Add crypto backend for signal-protocol

src/omemo/crypto.c

@@ -0,0 +1,136 @@
+#include <assert.h>
+#include <signal/signal_protocol.h>
+#include <signal/signal_protocol_types.h>
+#include <sodium.h>
+
+#include "omemo/crypto.h"
+
+int
+omemo_crypto_init(void)
+{
+    if (sodium_init() < 0) {
+        return -1;
+    }
+
+    if (crypto_aead_aes256gcm_is_available() == 0) {
+        return -1;
+    }
+
+    return 0;
+}
+
+int
+omemo_random_func(uint8_t *data, size_t len, void *user_data)
+{
+    randombytes_buf(data, len);
+    return 0;
+}
+
+int
+omemo_hmac_sha256_init_func(void **hmac_context, const uint8_t *key, size_t key_len, void *user_data)
+{
+    *hmac_context = sodium_malloc(sizeof(crypto_auth_hmacsha256_state));
+    return crypto_auth_hmacsha256_init(*hmac_context, key, key_len);
+}
+
+int
+omemo_hmac_sha256_update_func(void *hmac_context, const uint8_t *data, size_t data_len, void *user_data)
+{
+    return crypto_auth_hmacsha256_update(hmac_context, data, data_len);
+}
+
+int
+omemo_hmac_sha256_final_func(void *hmac_context, signal_buffer **output, void *user_data)
+{
+    int ret;
+    unsigned char out[crypto_auth_hmacsha256_BYTES];
+
+    if ((ret = crypto_auth_hmacsha256_final(hmac_context, out)) != 0) {
+        return ret;
+    }
+
+    *output = signal_buffer_create(out, crypto_auth_hmacsha256_BYTES);
+    return 0;
+}
+
+void
+omemo_hmac_sha256_cleanup_func(void *hmac_context, void *user_data)
+{
+    sodium_free(hmac_context);
+}
+
+int
+omemo_sha512_digest_init_func(void **digest_context, void *user_data)
+{
+    *digest_context = sodium_malloc(sizeof(crypto_hash_sha512_state));
+    return crypto_hash_sha512_init(*digest_context);
+}
+
+int
+omemo_sha512_digest_update_func(void *digest_context, const uint8_t *data, size_t data_len, void *user_data)
+{
+    return crypto_hash_sha512_update(digest_context, data, data_len);
+}
+
+int
+omemo_sha512_digest_final_func(void *digest_context, signal_buffer **output, void *user_data)
+{
+    int ret;
+    unsigned char out[crypto_hash_sha512_BYTES];
+
+    if ((ret = crypto_hash_sha512_final(digest_context, out)) != 0) {
+        return ret;
+    }
+
+    *output = signal_buffer_create(out, crypto_hash_sha512_BYTES);
+    return 0;
+}
+
+void
+omemo_sha512_digest_cleanup_func(void *digest_context, void *user_data)
+{
+    sodium_free(digest_context);
+}
+
+int
+omemo_encrypt_func(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)
+{
+    unsigned char *ciphertext;
+    unsigned long long ciphertext_len;
+
+    assert(cipher != SG_CIPHER_AES_GCM_NOPADDING);
+    assert(key_len == crypto_aead_aes256gcm_KEYBYTES);
+    assert(iv_len == crypto_aead_aes256gcm_NPUBBYTES);
+
+    ciphertext = malloc(plaintext_len + crypto_aead_aes256gcm_ABYTES);
+    crypto_aead_aes256gcm_encrypt(ciphertext, &ciphertext_len, plaintext, plaintext_len, NULL, 0, NULL, iv, key);
+
+    *output = signal_buffer_create(ciphertext, ciphertext_len);
+    free(ciphertext);
+
+    return 0;
+}
+
+int
+omemo_decrypt_func(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)
+{
+    unsigned char *plaintext;
+    unsigned long long plaintext_len;
+
+    assert(cipher != SG_CIPHER_AES_GCM_NOPADDING);
+    assert(key_len == crypto_aead_aes256gcm_KEYBYTES);
+    assert(iv_len == crypto_aead_aes256gcm_NPUBBYTES);
+
+    plaintext = malloc(ciphertext_len - crypto_aead_aes256gcm_ABYTES);
+    if (crypto_aead_aes256gcm_decrypt(plaintext, &plaintext_len, NULL, ciphertext, ciphertext_len, NULL, 0, iv, key) < 0) {
+        free(plaintext);
+        return -1;
+    }
+
+    *output = signal_buffer_create(plaintext, plaintext_len);
+    free(plaintext);
+
+    return 0;
+}