PARQUET-1621: [C++] Add encrypted parquet files to apache parquet-testing repository (#7)

* Add encrypted parquet files to apache parquet-testing repository

* Update README.md

Add encryption keys and explanation to data/README.md

* Update README.md

Additional fixes to encrypted files section.
diff --git a/data/README.md b/data/README.md
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--- a/data/README.md
+++ b/data/README.md
@@ -1,3 +1,34 @@
 # Test data files for Parquet compatibility and regression testing
 
-TODO: Document what each file is
\ No newline at end of file
+TODO: Document what each file is
+
+## Encrypted Files
+
+Tests files with .parquet.encrypted suffix are encrypted using Parquet Modular Encryption.
+
+A detailed description of the Parquet Modular Encryption specification can be found here:
+```
+ https://github.com/apache/parquet-format/blob/encryption/Encryption.md
+```
+
+Following are the keys and key ids (when using key\_retriever) used to encrypt the encrypted columns and footer in the all the encrypted files:
+* Encrypted/Signed Footer:
+  * key:   {0,1,2,3,4,5,6,7,8,9,0,1,2,3,4,5}
+  * key_id: "kf"
+* Encrypted column named double_field:
+  * key:  {1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,0}
+  * key_id: "kc1"
+* Encrypted column named float_field:
+  * key: {1,2,3,4,5,6,7,8,9,0,1,2,3,4,5,1}
+  * key_id: "kc2"
+
+The following files are encrypted with AAD prefix "tester":
+1. encrypt\_columns\_and\_footer\_disable\_aad\_storage.parquet.encrypted
+2. encrypt\_columns\_and\_footer\_aad.parquet.encrypted
+
+
+A sample that reads and checks these files can be found at the following tests:
+```
+cpp/src/parquet/encryption-read-configurations-test.cc
+cpp/src/parquet/test-encryption-util.h
+```
diff --git a/data/encrypt_columns_and_footer.parquet.encrypted b/data/encrypt_columns_and_footer.parquet.encrypted
new file mode 100644
index 0000000..460d05b
--- /dev/null
+++ b/data/encrypt_columns_and_footer.parquet.encrypted
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diff --git a/data/encrypt_columns_and_footer_aad.parquet.encrypted b/data/encrypt_columns_and_footer_aad.parquet.encrypted
new file mode 100644
index 0000000..863ccb2
--- /dev/null
+++ b/data/encrypt_columns_and_footer_aad.parquet.encrypted
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diff --git a/data/encrypt_columns_and_footer_ctr.parquet.encrypted b/data/encrypt_columns_and_footer_ctr.parquet.encrypted
new file mode 100644
index 0000000..0591df4
--- /dev/null
+++ b/data/encrypt_columns_and_footer_ctr.parquet.encrypted
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diff --git a/data/encrypt_columns_and_footer_disable_aad_storage.parquet.encrypted b/data/encrypt_columns_and_footer_disable_aad_storage.parquet.encrypted
new file mode 100644
index 0000000..abd40e7
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+++ b/data/encrypt_columns_and_footer_disable_aad_storage.parquet.encrypted
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diff --git a/data/encrypt_columns_plaintext_footer.parquet.encrypted b/data/encrypt_columns_plaintext_footer.parquet.encrypted
new file mode 100644
index 0000000..0625080
--- /dev/null
+++ b/data/encrypt_columns_plaintext_footer.parquet.encrypted
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diff --git a/data/uniform_encryption.parquet.encrypted b/data/uniform_encryption.parquet.encrypted
new file mode 100644
index 0000000..048f35f
--- /dev/null
+++ b/data/uniform_encryption.parquet.encrypted
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