZ(&ctx->cborEcdsa, "Signature1");
+    static const uint8_t coseEncodedProtectedHeadersEcdsa[] = {0xa1, 0x01, 0x26};
+    eicCborAppendByteString(&ctx->cborEcdsa, coseEncodedProtectedHeadersEcdsa,
+                            sizeof(coseEncodedProtectedHeadersEcdsa));
+    static const uint8_t externalAadEcdsa[0] = {};
+    eicCborAppendByteString(&ctx->cborEcdsa, externalAadEcdsa, sizeof(externalAadEcdsa));
+
+    // Append DeviceAuthentication prelude and open the DeviceSigned map...
+    ctx->expectedCborEcdsaSizeAtEnd =
+            appendDeviceAuthentication(&ctx->cborEcdsa, sessionTranscript, sessionTranscriptSize,
+                                       docType, docTypeLength, expectedDeviceNamespacesSize);
+    eicCborAppendMap(&ctx->cborEcdsa, numNamespacesWithValues);
+    ctx->buildCborEcdsa = true;
+
     return true;
 }
 
@@ -702,6 +748,7 @@
     // state objects here.
     ctx->requestMessageValidated = false;
     ctx->buildCbor = false;
+    ctx->buildCborEcdsa = false;
     ctx->accessControlProfileMaskValidated = 0;
     ctx->accessControlProfileMaskUsesReaderAuth = 0;
     ctx->accessControlProfileMaskFailedReaderAuth = 0;
@@ -724,6 +771,9 @@
     if (newNamespaceNumEntries > 0) {
         eicCborAppendString(&ctx->cbor, nameSpace, nameSpaceLength);
         eicCborAppendMap(&ctx->cbor, newNamespaceNumEntries);
+
+        eicCborAppendString(&ctx->cborEcdsa, nameSpace, nameSpaceLength);
+        eicCborAppendMap(&ctx->cborEcdsa, newNamespaceNumEntries);
     }
 
     // We'll need to calc and store a digest of additionalData to check that it's the same
@@ -778,6 +828,7 @@
 
     if (result == EIC_ACCESS_CHECK_RESULT_OK) {
         eicCborAppendString(&ctx->cbor, name, nameLength);
+        eicCborAppendString(&ctx->cborEcdsa, name, nameLength);
         ctx->accessCheckOk = true;
     }
     return result;
@@ -821,6 +872,7 @@
     }
 
     eicCborAppend(&ctx->cbor, content, encryptedContentSize - 28);
+    eicCborAppend(&ctx->cborEcdsa, content, encryptedContentSize - 28);
 
     return true;
 }
@@ -842,6 +894,40 @@
         return false;
     }
     eicCborFinal(&ctx->cbor, digestToBeMaced);
+
+    return true;
+}
+
+bool eicPresentationFinishRetrievalWithSignature(EicPresentation* ctx, uint8_t* digestToBeMaced,
+                                                 size_t* digestToBeMacedSize,
+                                                 uint8_t* signatureOfToBeSigned,
+                                                 size_t* signatureOfToBeSignedSize) {
+    if (!eicPresentationFinishRetrieval(ctx, digestToBeMaced, digestToBeMacedSize)) {
+        return false;
+    }
+
+    if (!ctx->buildCborEcdsa) {
+        *signatureOfToBeSignedSize = 0;
+        return true;
+    }
+    if (*signatureOfToBeSignedSize != EIC_ECDSA_P256_SIGNATURE_SIZE) {
+        return false;
+    }
+
+    // This verifies that the correct expectedDeviceNamespacesSize value was
+    // passed in at eicPresentationCalcMacKey() time.
+    if (ctx->cborEcdsa.size != ctx->expectedCborEcdsaSizeAtEnd) {
+        eicDebug("CBOR ECDSA size is %zd, was expecting %zd", ctx->cborEcdsa.size,
+                 ctx->expectedCborEcdsaSizeAtEnd);
+        return false;
+    }
+    uint8_t cborSha256[EIC_SHA256_DIGEST_SIZE];
+    eicCborFinal(&ctx->cborEcdsa, cborSha256);
+    if (!eicOpsEcDsa(ctx->deviceKeyPriv, cborSha256, signatureOfToBeSigned)) {
+        eicDebug("Error signing DeviceAuthentication");
+        return false;
+    }
+    eicDebug("set the signature");
     return true;
 }
 
diff --git a/identity/aidl/default/libeic/EicPresentation.h b/identity/aidl/default/libeic/EicPresentation.h
index a031890..cd3162a 100644
--- a/identity/aidl/default/libeic/EicPresentation.h
+++ b/identity/aidl/default/libeic/EicPresentation.h
@@ -76,6 +76,7 @@
     // aren't.
     bool requestMessageValidated;
     bool buildCbor;
+    bool buildCborEcdsa;
 
     // Set to true initialized as a test credential.
     bool testCredential;
@@ -101,6 +102,12 @@
 
     size_t expectedCborSizeAtEnd;
     EicCbor cbor;
+
+    // The selected DeviceKey / AuthKey
+    uint8_t deviceKeyPriv[EIC_P256_PRIV_KEY_SIZE];
+
+    EicCbor cborEcdsa;
+    size_t expectedCborEcdsaSizeAtEnd;
 } EicPresentation;
 
 // If sessionId is zero (EIC_PRESENTATION_ID_UNSET), the presentation object is not associated
@@ -214,14 +221,13 @@
     EIC_ACCESS_CHECK_RESULT_READER_AUTHENTICATION_FAILED,
 } EicAccessCheckResult;
 
-// Passes enough information to calculate the MACing key
+// Passes enough information to calculate the MACing key and/or prepare ECDSA signing
 //
-bool eicPresentationCalcMacKey(EicPresentation* ctx, const uint8_t* sessionTranscript,
-                               size_t sessionTranscriptSize,
-                               const uint8_t readerEphemeralPublicKey[EIC_P256_PUB_KEY_SIZE],
-                               const uint8_t signingKeyBlob[60], const char* docType,
-                               size_t docTypeLength, unsigned int numNamespacesWithValues,
-                               size_t expectedDeviceNamespacesSize);
+bool eicPresentationPrepareDeviceAuthentication(
+        EicPresentation* ctx, const uint8_t* sessionTranscript, size_t sessionTranscriptSize,
+        const uint8_t* readerEphemeralPublicKey, size_t readerEphemeralPublicKeySize,
+        const uint8_t signingKeyBlob[60], const char* docType, size_t docTypeLength,
+        unsigned int numNamespacesWithValues, size_t expectedDeviceNamespacesSize);
 
 // The scratchSpace should be set to a buffer at least 512 bytes (ideally 1024
 // bytes, the bigger the better). It's done this way to avoid allocating stack
@@ -253,6 +259,13 @@
 bool eicPresentationFinishRetrieval(EicPresentation* ctx, uint8_t* digestToBeMaced,
                                     size_t* digestToBeMacedSize);
 
+// Like eicPresentationFinishRetrieval() but also returns an ECDSA signature.
+//
+bool eicPresentationFinishRetrievalWithSignature(EicPresentation* ctx, uint8_t* digestToBeMaced,
+                                                 size_t* digestToBeMacedSize,
+                                                 uint8_t* signatureOfToBeSigned,
+                                                 size_t* signatureOfToBeSignedSize);
+
 // The data returned in |signatureOfToBeSigned| contains the ECDSA signature of
 // the ToBeSigned CBOR from RFC 8051 "4.4. Signing and Verification Process"
 // where content is set to the ProofOfDeletion CBOR.
diff --git a/identity/aidl/default/libeic/EicSession.c b/identity/aidl/default/libeic/EicSession.c
index d0c7a0d..e44fa68 100644
--- a/identity/aidl/default/libeic/EicSession.c
+++ b/identity/aidl/default/libeic/EicSession.c
@@ -84,30 +84,35 @@
 bool eicSessionGetEphemeralKeyPair(EicSession* ctx,
                                    uint8_t ephemeralPrivateKey[EIC_P256_PRIV_KEY_SIZE]) {
     eicMemCpy(ephemeralPrivateKey, ctx->ephemeralPrivateKey, EIC_P256_PRIV_KEY_SIZE);
+    ctx->getEphemeralKeyPairCalled = true;
     return true;
 }
 
 bool eicSessionSetReaderEphemeralPublicKey(
         EicSession* ctx, const uint8_t readerEphemeralPublicKey[EIC_P256_PUB_KEY_SIZE]) {
     eicMemCpy(ctx->readerEphemeralPublicKey, readerEphemeralPublicKey, EIC_P256_PUB_KEY_SIZE);
+    ctx->readerEphemeralPublicKeySize = EIC_P256_PUB_KEY_SIZE;
     return true;
 }
 
 bool eicSessionSetSessionTranscript(EicSession* ctx, const uint8_t* sessionTranscript,
                                     size_t sessionTranscriptSize) {
-    // Only accept the SessionTranscript if X and Y from the ephemeral key
-    // we created is somewhere in SessionTranscript...
+    // If mdoc session encryption is in use, only accept the
+    // SessionTranscript if X and Y from the ephemeral key we created
+    // is somewhere in SessionTranscript...
     //
-    if (eicMemMem(sessionTranscript, sessionTranscriptSize, ctx->ephemeralPublicKey,
-                  EIC_P256_PUB_KEY_SIZE / 2) == NULL) {
-        eicDebug("Error finding X from ephemeralPublicKey in sessionTranscript");
-        return false;
-    }
-    if (eicMemMem(sessionTranscript, sessionTranscriptSize,
-                  ctx->ephemeralPublicKey + EIC_P256_PUB_KEY_SIZE / 2,
-                  EIC_P256_PUB_KEY_SIZE / 2) == NULL) {
-        eicDebug("Error finding Y from ephemeralPublicKey in sessionTranscript");
-        return false;
+    if (ctx->getEphemeralKeyPairCalled) {
+        if (eicMemMem(sessionTranscript, sessionTranscriptSize, ctx->ephemeralPublicKey,
+                      EIC_P256_PUB_KEY_SIZE / 2) == NULL) {
+            eicDebug("Error finding X from ephemeralPublicKey in sessionTranscript");
+            return false;
+        }
+        if (eicMemMem(sessionTranscript, sessionTranscriptSize,
+                      ctx->ephemeralPublicKey + EIC_P256_PUB_KEY_SIZE / 2,
+                      EIC_P256_PUB_KEY_SIZE / 2) == NULL) {
+            eicDebug("Error finding Y from ephemeralPublicKey in sessionTranscript");
+            return false;
+        }
     }
 
     // To save space we only store the SHA-256 of SessionTranscript
diff --git a/identity/aidl/default/libeic/EicSession.h b/identity/aidl/default/libeic/EicSession.h
index 0303dae..ae9babf 100644
--- a/identity/aidl/default/libeic/EicSession.h
+++ b/identity/aidl/default/libeic/EicSession.h
@@ -31,6 +31,9 @@
     // A non-zero number unique for this EicSession instance
     uint32_t id;
 
+    // Set to true iff eicSessionGetEphemeralKeyPair() has been called.
+    bool getEphemeralKeyPairCalled;
+
     // The challenge generated at construction time by eicSessionInit().
     uint64_t authChallenge;
 
@@ -41,6 +44,7 @@
 
     uint8_t sessionTranscriptSha256[EIC_SHA256_DIGEST_SIZE];
 
+    size_t readerEphemeralPublicKeySize;
 } EicSession;
 
 bool eicSessionInit(EicSession* ctx);