1 files changed, 208 insertions, 0 deletions
diff --git a/src/include/taler_crypto_lib.h b/src/include/taler_crypto_lib.h
new file mode 100644
index 000000000..597c85cdd
--- /dev/null
+++ b/src/include/taler_crypto_lib.h
@@ -0,0 +1,208 @@
+/*
+  This file is part of TALER
+  (C) 2014, 2015 Christian Grothoff (and other contributing authors)
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file include/taler_crypto_lib.h
+ * @brief taler-specific crypto functions
+ * @author Sree Harsha Totakura <sreeharsha@totakura.in>
+ */
+#ifndef TALER_CRYPTO_LIB_H
+#define TALER_CRYPTO_LIB_H
+
+#include <gnunet/gnunet_util_lib.h>
+#include <gcrypt.h>
+
+
+/* ****************** Coin crypto primitives ************* */
+
+/**
+ * Public information about a coin (including the public key
+ * of the coin, the denomination key and the signature with
+ * the denomination key).
+ */
+struct TALER_CoinPublicInfo
+{
+  /**
+   * The coin's public key.
+   */
+  struct GNUNET_CRYPTO_EcdsaPublicKey coin_pub;
+
+  /**
+   * Public key representing the denomination of the coin
+   * that is being deposited.
+   */
+  struct GNUNET_CRYPTO_rsa_PublicKey *denom_pub;
+
+  /**
+   * (Unblinded) signature over @e coin_pub with @e denom_pub,
+   * which demonstrates that the coin is valid.
+   */
+  struct GNUNET_CRYPTO_rsa_Signature *denom_sig;
+};
+
+
+/**
+ * Check if a coin is valid; that is, whether the denomination key exists,
+ * is not expired, and the signature is correct.
+ *
+ * @param coin_public_info the coin public info to check for validity
+ * @return #GNUNET_YES if the coin is valid,
+ *         #GNUNET_NO if it is invalid
+ *         #GNUNET_SYSERROR if an internal error occured
+ */
+int
+TALER_test_coin_valid (const struct TALER_CoinPublicInfo *coin_public_info);
+
+
+/* ****************** Refresh crypto primitives ************* */
+
+/**
+ * Secret used to decrypt the key to decrypt link secrets.
+ */
+struct TALER_TransferSecret
+{
+  /**
+   * Secret used to encrypt/decrypt the `struct TALER_LinkSecret`.
+   * Must be (currently) a hash as this is what
+   * #GNUNET_CRYPTO_ecc_ecdh() returns to us.
+   */
+  struct GNUNET_HashCode key;
+};
+
+
+/**
+ * Secret used to decrypt refresh links.
+ */
+struct TALER_LinkSecret
+{
+  /**
+   * Secret used to decrypt the refresh link data.
+   */
+  char key[sizeof (struct GNUNET_HashCode)];
+};
+
+
+/**
+ * Encrypted secret used to decrypt refresh links.
+ */
+struct TALER_EncryptedLinkSecret
+{
+  /**
+   * Encrypted secret, must be the given size!
+   */
+  char enc[sizeof (struct TALER_LinkSecret)];
+};
+
+
+/**
+ * Representation of an encrypted refresh link.
+ */
+struct TALER_RefreshLinkEncrypted
+{
+
+  /**
+   * Encrypted blinding key with @e blinding_key_enc_size bytes,
+   * must be allocated at the end of this struct.
+   */
+  const char *blinding_key_enc;
+
+  /**
+   * Number of bytes in @e blinding_key_enc.
+   */
+  size_t blinding_key_enc_size;
+
+  /**
+   * Encrypted private key of the coin.
+   */
+  char coin_priv_enc[sizeof (struct GNUNET_CRYPTO_EcdsaPrivateKey)];
+
+};
+
+
+/**
+ * Representation of an refresh link in cleartext.
+ */
+struct TALER_RefreshLinkDecrypted
+{
+
+  /**
+   * Private key of the coin.
+   */
+  struct GNUNET_CRYPTO_EcdsaPrivateKey coin_priv;
+
+  /**
+   * Blinding key with @e blinding_key_enc_size bytes.
+   */
+  struct GNUNET_CRYPTO_rsa_BlindingKey *blinding_key;
+
+};
+
+
+/**
+ * Use the @a trans_sec (from ECDHE) to decrypt the @a secret_enc
+ * to obtain the @a secret to decrypt the linkage data.
+ *
+ * @param secret_enc encrypted secret
+ * @param trans_sec transfer secret
+ * @param secret shared secret for refresh link decryption
+ * @return #GNUNET_OK on success
+ */
+int
+TALER_transfer_decrypt (const struct TALER_EncryptedLinkSecret *secret_enc,
+                        const struct TALER_TransferSecret *trans_sec,
+                        struct TALER_LinkSecret *secret);
+
+
+/**
+ * Use the @a trans_sec (from ECDHE) to encrypt the @a secret
+ * to obtain the @a secret_enc.
+ *
+ * @param secret shared secret for refresh link decryption
+ * @param trans_sec transfer secret
+ * @param secret_enc[out] encrypted secret
+ * @return #GNUNET_OK on success
+ */
+int
+TALER_transfer_encrypt (const struct TALER_LinkSecret *secret,
+                        const struct TALER_TransferSecret *trans_sec,
+                        struct TALER_EncryptedLinkSecret *secret_enc);
+
+
+/**
+ * Decrypt refresh link information.
+ *
+ * @param input encrypted refresh link data
+ * @param secret shared secret to use for decryption
+ * @return NULL on error
+ */
+struct TALER_RefreshLinkDecrypted *
+TALER_refresh_decrypt (const struct TALER_RefreshLinkEncrypted *input,
+                       const struct TALER_LinkSecret *secret);
+
+
+/**
+ * Encrypt refresh link information.
+ *
+ * @param input plaintext refresh link data
+ * @param secret shared secret to use for encryption
+ * @return NULL on error (should never happen)
+ */
+struct TALER_RefreshLinkEncrypted *
+TALER_refresh_encrypt (const struct TALER_RefreshLinkDecrypted *input,
+                       const struct TALER_LinkSecret *secret);
+
+
+
+#endif