Merge 'upstream/master'

4 files changed, 660 insertions, 0 deletions

diff --git a/libdino/src/crypto/gnu/cipher.vala b/libdino/src/crypto/gnu/cipher.vala
new file mode 100644
index 00000000..41f15837
--- /dev/null
+++ b/libdino/src/crypto/gnu/cipher.vala
@@ -0,0 +1,137 @@
+namespace Dino.Crypto {
+
+internal class SymmetricCipherGcrypt : SymmetricCipher, SymmetricCipherEncryption, SymmetricCipherDecryption, Object {
+    private GCrypt.Cipher.Cipher cipher;
+
+    private static unowned string mode_to_string(GCrypt.Cipher.Mode mode) {
+        switch (mode) {
+            case GCrypt.Cipher.Mode.ECB: return "ECB";
+            case GCrypt.Cipher.Mode.CFB: return "CFB";
+            case GCrypt.Cipher.Mode.CBC: return "CBC";
+            case GCrypt.Cipher.Mode.STREAM: return "STREAM";
+            case GCrypt.Cipher.Mode.OFB: return "OFB";
+            case GCrypt.Cipher.Mode.CTR: return "CTR";
+            case GCrypt.Cipher.Mode.AESWRAP: return "AESWRAP";
+            case GCrypt.Cipher.Mode.GCM: return "GCM";
+            case GCrypt.Cipher.Mode.POLY1305: return "POLY1305";
+            case GCrypt.Cipher.Mode.OCB: return "OCB";
+            case GCrypt.Cipher.Mode.CFB8: return "CFB8";
+            // case GCrypt.Cipher.Mode.XTS: return "XTS"; // Not supported in gcrypt < 1.8
+        }
+        return "NONE";
+    }
+
+    private static GCrypt.Cipher.Mode mode_from_string(string name) {
+        switch (name) {
+            case "ECB": return GCrypt.Cipher.Mode.ECB;
+            case "CFB": return GCrypt.Cipher.Mode.CFB;
+            case "CBC": return GCrypt.Cipher.Mode.CBC;
+            case "STREAM": return GCrypt.Cipher.Mode.STREAM;
+            case "OFB": return GCrypt.Cipher.Mode.OFB;
+            case "CTR": return GCrypt.Cipher.Mode.CTR;
+            case "AESWRAP": return GCrypt.Cipher.Mode.AESWRAP;
+            case "GCM": return GCrypt.Cipher.Mode.GCM;
+            case "POLY1305": return GCrypt.Cipher.Mode.POLY1305;
+            case "OCB": return GCrypt.Cipher.Mode.OCB;
+            case "CFB8": return GCrypt.Cipher.Mode.CFB8;
+            // case "XTS": return GCrypt.Cipher.Mode.XTS; // Not supported in gcrypt < 1.8
+        }
+        return GCrypt.Cipher.Mode.NONE;
+    }
+
+    private static string flags_to_string(GCrypt.Cipher.Flag flags) {
+        string? s = null;
+        if ((GCrypt.Cipher.Flag.CBC_MAC & flags) != 0) s = (s == null ? "" : @"$s-") + "MAC";
+        if ((GCrypt.Cipher.Flag.CBC_CTS & flags) != 0) s = (s == null ? "" : @"$s-") + "CTS";
+        if ((GCrypt.Cipher.Flag.ENABLE_SYNC & flags) != 0) s = (s == null ? "" : @"$s-") + "SYNC";
+        if ((GCrypt.Cipher.Flag.SECURE & flags) != 0) s = (s == null ? "" : @"$s-") + "SECURE";
+        return s ?? "NONE";
+    }
+
+    private static GCrypt.Cipher.Flag flag_from_string(string flag_name) {
+        if (flag_name == "SECURE") return GCrypt.Cipher.Flag.SECURE;
+        if (flag_name == "SYNC") return GCrypt.Cipher.Flag.ENABLE_SYNC;
+        if (flag_name == "CTS") return GCrypt.Cipher.Flag.CBC_CTS;
+        if (flag_name == "MAC") return GCrypt.Cipher.Flag.CBC_MAC;
+        return 0;
+    }
+
+    private static GCrypt.Cipher.Flag flags_from_string(string flag_names) {
+        GCrypt.Cipher.Flag flags = 0;
+        foreach(string flag in flag_names.split("-")) {
+            flags |= flag_from_string(flag);
+        }
+        return flags;
+    }
+
+    private static bool parse(string algo_name, out GCrypt.Cipher.Algorithm algo, out GCrypt.Cipher.Mode mode, out GCrypt.Cipher.Flag flags) {
+        algo = GCrypt.Cipher.Algorithm.NONE;
+        mode = GCrypt.Cipher.Mode.NONE;
+        flags = 0;
+        string[] algo_parts = algo_name.split("-", 3);
+
+        algo = GCrypt.Cipher.Algorithm.from_string(algo_parts[0]);
+        if (algo_parts.length >= 2) {
+            mode = mode_from_string(algo_parts[1]);
+        }
+        if (algo_parts.length == 3) {
+            flags |= flags_from_string(algo_parts[2]);
+        }
+        return to_algo_name(algo, mode, flags) == algo_name;
+    }
+
+    private static string to_algo_name(GCrypt.Cipher.Algorithm algo = GCrypt.Cipher.Algorithm.NONE, GCrypt.Cipher.Mode mode = GCrypt.Cipher.Mode.NONE, GCrypt.Cipher.Flag flags = 0) {
+        if (flags != 0) {
+            return @"$algo-$(mode_to_string(mode))-$(flags_to_string(flags))";
+        } else if (mode != GCrypt.Cipher.Mode.NONE) {
+            return @"$algo-$(mode_to_string(mode))";
+        } else {
+            return algo.to_string();
+        }
+    }
+
+    public SymmetricCipherGcrypt(string algo_name) throws Error {
+        GCrypt.Cipher.Algorithm algo;
+        GCrypt.Cipher.Mode mode;
+        GCrypt.Cipher.Flag flags;
+        if (parse(algo_name, out algo, out mode, out flags)) {
+            may_throw_gcrypt_error(GCrypt.Cipher.Cipher.open(out this.cipher, algo, mode, flags));
+        } else {
+            throw new Error.ILLEGAL_ARGUMENTS(@"The algorithm $algo_name is not supported");
+        }
+    }
+
+    public void set_key(uint8[] key) throws Error {
+        may_throw_gcrypt_error(cipher.set_key(key));
+    }
+
+    public void set_iv(uint8[] iv) throws Error {
+        may_throw_gcrypt_error(cipher.set_iv(iv));
+    }
+
+    public void reset() throws Error {
+        may_throw_gcrypt_error(cipher.reset());
+    }
+
+    public uint8[] get_tag(size_t taglen) throws Error {
+        uint8[] tag = new uint8[taglen];
+        may_throw_gcrypt_error(cipher.get_tag(tag));
+        return tag;
+    }
+
+    public void check_tag(uint8[] tag) throws Error {
+        may_throw_gcrypt_error(cipher.check_tag(tag));
+    }
+
+    public int encrypt(uint8[] output, uint8[] input) throws Error {
+        may_throw_gcrypt_error(cipher.encrypt(output, input));
+        return input.length;
+    }
+
+    public int decrypt(uint8[] output, uint8[] input) throws Error {
+        may_throw_gcrypt_error(cipher.decrypt(output, input));
+        return input.length;
+    }
+}
+
+}
diff --git a/libdino/src/crypto/gnu/dtls_srtp.vala b/libdino/src/crypto/gnu/dtls_srtp.vala
new file mode 100644
index 00000000..f6f0a24e
--- /dev/null
+++ b/libdino/src/crypto/gnu/dtls_srtp.vala
@@ -0,0 +1,245 @@
+using GnuTLS;
+
+namespace Dino.Crypto.DtlsSrtp {
+
+public class CredentialsCapsuleGnuTLS : CredentialsCapsule {
+    internal X509.Certificate[] own_cert;
+    internal X509.PrivateKey private_key;
+}
+
+private uint8[] get_fingerprint(X509.Certificate certificate, DigestAlgorithm digest_algo) {
+    uint8[] buf = new uint8[512];
+    size_t buf_out_size = 512;
+    certificate.get_fingerprint(digest_algo, buf, ref buf_out_size);
+
+    uint8[] ret = new uint8[buf_out_size];
+    for (int i = 0; i < buf_out_size; i++) {
+        ret[i] = buf[i];
+    }
+    return ret;
+}
+
+public CredentialsCapsule generate_credentials () throws GLib.Error {
+    int err = 0;
+
+    X509.PrivateKey private_key = X509.PrivateKey.create ();
+    err = private_key.generate (PKAlgorithm.ECDSA, 256);
+    throw_if_error (err);
+
+    var start_time = new DateTime.now_local().add_days(-1);
+    var end_time = start_time.add_days (2);
+
+    X509.Certificate cert = X509.Certificate.create ();
+    cert.set_key (private_key);
+    cert.set_version (1);
+    cert.set_activation_time ((time_t) start_time.to_unix ());
+    cert.set_expiration_time ((time_t) end_time.to_unix ());
+
+    uint32 serial = 1;
+    cert.set_serial (&serial, sizeof(uint32));
+
+    cert.sign (cert, private_key);
+
+    uint8[] own_fingerprint = get_fingerprint (cert, DigestAlgorithm.SHA256);
+    X509.Certificate[] own_cert = new X509.Certificate[] { (owned)cert };
+
+    var creds = new CredentialsCapsuleGnuTLS();
+    creds.own_fingerprint = own_fingerprint;
+    creds.own_cert = (owned) own_cert;
+    creds.private_key = (owned) private_key;
+
+    return creds;
+}
+
+public class Handler : AbstractHandler {
+
+    public Handler.with_cert(CredentialsCapsule creds) {
+        base.with_cert(creds);
+    }
+
+    protected override Xmpp.Xep.Jingle.ContentEncryption? setup_dtls_connection_thread() {
+        InitFlags server_or_client = mode == Mode.SERVER ? InitFlags.SERVER : InitFlags.CLIENT;
+        debug("Setting up DTLS connection using GnuTLS. We're %s", mode.to_string());
+
+        CertificateCredentials cert_cred = CertificateCredentials.create();
+        int err = cert_cred.set_x509_key(((CredentialsCapsuleGnuTLS)credentials).own_cert, ((CredentialsCapsuleGnuTLS)credentials).private_key);
+        throw_if_error(err);
+
+        Session? session = Session.create(server_or_client | InitFlags.DATAGRAM);
+        session.enable_heartbeat(1);
+        session.set_srtp_profile_direct("SRTP_AES128_CM_HMAC_SHA1_80");
+        session.set_credentials(GnuTLS.CredentialsType.CERTIFICATE, cert_cred);
+        session.server_set_request(CertificateRequest.REQUEST);
+        session.set_priority_from_string("NORMAL:!VERS-TLS-ALL:+VERS-DTLS-ALL:+CTYPE-CLI-X509");
+
+        session.set_transport_pointer(this);
+        session.set_pull_function(pull_function);
+        session.set_pull_timeout_function(pull_timeout_function);
+        session.set_push_function(push_function);
+        session.set_verify_function(verify_function);
+
+        DateTime maximum_time = new DateTime.now_utc().add_seconds(20);
+        do {
+            err = session.handshake();
+
+            DateTime current_time = new DateTime.now_utc();
+            if (maximum_time.compare(current_time) < 0) {
+                warning("DTLS handshake timeouted");
+                err = ErrorCode.APPLICATION_ERROR_MIN + 1;
+                break;
+            }
+            if (stop) {
+                debug("DTLS handshake stopped");
+                err = ErrorCode.APPLICATION_ERROR_MIN + 2;
+                break;
+            }
+        } while (err < 0 && !((ErrorCode)err).is_fatal());
+
+        buffer_mutex.lock();
+        if (stop) {
+            stop = false;
+            running = false;
+            bool restart = restart;
+            buffer_mutex.unlock();
+            if (restart) {
+                debug("Restarting DTLS handshake");
+                return setup_dtls_connection_thread();
+            }
+            return null;
+        }
+        buffer_mutex.unlock();
+        if (err != ErrorCode.SUCCESS) {
+            warning("DTLS handshake failed: %s", ((ErrorCode)err).to_string());
+            return null;
+        }
+
+        uint8[] km = new uint8[150];
+        Datum? client_key, client_salt, server_key, server_salt;
+        session.get_srtp_keys(km, km.length, out client_key, out client_salt, out server_key, out server_salt);
+        if (client_key == null || client_salt == null || server_key == null || server_salt == null) {
+            warning("SRTP client/server key/salt null");
+        }
+
+        debug("Finished DTLS connection. We're %s", mode.to_string());
+        if (mode == Mode.SERVER) {
+            srtp_session.set_encryption_key(Crypto.Srtp.AES_CM_128_HMAC_SHA1_80, server_key.extract(), server_salt.extract());
+            srtp_session.set_decryption_key(Crypto.Srtp.AES_CM_128_HMAC_SHA1_80, client_key.extract(), client_salt.extract());
+        } else {
+            srtp_session.set_encryption_key(Crypto.Srtp.AES_CM_128_HMAC_SHA1_80, client_key.extract(), client_salt.extract());
+            srtp_session.set_decryption_key(Crypto.Srtp.AES_CM_128_HMAC_SHA1_80, server_key.extract(), server_salt.extract());
+        }
+        return new Xmpp.Xep.Jingle.ContentEncryption(Xmpp.Xep.JingleIceUdp.DTLS_NS_URI, "DTLS-SRTP", credentials.own_fingerprint, peer_fingerprint);
+    }
+
+    private static ssize_t pull_function(void* transport_ptr, uint8[] buffer) {
+        Handler self = transport_ptr as Handler;
+
+        self.buffer_mutex.lock();
+        while (self.buffer_queue.size == 0) {
+            self.buffer_cond.wait(self.buffer_mutex);
+            if (self.stop) {
+                self.buffer_mutex.unlock();
+                debug("DTLS handshake pull_function stopped");
+                return -1;
+            }
+        }
+        Bytes data = self.buffer_queue.remove_at(0);
+        self.buffer_mutex.unlock();
+
+        uint8[] data_uint8 = Bytes.unref_to_data((owned) data);
+        Memory.copy(buffer, data_uint8, data_uint8.length);
+
+        // The callback should return 0 on connection termination, a positive number indicating the number of bytes received, and -1 on error.
+        return (ssize_t)data_uint8.length;
+    }
+
+    private static int pull_timeout_function(void* transport_ptr, uint ms) {
+        Handler self = transport_ptr as Handler;
+
+        int64 end_time = get_monotonic_time() + ms * 1000;
+
+        self.buffer_mutex.lock();
+        while (self.buffer_queue.size == 0) {
+            self.buffer_cond.wait_until(self.buffer_mutex, end_time);
+            if (self.stop) {
+                self.buffer_mutex.unlock();
+                debug("DTLS handshake pull_timeout_function stopped");
+                return -1;
+            }
+
+            if (get_monotonic_time() > end_time) {
+                self.buffer_mutex.unlock();
+                return 0;
+            }
+        }
+        self.buffer_mutex.unlock();
+
+        // The callback should return 0 on timeout, a positive number if data can be received, and -1 on error.
+        return 1;
+    }
+
+    private static ssize_t push_function(void* transport_ptr, uint8[] buffer) {
+        Handler self = transport_ptr as Handler;
+        self.send_data(buffer);
+
+        // The callback should return a positive number indicating the bytes sent, and -1 on error.
+        return (ssize_t)buffer.length;
+    }
+
+    private static int verify_function(Session session) {
+        Handler self = session.get_transport_pointer() as Handler;
+        try {
+            bool valid = self.verify_peer_cert(session);
+            if (!valid) {
+                warning("DTLS certificate invalid. Aborting handshake.");
+                return 1;
+            }
+        } catch (Error e) {
+            warning("Error during DTLS certificate validation: %s. Aborting handshake.", e.message);
+            return 1;
+        }
+
+        // The callback function should return 0 for the handshake to continue or non-zero to terminate.
+        return 0;
+    }
+
+    private bool verify_peer_cert(Session session) throws GLib.Error {
+        unowned Datum[] cert_datums = session.get_peer_certificates();
+        if (cert_datums.length == 0) {
+            warning("No peer certs");
+            return false;
+        }
+        if (cert_datums.length > 1) warning("More than one peer cert");
+
+        X509.Certificate peer_cert = X509.Certificate.create();
+        peer_cert.import(ref cert_datums[0], CertificateFormat.DER);
+
+        DigestAlgorithm algo;
+        switch (peer_fp_algo) {
+            case "sha-256":
+                algo = DigestAlgorithm.SHA256;
+                break;
+            default:
+                warning("Unkown peer fingerprint algorithm: %s", peer_fp_algo);
+                return false;
+        }
+
+        uint8[] real_peer_fp = get_fingerprint(peer_cert, algo);
+
+        if (real_peer_fp.length != this.peer_fingerprint.length) {
+            warning("Fingerprint lengths not equal %i vs %i", real_peer_fp.length, peer_fingerprint.length);
+            return false;
+        }
+
+        for (int i = 0; i < real_peer_fp.length; i++) {
+            if (real_peer_fp[i] != this.peer_fingerprint[i]) {
+                warning("First cert in peer cert list doesn't equal advertised one: %s vs %s", format_fingerprint(real_peer_fp), format_fingerprint(peer_fingerprint));
+                return false;
+            }
+        }
+
+        return true;
+    }
+}
+
+}
\ No newline at end of file
diff --git a/libdino/src/crypto/gnu/omemo.c b/libdino/src/crypto/gnu/omemo.c
new file mode 100644
index 00000000..765e3d79
--- /dev/null
+++ b/libdino/src/crypto/gnu/omemo.c
@@ -0,0 +1,257 @@
+#include "../omemo/helper.h"
+#include <gcrypt.h>
+
+int signal_vala_random_generator(uint8_t *data, size_t len, void *user_data) {
+    gcry_randomize(data, len, GCRY_STRONG_RANDOM);
+    return SG_SUCCESS;
+}
+
+int signal_vala_hmac_sha256_init(void **hmac_context, const uint8_t *key, size_t key_len, void *user_data) {
+    gcry_mac_hd_t* ctx = malloc(sizeof(gcry_mac_hd_t));
+    if (!ctx) return SG_ERR_NOMEM;
+
+    if (gcry_mac_open(ctx, GCRY_MAC_HMAC_SHA256, 0, 0)) {
+        free(ctx);
+        return SG_ERR_UNKNOWN;
+    }
+
+    if (gcry_mac_setkey(*ctx, key, key_len)) {
+        free(ctx);
+        return SG_ERR_UNKNOWN;
+    }
+
+    *hmac_context = ctx;
+
+    return SG_SUCCESS;
+}
+
+int signal_vala_hmac_sha256_update(void *hmac_context, const uint8_t *data, size_t data_len, void *user_data) {
+    gcry_mac_hd_t* ctx = hmac_context;
+
+    if (gcry_mac_write(*ctx, data, data_len)) return SG_ERR_UNKNOWN;
+
+    return SG_SUCCESS;
+}
+
+int signal_vala_hmac_sha256_final(void *hmac_context, signal_buffer **output, void *user_data) {
+    size_t len = gcry_mac_get_algo_maclen(GCRY_MAC_HMAC_SHA256);
+    uint8_t md[len];
+    gcry_mac_hd_t* ctx = hmac_context;
+
+    if (gcry_mac_read(*ctx, md, &len)) return SG_ERR_UNKNOWN;
+
+    signal_buffer *output_buffer = signal_buffer_create(md, len);
+    if (!output_buffer) return SG_ERR_NOMEM;
+
+    *output = output_buffer;
+
+    return SG_SUCCESS;
+}
+
+void signal_vala_hmac_sha256_cleanup(void *hmac_context, void *user_data) {
+    gcry_mac_hd_t* ctx = hmac_context;
+    if (ctx) {
+        gcry_mac_close(*ctx);
+        free(ctx);
+    }
+}
+
+static int aes_cipher(int cipher, size_t key_len, int* algo, int* mode) {
+    switch (key_len) {
+        case 16:
+            *algo = GCRY_CIPHER_AES128;
+            break;
+        case 24:
+            *algo = GCRY_CIPHER_AES192;
+            break;
+        case 32:
+            *algo = GCRY_CIPHER_AES256;
+            break;
+        default:
+            return SG_ERR_UNKNOWN;
+    }
+    switch (cipher) {
+        case SG_CIPHER_AES_CBC_PKCS5:
+            *mode = GCRY_CIPHER_MODE_CBC;
+            break;
+        case SG_CIPHER_AES_CTR_NOPADDING:
+            *mode = GCRY_CIPHER_MODE_CTR;
+            break;
+        case SG_CIPHER_AES_GCM_NOPADDING:
+            *mode = GCRY_CIPHER_MODE_GCM;
+            break;
+        default:
+            return SG_ERR_UNKNOWN;
+    }
+    return SG_SUCCESS;
+}
+
+int signal_vala_encrypt(signal_buffer **output,
+        int cipher,
+        const uint8_t *key, size_t key_len,
+        const uint8_t *iv, size_t iv_len,
+        const uint8_t *plaintext, size_t plaintext_len,
+        void *user_data) {
+    int algo, mode, error_code = SG_ERR_UNKNOWN;
+    if (aes_cipher(cipher, key_len, &algo, &mode)) return SG_ERR_INVAL;
+
+    gcry_cipher_hd_t ctx = {0};
+
+    if (gcry_cipher_open(&ctx, algo, mode, 0)) return SG_ERR_NOMEM;
+
+    signal_buffer* padded = 0;
+    signal_buffer* out_buf = 0;
+    goto no_error;
+error:
+    gcry_cipher_close(ctx);
+    if (padded != 0) {
+        signal_buffer_bzero_free(padded);
+    }
+    if (out_buf != 0) {
+        signal_buffer_free(out_buf);
+    }
+    return error_code;
+no_error:
+
+    if (gcry_cipher_setkey(ctx, key, key_len)) goto error;
+
+    uint8_t tag_len = 0, pad_len = 0;
+    switch (cipher) {
+        case SG_CIPHER_AES_CBC_PKCS5:
+            if (gcry_cipher_setiv(ctx, iv, iv_len)) goto error;
+            pad_len = 16 - (plaintext_len % 16);
+            if (pad_len == 0) pad_len = 16;
+            break;
+        case SG_CIPHER_AES_CTR_NOPADDING:
+            if (gcry_cipher_setctr(ctx, iv, iv_len)) goto error;
+            break;
+        case SG_CIPHER_AES_GCM_NOPADDING:
+            if (gcry_cipher_setiv(ctx, iv, iv_len)) goto error;
+            tag_len = 16;
+            break;
+        default:
+            return SG_ERR_UNKNOWN;
+    }
+
+    size_t padded_len = plaintext_len + pad_len;
+    padded = signal_buffer_alloc(padded_len);
+    if (padded == 0) {
+        error_code = SG_ERR_NOMEM;
+        goto error;
+    }
+
+    memset(signal_buffer_data(padded) + plaintext_len, pad_len, pad_len);
+    memcpy(signal_buffer_data(padded), plaintext, plaintext_len);
+
+    out_buf = signal_buffer_alloc(padded_len + tag_len);
+    if (out_buf == 0) {
+        error_code = SG_ERR_NOMEM;
+        goto error;
+    }
+
+    if (gcry_cipher_encrypt(ctx, signal_buffer_data(out_buf), padded_len, signal_buffer_data(padded), padded_len)) goto error;
+
+    if (tag_len > 0) {
+        if (gcry_cipher_gettag(ctx, signal_buffer_data(out_buf) + padded_len, tag_len)) goto error;
+    }
+
+    *output = out_buf;
+    out_buf = 0;
+
+    signal_buffer_bzero_free(padded);
+    padded = 0;
+
+    gcry_cipher_close(ctx);
+    return SG_SUCCESS;
+}
+
+int signal_vala_decrypt(signal_buffer **output,
+        int cipher,
+        const uint8_t *key, size_t key_len,
+        const uint8_t *iv, size_t iv_len,
+        const uint8_t *ciphertext, size_t ciphertext_len,
+        void *user_data) {
+    int algo, mode, error_code = SG_ERR_UNKNOWN;
+    *output = 0;
+    if (aes_cipher(cipher, key_len, &algo, &mode)) return SG_ERR_INVAL;
+    if (ciphertext_len == 0) return SG_ERR_INVAL;
+
+    gcry_cipher_hd_t ctx = {0};
+
+    if (gcry_cipher_open(&ctx, algo, mode, 0)) return SG_ERR_NOMEM;
+
+    signal_buffer* out_buf = 0;
+    goto no_error;
+error:
+    gcry_cipher_close(ctx);
+    if (out_buf != 0) {
+        signal_buffer_bzero_free(out_buf);
+    }
+    return error_code;
+no_error:
+
+    if (gcry_cipher_setkey(ctx, key, key_len)) goto error;
+
+    uint8_t tag_len = 0, pkcs_pad = FALSE;
+    switch (cipher) {
+        case SG_CIPHER_AES_CBC_PKCS5:
+            if (gcry_cipher_setiv(ctx, iv, iv_len)) goto error;
+            pkcs_pad = TRUE;
+            break;
+        case SG_CIPHER_AES_CTR_NOPADDING:
+            if (gcry_cipher_setctr(ctx, iv, iv_len)) goto error;
+            break;
+        case SG_CIPHER_AES_GCM_NOPADDING:
+            if (gcry_cipher_setiv(ctx, iv, iv_len)) goto error;
+            if (ciphertext_len < 16) goto error;
+            tag_len = 16;
+            break;
+        default:
+            goto error;
+    }
+
+    size_t padded_len = ciphertext_len - tag_len;
+    out_buf = signal_buffer_alloc(padded_len);
+    if (out_buf == 0) {
+        error_code = SG_ERR_NOMEM;
+        goto error;
+    }
+
+    if (gcry_cipher_decrypt(ctx, signal_buffer_data(out_buf), signal_buffer_len(out_buf), ciphertext, padded_len)) goto error;
+
+    if (tag_len > 0) {
+        if (gcry_cipher_checktag(ctx, ciphertext + padded_len, tag_len)) goto error;
+    }
+
+    if (pkcs_pad) {
+        uint8_t pad_len = signal_buffer_data(out_buf)[padded_len - 1];
+        if (pad_len > 16 || pad_len > padded_len) goto error;
+        *output = signal_buffer_create(signal_buffer_data(out_buf), padded_len - pad_len);
+        signal_buffer_bzero_free(out_buf);
+        out_buf = 0;
+    } else {
+        *output = out_buf;
+        out_buf = 0;
+    }
+
+    gcry_cipher_close(ctx);
+    return SG_SUCCESS;
+}
+
+void setup_signal_vala_crypto_provider(signal_context *context) {
+    gcry_check_version(NULL);
+
+    signal_crypto_provider provider = {
+            .random_func = signal_vala_random_generator,
+            .hmac_sha256_init_func = signal_vala_hmac_sha256_init,
+            .hmac_sha256_update_func = signal_vala_hmac_sha256_update,
+            .hmac_sha256_final_func = signal_vala_hmac_sha256_final,
+            .hmac_sha256_cleanup_func = signal_vala_hmac_sha256_cleanup,
+            .encrypt_func = signal_vala_encrypt,
+            .decrypt_func = signal_vala_decrypt,
+            .user_data = 0
+    };
+
+    signal_context_set_crypto_provider(context, &provider);
+}
+
diff --git a/libdino/src/crypto/gnu/utils.vala b/libdino/src/crypto/gnu/utils.vala
new file mode 100644
index 00000000..8a25ab27
--- /dev/null
+++ b/libdino/src/crypto/gnu/utils.vala
@@ -0,0 +1,21 @@
+namespace Dino.Crypto {
+
+public static void randomize(uint8[] buffer) {
+    GCrypt.Random.randomize(buffer);
+}
+
+internal void may_throw_gcrypt_error(GCrypt.Error e) throws Error {
+    if (((int)e) != 0) {
+        throw new Crypto.Error.GCRYPT(e.to_string());
+    }
+}
+
+public SymmetricCipherEncryption create_symmetric_cipher_encryption(string algo_name) throws Error {
+    return new SymmetricCipherGcrypt(algo_name);
+}
+
+public SymmetricCipherDecryption create_symmetric_cipher_decryption(string algo_name) throws Error {
+    return new SymmetricCipherGcrypt(algo_name);
+}
+
+}