Update NIST urls in docs (#3418)

diff --git a/docs/hazmat/primitives/key-derivation-functions.rst b/docs/hazmat/primitives/key-derivation-functions.rst
index 607eeb2..b082ea3 100644
--- a/docs/hazmat/primitives/key-derivation-functions.rst
+++ b/docs/hazmat/primitives/key-derivation-functions.rst
@@ -894,8 +894,8 @@
         stored derived key.
 
 
-.. _`NIST SP 800-132`: http://csrc.nist.gov/publications/nistpubs/800-132/nist-sp800-132.pdf
-.. _`NIST SP 800-108`: http://csrc.nist.gov/publications/nistpubs/800-108/sp800-108.pdf
+.. _`NIST SP 800-132`: http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-132.pdf
+.. _`NIST SP 800-108`: http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-108.pdf
 .. _`NIST SP 800-56Ar2`: http://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-56Ar2.pdf
 .. _`ANSI X9.63:2001`: https://webstore.ansi.org
 .. _`SEC 1 v2.0`: http://www.secg.org/sec1-v2.pdf
diff --git a/docs/hazmat/primitives/symmetric-encryption.rst b/docs/hazmat/primitives/symmetric-encryption.rst
index 1fd5a54..a3b9fea 100644
--- a/docs/hazmat/primitives/symmetric-encryption.rst
+++ b/docs/hazmat/primitives/symmetric-encryption.rst
@@ -650,7 +650,7 @@
 
 .. _`described by Colin Percival`: http://www.daemonology.net/blog/2009-06-11-cryptographic-right-answers.html
 .. _`recommends a 96-bit IV length`: http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/proposedmodes/gcm/gcm-spec.pdf
-.. _`NIST SP-800-38D`: http://csrc.nist.gov/publications/nistpubs/800-38D/SP-800-38D.pdf
+.. _`NIST SP-800-38D`: http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38D.pdf
 .. _`Communications Security Establishment`: https://www.cse-cst.gc.ca
 .. _`encrypt`: https://ssd.eff.org/en/module/what-encryption
 .. _`CRYPTREC`: https://www.cryptrec.go.jp/english/