Add view tags to outputs to reduce wallet scanning time

Implements view tags as proposed by @UkoeHB in MRL issue
https://github.com/monero-project/research-lab/issues/73

At tx construction, the sender adds a 1-byte view tag to each
output. The view tag is derived from the sender-receiver
shared secret. When scanning for outputs, the receiver can
check the view tag for a match, in order to reduce scanning
time. When the view tag does not match, the wallet avoids the
more expensive EC operations when deriving the output public
key using the shared secret.

1 files changed, 56 insertions, 0 deletions

diff --git a/tests/crypto/tests.txt b/tests/crypto/tests.txt
index 3a7fe5453..d387aa09d 100644
--- a/tests/crypto/tests.txt
+++ b/tests/crypto/tests.txt
@@ -5473,3 +5473,59 @@ check_ge_p3_identity 046e1450f147f3ade34d149973913cc75d4e7b9669eb1ed61da0f1d4a0b
 check_ge_p3_identity ca8a2f621cfc7aa3efcd7ddf55dce5352e757b38aca0869b050c0a27824e5c5e true true
 check_ge_p3_identity 64a247eef6087d86e1e9fa048a3c181fdb1728431f29ba738634bdc38f02a859 true true
 check_ge_p3_identity cff0c7170a41395b0658ee42b76545c45360736b973ab2f31f6f227b9415df67 true true
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