[taler-docs] branch master updated: protocol for exchange complete

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     new e17e525  protocol for exchange complete
e17e525 is described below

commit e17e525244f81adbc8d1baa18b5249693758fcb9
Author: Özgür Kesim <oec-taler@kesim.org>
AuthorDate: Sat Oct 16 16:48:11 2021 +0200

    protocol for exchange complete
---
 design-documents/024-age-restriction.rst | 36 +++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/design-documents/024-age-restriction.rst 
b/design-documents/024-age-restriction.rst
index 725d172..efa140c 100644
--- a/design-documents/024-age-restriction.rst
+++ b/design-documents/024-age-restriction.rst
@@ -320,7 +320,41 @@ and compares them to the one in ``.old_age_commitment``.
 Deposit
 ~~~~~~~
 
-TODO: Add opaque hash value of the commitments to the protocol
+As always, the merchant has to provide the public key of a coin during a POST
+to ``/coins/$COIN_PUB/deposit``.  However, for coins with age restriction, the
+signature check requires the hash of the age commitment.  Therefore the request
+object ``DepositRequest`` is extended by an optional field
+``age_commitment_hash`` which MUST be set (with the SHA512 hash of the age
+commitment), iff the corresponding denomination had support for age restriction
+enabled.  The merchant has received this value prior from the customer during
+purchase.
+
+.. ts:def:: DepositRequest
+
+   interface DepositRequest {
+   ...
+
+   // Iff the corresponding denomination had support for age restriction
+   // enabled, this field MUST contain the SHA512 value of the age commitment 
that
+   // was provided during the purchase.
+   age_commitment_hash?: HashCode;
+
+   ...
+   }
+
+Again, the exchange can now check the validity of the coin by evaluating
+
+.. math::
+   \text{FDH}_N(C_p, h_a)\; \stackrel{?}{=}\; \left(\sigma_C\right)^{e} 
\;\;\text{mod}N
+
+Also again, :math:`C_p` is the EdDSA public key of a coin, :math:`\sigma_C` is
+its signature, :math:`\langle e, N \rangle` is the RSA public key of the
+denomination and :math:`h_a` is the value from ``age_commitment_hash``.
+
+TODO: maybe rename this field into something more opaque, like
+``opaque_signature_salt`` or so?
+
+
 
 
 Changes in the Merchant

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