doc: Remove links to further reading from pgcrypto docs

The pgcrypto docs contained a set of links for useful reading and
technical references. These sets of links were however not actively
curated and had stale content and dead links. Rather than investing
time into maintining these, this removes them altogether since there
are lots of resources online which are actively maintained.

Backpatch to all supported versions since these links have been in
the docs for a long time.

Reported-by: Hanefi Onaldi 
Reviewed-by: Magnus Hagander 
Reviewed-by: Tom Lane 
Discussion: https://postgr.es/m/170774255387.3279713.2822272755998870925@wrigleys.postgresql.org
Backpatch-through: v12

diff --git a/doc/src/sgml/pgcrypto.sgml b/doc/src/sgml/pgcrypto.sgml
index 2e29f1d6f774981c1b68afd4cf228c1e8f524d0a..2db159be71cdf609e5b27d0ae6c37501c1391285 100644 (file)
--- a/doc/src/sgml/pgcrypto.sgml
+++ b/doc/src/sgml/pgcrypto.sgml
@@ -1220,72 +1220,6 @@ gen_random_uuid() returns uuid
     ciphertexts of a given size.
    
   
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-   Useful Reading
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-     The GNU Privacy Handbook.
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-     Describes the crypt-blowfish algorithm.
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-      
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-     How to choose a good password.
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-     Interesting idea for picking passwords.
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-      
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-     Describes good and bad cryptography.
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-   Technical References
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-     OpenPGP message format.
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-     The MD5 Message-Digest Algorithm.
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-     HMAC: Keyed-Hashing for Message Authentication.
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-      
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-     Comparison of crypt-des, crypt-md5 and bcrypt algorithms.
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-     Description of Fortuna CSPRNG.
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-     Jean-Luc Cooke Fortuna-based /dev/random driver for Linux.
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